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Cell Biology
Chapter 12
206
Biology
Undergraduate 3
10/29/2012

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Term
Endomembrane system
Definition
Comprised of the: Rough ER Smooth ER Golgi Complex Endosomes Lysosomes
Term
Rough ER
Definition
Synthesizes proteins
Contains ribosomes and is continuous with the nuclear membrane
Term
Smooth ER
Definition
Synthesizes lipids
Contains NO ribosomes and is continuous with the rough ER
Term
Golgi Complex
Definition
Further processes lipids and proteins further
Sorts them for transportation
Physically and functionally linked to the ER
Term
Lysosomes
Definition
Contains digestive enzymes capable of degrading all the major classes of biological macromolecules: lipids, carbs, nucleic acids, and proteins
Term
Endosomes
Definition
Lysosomes are made from late Endosomes
Used for transportation
Term
Endoplasmic Reticulum (ER)
Definition
A continuous network of flattened sacs, tubules, and associated vesicles that stretches throughout the cytoplasm of the eukaryotic cell
Term
ER cisternae
Definition
The membrane bound sacs
Term
ER lumen
Definition
The spaced enclosed by the cisternae
Term
Light microscope, electron microscope
Definition
The ER is not visible with the __ __, but is visible with the __ __.
Term
Synthesis of proteins, plasma membrane, organelles, export
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.
Term
Synthesis of lipids, intracellular membranes, plasma membrane
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 __ __.
Term
Structure
Function
Definition
The two basic kinds of ER differ in __ and __
Term
Ribosomes
Definition
The two basic kinds of ER are distinguished from one another by the presence or absence of __ attached to the ER membrane
Term
Rough ER
Definition
Is characterized by ribosomes attached to the cytosolic side of the membrane (the side that faces away from the ER lumen)
Term
Cytosol
Definition
Translation by these ribosomes occurs in the __, but newly synthesized proteins will enter the ER lumen shortly
Term
RNA
Definition
Because ribosomes contain __, it was the RNA that reacted strongly with the basic dies that were originally used to identify the rough ER
Term
Transitional elements (TE's)
Definition
A subdomain of rough ER, the __ __, plays an important role in the formation of transition vesicles
Term
Transition vesicles
Definition
Shuttle lipids and proteins from the ER to the Golgi Complex
Term
Smooth ER
Definition
Appears smooth due to the absence of ribosomes attached to the membrane
Term
Large flattened sheets
Definition
Morphologically, rough ER usually form __ __ __ .
Term
Tubular structures
Definition
Morphologically Smooth ER generally form __ __.
Term
Smooth ER (tubular structure)
Definition
Transition elements of the rough ER are an exception to this rule. They often resemble __ __ (__ __).
Term
Separate organelles
Definition
Rough ER and Smooth ER are not __ __.
This materials can travel between the rough and smooth ER without the aid of vesicles
Term
Variation
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
Term
Rough ER
Definition
Liver cells producing digestive enzymes, tend to have prominent __ __ networks
Term
Smooth ER
Definition
Cells producing steroid hormones, such as testis and ovary tend to have extensive networks of __ __.
Term
Microsomes
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 __.
Term
Outside the cell
Definition
Microsomes do not exist __ __ __
Term
Biosynthesis, process, proteins
Definition
The rough ER is involved in the __ and __ of __.
Term
Membrane bound, soluble proteins, Endomembrane system
Definition
The ribosomes attached to the cytosolic side of the rough ER membrane are responsible for synthesizing both __ __ and __ __ for the __ __.
Term
Cytoplasmic ribosomes
Definition
Synthesis of proteins destined for the Endomembrane system begins on __ __.
Term
Receptor proteins
Definition
Cytoplasmic ribosomes attach to the rough ER via __ __ in the ER membrane shortly after translation initiation
Term
Cotranslationally
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
Term
Membrane spanning proteins
Definition
After biosynthesis, __ __ __ remain anchored to the ER membrane either by hydrophobic regions of the polypeptide or by covalent attachment to membrane lipids
Term
Soluble proteins
Definition
__ __, including secretory proteins, are released into the ER lumen
Term
Glycoproteins, folding, polypeptides, multimeric proteins
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 __ __.
Term
Glycosylation
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
Term
Quality control
Definition
The ER is also a site for __ __
Term
ER- associated degradation (ERAD)
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
Term
Drug detoxification
Carbohydrate metabolism
Calcium storage
Steroid biosynthesis
Definition
Smooth ER is involved in __ __, __ __, __ __, and __ __.
Term
Hydroxylation, cytochrome P-450
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
Term
Liver (hepatocytes)
Definition
Carbohydrate metabolism is prominent in the __ cells
Term
Tolerance
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 __.
Term
cytosol, nucleus
Definition
Gated transport goes from the __ to the __.
Term
cytosol, mitochondria, endoplasmic reticulum, plastids, peroxiosomes
Definition
transmembrane transport goes from the __ to the __, __, __, and __
Term
endoplasmic reticulum, golgi, golgi, endoplasmic reticulum
Definition
vescular transport occurs from the endoplasmic reticulum to the __, and from the __ to the __ __
Term
cell surface, secretory vessels, late endosome
Definition
vesicular transport occurs from the golgi to the __, __, and the __ also
Term
golgi, lysosome
Definition
vesicular transport occurs from the __ to the late endosome and the __
Term
cell surface, early endosome, cell surface, late endosome
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 __ __.
Term
flippases
Definition
How to move phospholipids from inside to outside (for those that belong on the outside) --like glycolipids
Term
proteins
Definition
phospholipids can exchange (transfer) __. This is an important property (in SER) for amphibians because of the varying outside temperatures.
Term
aryl hydrocarbon hydroxylase, cigarette smoke
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
Term
stored glycogen, glucose-6-phosphatase
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.
Term
liver
Definition
glucose-6-phosphatase is abundant in the __ because its major role is to keep the level of glucose in the blood relatively constant
Term
liver glycogen, phosphorolysis, glucose-6-phosphate
Definition
when glucose is needed by the body, especially between meals and in response to increased muscular activity, __ __ is broken down by __ producing __-__-__.
Term
phosphorylated sugars, free glucose, glucose-6-phosphatases
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
Term

liver, kidney, intestinal,

muscle, brain

Definition
glucose-6-phosphatase activity is present in __ , __ , __ cells. NOT in __ and __ cells
Term
sarcoplasmic reticulum, muscle cells
Definition
the __ __ found the the __ __ is an example of SER that specializes in the storage of calcium
Term
ER lumen
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
Term
neurotransmitter molecules
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
Term
adrenal, Leydig, liver, follicular, plastids steroids (hormones)
Definition
The SER of cells in the __ glands, __ cells, __ cells, __ cells, and possibly __ of plants are the site for the synthesis of __
Term
carbon, hydroxyl
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
Term
Hydrozymethylglutaryl-CoA reductase (HMG-CoA reductase), large, liver
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
Term
P-450, hydroxylation
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 __
Term
phospholipids, cholesterol 
Definition
The SER is the primary source of membrane lipids, including __ and __.
Term
cytosoplasm, monolayer, cytosol
Definition
Biosynthesis of fatty acids for membrane phospholipid molecules occurs in the __ and incorporation is restricted to the __ of the SER membrane facing the __.
Term
flippases
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 __.
Term
particular translocator, membrane assymetry
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 __ __.
Term
phosoholipid exchange proteins,  (phospholipid transfer protiens), phospholipid
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
Term
contractions, breast feeding
Definition

Dual actions of oxytocin: one path for __ and the other path for __ __

 

Term
Smooth ER
Definition

[image]

where is HGM-CoA reductase found?

its a pathway with acetyl CoA...dressing up of pyruvate to enter the citric acid cycle

Term
Cisternae
Definition
The Golgi Complex consists of a series of flattened membrane-bounded __, disk-shaped sacs that are stacked together.
Term
Golgi stack, electron, stacks, type, metabolic
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.
Term
transport vesicles, Golgi complex, endosomes, lysosomes, secretory granules
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 __ __ 
Term
intracisternal space
Definition
the Golgi complex lumen, or __ __, is part of the endomembrane system's network of internal spaces
Term
cis face, cis-Golgi network (CGN), arrive, CGN, CGN membranes
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 __ __.

Term
trans face, trans-Golgi network (TGN), leave, transport vesicles, TGN cisternae
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 __ __.
Term
secretory granules, endosomes, lysosomes, plasma membrane
Definition
transport vesicles carry lipids and proteins from the golgi complex to __ __, __, __, and the __ __. 
Term
medial cisternae, processing
Definition
central sacs between the CGN and the TGN comprise the __ __ of the Golgi stack, in which much of the __ of proteins occurs.
Term
biochemically, functionally, receptor proteins, enzymes
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
Term
glycosylation, glycoproteins 
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 __.
Term
N-linked Glycosylation, O-linked Glycosylation
Definition
The two general kinds of glycosylation that are observed in cells are _-__ __ and _-__ __. 
Term
nitrogen, amino group, asparagine
Definition
N-linked Glycosylation (N-glycosylation) involves the addition of a specific oligosaccharide unit to the __ atom to the terminal __ __ of certain __ residues.
Term
oxygen, hydroxyl group, serine, theronine
Definition
O-linked Glycosylation involves the addition of an oligosaccharide to the __ atom on the __ __ of certain __ or __ residues.
Term
preceding, block, disease
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.
Term
cytosolic, ER, ER lumen
Definition
Initial steps of N-glycosylation take place on the __ surface of the __ membrane. The later steps take place in the __ __.
Term
carbohydrate, ER, core oligosaccharide
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
Term
dolichol phosphate, ER
Definition
glycosylation begins as __ __, an oligosaccharide carrier, is inserted into the __ membrane .
Term
GlcNAc, mannose
Definition
__ and __ groups are then added to the phosphate group of dolichol phosphate. Currently, the growing protien is facing the cytosolic side.
Term
cytosol, ER lumen, flippase
Definition
The growing core oligosaccharide is then translocated from the __ to the __ __ by a __.
Term
mannose, glucose
Definition
Once inside the ER lumen, more __ and __ units are added 
Term
core oligosaccharide, dolichol, asparagine residue
Definition
The completed __ __ is then transferred as a single unit from __ to an __ __ of the recipient protein.
Term
trimmed, modified
Definition
Finally, the core oligosaccharide attached to the protien is __ and __.
Term
cotranslational glycolsyation, proper, misfolded, aggregated 
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
Term
ER proteins, proper folding
Definition
Addition of a single glucose unit allows other __ __ to interact with the newly synthesized glycoprotein to ensure __ __.
Term
calnexin (CNX), calreticulin (CRT), disulfide bond, disulfide bond
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.
Term
glucosyl transferase, UGGT (UDP-glucose:glycoprotein glucotransferase), UGGT, improperly,UGGT, ER, Golgi
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 __.
Term
intracellular, ER, Golgi complex, endosomes, lysosomes, protein, leaving
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 __. 
Term
rough ER, plasma membrane, outside
Definition
Other groups of proteins synthesized in the __ __ are destined for incorporation into the __ __ of for release to the __ of the cell
Term
"tag", transport vesicle
Definition
Each protein contains a specific "__" targeting the protein to a __ __ that wil carry material from one specific cellular location to another.
Term
amino acid, oligosaccharide side, hydrophobic, excluding
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.
Term
destination, phosphate, phosphatidylinositol (PI), kinases
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 __.
Term
inhibition, lysosome
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 __.
Term
lenght, degree, trafficking
Definition
The __ and __ of saturation of certain membrane lipids have also been shown to be important in vesicle __.
Term
ER, Golgi stack retrieving, retaining
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.
Term
TGN, lipids, proteins, transport vesicles
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.
Term
Golgi complex, endocytosis
Definition
In some cells, the __ __ is also involved in the processing of proteins that enter the cell by __
Term
cis, trans
Definition
The protein enters on the __ side of the golgi, and after glycosylation (processing) exist on the __ side.
Term
retention, retrieval
Definition
ER specific protiens contain __ and __ tags.
Term
preventing, ER membrane, retrieving, ER, CGN
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 __.
Term
tripeptide sequence, Arg-X-Arg, retention tag, plasma membrane
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.
Term
retrieval tags, Golgi complex lumen, C-terminal amino acid, conformational change
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.
Term
protein sorting, TGN
Definition
Targeting of soluble lysosomal proteins to endosomes and lysomes is a model for __ __ in the __
Term
lysosomal enzymes, N-glycosyation, glucose, mannose
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
Term
mannose, carbohydrate side chain, phosphorylated, mannose-6-phosphate, lysosome
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 __.
Term
Golgi-specific, Golgi stack, GlcNAc-1-phosphate, GlcNAc, mannose-6-phosphate
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
Term
mannose-6-phosphate (MPRs), mannose-6-phosphate, favors
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. 
Term
endosome, late endosome, early endosome, TGN, plasma membrane
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 __ __ 
Term
late endosome, pH, late endosome, lysosome, active lysosome 
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 __ __.
Term
mannose-6-phosphate, mannose-6-phosphate, extracellular medium, lysosomes
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  __.
Term
KDEL, HDEL, mannose-6-phosphate
Definition

Trafficking label: mammals= __ , yeast= __ , these send them back to ER. 

__-_-__ =sends it back to endosome (lysosomes) where it gets degraded

Term
secretory pathways, secretory vesicles, secretory granules, discharge
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
Term
zymogen granules
Definition
__ __ are vesicles that discharge secretory proteins to the exterior of the cell
Term
constitutive secretion, plasma membrane surface, regulated secretion, extracellular signal
Definition
__ __ involves the continuous discharge of vesicles at the __ __ __, wheras __ __ involves controlled, rapid releases that happen in response to an __ __.
Term
plasma membrane, exocytosis, constitutive secretion, intestines
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 __.
Term
default pathway, amino acid tags
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.
Term
N-glycosylation 
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.
Term
regulated secretion, extracellular signals, neurotransmitters
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 __.
Term
maturation process, maturation, condensation, proteolytic, hormonal, chemical
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
Term
amino acid sequence
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.
Term
exocytosis, endocytosis, delivery, recycling, turnover
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. 
Term
exterior, vesicle, plasma membrane
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
Term
cell surface
Definition
1: vesicles containing cellular products destined for secretion move to the __ __.
Term
fusion, plasma membrane, exterior
Definition
2. __ with the __ __ discharges the vesicle contents to the __ of the cell
Term
vesicle, plasma membrane, plasma membrane, glycoproteins, glycolipids, extracellular space
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 __ __
Term
hormone, neurotransmitter, cell surface, second messenger, calcium ions
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.
Term
protein kinase
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
Term
specific site, polarized secretion, nerve cells, neurotransmitter
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 __ __. 
Term
endocytosis, plasma membrane, inward, pinches, endocytic vesicle
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. 
Term
ingestion, defense, white blood
Definition
Endocytosis is important for several cellular processes, including __ of essential nutrients by some unicellular organism and __ against microorganisms by __ __ cells.
Term
opposite, exocytosis, endocytosis, plasma membrane
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.
Term
recycle, reuse
Definition
Through endocytosis and retrograde transport, the cell can __ and __ molecules deposited in the plasma membrane by secretory vesicle during exocytosis.
Term
endocytic vesicle, cytosol
Definition
During endocytosis, the membrane of an __ __ isolates the internalized substances from the __. 
Term
early endosomes, TGN, lysosome, phagocytosis, pinocytosis
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.
Term
phagocytosis
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 __. 
Term
food, phagocytes, defense, nutrition
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 __.
Term
foreign material, invasive, scavengers
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
Term
receptor-mediated endocytosis, clathrin-dependent endocytosis, outer surface
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.
Term
eukaryotic
Definition
Receptor-mediated endocytosis is the primary mechanism for the specific internalization of most macromolecules by __ cells.
Term
hormones, enzymes, cholesterol, antibodies, toxins
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.
Term
ligand, receptor, ligand-binding 
Definition
Receptor-mediated endocytosis begins with the binding of a __to their __ (specific __-__ proteins) found on the outer surface of the plasma membrane 
Term
coated pits
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.
Term
proteins, plasma membrane, curvature, invagination 
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
Term
pinches, coated vesicle
Definition
Invagination continues until the pit __ off from the plasma membrane, forming a __ __. 
Term
uncoated
Definition
The clathrin coat is released, leaving an __ vesicle.
Term
recycled, early endosome
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 __ __.
Term
lysosomal proteins, lysosome
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 __.
Term
acidification, pH, acidic, freeing
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.
Term
degradation
Definition
Some receptor-ligand complexes (EGF--epidermal growth factor-- and its receptor) are carried to a lysosome for __.
Term
TGN, endomembrane system
Definition
Others are carried to the __, where they enter a variety of pathways transporting material throughout the __ __.
Term
transport vesicles, transcytosis, endocytosis, cytoplasm, exocytosis
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.
Term
coated vesicles, coats
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.
Term
membrane bounded, inside, outside
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.
Term
endomembrane system, transport
Definition
Coated vesicles are involved in vesicular traffic throughout the __ __, as well as __ during exocytosis and endocytosis.
Term
cytosolic
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.
Term
transport vesicles, destinations
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.
Term
spherical, membranes, moving
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.
Term
origin, destination
Definition
The specific set of proteins coverind the exterior of a vesicle is an indicator of the __ and __ of the vesicle within the cell.
Term
TGN, endosomes, plasma membrane, outside
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.
Term
Golgi, ER, cisternae, Golgi complex, inside
Definition
COPI-coated vesicles facilitate retrograde transport of proteins from the __ back to the __, as well as between __ of the __ __. Staying __ the cell.
Term
ER, Golgi, inside 
Definition
COPII-coated vesicles are involved in to transport of material from the __ to the __. Staying __ the cell.
Term
highly specific
Definition
Much of the intracellular traffic mediated by coated vessicles is __ __.
Term
vesicles
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.
Term
specificity
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.
Term
proteins, wrong, SNARE hypothesis
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.
Term
v-SNAREs, t-SNAREs
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.
Term
complementary
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.
Term
Rab GTPases, Rab GTPases, Rab
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.
Term
stable complex, Rab, lock, membrane fusion
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 __ __.
Term
NSF, SNAPs, specificity
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.
Term
neurotransmitter-containing, nerve, neurotransmitter
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
Term
tethering proteins, vesicles, target
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.
Term
golgins, Golgi, plasma membrane, vesicles, export
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 __.
Term
lysosome, hydrolytic, lipids, carbohydrates, nucleic acids, proteins
Definition
The __ is an organelle of the endomembrane systen that contains __ (digestive) enzymes capable of degrading all the major classes of biological macromolecules: __, __, __ __, and __. 
Term
hydrolytic, endocytosis, damages, needed
Definition
These __ enzymes degrade extracellular materials brought into the cell by __ and digest intracellular structures and macromolecules that are __ or no longer __.
Term
lysosome, single, lysosomal lumen
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 __ __.
Term
glycosylated, carbohydrate
Definition
The lumenal side of lysosomal membrane proteins is highly __, forming a nearly continuous __ coating that appears to protect membrane proteins from lysosomal proteases.
Term
acidic, degredation
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 __.
Term
cytosol, exported
Definition
The products of digestion are then transported across the membrane to the __, where they enter various synthetic pathways, or are __ from the cell.
Term
ribosomes, Golgi
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 __.
Term
TGN
Definition
After modification and processing in the ER and Golgi complex compartments, the lysosomal enzymes are sorted from other proteins in the __.
Term
mannose-6-phosphate, clathrin-coated, protein, endosomal
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
Term
late endosome, acid hydrolases
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.
Term
lumen, endocytic, extracellular, intracellular, hydrolytic
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.
Term
acid hydrolases, ATP-dependent, lysosome, transfer
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.
Term
nutrition, defense, recycling, diferentiation
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.
Term
heterophagic lysosomes, autophagic lysosomes
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 __ __.
Term
heterophagic lysosome
Definition
Phagocytosis and Receptor-mediated endocytosis= __ __
Term
autophagic lysosomes
Definition
autophagy and extracellular digestion = __ __.
Term
peroxisomes, peroxisomes, endomembrane system
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.
Term
kidney, liver, plants, fat
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.
Term
catalase
Definition
The defining characterist of a perozisome is the presence of __, an enzyme essential for the degradation of hydrogen peroxide (H2O2).
Term
oxidative, oxidases, catalase, oxidases, generation, degredation
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.
Term
Hydrogen Peroxide, detoxification, oxidation, nitrogen, catabolism
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.
Term
leaf peroxisomes, glyoxysomes
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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