Term
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Definition
| Comprised of the: Rough ER Smooth ER Golgi Complex Endosomes Lysosomes |
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Term
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Definition
Synthesizes proteins
Contains ribosomes and is continuous with the nuclear membrane |
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Term
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Definition
Synthesizes lipids
Contains NO ribosomes and is continuous with the rough ER |
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Term
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Definition
Further processes lipids and proteins further
Sorts them for transportation
Physically and functionally linked to the ER |
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Term
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Definition
| Contains digestive enzymes capable of degrading all the major classes of biological macromolecules: lipids, carbs, nucleic acids, and proteins |
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Term
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Definition
Lysosomes are made from late Endosomes
Used for transportation |
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Term
| Endoplasmic Reticulum (ER) |
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Definition
| A continuous network of flattened sacs, tubules, and associated vesicles that stretches throughout the cytoplasm of the eukaryotic cell |
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Term
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Definition
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Term
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Definition
| The spaced enclosed by the cisternae |
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Term
| Light microscope, electron microscope |
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Definition
| The ER is not visible with the __ __, but is visible with the __ __. |
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Term
| Synthesis of proteins, plasma membrane, organelles, export |
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Definition
We now know thy enzymes associated with the ER ate responsible for for the __.
Which are destined for incorporation into the __ __, or into __ of the Endomembrane system, or for __from the cell. |
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Term
| Synthesis of lipids, intracellular membranes, plasma membrane |
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Definition
The ER plays a central role in the __.
Including triaclglycerols, cholesterol, and related compounds
It's the source of most of them that are used to assemble the __ __, and the __ __. |
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Term
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Definition
| The two basic kinds of ER differ in __ and __ |
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Term
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Definition
| The two basic kinds of ER are distinguished from one another by the presence or absence of __ attached to the ER membrane |
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Term
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Definition
| Is characterized by ribosomes attached to the cytosolic side of the membrane (the side that faces away from the ER lumen) |
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Term
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Definition
| Translation by these ribosomes occurs in the __, but newly synthesized proteins will enter the ER lumen shortly |
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Term
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Definition
| Because ribosomes contain __, it was the RNA that reacted strongly with the basic dies that were originally used to identify the rough ER |
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Term
| Transitional elements (TE's) |
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Definition
| A subdomain of rough ER, the __ __, plays an important role in the formation of transition vesicles |
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Term
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Definition
| Shuttle lipids and proteins from the ER to the Golgi Complex |
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Term
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Definition
| Appears smooth due to the absence of ribosomes attached to the membrane |
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Term
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Definition
| Morphologically, rough ER usually form __ __ __ . |
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Term
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Definition
| Morphologically Smooth ER generally form __ __. |
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Term
| Smooth ER (tubular structure) |
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Definition
| Transition elements of the rough ER are an exception to this rule. They often resemble __ __ (__ __). |
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Term
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Definition
Rough ER and Smooth ER are not __ __.
This materials can travel between the rough and smooth ER without the aid of vesicles |
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Term
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Definition
Both ER are present on eukaryotic cells.
However there is considerable __ in the relative amounts of each types, depending on the activity of the cell |
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Term
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Definition
| Liver cells producing digestive enzymes, tend to have prominent __ __ networks |
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Term
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Definition
| Cells producing steroid hormones, such as testis and ovary tend to have extensive networks of __ __. |
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Term
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Definition
| When tissue is homogenized for subcellular fractionation, the ER membranes often break into smaller fragments that spontaneously close to form sealed vesicles known as __. |
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Term
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Definition
| Microsomes do not exist __ __ __ |
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Term
| Biosynthesis, process, proteins |
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Definition
| The rough ER is involved in the __ and __ of __. |
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Term
| Membrane bound, soluble proteins, Endomembrane system |
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Definition
| The ribosomes attached to the cytosolic side of the rough ER membrane are responsible for synthesizing both __ __ and __ __ for the __ __. |
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Term
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Definition
| Synthesis of proteins destined for the Endomembrane system begins on __ __. |
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Term
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Definition
| Cytoplasmic ribosomes attach to the rough ER via __ __ in the ER membrane shortly after translation initiation |
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Term
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Definition
| Newly synthesized proteins enter the Endomembrane system __ - that is, they are inserted through a pore complex in the ER membrane into the rough ER lumen as the polypeptide is synthesized by the ER bound ribosomes |
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Term
| Membrane spanning proteins |
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Definition
| After biosynthesis, __ __ __ remain anchored to the ER membrane either by hydrophobic regions of the polypeptide or by covalent attachment to membrane lipids |
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Term
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Definition
| __ __, including secretory proteins, are released into the ER lumen |
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Term
| Glycoproteins, folding, polypeptides, multimeric proteins |
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Definition
| The rough ER is the site of several other processes, including the initial step of addition and processing of carbohydrate groups to __, the __ of polypeptides, the recognition and removal of misfolded __, and the assembly of __ __. |
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Term
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Definition
| These modifications include __, which is important for sorting of proteins to their proper destination, an disulfide bond formation, which is essential for proper protein folding |
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Term
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Definition
| The ER is also a site for __ __ |
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Term
| ER- associated degradation (ERAD) |
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Definition
| Proteins improperly modified, folded, or assembled ate exported from the ER for degradation by cytosolic proteasomes before they can move to the Golgi Complex |
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Term
Drug detoxification
Carbohydrate metabolism
Calcium storage
Steroid biosynthesis |
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Definition
| Smooth ER is involved in __ __, __ __, __ __, and __ __. |
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Term
| Hydroxylation, cytochrome P-450 |
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Definition
| Drug detoxification often involves enzyme-catalyzed __ because the addition of hydroxyl groups to hydrophobic drugs makes them more soluble and easier to excrete from the body. Typically catalyzed by a member of the __ __ family of proteins |
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Term
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Definition
| Carbohydrate metabolism is prominent in the __ cells |
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Term
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Definition
| Injection of the sedative phenobarbital into a rat causes a rapid increase in the level of barbiturate- detoxifying enzymes in the liver, accompanied by a dramatic proliferation of smooth ER. However, this means that increasingly higher doses of the drug are necessary to achieve the Same sedative effect, an effect known as __. |
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Term
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Definition
| Gated transport goes from the __ to the __. |
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Term
| cytosol, mitochondria, endoplasmic reticulum, plastids, peroxiosomes |
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Definition
| transmembrane transport goes from the __ to the __, __, __, and __ |
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Term
| endoplasmic reticulum, golgi, golgi, endoplasmic reticulum |
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Definition
| vescular transport occurs from the endoplasmic reticulum to the __, and from the __ to the __ __ |
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Term
| cell surface, secretory vessels, late endosome |
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Definition
| vesicular transport occurs from the golgi to the __, __, and the __ also |
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Term
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Definition
| vesicular transport occurs from the __ to the late endosome and the __ |
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Term
| cell surface, early endosome, cell surface, late endosome |
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Definition
| vesicular transport occurs from the secretory vessels to the __ __. From the cell surface an __ __ can form which can either form with the __ __ again, or become a __ __. |
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Term
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Definition
| How to move phospholipids from inside to outside (for those that belong on the outside) --like glycolipids |
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Term
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Definition
| phospholipids can exchange (transfer) __. This is an important property (in SER) for amphibians because of the varying outside temperatures. |
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Term
| aryl hydrocarbon hydroxylase, cigarette smoke |
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Definition
| another cytochrome P-450 protein, __ __ __, is involved in metabolixing polycyclic hydrocarbons that are often toxic. However oxidation of these hydrocarbons often convert the potential carcinogens into thier chemically active form causing a higher incidence of spontaneous cancer. One inhancer is __ __. Whereas an inhibiter would significantly reduce the amount of tumors |
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Term
| stored glycogen, glucose-6-phosphatase |
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Definition
| The SER of hepatocytes (liver cells) is also involved in the enxymatic breakdown of __ __, as evidenced by presence of __-__-__, a membrane bound enzyme that is unique to the ER. |
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Term
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Definition
| glucose-6-phosphatase is abundant in the __ because its major role is to keep the level of glucose in the blood relatively constant |
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Term
| liver glycogen, phosphorolysis, glucose-6-phosphate |
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Definition
| when glucose is needed by the body, especially between meals and in response to increased muscular activity, __ __ is broken down by __ producing __-__-__. |
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Term
| phosphorylated sugars, free glucose, glucose-6-phosphatases |
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Definition
| membranes are generally impermeable to __ __, therefore glucose-6-phosphate must be converted into __ __ by __-__-__ in order to leave the liver cell (via GLUT2) and enter the blood stream for transport to other cells that need energy |
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Term
liver, kidney, intestinal,
muscle, brain |
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Definition
| glucose-6-phosphatase activity is present in __ , __ , __ cells. NOT in __ and __ cells |
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Term
| sarcoplasmic reticulum, muscle cells |
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Definition
| the __ __ found the the __ __ is an example of SER that specializes in the storage of calcium |
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Term
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Definition
| In the sarcoplasmic reticulum, the __ __ contains a high concentration of calcium-binding protiens. Ca+ are pumped into the ER by ATP-dependent Ca+ ATPases and are released in response to extracellular signals to aid in muscle contraction |
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Term
| neurotransmitter molecules |
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Definition
| Binding of __ __ to receptors onthe surface of the muscle cell triggers a signal cascade that leads to the release of calcium from the sarcoplasmic reticulum that causes the contraction of muscle fibers |
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Term
| adrenal, Leydig, liver, follicular, plastids steroids (hormones) |
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Definition
| The SER of cells in the __ glands, __ cells, __ cells, __ cells, and possibly __ of plants are the site for the synthesis of __ |
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Term
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Definition
| Cholesterol, cortisol, and the male and female steroid horomones share a common 4 ring structure but differ inthe number and arrangement of __ side chains and __ groups |
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Term
| Hydrozymethylglutaryl-CoA reductase (HMG-CoA reductase), large, liver |
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Definition
| __-__ __, the committed step in cholesterol biosynthesis, is present in __ amouts in SER of __ cells. This is also the target for inhibition by a class of cholesterol-lowering drugs known as statins |
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Term
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Definition
| The __ of SER are important not only for the synthesis of cholseterol, but also for the conversion of cholesterol into on of the other steroid hormones by __ |
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Term
| phospholipids, cholesterol |
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Definition
| The SER is the primary source of membrane lipids, including __ and __. |
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Term
| cytosoplasm, monolayer, cytosol |
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Definition
| Biosynthesis of fatty acids for membrane phospholipid molecules occurs in the __ and incorporation is restricted to the __ of the SER membrane facing the __. |
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Term
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Definition
| Because transfering phospholipids from one layer of the membrane to the other is thermodynamically unfavorable, we must have a mechanism for it. Transfer depends of phospholipid translocators called __. |
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Term
| particular translocator, membrane assymetry |
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Definition
| phospholipid translocators are quite specific and affect only the rate of a process. therefore, the type of phospholipid transferred across a membrane depends on the __ __ present, contributing to __ __. |
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Term
| phosoholipid exchange proteins, (phospholipid transfer protiens), phospholipid |
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Definition
| cytosolic __ __ __ ( __ __ __) convey phospholipid molecules from the ER membrane to the outer mitochondrial and choloroplast membranes. Each exchange protein recognizes a specific __, removes it from one membrane, and carries it through the cytosol to another membrane |
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Term
| contractions, breast feeding |
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Definition
Dual actions of oxytocin: one path for __ and the other path for __ __
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Term
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Definition
[image]
where is HGM-CoA reductase found?
its a pathway with acetyl CoA...dressing up of pyruvate to enter the citric acid cycle |
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Term
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Definition
| The Golgi Complex consists of a series of flattened membrane-bounded __, disk-shaped sacs that are stacked together. |
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Term
| Golgi stack, electron, stacks, type, metabolic |
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Definition
| A series of such cisternae is called a __ __ and can be visualized by __ microscopy. The number and size of these __ will vary with cell __ and __ activity of the cell. |
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Term
| transport vesicles, Golgi complex, endosomes, lysosomes, secretory granules |
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Definition
| Both the ER and the golgi are typically surronded by numerous __ __ that carry lipids and protiens from the ER to the __ __, between the cisternae of a Golgi stack, and from there to various destinations of the cell including: __, __, and __ __ |
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Term
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Definition
| the Golgi complex lumen, or __ __, is part of the endomembrane system's network of internal spaces |
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Term
| cis face, cis-Golgi network (CGN), arrive, CGN, CGN membranes |
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Definition
the __ __ origionates toward the ER. It's the Golgi compartment closest to the ER is a network of flattened membrane-bounded tubules referred to as the __ __ __ (__).
Vesicles containing newly synthesizes lipids and protiens __ at the __ and fuse with __ __. |
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Term
| trans face, trans-Golgi network (TGN), leave, transport vesicles, TGN cisternae |
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Definition
| The opposite side of the golgi complex is called the __ __. This compartment has similiar morphology and is referred to as the __ __ __ (__). Here protiens and lipids __ the Golgi in __ __ that continually bud from the tips of __ __. |
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Term
| secretory granules, endosomes, lysosomes, plasma membrane |
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Definition
| transport vesicles carry lipids and proteins from the golgi complex to __ __, __, __, and the __ __. |
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Term
| medial cisternae, processing |
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Definition
| central sacs between the CGN and the TGN comprise the __ __ of the Golgi stack, in which much of the __ of proteins occurs. |
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Term
| biochemically, functionally, receptor proteins, enzymes |
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Definition
| the CGN, TGN, and medial cisternae of the Golgi complex are __ and __ distinct. Each compartment contains specific __ __ and __ necessary for specific steps in protein and membrane processing |
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Term
| glycosylation, glycoproteins |
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Definition
| Much of the protien processing carries out within the ER and Golgi complex involves __ -- the addition of carbohydrate side chains to specific amino acid residues of protiens, forming __. |
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Term
| N-linked Glycosylation, O-linked Glycosylation |
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Definition
| The two general kinds of glycosylation that are observed in cells are _-__ __ and _-__ __. |
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Term
| nitrogen, amino group, asparagine |
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Definition
| N-linked Glycosylation (N-glycosylation) involves the addition of a specific oligosaccharide unit to the __ atom to the terminal __ __ of certain __ residues. |
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Term
| oxygen, hydroxyl group, serine, theronine |
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Definition
| O-linked Glycosylation involves the addition of an oligosaccharide to the __ atom on the __ __ of certain __ or __ residues. |
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Term
| preceding, block, disease |
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Definition
| Each step of glycosylation is strictly dependent on __ modifications. An error at one step perhaps due to a defective enzyme, can __ further modification of a carbohydrate side chain and can lead to __ in the organism. |
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Term
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Definition
| Initial steps of N-glycosylation take place on the __ surface of the __ membrane. The later steps take place in the __ __. |
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Term
| carbohydrate, ER, core oligosaccharide |
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Definition
| Despite the variety of oligosaccharides found in mature glycoprotiens, all of the __ side chains added to protiens in the __ initially have a common __ __ consisting of two units of N-acetylglucosamine (GlcNAc), nine mannos units, and three glucose units |
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Term
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Definition
| glycosylation begins as __ __, an oligosaccharide carrier, is inserted into the __ membrane . |
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Term
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Definition
| __ and __ groups are then added to the phosphate group of dolichol phosphate. Currently, the growing protien is facing the cytosolic side. |
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Term
| cytosol, ER lumen, flippase |
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Definition
| The growing core oligosaccharide is then translocated from the __ to the __ __ by a __. |
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Term
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Definition
| Once inside the ER lumen, more __ and __ units are added |
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Term
| core oligosaccharide, dolichol, asparagine residue |
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Definition
| The completed __ __ is then transferred as a single unit from __ to an __ __ of the recipient protein. |
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Term
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Definition
| Finally, the core oligosaccharide attached to the protien is __ and __. |
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Term
| cotranslational glycolsyation, proper, misfolded, aggregated |
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Definition
| Usually, the core oligosaccharide is added to the protein as the polypeptide is being synthesized by a ribosome bound to the ER membrane. We know that this __ __ helps to promote __ protien folding because experimental inhibition of glycosylation leads to the appearance of __, __ proteins |
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Term
| ER proteins, proper folding |
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Definition
| Addition of a single glucose unit allows other __ __ to interact with the newly synthesized glycoprotein to ensure __ __. |
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Term
| calnexin (CNX), calreticulin (CRT), disulfide bond, disulfide bond |
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Definition
| One of two ER proteins known as __ ( _ ), membrane bound, and __ ( _ ), soluble, can bind to the monoglucosylated glycoprotien and promote __ __ formation by forming a complex with the glycoprotien and a thiol oxidoreductase known as ERp57, which catalizes __ __ formation. |
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Term
| glucosyl transferase, UGGT (UDP-glucose:glycoprotein glucotransferase), UGGT, improperly,UGGT, ER, Golgi |
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Definition
| specific __ __ in the ER known as __ ( _-__:__ __) acts as a sensor for proper folding of the newly synthesized glycoprotein. __ binds to __ folded proteins and adds back a single glucose unit, making the protein a substrate for another round or CNX/CRT binding and disulfide bond formation. Once proper __ no longer binds to the new glycoprotein, which is then free to exit the __ and move to the __. |
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Term
| intracellular, ER, Golgi complex, endosomes, lysosomes, protein, leaving |
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Definition
| Membrane bound and soluble proteins synthesized in the rough ER must be directed to a variety of __ locations, including the __ itself, the __ __, __, and __. Moreover, once a __ reaches an organelle where it is to remain, there must be a mechanism preventing it from __. |
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Term
| rough ER, plasma membrane, outside |
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Definition
| Other groups of proteins synthesized in the __ __ are destined for incorporation into the __ __ of for release to the __ of the cell |
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Term
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Definition
| Each protein contains a specific "__" targeting the protein to a __ __ that wil carry material from one specific cellular location to another. |
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Term
| amino acid, oligosaccharide side, hydrophobic, excluding |
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Definition
| Depending on the protein and its destination the tag may be a short __ __ sequence, and __ __ chain, a __ domain, or some other structural feathre. Tags may also be involved in __ materials from certain vesicles. |
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Term
| destination, phosphate, phosphatidylinositol (PI), kinases |
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Definition
| Membrane lipids may also be tagged to help besicles reach their proper __. This tag can be one or more __ groups, and/or 5 of a membrane __ ( _ ) molecule by a specific __. |
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Term
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Definition
| Ex. A functional PI 3-kinase is required for proper sorting of vesicles to the vacuole in yease. In mamalian cells, __ of inositol kinases disrupts vesicle trafficking to the __. |
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Term
| lenght, degree, trafficking |
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Definition
| The __ and __ of saturation of certain membrane lipids have also been shown to be important in vesicle __. |
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Term
| ER, Golgi stack retrieving, retaining |
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Definition
| Sorting of proteins begins in the __ and early compartments of the __ __, which contain mechanisms for __ or __ compartment-specific protiens. This important step preserves the compartment-specific functions needed to maintain the integrity of glycosylationo and processing pathways. |
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Term
| TGN, lipids, proteins, transport vesicles |
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Definition
| The final sorting of material that will leave the Golgi Complex occurs in the __, where __ and __ are selectively packaged into distinct populations of __ __ that are destined for different locations. |
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Term
| Golgi complex, endocytosis |
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Definition
| In some cells, the __ __ is also involved in the processing of proteins that enter the cell by __ |
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Term
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Definition
| The protein enters on the __ side of the golgi, and after glycosylation (processing) exist on the __ side. |
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Term
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Definition
| ER specific protiens contain __ and __ tags. |
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Term
| preventing, ER membrane, retrieving, ER, CGN |
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Definition
| The protien composition required in the ER is maintained both by __ some protiens from excaping when vesicles bud from the __ __ and by __ other protiens that have left the __ and reached the __. |
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Term
| tripeptide sequence, Arg-X-Arg, retention tag, plasma membrane |
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Definition
| Several protiens localized to the ER contain the __ __ RXR ( _-X-_ where X is any amino acid), which appears to promote retention in the ER. This __ __ is also found in some multisubunit protiens that are destined for the __ __. WHY? It is thought because the RXR sequence allows the subunit to be maintained in the ER until assembly of the multisubunit complex in the ER is complete. |
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Term
| retrieval tags, Golgi complex lumen, C-terminal amino acid, conformational change |
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Definition
| Many soluble ER-specific protiens contain __ __ that bind to specific transmembrane receptors facing the __ __ __. The tags are short _-__ __ __ sequences such as KDEL (Lys-Asp-Glu-Leu) or KKXX (where X can be any amino acid). When a protein containing such a tag binds to its receptor, the receptor undergos a __ __, and the receptor-ligand complex is packaged into a transport vesicle for return to the ER. |
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Term
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Definition
| Targeting of soluble lysosomal proteins to endosomes and lysomes is a model for __ __ in the __ |
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Term
| lysosomal enzymes, N-glycosyation, glucose, mannose |
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Definition
| During their journey through the ER and early compartments of the Golgi complex, __ ____ like other glycoprotiens undergo _-__ followed by the removal of __ and __ units |
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Term
| mannose, carbohydrate side chain, phosphorylated, mannose-6-phosphate, lysosome |
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Definition
| Within the Golgi complex, however, __ residues on the __ __ __ of lysosomal enzymes are __ forming an oligosaccharide containing __-_-__. This oligosaccharide tag distinguishes soluble lysosomal proteins from other glycoproteins and ensures their delivery to __. |
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Term
| Golgi-specific, Golgi stack, GlcNAc-1-phosphate, GlcNAc, mannose-6-phosphate |
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Definition
| The phosphorylation of mannose residues is catalyzed by two __-__ enzymes. The first, located in an early compartment of the __ __, is a phosphotransferase that adds __-_-__ to carbon atom number 6 of mannose. The second, located in a mid-Golgi compartment, removes __, leaving behing the __-_-__ residue |
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Term
| mannose-6-phosphate (MPRs), mannose-6-phosphate, favors |
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Definition
| The interior surface of the TGN membrane has __-_-__ receptors ( _ ) that bind to __-_-__ residues of lysosomal proteins. The pH of TGN is around 6.4 which __ binding of the protein to these receptors. |
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Term
| endosome, late endosome, early endosome, TGN, plasma membrane |
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Definition
| Following binding of tagged lysosomal protiens to the MPRs, the receptor-ligand complexes are packages into transport vesicles and conveyed to an __. In animal cells, lysosomal enzymes needed for degradation of material brought into the cell by endocytosisare transported from the TGN to organelles known as __ __, which developed from __ __, which formed by the coalesence of vesicles from the __ and __ __ |
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Term
| late endosome, pH, late endosome, lysosome, active lysosome |
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Definition
| As an early endosome matures to form a __ __, the __ of the lumen decreases to about 5.5 causing the bound lysosomal enzyme to dissociate from the MPRs. This prevents retrograde movement of the enzymes back to the golgi along with the receptors that are recycled in vesicles that are returned to TGN. Finally, the __ __ either matures to form a new __ or delivers its contents to an __ __. |
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Term
| mannose-6-phosphate, mannose-6-phosphate, extracellular medium, lysosomes |
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Definition
| I-cell diseae results from a defective phosphotransferase that is needed to add __-_-__ to oligosaccharide chans on lysosomal enzymes. The absence of __-_-__results is the lysosomal enzymes release most of the soluble proteins to the __ __ instead of incorporating them into __. |
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Term
| KDEL, HDEL, mannose-6-phosphate |
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Definition
Trafficking label: mammals= __ , yeast= __ , these send them back to ER.
__-_-__ =sends it back to endosome (lysosomes) where it gets degraded |
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Term
| secretory pathways, secretory vesicles, secretory granules, discharge |
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Definition
| Integral to the vesicular traffic are __ __ by which proteins move from the ER through the Golgi complex to __ __ and __ __, which then __ their contents to the exterior of the cell |
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Term
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Definition
| __ __ are vesicles that discharge secretory proteins to the exterior of the cell |
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Term
| constitutive secretion, plasma membrane surface, regulated secretion, extracellular signal |
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Definition
| __ __ involves the continuous discharge of vesicles at the __ __ __, wheras __ __ involves controlled, rapid releases that happen in response to an __ __. |
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Term
| plasma membrane, exocytosis, constitutive secretion, intestines |
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Definition
| After budding from the TGN, some secretory vesicles move directly to the cell surface where they immediatly fuse with the __ __ and release their contents by __. This unregulated process, which is continuous and independant of specific extracellular signals is called __ __. One example is the continuous release of mucus by cells that line your __. |
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Term
| default pathway, amino acid tags |
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Definition
| Constitutive secretion was once thought to be a __ __ for proteins synthesized in the rough ER, but recent studies suggest that a variety of short __ __ __ may identify specific protiens for constitutive secretion. |
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Term
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Definition
| For some protiens, consecutive secretion may require _-__ of the protein, as was recently shown for mouse interlukin-31, a secreted protein involved in extracellular cell-to-cell signaling. |
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Term
| regulated secretion, extracellular signals, neurotransmitters |
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Definition
| While vesicles containing constitutively secreted proteins move continuously and directly from the TGN to the plasma membrane, secretory vesicles involved in __ __ accumulate in the cell and the fuse with the plasma membrane only in response to specific __ __. An importand example is the release of __. |
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Term
| maturation process, maturation, condensation, proteolytic, hormonal, chemical |
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Definition
| Regulated secretory vesicles form by budding from the TGN as immature secretory vesicles, which undergo a subsequent __ __. __ of secretory proteins involves concentration of the proteins -referred to as __- and frequently some __ processing. The mature secretory vesicle then move close to the site of secretion and remain near the plasma membrane until recieving a __ or other __ signal that triggers release of their contents by fusion with the plasma membrane |
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Term
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Definition
| The information needed to direct a protein to a regulated secretory vesicle is presumable inherent in the __ __ __ of the protein, though the precise signals and mechanisms are not yet known. |
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Term
| exocytosis, endocytosis, delivery, recycling, turnover |
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Definition
| Two methods of transporting materials across the plasma membrane are __ , the process by which secretory granules release their contents to the exterior of the cell, and __, the process by which cells internalize external materials. Both processes are unique to __ cells and are also involved in __, __, and __ of membrane proteins. |
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Term
| exterior, vesicle, plasma membrane |
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Definition
| In exocytosis, proteins in a vesicle are released to the __ of the cell as the membrane of the __ fuses with the __ __. A variety of proteins are exported from both animal and plant cells by exocytosis. Animal ex: peptide, hormone proteins, mucus, milk proteins, and digestive enzymes. Plant and fungal cell ex: enzymes and proteins associated with the cell wall. Carnivorous plants ex: hydrolytic enzymes that are used to digest trapped insects |
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Term
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Definition
| 1: vesicles containing cellular products destined for secretion move to the __ __. |
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Term
| fusion, plasma membrane, exterior |
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Definition
| 2. __ with the __ __ discharges the vesicle contents to the __ of the cell |
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Term
| vesicle, plasma membrane, plasma membrane, glycoproteins, glycolipids, extracellular space |
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Definition
| 3. In the process, the membrane of the __ becomes integrated into the __ __ with the inner surface of the vesicle becoming the outer surface of the __ __. Thus, __ and __ that were origionally formed in the ER and Golgi lumens will face the __ __ |
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Term
| hormone, neurotransmitter, cell surface, second messenger, calcium ions |
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Definition
| Fusion of regulated secretory vesicles with the plasma membrane is generally triggered by a specific extracellular signal. In most cases the signal is a __ or a __ that binds to specific receptors on the __ __ and triggers the synthesis or release of a __ __ within the cell. During regulated secretion, a transient elevation of the intracellular concentration of __ __ often appears to be an essential step in the signal cascade leading from the receptor on the cell surface to exocytosis. |
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Term
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Definition
| The specific role of Ca+ is not yet clear, but it appears that in elevation in the intracellular calcium concentration leads to activation of __ __ whose target proteins are components of either the vesicle membrane or the plasma membrane |
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Term
| specific site, polarized secretion, nerve cells, neurotransmitter |
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Definition
| In many cases, exocytosis of specific proteins is limited to a __ __ of the cell. For ex. the secretory cells that line your intestine release digestive enzymes on the side of the cell that faces the interior of the intestine. This phenomenon is called __ __, and is also seen in __ __ which secrete __ molecules only at junctions with other __ __. |
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Term
| endocytosis, plasma membrane, inward, pinches, endocytic vesicle |
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Definition
| Most eukaryotic cells carry out one or more forms of __ for uptake of extracellular material. A small segment of the __ __ progressively folds __, and then it __ off to form an __ __ containing ingested substances or particles. |
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Term
| ingestion, defense, white blood |
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Definition
| Endocytosis is important for several cellular processes, including __ of essential nutrients by some unicellular organism and __ against microorganisms by __ __ cells. |
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Term
| opposite, exocytosis, endocytosis, plasma membrane |
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Definition
| In terms of membrane flow, exocytosis and endocytosis clearly have __ effects. Wheras __ adds lipids and proteins to the plasma membrane, __ removes them. Thus a steady-state composition of the __ __ results from a balance between exocytosis and endocytosis. |
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Term
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Definition
| Through endocytosis and retrograde transport, the cell can __ and __ molecules deposited in the plasma membrane by secretory vesicle during exocytosis. |
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Term
| endocytic vesicle, cytosol |
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Definition
| During endocytosis, the membrane of an __ __ isolates the internalized substances from the __. |
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Term
| early endosomes, TGN, lysosome, phagocytosis, pinocytosis |
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Definition
| Most endocytic vesicle develop into __ __, which then fuse with vesicles from the __, acquiring digestive enzymes and maturing to form a new __. A distinction is uaually made between __, in which large solid particles are ingested, and __, in which liquids containing soluble or suspended molecules are taken up. |
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Term
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Definition
| The ingestion of large particles (>0.5µm) , including aggregates of macromolecules, parts of other cells, and even whole microorganisms or other cells, is known as __. |
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Term
| food, phagocytes, defense, nutrition |
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Definition
| For many unicellular udaryotes, such as amoebas and ciliated protozoa, phagocytosis is a routine means for acquiring __. In more complex organisms, phagocytosis is usually restricted to specialized cells called __. For example, your body contains two classes of white blood cells -- mutrophils and macrophages -- which use phagocytosis for __ rather than __. |
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Term
| foreign material, invasive, scavengers |
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Definition
| White blood cells engulf and digest __ __ or __ microorganisms found in the bloodstream or injured tissues. Macrophages have an additional role as __, ingesting cellular debris and whole damaged cells from injured tissues. Under certain conditions, other mammalian cells engage in phagocytosis |
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Term
| receptor-mediated endocytosis, clathrin-dependent endocytosis, outer surface |
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Definition
| Cells can acquire certain soluble and suspended materials by a process known as __-__ __ (also called __-__ __). For this process, cells use specific receptors that are found on the __ __ of the plasma membrane. |
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Term
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Definition
| Receptor-mediated endocytosis is the primary mechanism for the specific internalization of most macromolecules by __ cells. |
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Term
| hormones, enzymes, cholesterol, antibodies, toxins |
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Definition
| Depending on the type of cell, mammalian cells can ingest __, growth factors, __, serum proteins, __, __, iron, and even some viruses and bacterial __ by this mechanism. |
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Term
| ligand, receptor, ligand-binding |
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Definition
| Receptor-mediated endocytosis begins with the binding of a __to their __ (specific __-__ proteins) found on the outer surface of the plasma membrane |
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Term
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Definition
| Step 2: As the receptor-ligand complexes diffuse laterally in the membrane, they encounter specialized membrane regions called __ __ that serve as sites for the collection and internalization of these complexes. |
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Term
| proteins, plasma membrane, curvature, invagination |
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Definition
| Accumulation of the receptor-ligand complexes within the coated pits triggers accumulation of additional __ on the inner surface of the __ __. These additional proteins- including adaptor protien, clathrin, and dynamin- are required for promoting membrane __ and __ of the pit |
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Term
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Definition
| Invagination continues until the pit __ off from the plasma membrane, forming a __ __. |
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Term
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Definition
| The clathrin coat is released, leaving an __ vesicle. |
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Term
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Definition
| The coat proteins and dynamin are then __ to the plasma membrane, where they become available for forming new vesicles, while the uncoated vesicle is free to fuse with an __ __. |
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Term
| lysosomal proteins, lysosome |
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Definition
| Following receptor-mediated endocytosis, the uncoated vesicles fuse with vesicles budding from the TGN to form and early endosome in peripheral regions of the cell. The early endosome continues to acquire __ __ from the TGN and matures to form a late endosome, which then developes into a __. |
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Term
| acidification, pH, acidic, freeing |
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Definition
| Recycling of plasma membrane receptor molecules is facilitated by __ of the early endosome. The lower __ is maintained by an ATP-dependent proton punt in the endosomal membrane. The slightly __ environment of the early endosome decreases the affinity of most receptor-ligand complexes, therby __ receptors to be recycled to the plasma membrane while newly ingested material is diverted to other locations. |
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Term
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Definition
| Some receptor-ligand complexes (EGF--epidermal growth factor-- and its receptor) are carried to a lysosome for __. |
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Term
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Definition
| Others are carried to the __, where they enter a variety of pathways transporting material throughout the __ __. |
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Term
| transport vesicles, transcytosis, endocytosis, cytoplasm, exocytosis |
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Definition
| Receptor-ligand complexes can also travel by __ __ to a different region of the plasma membrane, where they are secreted as part of a process called __. This pathway accommodates the transfer of extracellular material from one side of the cell, where __ occurs, through the __ to the opposite side, where __ occurs. |
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Term
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Definition
| Most of the vesicles involved in lipid and protein transfer are referred to as __ __ because of the characteristic __, or layers, of proteins covering their cytosolic surfaces as they form. |
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Term
| membrane bounded, inside, outside |
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Definition
| Coated vesicles are a common feature of most cellular processes that involve the transfer or exchange of substances between specific __ __ compartments of eukaryotic cells or between the __ and __ of a cell. |
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Term
| endomembrane system, transport |
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Definition
| Coated vesicles are involved in vesicular traffic throughout the __ __, as well as __ during exocytosis and endocytosis. |
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Term
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Definition
| A common feature of coated vesicles is the present of a layer, or coat, of protein on the __ side of the membrane surronding the vesicle. |
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Term
| transport vesicles, destinations |
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Definition
| Coat proteins participate in several steps of formation of __ __. The type of coat protein on a vesicle helps in the sorting of molecules that are fated for different __ in the cell. |
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Term
| spherical, membranes, moving |
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Definition
| More general roles for coat proteins (COPs) may include forcing nearly flat membranes to form __ vesicles, preventing premature, nonspecific fusion of a budding vesicle with nearby __, and regulating the interactions between budding vesicles and microtubules that are important for __ vesicles through the cell. |
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Term
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Definition
| The specific set of proteins coverind the exterior of a vesicle is an indicator of the __ and __ of the vesicle within the cell. |
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Term
| TGN, endosomes, plasma membrane, outside |
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Definition
| Clathrin-coated vesicles are involved in the selective transport of proteins from the __ to __ and in the endocytosis of receptor-ligand complexes from the __ __. Going __ the cell. |
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Term
| Golgi, ER, cisternae, Golgi complex, inside |
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Definition
| COPI-coated vesicles facilitate retrograde transport of proteins from the __ back to the __, as well as between __ of the __ __. Staying __ the cell. |
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Term
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Definition
| COPII-coated vesicles are involved in to transport of material from the __ to the __. Staying __ the cell. |
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Term
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Definition
| Much of the intracellular traffic mediated by coated vessicles is __ __. |
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Term
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Definition
| As we have seen, the final sorting of proteins synthesized in the ER occurs in the TGN when lipids and proteins are packaged into __ for transportaion to various destinations. |
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Term
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Definition
| Recall that when clathrin-coated vesicles from from TGN, the adaptor complexes include two adaptin subunits that are partially responsible for the __ displayed when receptors are concentrated for inclusion in a budding vesicle. |
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Term
| proteins, wrong, SNARE hypothesis |
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Definition
| Once a vesicle forms additional __ are needed to ensure delivery of the vesicle to the appropriate destination. Therefore there must be a mechanism to keep the various vesicles in the cell from accidentally fusing with the __ membrane. The __ __ provides a working model for this important sorting and targeting step in intracellular transport. |
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Term
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Definition
| According to the SNARE hypothesis, the proper sorting and targeting of besicles in eukaryotic cells involves two families of SNARE (SNAP receptor) proteins: the _- __ (vesicle-SNAP receptors) found on transport vesicles and _-__ (target-SNAP receptors) found on target membranes. |
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Term
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Definition
| the v-SNAREs and t-SNAREs are __ molecules that, along with additional tethering proteins, allow a vesicle to reorganize and fuse with a target membrane. |
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Term
| Rab GTPases, Rab GTPases, Rab |
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Definition
| When a vesicle reaches its destination, a third family of protiens, the __ __ , comes into play. __ __ are also specific: Vesicles fated for different destinations have distinct members of the __ family associated with them. |
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Term
| stable complex, Rab, lock, membrane fusion |
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Definition
| The affinity of complementary v-SNAREs and t-SNAREs for one another enables then to form a __ __. This ensures that, when these proteins collide, they will remain in contact long enough for a __ protein associated with the vesicle to __ the complementary t-SNARE and v-SNARE together, facilitating __ __. |
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Term
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Definition
| Following vesicle fusion, N-ethylmaleimide-sensitive factor ( __ ) and a group of soluble NSF attachment proteins ( __ ) mediate __ of the v- and t-SNAREs of the donor and target membranes. These are involved in fusion between a variety of cellular membranes, indicating they are not responsible for __ during targeting. |
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Term
| neurotransmitter-containing, nerve, neurotransmitter |
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Definition
| SNARE proteins are required for the fusion of __-__ vesicles with the plasma membrane of __ cells. This fusion event releases the __ by exocytosis, leading to an electrical impluse that will initiate muscle contraction. Ex. botox: a protease that cleaves a SNARE protein that is required for this fusion. Thus, botox can be used to control muscle spasms or correct crossed eyes |
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Term
| tethering proteins, vesicles, target |
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Definition
| A different class of proteins known as __ __ acts of longer distances and provides specificty by connecting __ to their __ membranes prior to v-SNARE/t-SNARE. |
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Term
| golgins, Golgi, plasma membrane, vesicles, export |
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Definition
| Two main groups of tethering proteins are known: coiled-coil proteins such as the __ are importnat in the initial recognition and binding of the COPI- or COPII- coated vesicles to the __, and the multisubunit complexes such as the exocyst complex of yeast and mammals is important for protein secretion, binding both to the __ __ and to __ from the TGN whose contents are destined for __. |
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Term
| lysosome, hydrolytic, lipids, carbohydrates, nucleic acids, proteins |
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Definition
| The __ is an organelle of the endomembrane systen that contains __ (digestive) enzymes capable of degrading all the major classes of biological macromolecules: __, __, __ __, and __. |
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Term
| hydrolytic, endocytosis, damages, needed |
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Definition
| These __ enzymes degrade extracellular materials brought into the cell by __ and digest intracellular structures and macromolecules that are __ or no longer __. |
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Term
| lysosome, single, lysosomal lumen |
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Definition
| Like the ER and the Golgi, the __ is bounded by a __ membrane. This membrane protects the rest of the cell from the hydrolytic enzymes in the __ __. |
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Term
| glycosylated, carbohydrate |
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Definition
| The lumenal side of lysosomal membrane proteins is highly __, forming a nearly continuous __ coating that appears to protect membrane proteins from lysosomal proteases. |
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Term
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Definition
| ATP-dependant proton pumps in the membrane maintain an __ environment (pH 4.0-5.0) within the lysosome. This favors enzymatic digestion of macromolecules both by activating acid hydrolases and by partially denaturing the macromolecules targeted for __. |
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Term
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Definition
| The products of digestion are then transported across the membrane to the __, where they enter various synthetic pathways, or are __ from the cell. |
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Term
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Definition
| Lysosomal enzymes are synthesized by __ attached to the rough ER and are translocated through a pore in teh ER membrane into the ER lumen before transport to the __. |
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Term
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Definition
| After modification and processing in the ER and Golgi complex compartments, the lysosomal enzymes are sorted from other proteins in the __. |
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Term
| mannose-6-phosphate, clathrin-coated, protein, endosomal |
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Definition
| Earlier we described the addition of __-_-__ tag to soluble lysosomal enzymes are packaged in __-__ vesicles that bud from the TGN, lose their __ coats, and travel to one of the __ compartments |
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Term
| late endosome, acid hydrolases |
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Definition
| Recall that early endosomes are formed by the coalesence of vesicles from the TGN and vesicles from the plasma membrane. Over time, the early endosome matures to form a __ __, an organelle having a full complement of __ __ but not engaged in digestive activity yet. |
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Term
| lumen, endocytic, extracellular, intracellular, hydrolytic |
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Definition
| As the pH of the early endosomal __ drops from about 6.0 to 5.5, the organelle loses its capacity to fuse with __ vesicles. The late endosome is essentially a collection of newly synthesized digestive enzymes as well as __ and __ material fated for digestion, packaged in a way that protects the cell from __ enzymes. |
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Term
| acid hydrolases, ATP-dependent, lysosome, transfer |
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Definition
| The final step in lysosome development is the activation of __ __, which occurs as the enzymes and their substrates encounter a more acidic environment. There are two ways eukaryotic cells accomplish this step: __-__ proton pumps may lower the pH of the late endosomal lumen to 4.0-5.0, transforming the late endosome to a __, therby generating a new organelle, or the late endosome may __ material to the acidic lumen of an existing lysosome. |
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Term
| nutrition, defense, recycling, diferentiation |
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Definition
| Lysosmes are important for cellular activities as diverse as __, __, __ of cellular components, and __. We can distinguish the digestive processes that depend on lysosomal enzymes by the site of their activity and by the origin of the material that is digested. |
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Term
| heterophagic lysosomes, autophagic lysosomes |
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Definition
| To distinguish between mature lysosomes of different origins, we refer to those containing substances of extracellular origin as __ __, wheras those with materials of intracellular origin are called __ __. |
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Term
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Definition
| Phagocytosis and Receptor-mediated endocytosis= __ __ |
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Term
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Definition
| autophagy and extracellular digestion = __ __. |
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Term
| peroxisomes, peroxisomes, endomembrane system |
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Definition
| __, like the Golgi complex, endosomes, and lysosomes, are bounded by single membranes. __, however, are not derived from the ER and therefore are not part of the __ __ that includes the other organelles discussed. |
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Term
| kidney, liver, plants, fat |
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Definition
| Perozisomes are found in all eukaryotic cells, but are expecially prominent in mamalian __ and __ cells, in algae and photosynthetic cells of __, and in germinating seedlings of plant species that store __ in their seeds. |
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Term
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Definition
| The defining characterist of a perozisome is the presence of __, an enzyme essential for the degradation of hydrogen peroxide (H2O2). |
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Term
| oxidative, oxidases, catalase, oxidases, generation, degredation |
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Definition
| Hydrogen peroxide is a potentially toxic compound that is formed by a variety of __ reactions catalyzed by __. Both __ and the __ are confined to the peroxisomes. Thus, the __ and __ of H2O2 occur within the same organelle, therby protecting other parts of the cell from exposure to this harmful compound. |
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Term
| Hydrogen Peroxide, detoxification, oxidation, nitrogen, catabolism |
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Definition
| Most peroxisomal functions are linked to __ __ metabolisim. There are at least 4 other categories of H2O2 functions: __ of harmful compounds, __ of fatty acids, metabolism of __-containing compounds, and __ of unusual substances. |
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Term
| leaf peroxisomes, glyoxysomes |
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Definition
| Plant cells contain types of peroxisomes not found in animal cells: __ __ which often appear in close contact with chloroplast and mitochondria and is involved in the light-dependent uptake of O2 and release of CO2. __ are another plant peroxisome that includes β oxidation of fatty acids as well as a pathway known as the glyoxylate cycle. Once they fufull their role in the seedling, the glycosome is converted into a peroxisome |
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