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83 Cards in this Set
- Front
- Back
Aerobic Oxidation
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o Stage I (cytosol)
Glucose Pyruvate (produces ATP and NADH) o Stage II (mito) Citric acid cycle (CO2 and ATP/GTP are produced) NADH and FADH2 also produced, utilized as electron carriers o Stage III (mito) Electron transport (O2 H2O) Proton motive force (proton gradient) o Stage IV (mito) ATP produced and exported out of mitochondria |
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Photosynthesis (all in chloroplast)
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o Stage 1
Energy is absorbed w/ absorption of photon of light and transferred to electrons o Stage 2 Electron transport (H2O O2), also NADPH produced Proton motive force (proton gradient) o Stage 3 ATP produced o Stage 4 ATP, NADPH and CO2 needed for carbon fixation Sugar released into cytosol |
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Proton Motive Force
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Generated when a high concentration of protons move down their gradient, and enter the membrane through ATP synthase, allowing the production of ATP
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Phosphofructokinase
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is key regulatory step in glycolysis
Activated by AMP and fructose-2,6-bisphosphate Inhibited by ATP and citrate |
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Aerobic Metabolism
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o Glucose + 6O2 6CO2 + 30ATP (slow, but lots of energy)
o End product of glycolysis (pyruvate) must be converted to acetyl CoA before it can enter citric acid cycle |
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Anaerobic Metabolism
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o In yeast (NOT mammals),
Glucose 2ethanol + 2CO2 + 2ATP o In muscle (mammals) Glucose 2lactate + 2ATP |
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How are the compartments of a mitochondria designed?
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two compartments
o Outer membrane, innermembrane space, inner membrane, matrix |
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Wher does the electron transport chain take place?
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inner mito membrane
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Citric Acid Cycle
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o PyruvateAcetyl-CoA (2NADH produced = 6ATP)
o Acetyl CoA2 cycles of CAC (2 cycles b/c 2 pyruvate give 2 acetyl-CoA) producing 6NADH, 2FADH2, 2ATP 1FADH2 = 2ATP So, 18ATP + 4ATP + 2ATP = 24ATP Total ATP for aerobic metabolism (GlycolysisCitric Acid Cycle) = 8 + 6 + 24 = 38 ATP total |
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Electron Transport Chain
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o Inner mito membrane impermeable to NADH and oxaloacetate
o Oxaloacetate converted to malate by malate dehydrogenase in cytosol, malate enters mito through transmembrane protein, then malate dehydrogenase converts malate to oxaloacetate w/in matrix o Transaminase converts oxaloacetate to aspartate in matrix and back to oxaloacetate in cytosol once aspartate exits matrix into cytosol through transmembrane protein NADH transfers electrons to Complex I (transmembrane) Electrons transferred to Complex II (peripheral) CoQ accepts electrons from Complex I and II and transfers them to Complex III (transmembrane) Cytochrome c transfers electrons from Complex III to Complex IV (transmembrane) In Complex IV, 1 O22H2O At each transmembrane protein, protons are pumped out of matrix, establishing a proton gradient For each pair of electrons that flow from NAHD to O2, 10 protons are translocated across the inner mito membrane |
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Chemiosmosis
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the demonstration that ATP synthesis depends on a pH gradient across a membrane
o Bacteria, mitochondria and chloroplasts all use chemiosmosis to synthesize ATP; ATP synthases are similar in all 3 o ATP synthesis always occurs on cytosolic face of membrane (aka: ATP pumped into bacterium, into matrix and into stroma o Proton movement through ATP synthase allows for exchange of ADP for ATP o FoF1 of ATP synthase located on inner mitochondrial membrane |
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Photosynthesis
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Photon of light strikes light harvesting complex (LHC) and PSII, also, O2 formed from water in PSII
All complexes found in thylakoid membrane o Chlorophyll a and b absorbed b/t 400 and 500nm, which are the primary photosynthetic pigments in plants o Carbon Fixation Catalyzed by RUBP carboxylase (Rubisco) Occurs in stroma In Calvin cycle, 3-phosphoglycerate converted to glyceraldehydes-3-phosphate, which is then transported into cytosol and converted to sucrose Rubisco catalyzes first step in CO2 fixation and photorespiration |
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Extracellular signal molecules
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include proteins, peptides, steroids (lipophilic molecules), catecholamines, gases and physical stimuli (light)
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Endrocrine
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hormones secreted into bloodstream, targeting distant cells
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Paracrine
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target neighboring cells; neurotransmitters and growth factors
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Autocrine
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cell responds to self; growth factors (in tumors)
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Receptor Activation
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o Signal binds to receptor on target cell, causing a conformational change in receptor, which initiates a specific sequence of reactions
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Kd
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measures the affinity of a receptor for its ligand; it is the required concentration of a ligand to bind to half of the surface receptors
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How does a maximum affinity occur?
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hyperbolic graph plateau’s at highest point on y-axis
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How can expression assays can be used to identify cDNA clones?
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• Cell has receptor for ligand other than X
• Add ligand X • If ligand X does not bind, there is no cellular response • Transfect the target cell with a cDNA expression vector, which allows binding of ligand X, allowing for a normal cellular response |
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G-Protein- GTP-bound
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on
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G-Protein- GDP-bound
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off
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G-Protein switch I contains:
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threonine residue
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G-Protein switch II contains:
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glycine residue
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G-protein coupled receptors
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multipass integral membrane proteins (7 membrane spanning helices)
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Where do G-Protein interactions occur?
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on the cytosolic side
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Second Messengers of Cell Signaling
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o cAMP – activates protein kinase A
o cGMP – activates protein kinase G and opens cation channels in rod cells o DAG – activates protein kinase C o IP3 – opens calcium channels in ER |
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cAMP
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activates protein kinase A
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cGMP
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activates protein kinase G and opens cation channels in rod cells
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DAG
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activates protein kinase C
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IP3
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opens calcium channels in ER
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Activation of Effector Proteins
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activated receptor triggers dissociation of G-alpha from trimer, GTP binds to G-alpha activating G-alpha so it binds to an effector, once bound effector is activated
• Once hormone released from receptor, GTP bound to G-alpha is hydrolyzed and Gprotein is again inactive |
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What happens in slime molds when cAMP is added?
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addition of cAMP leads to activation of G proteins and yellow fluorescence is decreased
o Slime molds use cAMP as signals when food is scarce |
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What happens during slowing contractions of the heart muscle?
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o Activation of acetylcholine receptor in heart muscle cells slows contraction of heart muscle
o Once activated, G-alpha binds GTP and it is G-beta/gamma that binds to K+ channel directly, opening it and inducing a membrane potential (neg charge inside cell) |
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Rhodopsin
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light receptor in rod cells; located in outer segment, flattened rods
absorbs photon of light, causing a conformational change in opsin, activating it |
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Transducin (Gt)
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trimeric Gprotein coupled to rhodopsin
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What happens during the perception of light?
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Opsin activated by light, activated opsin binds Gt-alpha-GDP, which activates it so GTP binds to Gt-alpha
Gt-alpha activates phophodiesterase, converting cGMP to GMP Low cGMP = closing of ion channels (hyperpolarization), light is perceived |
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Pathway for activation of protein kinase A
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o ligand binds, activating trimeric G protein, activating adenylyl cyclase, leading to cAMP synthesis
o cAMP activates cAMP-dependent protein kinase, leading to phosphorylation of target proteins o cAMP binds regulatory subunits of protein kinase A, catalytic units dissociate and protein kinase A is active |
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increased cAMP
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glycogen is degraded and phosphoprotein phosphatase prevented from dephosphorylatin activated enzymes
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decreased cAMP
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glycogen synthesis promoted
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How are DAG and IP3 created?
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o Active Gprotein (GTP-bound) activates phospholipase C, which cleaves phosphotidyl inositol (PIP2) to DAG and IP3
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DAG and IP3
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second messengers that function in elevating cytosolic calcium levels and activating protein kinase C
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Why is insulin secreted from the pancreas?
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in response to high blood glucose
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Where is the calcium released from when cytosolic calcium levels are elevated?
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Calcium released from ER into cytosol
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How are transcription factors activated and what results from activation in eukaryotes?
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via extracellular signals, resulting in regulated gene expression in eukaryotes
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What do changes in gene expressions affect?
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cell division, differentiation, cell-cell communication and immune response
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What happens when transcription factors bind to regulatory sites?
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turns on transcription of genes regulated by those sites
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TGF-beta signaling pathway
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o TGF-beta binds to type III receptor, transcription of plasminogen activator inhibitor occurs
o NLS (nuclear-localization signal) required to transport Smad complex into nucleus, so transcription can occur |
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Ras/MAP kinase pathway
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o Activated by ligand binding to receptor tyrosine kinases
o Ras is a monomeric Gprotein o MAP kinase enters nucleus and phosphorylates many transcription factors important in cell cycle and differentiation o Active Ras and active MAP kinase turn on target genes via phosphorylation of transcription factors |
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Receptor Tyrosine Kinase
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o Extracellular part binds ligand, receptor forms dimer
o RTKs phosphorylate each other on tyrosine residues on interior region of receptor (in cytosol) |
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GPCR (Gprotein coupled receptor)
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a multipass transmembrane protein w/ 7-membrane spanning domains
o Ligand binding to Gs protein-coupled receptor results in activation of CREB transcription factor |
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Wnt Signaling Pathway
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controles brain development, limb patterning and organogenesis
o Also controls formation of osteoblasts in humans, affecting bone desity |
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Hedgehog signaling pathway
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o Acts through smoothened and patched proteins and contains Cubitis interruptus transcription factor (Ci)
o w/ a hedgehog, Ci is in activating form o w/out a hedgehog, a repressing Ci fragment is generated |
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NF-KB Signaling Pathway
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o In nucleus, NF-KB activates transcription of gene encoding I-KB-alpha, which terminates signaling and genes encoding inflammatory cytokines, which promote signaling
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Notch/Delta Signaling Pathway
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o Delta and Notch interact w/ transcription factors, affecting expression of genes that influence determination of cell fate during development
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What is the function of Cell adhesion molecules (CAMs)?
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bind to CAMs on adjacent cell
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Cell-Cell Adhesions
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o Cell adhesion molecules (CAMs) bind to CAMs on adjacent cell
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Cell-Matrix Adhesions
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o Adhesion receptors bind components of ECM
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4 Families of Cell Adhesion Molecules
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o Cadherins, w/ calcium binding sites
o Ig-superfamily CAMs, w/ Ig domain o Integrins, w/ fibronectin o Selectins, w/ lectin domains |
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What does blocking function of ECM proteins?
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blocks development
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What does blocking fibronectin w/ antibodies do?
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blocks branching during morphogenesis in mouse tissues
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What does blocking collagen or perlecan gene activity do?
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results in defects in cartilage and bone development
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How are epithelial cells held together?
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o Held together by anchoring junctions and tight junctions
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Anchoring Junctions
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interact w/ adapter proteins and cytoskeleton
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Adherens junctions
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connect connect lateral membranes, interact with a belt of actin and myosin filaments, internally bracing the cell
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Desmosomes
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connect lateral membranes, spot-welds cells together - transfer shear forces to the epithelium as a whole, strengthening it
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Hemidesmosomes
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mostly on basal surface, connecting epithelium to extracellular matrix - also transfer shear forces
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Tight junctions
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adhesion proteins connect cells, interact with adapter proteins, connect to the cytoskeleton. Control flow of solutes through extracellular spaces between cells.
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Gap junctions
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allow diffusion of small water-soluble materials between adjacent cells.
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Cadherin
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allows clumping of cells due to presence of calcium
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ECM in bone
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calcified
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ECM in cartilage
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flexible
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ECM in connective tissue
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fibroblasts
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4 protein components of the basal lamina
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Type IV collagen
Laminin Entactin Perlecan |
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How is collagen structured?
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Collagen has triple helix w/ glycine sidechains in the middle of the helix for flexibility; globular domains interact head-to-head
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What is the structure of Laminin?
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Laminin has 3 chains linked by S-S bonds
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Synthesis of fibrillar collagens
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Procollagen associates to form collagen fibril w/ cross striations
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Why is fibornectin important?
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Fibronectin structure is important in wound healing and cell development
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How are multiple forms of fibronectin formed?
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Fibronectin has many forms generated by alternative splicing of mRNA
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What do integrins link?
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Integrins link fibronectin and the cytoskeleton
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Cell Migration
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Selectin ligand on leukocyte binds to P-selectin on endothelial cell
Active integrin binds to ICAM-2, resulting in extravasation |
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structural components of plant cell wall
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o Pectin (polysaccharides)
o Cellulose microfibril o Hemicellulose o Plasmodesmata – junctions in plant cell walls |
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Plasmodesmata
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junctions in plant cell walls
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