LIFESCI 3M03 Module 3 Test Questions And Correct Detailed Answers Guaranteed Pass.

MODULE 3 LECTURE 1: Define diffusion Which 4 factors does it depend on? What are the 2 components of random motion? - correct answer diffusion: random/non-directed motion of molecules and small particles in a liquid factors: 1) driving force (i.e. gradient, temp.) 2) mechanical resistance of the surrounding medium 3) structural properties of the molecule 4) active forces causing non-thermal fluctuations (i.e. contraction/relaxation of cytoskeleton moves cytoplasm causing active diffusion) components of random motion: 1) passive/thermal component 2) active/motor-driven component How does the function of diffusion differ between prokaryotic and eukaryotic cells? What is the function of diffusion in embryos? When is diffusion favourable? - correct answer prokaryotes: suitable for transportation eukaryotes: - suitable for transportation in micro-environments - provides primary basis for signal transduction network in cytoplasm embryos: important in development (i.e. morphogenesis to establish embryonic domains) favourable when: molecules must travel relatively short distances Time scales in diffusion: - diffusion is dependant on _________ - why is diffusion sufficient at the synaptic cleft? - as the distance traveled increases, the time it takes _________ - correct answer - diffusion is dependent on DISTANCE THAT MUST BE TRAVELLED - synaptic cleft: small distance must be traveled for molecule to have an effect (i.e. diffusion can occur quickly) - as distance increases, time also increases Active Transport: - Why is active transport needed between different cellular components and living cells? - What are 2 characteristics of active transport? - What are the 2 active transport mechanisms seen? - correct answer - cellular components/living cells: associations between them cannot be accomplished by diffusion alone 1) directed motion via molecular motors along biopolymers (i.e. MTs or MFs) 2) useful when movement is required along long distances ------------ 1) assembly/disassembly of cytoskeletal filaments 2) molecular motor-directed active motion Molecular Motors: - Important for transport of which 3 components within a cell? - What is required for their function? - How is movement achieved? - correct answer - molecules, particles, organelles - ATP or GTP hydrolysis - chemo-mechanical coupling: chemical energy from ATP/GTP is converted into force via conformational changes in motor proteins Classes of Molecular Motors: - What are the 4 classes of molecular motors, and how do they function? - correct answer 1) polymerization motors: use actin/MT assembly to help cells generate direct force during movement 2) translational motors: move in a directional step-like fashion along polymerized protein track 3) translocation motors: help thread/pass through a hole (i.e. push/pull actions) 4) rotary motors: embedded in cell membrane and use rotation of mechanical elements to generate torque Cytoplasmic Streaming: - what is it? - where is this phenomenon observed? (5) - what is its proposed purpose? - correct answer - cytoplasmic streaming: circulation of cellular fluid (i.e. cyclosis) driven by motor proteins walking along filaments containing organelles - large cells in: algae, plants, amoebae, nematodes, flies - purpose: by-product of transportation (i.e. may help overcome slowness of diffusion in large cells) Cytoplasmic Streaming in Algal cells: - which 2 components was myosin V found to interact with? - what do actin filaments serve as? - what is seen as vesicles move along actin filaments? - correct answer - ER and stationary actin bundles - actin filaments: serve as TRACKS for motor proteins - as vesicles move, cytoplasm moves with it (i.e. directional/stream-like movement) MODULE 3 LECTURE 2: Translational Motors: - cargo carried at the _____ end, whereas catalysis/hydrolysis of ATP at the ______ end - what are they associated to? - _________ motion via step-by-step fashion - relationship between ATP hydrolysis and stepping motion? - association to filament depends on __________ not ___________. - Explain processivity, and which 2 factors influence it - correct answer - cargo --> tail end - ATP hydrolysis --> catalytic motor head - associated to filamentous polymer (i.e. actin, MTs) - unidirectional - ATP hydrolysis is coupled to stepping motion (i.e. to generate movement) - AFFINITY not covalent interactions - processivity: number of steps that a single motor can take before it falls off *depends on: a) protein type b) polymer network What are the 3 translational motors discussed in lecture? What end do the following proteins move towards: - dynein - kinesin - myosin - correct answer 1) dynein --> (-) end mostly 2) kinesin --> (+) end mostly