5BBB0209 - Cell biology Real Exam Prep Questions And Correct Answers With Detailed Rationales.

what is the cytoskeleton made up of - correct answer actin filaments, intermediate filaments ,microfilaments role of actin filaments - correct answer works with myosin for motility in cells role of intermediate filaments - correct answer structural stability role of microtubules - correct answer cell division and intracellular transport what is actin made of - correct answer globular protein bound to 2 twisted actin monomers (f-actin) what causes polarity in filaments - correct answer ATP hydrolysis what causes different F actin molecules - correct answer GTP binding proteins what is CDC42 - correct answer GTP binding protein that forms filopodia what is Rac - correct answer GTP binding protein that forms lamellipodia what is Rho - correct answer GTP binding protein that forms stress fibres what does Arp 2/3 do - correct answer initiates growth of new branched actin filaments on old filaments function of FH1 - correct answer initiate actin formation; binds to profilin which catches globular proteins function of Fh2 - correct answer actin polymerisation; dimerises to form doughnut an bind to barbed (+) end of filament what forms microtubules - correct answer tubulin dimers advantages of cultured cells - correct answer 1. defined system 2. easier to manipulate 3. potentially limitless supply of cells disadvantages of cultured cells - correct answer 1. potential of artefacts 2. lack of psychological input 3 things cells need to grow - correct answer 1. food 2. pH (pH7.4) 3. accommodation 2 types of cell culturing - correct answer primary culture; cell lines differences between primary culture and cell line cultures - correct answer primary - directly from tissue of interest; limited life span cell line - from primary culture; immortalised 3 growth phases of cells - correct answer 1. lag phase 2. log phase 3. plateau phase what dye used to stain nucleus - correct answer DAPI/Hoechst advantages of DAPI/Hoechst - correct answer reliable; cheap; stable disadvantages pf DAPI/Hoechst - correct answer need UV/blue diode laser; need UV compatible lens; too much UV can damage cells dye used to stain mitochondria - correct answer MitoTracker what is GFP - correct answer Green fluorescent protein that can mark another protein how is GFP used - correct answer 1. sequence encoding GFP inserted into plasmid of desired protein 2. cell cultured and produce proteins with encoded GFP 3. placed under UV to see fluorescence What does FRET mean - correct answer frequency resonance energy transfer what is the purpose of FRET - correct answer study where and when 2 different proteins interact in cells What does FRAP mean - correct answer Fluorescence Recovery After Photobleaching what is the purpose of FRAP - correct answer investigate protein dynamics 2 forms of cell death - correct answer necrosis and apoptosis what is necrosis - correct answer 1. sudden cell death 2. plasma membrane damaged and contents leak 3. inflammatory response what is apoptosis - correct answer 1. programmed cell death 2. no leakage or inflammatory response 3. organelles condense and separate and engulfed by phagocytes role of apoptosis - correct answer 1. sculpt tissues 2. prevent overgrowth how is apoptosis regulated - correct answer trophic factors and extrinsic factors how do trophic factors regulate apoptosis - correct answer essential for cell life so absence causes apoptosis how does apoptosis change cell structure - correct answer 1. externalisation of phosphatidylserine (PS) 2. causes 'blebbing' 3. condenses chromatin and cleaves DNA describe process of externalisation of phosphatidylserine (PtdSer) - correct answer 1. calcium activates phospholipid enzyme 2. flips internal healthy cells to outer leaflet of plasma membrane 3. countered by flippase enzyme by moving PS to inside leaflet how does membrane blebbing happen - correct answer 1. RhoA GTPase activates Rho kinase-1 (ROCK1) 2. phosphorylates myosin light chain (MLC), causes contraction 3. MLC phosphatase also activated, inhibits contraction 3. ROCK-1 always activated during apoptosis, leads to high contractility what can occur if if no apoptosis - correct answer autoimmune diseases 2 pathways that induce apoptosis - correct answer Intrinsic pathway and extrinsic pathway describe intrinsic pathway - correct answer stress within cell causes apoptosis (e.g. DNA damage, growth factor withdraw) describe extrinsic pathway - correct answer death receptors trigger apoptosis what happens to mitochondria in apoptosis - correct answer releases Cytochrome C that forms apoptosome 3 phases of apoptosis in c. elegans - correct answer 1. specification - instructions to die 2. killing - initiation of death 3. execution - engulfment signals what are caspases - correct answer intracellular proteases that execute cells in apoptosis what activates caspases - correct answer death receptors and (TNF) cytochrome C give 3 examples of caspases - correct answer 1. CAD - cleaves DA 2. nuclear lamina - releases nuclear membrane 3. ROCK1 - induces blebbing what are the 2 types of caspases - correct answer initiator and effector what are initiator caspases - correct answer trigger signal and commitment into apoptosis what are effector caspases - correct answer degraddation of substrate explain how caspases are activated - correct answer 1. cytotoxin T cell recognise target cell and release perforin and granzyme 2. perforin binds to target cell and creates a pore