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Biology 3355A/B- Final Exam Guide - Comprehensive Notes for the exam ( 28 pages long!)

28 Pages

Course Code
Biology 3355A/B
Alexander Timoshenko

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[Biology 3355A/B] Comprehensive spring guide including any lecture notes, textbook notes and exam guides.find more resources at UNIT 1: HEAT SHOCK RESPONSE Heat Shock Response • Cellular response pathway • Transient expression of HSP (protect cells from physical & chemical insults) Heat Shock  HSF enters nucleus  HSP proteins formed while Inhibit misfolded proteins HS = 3-5 degrees above normal How does global heat shock- • Discovery of HSR  high temp = Formation of polytene chromosome puffs induce change the cells? 1)Cell Morphology • Reorganization & defects of cytoskeleton: o Decrease in cell size  cytoskeleton determines size & shape of cell o Microfilaments depolymerized  no more fibers (most sensitive to heat shock) o Microtubules fibers become smaller • Fragmentation and disassembly of Golgi & ER • Decrease number and integrity of mitochondria and lysosome • Swelling of nucleoli (sites of ribosome assembly) • Protein aggregates in cytosol • Increase membrane fluidity 2) Global Gene Expression • Global reduction in protein synthesis to save energy • Stress  activates PERK (kinase)  Phosphorylates elf2a  Reduces levels of elf2-GTP  inhibits general translation & induces AT4 ▪ EIf-GTP  mediates binding initiator Met-tRNA with small ribosome 40S • How is translation of selected proteins stimulated by stress, even through general translation inhibited? o No Stress: High elf2-GTP, low elf2a-p ▪ Upstream ORF1 are inhibitors of downstream translation at protein coding sequences (CDS) because uORF2 overlaps out-of-frame CDSs o Stress: Low elf2-GTP, high elf2a-p ▪ 40s ribosome (light grey oval) scans pass initiation codon of inhibitory uORF2 before requiring new ternary complex. ▪ Delayed Translation Reinitiation: Delayed acquisition of elF2 ternary complex = translation initiation at the CDS and increase ATF4 expression ▪ Elf2a-p doesn’t allow ElF2 to bind GTP (needed for normal transcription) ▪ So, AT4 activation with high stress Protein Folding Require 1. Primary Structure  Amino acid sequence Chaperones 1 find more resources at
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