Cell Bio Final

anskorczewski12's version from 2015-05-17 05:01

Section 1

Question Answer
Checks: G1 phase, g2 phase (is DNA replicated only once and not damaged, enough ATP), after metaphase (are chromosomes properly attached)
Anaphase microtubules: kinetochore mt shorten and attached chromosomes move (loss of tubulin subunits), spindle poles move apart (kinesin on interpolar mt slide mt from opposite poles past each other and push spindles apart, dynein anchored to cell cortex, pulls apart)
How to study cell cycle genes: 1. make conditional mutants (temp. sensitive mutants, induced knockout) 2. squeeze out female's eggs, fertilize and take proteins from different phases out and inject into immature oocyte to observe
cyclinproteins that regulate switching kinase on and off, bind to Cdk so kinase can activate
regulation of Cdk complex; 1. transcription of cyclin gene 2. degrade cyclin wtih APC to inactivate Cdk 3. phosphorylate Cdk (inhibitory phosphates are on cyclin Cdk complex which need to come off to activate) 4. inhibitor blocks assembly or activity of complex
Anaphase-promoting complexdegrades cyclin (m and S) by tagging with ubiquiton (ubiquitylation) which sends it to proteasome to degrade
mitogensbind to receptor and start signalling pathway for G1 cyclin, DNA synthesis proteins, etc. produced by other cells or in ECM, stop the block from Rb by phosphorylating
survival factorsactivate cell-surface receptors, turn on signalling pathways that keep apoptotic death suppressed (regulate Bcl2-which regulates caspase activation)
Extracellular cues: 1. mitogens (stimulate cell division) 2. survival factors (suppress apoptosis) 3. growth factors (signal cell growth by promoting synthesis and inhibiting degradation)
microtubules: 1. kinetochore (attach to chromosome) 2. aster (keeps complex attached to side of cell-actin cortex) 3. interpolar (push-motor proteins (dynein and kinesin) push apart)
separasebreaks cohesin linkage of chromatids (active when APC destroys inhibitory protein)
phragmoblastsguides assembly of new plant cell wall (uses mt not actin)

Section 2

Question Answer
when is cell dead: lost integrity of plasma membrane (doesn't rid dyes), cell and nucleus has completely fragmented into apoptotic bodies or been engulfed
necrosismessy, mechanical death, swells and bursts
apoptosischoose, regulated, develops blebs, shrinks, cytoskeleton collapses, nuclear envelope disassembles, DNA breaks up and is engulfed
intrinsic pathway: internally sensed issue (short telomers, dNA damage) activated Bax/Bak which indices the release of cytochrome C from ETC into cytosol, which activates procaspases by promoting assembly of apoptosome which recruits and activates initiator procaspases that trigger caspase cascade to death
extrinsic pathway; neighboring cells send signals that are received by death receptor, activates caspases
signaling that prevents apoptosissome Bcl2 inhibit caspases (ratio), survival factors activate Bcl2 (inhibit Bax/Bak)
Ways to measure apoptosis: 1. Dna laddering of gel 2. western blot probbed with ab specific for cleaved caspase 3 3. TUNEL stain 4. phosphatidylserine exposure on extracellular side (ab and flow cytometry) 5. membrane blebbing 6. vacuole formation
TUNEL stainlooks for fragmented DNA (labels cleaved ends with fluorescence)