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23 Cards in this Set
- Front
- Back
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what energy factor is required for:
1. tRNA aminoacylation? 2. loading tRNA onto ribosome? 3. translocation 4. how much total energy is expended |
1. ATP-->AMP (NOTE: 2 phosphoanhydride bonds!!!)
2. GTP-->GDP 3. GTP-->GDP 4. 4 high energy phopspoanhydride bonds |
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define these post-translational modifications:
1. trimming 2. covalent alterations 3. proteasomal degradation |
1. trimming = removal of N- or C-terminal propeptides from ZYMOGENS to generate mature proteins
2. covalent alterations: phosphorylation, glycosylation, hydroxylation 3. proteasomal degradation: attachment of UBIQUITIN to defective proteins to TAG THEM FOR BREAKDOWN |
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list the enzyme regulation methods
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- enzyme concentration alteration (synthesis and/or destruction)
- covalent modification (eg - phosphorylation) - proteolytic modification (zymogen) - allosteric regulation (eg - feedback inhibition) - pH - temperature - transcriptional regulation (eg - steroid hormones) |
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cell cycle phases
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- mitosis (SHORTEST PHASE!): prophase, metaphase, anaphase, telophase
- G1 - variable duration (at which time you can go in and out of G0 - variable duration - S - G2 |
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factors which control transitions between phases (3 things)
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1. cyclins - phase, specific and activate CDKs
2. CDKs - constitutive and inactive Cyclin-CDK complexes must be both activated and inactivated for cell cycle to progress 3. tumor supressors - Rb p53 - both INHIBIT G1-->S PROGRESSION; mutations in these genes result in unrestrained growth! |
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Permanent cells
- what phase of cell cycle are they in? - how to they regenerate - 4 examples of this cell type? |
remain in G0
- regenerate from stem cells - neurons skeletal muscle cardiac muscle RBCs |
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Stabile (quiescent) cells
- how are they involved with cell cycle? - examples? (2 of them) |
- enter G1 from G0 when stimulated!
- hepatocytes lymphocytes |
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Labile cells
- how are they involved with cell cycle? - examples? (4 of them) |
- NEVER GO to G0!!!
- divide rapidly with SHORT G1 - bone marrow gut epithelium skin hair follicles |
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RER
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- site of synthesis of SECRETORY PROTEINS
- site of synthesis of N-LINKED OLIGOSACCHARIDE - site of synthesis of many other protiens too :) - NOTE: Mucus-secreting GOBLET CELLS of small intestine and Ab-secreting PLASMA CELLS are rich in RER!!! |
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Nissl bodies
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found in neurons
- synthesize enzymes (ChAT) and peptide neurotransmitters |
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free ribosomes
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unattached to any membrane
- site of synthesis of CYTOSOLIC and ORGANELLAR PROTEINS |
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Smooth ER
- function - what cells are rich in it? |
- site of STEROID SYNTHESIS (smooth steroid!)
- site of DETOXIFICATION OF DRUGS (smooth out the bad effects of drugs by detoxifying!) - LIVER HEPATOCYTES and steroid-hormone producing cells of ADRENAL CORTEX - rich in SER!!! |
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Functions of the golgi apparatus
(6 of them) |
1. distribution center of proteins and lipids from ER to plasma membrane, lysosomes, secretory vesicles
2. modification of N-oligosaccharides on asparagine 3. addition of O-oligosaccharides to SERINE and THREONINE residues 4. addition of MANNOSE-6-PHOSPHATE to specific lysosomal enzymes, which targets the protein to the lysosome (NOTE: Failure of this ftn --> I-Cell Disease!) 5. proteoglycan assembly from proteoglycan core progeins 6. sulfation of sugars in proteoglycans and of selected tyrosine proteins |
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vesicular trafficking proteins
- COPI - COPII - Clathrin |
COPI:
- retrograde!!! - GOLGI-->ER COPII - anterograde - RER-->cis-Golgi CLATHRIN: - trans-Golgi-->lysosomes - plasma membrane-->endosomes (receptor mediated endocytosis) - key for internalization of lysosomal enzymes - key for internalization of LDL receptor |
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microtubule
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- cylindrical structure composed of HELICAL array of polymerized DIMERS of alpha- and beta-tubulin
- each dimer has 2 GTP bound - incorporated into flagella, cilia, mitotic spindles - grows SLOWLY - collapses QUICKLY - also involved in SLOW AXOPLASMIC TRANSPORT IN NEURONS! |
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drugs that act on microtubules (5 of them)
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1. mebendazole/thiabendazole (anti-helminthic)
2. paclitaxel (taxol) - anti-breast cancer 3. Griseofluvin (antifungal) 4. Vincristine/Vinblastine (anti-cancer) 5. Colchicine (anti-GOUT!) |
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chediak higashi syndrome
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microtubule polymerization defect!
--> decreased phagocytosis!!! |
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celia structure
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9+2 arr of microtubules
- DYNEIN is an ATPase (not use of ATP!!!) that links peripheral 9 doublets and causes bending of cilium by differential sliding of doublets - DYNEIN = RETROGRADE to microtubule (+ --> -) - KINESIN = ANTEROGRADE to microtubule (- --> +) |
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kartagener's sydnrome
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immotile cilia due to dynein arm defect
--> male and female infertility (sperm immotile) - bronchiectasis - recurrent sinusitis (bacteria and particles not pushed out) - associated with SITUS INVERSUS |
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cytoskeletal elements - give examles of where each of these are found:
1. actin and myosin 2. microtubule 3. intermediate filaments |
1. ACTIN & MYOSIN:
- microvilli - muscle contraction - cytokinesis - adherens junctions (along with E-cadherin) MICROTUBULE: - cilia - flagella - mitotic spindle - neurons - centrioles INTERMEDIATE FILAMENTS: - vimentin - desmin - cytokeratin - glial fibrillary acid proteins (GFAP) - neurofilaments |
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plasma membrane composition
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asymmetric fluid bilayer
- cholesterol (50%) - phospholipids (50%) - spingolipids - glycolipids - proteins HIGH CHOLESTEROL or LONG SATURATED FATTY ACID CONTENT --> increased melting temperature & decreased fluidity |
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phosphatidycholine function
- aka? |
aka LECITHIN!
- major component of: rbc membranes myelin bile surfactant (DPPC - dipalmitoyl phosphatidycholine) phosphatidylcholine/lecithin is used in ESTERIFICATION OF CHOLESTEROL (LCAT = lecithin-cholesterol acyltransferase) |
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immuno histochemical stains - name what staining these proteins allows you to see:
1. vimentin 2. desmin 3. cytokeratin 4. GFAP 5. neurofilaments |
1. vimentin for connective tissue
2. desmin for muscle 3. cytokeratin for epithelial cells 4. GFAP for neuroglia 5. neurofilaments for neurons |
