BIOL 4100 TEST 4 EXAM QUESTIONS AND ANSWERS WITH
COMPLETE SOLUTIONS VERIFIED LATEST UPDATE
Muscle contraction is triggered by nerve impulses which stimulate release of
______ from _______
Ca2+; sarcoplasmicreticulum
Increased Ca2+ affects 2 actin filament binding proteins:
tropomyosin and troponin (see slide 2 lecture 16)
Action potential propagates across
plasma membrane
It propagates thought T-tubules (thatextend to each myofibril)
inwards
Voltage gated T-tubule Ca2+channel opens and triggers ______ and leads to
________
opening ofCa2+ sarcoplasmic reticulum channel; rapid calcium ion influx
Influx is _______ as calcium is pumped back by an abundant ________
transient; ATP-dependent Ca2+ pump
Muscle fibers are large cells formed by ______ of many cells during development
Fusion
Smooth muscle cells lack
Regular striations
Contractile bundles are oriented
,to the long axisof the cells
Contractile bundles
greatly shortens the cell
long axis of the cell coincides with
direction of contraction
Smooth muscle cells do not express
troponin
Muscle stimulation triggers (pathway)
Ca2+ released from sarcoplasmic/endoplasmic reticulum -> Calcium binds to
calmodulin -> Calmodulin binds to myosin light chain kinase -> MLCK phosphorylates
myosin light chain -> Phosphorylation stimulates myosin activity
In non-muscle cells, contractile assemblies are similar to
muscle fibers
Examples of contractile assemblies:
Stress fibers and adhesion belts
Displacement is ______ dependent
myosin
Myosin 5
Lower force generation + Longer steps = Efficiency
Myosin VI
walks in opposite direction (-) direction
Myosin directionality is defined by
lever arms and converter domain
, Microtubules are______ that undergo _______
rigid hollow rods; continual assembly and disassembly
Microtubules functions
cell movements and determining cell shape.
_______ polymerize to form microtubules: ______ protofilaments around a _____
core
Tubulin dimers; 13; hollow
Protofilaments are _____ arrays of tubulin dimers arranged ____
head-to-tail; parallel
What determines the direction of movement?
polarity (plus and minusends)
What are microtubules made of?
globular protein tubulin
Tubulin dimers consist of
α-tubulin and β-tubulin, which are encodedby related genes.
Microtubular lattice is imperfect. True of False
True (discontinuity exists in the microtubule wall; a seam which is a weak point)
The are two types of microtubules in the cell:
-axonemal
-non axonemal
axonemal microtubules
-form cytoskeletal part of cilia and flagella
-easy to purify
COMPLETE SOLUTIONS VERIFIED LATEST UPDATE
Muscle contraction is triggered by nerve impulses which stimulate release of
______ from _______
Ca2+; sarcoplasmicreticulum
Increased Ca2+ affects 2 actin filament binding proteins:
tropomyosin and troponin (see slide 2 lecture 16)
Action potential propagates across
plasma membrane
It propagates thought T-tubules (thatextend to each myofibril)
inwards
Voltage gated T-tubule Ca2+channel opens and triggers ______ and leads to
________
opening ofCa2+ sarcoplasmic reticulum channel; rapid calcium ion influx
Influx is _______ as calcium is pumped back by an abundant ________
transient; ATP-dependent Ca2+ pump
Muscle fibers are large cells formed by ______ of many cells during development
Fusion
Smooth muscle cells lack
Regular striations
Contractile bundles are oriented
,to the long axisof the cells
Contractile bundles
greatly shortens the cell
long axis of the cell coincides with
direction of contraction
Smooth muscle cells do not express
troponin
Muscle stimulation triggers (pathway)
Ca2+ released from sarcoplasmic/endoplasmic reticulum -> Calcium binds to
calmodulin -> Calmodulin binds to myosin light chain kinase -> MLCK phosphorylates
myosin light chain -> Phosphorylation stimulates myosin activity
In non-muscle cells, contractile assemblies are similar to
muscle fibers
Examples of contractile assemblies:
Stress fibers and adhesion belts
Displacement is ______ dependent
myosin
Myosin 5
Lower force generation + Longer steps = Efficiency
Myosin VI
walks in opposite direction (-) direction
Myosin directionality is defined by
lever arms and converter domain
, Microtubules are______ that undergo _______
rigid hollow rods; continual assembly and disassembly
Microtubules functions
cell movements and determining cell shape.
_______ polymerize to form microtubules: ______ protofilaments around a _____
core
Tubulin dimers; 13; hollow
Protofilaments are _____ arrays of tubulin dimers arranged ____
head-to-tail; parallel
What determines the direction of movement?
polarity (plus and minusends)
What are microtubules made of?
globular protein tubulin
Tubulin dimers consist of
α-tubulin and β-tubulin, which are encodedby related genes.
Microtubular lattice is imperfect. True of False
True (discontinuity exists in the microtubule wall; a seam which is a weak point)
The are two types of microtubules in the cell:
-axonemal
-non axonemal
axonemal microtubules
-form cytoskeletal part of cilia and flagella
-easy to purify
