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Bio 414 Exam 2 Concepts
Endomembrane, Cytoskeleton, Cellular Movement, Phagocytes in Immunity and Cell-Cell Communication
62
Biology
Undergraduate 4
02/26/2018

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Term
Rough ER
Definition
Protein packaging
Term
Smooth ER
Definition
Lipid production
Term
Smooth ER in the liver (hepatocytes)
Definition
Cuts up glycogen, exports glucose to the blood with GLUT2
Drug hydroxylation
Term
Smooth ER in the muscles
Definition
Calcium storage
Term
Cisternae
Definition
Long sheets of the Rough ER and Golgi
Term
CGN (cis); TGN (trans)
Definition
Golgi's nucleus facing; membrane facing sides
Term
Movement of lipids and enzymes through the Golgi
Definition
Stationary cisternae with transition vesicles moving in both directions, or maturing cisternae for larger proteins that shift to the trans face
Term
Glycosylation
Definition
Carbohydrates (among other things) are added (and removed) as proteins move anterograde through the Golgi
Term
Anterograde
Definition
In the direction of the plus end, or towards the cell membrane.
Term
Retrograde
Definition
In the direction of the minus end, or towards the nucleus.
Term
Secretory vesicles
Definition
Have no membrane proteins, as the contents are dumped outside the cell and not integrated into the cell membrane.
Term
Endosomes
Definition
Can move in either direction, to mature, fuse or be digested.
Term
Lysosomes
Definition
A state of vesicle development wherein a late endosome either acidifies on its own or fuses with a lysosome.
Term
Late Endosomes
Definition
A state of vesicle development wherein an early endosome matures on its own or fuses with another vesicle in order to mature.
Term
Autophagy
Definition
When a cell cannibalizes its own organelles by creating a membrane around it and fuses this with a lysosome, as in maturing red blood cells.
Term
Endocytosis
Definition
The opposite of secretion, wherein the cell takes in material by creating an invagination, squeezing to form a neck and then cutting the sealed membrane loose from the cell membrane.
Term
Phagocytosis
Definition
Large scale endocytosis performed by amoeba to eat as well as by macrophages, dendritic cells and neutrophils in the human immune system.
Term
Clathrin coated pits
Definition
Ever present shallows to which membrane receptors move on binding, whereupon more clathrin is recruited to create an invagination before the membrane fuses and is cut to form a vesicle.
Term
Clathrin structure
Definition
Triskelions which polymerize to form hexagons and pentagons as a net, like a soccer ball.
Term
Membrane fusion
Definition
Tethering complexes bind to vesicle receptors, then draw the vesicle in so that it can bind snare proteins with the membrane. This forces the membranes together then triggers a GTPase to open the joined membranes.
Term
Peroxisomes
Definition
Not part of the ER-Golgi system, responsible only for dealing with hydrogen peroxide.
Term
Peroxisome development
Definition
Can gather parts directly from the cytoplasm or divide into two fully developed peroxisomes.
Term
Microtubule subunit
Definition
α and β tubulin as heterodimers.
Term
Microtubule growth
Definition
Proceeds in a spiral one αβ heterodimer at a time at a sigmoidal speed. May proceed in both directions, but usually from the (β) plus end.
Term
Microtubule arrangement
Definition
13 protofilaments around a 15nm hollow core. Usually in a 13 singlet, 13+11 doublet or 13+11+11 triplet.
Term
GTP Cap
Definition
Tubulin bound to GTP at the N-terminal, probably for stabilization of the microtubule. Hydrolysis causes maturation, but is not necessarily required.
This is the dynamic instability model.
Term
MTOC
Definition
MicroTubule Organizing Center, often the centrosome, from which microtubules grow.
Term
Centriole
Definition
A circle of 13 microtubule triplets, which produces less complex TuRCs to encourage the growth of normal microtubules.
Term
TuRCs
Definition
γ-Tubulin Ring Complexes which form in a circle and grow normal αβ microtubules.
Term
Colchicine
Definition
A plant derived poison which binds to the middle of β tubulin and inhibits microtubule growth.
Term
Microtubule function
Definition
To move large structures such as organelles through the cell and create a polarity seen in axons, cilia, RBCs, etc.
Term
Microfilament subunit
Definition
G-(globular)-actin, which forms two strings that make up F-(filamental)-actin.
Term
Microfilament growth
Definition
Similar to growth in microtubules, but with ATP caps instead of GTP. Can only proceed in the plus direction.
Term
Microfilament function
Definition
Provide structure in stress fibers (sarcomeres), cell cortex (membrane regulation), filopodium (motility 'foot' with straight bundles), lamellipodium (branched actin for adhesion in motility) and microvilli (for absorption, secretion and cell adhesion)
Term
Rho GTPases
Definition
Regulators which shut down microfilament alteration in the absence of GTP.
Term
Intermediate filament subunit
Definition
Various proteins, which form dimers that stack head-to-tail in tetramers to form protofilaments and then intermediate filaments in groups of 8.
Term
Kinesins
Definition
Microtubule motors with a heavy chain, cargo-binding light chain and ATP binding head which steps forward on hydrolysis. Responsible for moving anterograde.
Term
Dyneins
Definition
Microtubule motors with cargo-binding dynactin complexes and an ATP binding head in the shape of a wheel which cocks on hydrolysis. Responsible for moving retrograde.
Term
Axonemal dyneins
Definition
Motor proteins which move cilia and flagella. The basal body consists of 9 microtubule triplets. The axoneme consists of 9 microtubule doublets around a singlet pair. Outer tubules are connected by covalent crosslinks while the dyneins create motion.
Term
Myosins
Definition
Microfilament motors with a double globular actin-binding head (esp. Myosin II), one or two heavy chains and a tail. Make up the thick filaments of sarcomeres.
Term
Muscle contraction
Definition
Sarcomeres contract as myosins "walk" along actin, pulling the ends together. Sarcomeres exist in a grid that makes up a vertical unit of myofibrils.
Term
Myosin-actin binding mechanism
Definition
When ATP binds, one myosin detaches. On hydrolysis the mysosin cocks and can now bind to actin. It "shoots" when the detached phosphate releases. ADP is then released so that a new ATP can bind.
Term
Calcium regulation in sarcomeres
Definition
Muscle cells have a specialized ER called the SR which stores and releases calcium, interconnected to T tubules which are connected to neurons. On the neuron's signal, depolarization tells the SR to release calcium and allow contraction.
Term
Cardiac muscle specialization
Definition
Instead of fused cells forming a string, these muscle cells are connected head to tail by intercalated disks. The cells branch, and contain plenty of mitochondria for energy.
Term
Smooth muscle specialization
Definition
Internal organ muscle is made up of individual oblong cells with muscle fibers spaced out in the middle. Dense bodies are connected in a net by intermediate filaments regulated by Calmodulin instead of an SR.
Term
Actin in motility
Definition
Actin filaments in lamellipodia and filopodia polymerize to grow, and once adhesion proteins attach the cell membrane to outside subtrate they detach from the trailing edge and actin contraction moves the trailing edge toward the leading edge.
Term
Macrophages and Dendritic Cells
Definition
Sister cells which both develop from a monocyte that circulates in the blood. They both stay in tissue, don't circulate through blood and are functionally equivalent, but dendritic cells are only there to recruit lymphocytes.
Term
Macrophage function
Definition
To engulf and destroy pathogens, release inflammatory mediators and tag antigens for other immune cells.
Term
Neutrophil function
Definition
To engulf pathogens via endo- or phagocytosis, release reactive oxygen and nitrogen, then lyse to form extracellular bacteria traps (this is what puss is).
Term
Macrophage identity-determining receptors
Definition
Identify bacterial compounds or complement protein as "other", but also host cell ligands in order to prevent phagocytosis of "self" cells.
Term
Inflammation
Definition
Macrophages release cytokines which bring fluid to the infection site (to prevent the pathogen from spreading), tell the brain to increase body temperature and respiration, recruit neutrophils, but also decrease blood pressure.
Term
Neutrophils
Definition
Live in bone marrow, have an unusual nucleus shape, and work much like macrophages but in much larger numbers.
Term
Neutrophil mechanism
Definition
The antigen is phagocytosed into a phagosome. Granules fuse to the basic phagosome to kill the contents. This acidifies the phagosome, causing lysosomes to fuse and digest the remnants of the antigen. Once the granules are depleted, the neutrophil lyses to form an extracellular bacteria trap.
Term
Extravasation
Definition
The process by which neutrophils leave the bone marrow and squeeze between the sides of two blood vessel using lamellipodia and filopodia.
Term
Neutrophil motion
Definition
Once neutrophils are in the tissue they crawl through the basement membrane and connective tissue, secreting lysosomal enzymes to digest the protein matrix.
Term
Innate Immune Response
Definition
1. Macrophage sees pathogen
2. Phagocytoses pathogen, induces inflammation
3. Neutrophils leave marrow and extravasate
4. Neutrophils and macrophages continue phagocytosis to completion
Term
Adherens junctions
Definition
The glue that surrounds cells, linking cells to cells and those bonds to the actin cytoskeleton.
Term
Desmosomes
Definition
Spot-welds between cells, making use of cadherins (desmocollin and desmoglein) and adaptor proteins (plakophilin, plakoglobin and desmoplakin) which connect to intermediate filaments rather than microfilaments.
Term
Hemidesmosomes
Definition
Similar to desmosomes, but attaching cells to the basal lamina rather than each other.
Term
Tight junctions
Definition
Essentially impermeable junctions between cells which keep food and other undesirables away from connective tissue.
Term
Gap junctions
Definition
Channels for ions, nutrients and signals, typically about 3nm per opening.
Term
Collagen
Definition
A protein complex fiber which forms a triple helix that repeats in a staggered pattern of fibrils, creating a stripe patten.
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