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Bio 264 Exam 3|150 Questions with Verified Solutions
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Bio 264 Exam 3|150 Questions withVerified Solutions
What structure runs from Z line to Z line? - -Sarcomere
-The movement of the troponin-tropomyosin complex requires _______ - -
Ca2+.
-The actin filament is a polymer formed from 300 to 400 globular subunits
called ______ - -G-actin.
-A myofilament is the _________. - -Protein strand composed of actin or
myosin
-T tubules ________. - -Conduct action potentials deep into the muscle cell
-A drug that interferes with the active transport of calcium ions from the
sarcoplasm back into the sarcoplasmic reticulum would result in _______. - -
Contraction with no relaxation
-Cardiac muscle cells are like skeletal muscle cells in that they both ________.
- -have striations
-Predict the consequences of administration of a compound that blocks the
calcium channels on presynaptic motor neuron terminals.
A. This should ultimately inhibit the release of acetylcholine
B. This should ultimately inhibit the muscle membrane from depolarization
C. This should ultimately inhibit the release of calcium from the sarcoplasmic
reticulum
D. All of the above are correct answers - -D. All of the above are correct
answers
-Predict the consequences of administration of a compound that inhibits
acetylcholinesteras - -The muscle will stay contracted
-Myofibrils are composed primarily of ________. - -Actin and myosin
-Binding of ________ to myosin permits cross-bridge _____________ between
actin and myosin. - -ATP; detachment
-The part of the sarcolemma that invaginates into the interior of skeletal
muscle fibers is the - -T tubule system.
, -Somatic motor neurons release the neurotransmitter _________ at the
neuromuscular junction. - -Acetylcholine
-The gangster movies call a dead person a stiff, rigor mortis is the proper
name. How does this occur? - -Without ATP, muscles remain fixed in their
last state of contraction.
-T tubules are invaginations of the ________. - -Sarcolemma
-One cause of spastic paralysis might be ________. - -Inhibition of
acetylcholinesterase
-Somatic motor neurons release the neurotransmitter _________ at the
myoneural junction. - -Acetylcholine
-Rigor mortis occurs after death because - -Cross-bridges form but can't
release.
-Given these events:
(1) Acetylcholine is broken down into acetic acid and choline.
(2) Acetylcholine diffuses across the synaptic cleft.
(3) An action potential reaches the terminal branch of the motor neuron.
(4) Acetylcholine combines with a ligand-gated ion channel.
(5) An action potential is produced on the muscle fiber's plasma membrane.
Choose the arrangement that lists the events in the order they occur at a
neuromuscular junction. - -3,2,4,5,1
-The sites where a chemical substance is transmitted from the presynaptic
terminal of an axon to the postsynaptic membrane of a muscle fiber are
called ________. - -Neuromuscular junctions
-Acetylcholine is released from the presynaptic terminal by the process of
_________. - -Exocytosis
-Arrange the following list of biochemical events in the correct sequence.
1.An action potential is conducted deep into the muscle fiber by the T tubule.
2.Calcium ions bind to troponin.
3.The membranes of the sarcoplasmic reticulum become more permeable to
calcium ions.
4.Calcium ions diffuse into the sarcoplasm around the myofibril.
5.The troponin-tropomyosin complex moves exposing active sites. - -1, 3, 4,
2, 5
, -Curare blocks acetylcholine receptors at the motor end plate. This would
result in _______. - -Inability of the muscle fiber to respond to nervous
stimulation
-Subunits of skeletal muscle cells that are composed of sarcomeres are
called - -Myofibrils.
-In excitation-contraction coupling, _________. - -Myosin heads bind to
exposed active sites on actin
-Predict the consequences of administration of a compound that binds to
acetylcholine receptors in a neuromuscular junction but does not open them.
- -The muscle membrane will not reach threshold
-Given these events:
(1) sarcoplasmic reticulum releases Ca2+
(2) sarcoplasmic reticulum takes up Ca2+
(3) Ca2+ diffuse into myofibrils
(4) action potential moves down the T tubule
(5) sarcomere shortens
(6) muscle relaxes
Choose the arrangement that lists the events in the order they occur
following a single stimulation of a skeletal muscle cell. - -4,1,3,5,2,6
-The sarcolemma is the _________. - -Cell membrane of a muscle fiber
-What is a cross-bridge? - -The combination of myosin heads with active
sites on actin molecules
-Arrange the following steps for contraction in the correct sequence.
(1) The muscle impulse reaches the sarcoplasmic reticulum and calcium is
released.
(2) Thin filaments are pulled over the thick filaments.
(3) Calcium floods the sarcoplasm and binds to troponin molecules leaving
active sites.
(4) The impulse arrives at the synapse and travels through the transverse
tubules.
(5) The muscle fiber shortens and contracts.
(6) Tropomyosin molecules bind to exposed active sites, linking actin and
myosin - -4, 1, 3, 6, 2, 5
-Myasthenia gravis is an autoimmune disease - that is, a disease in which
one's immune system gradually attacks a part of one's own body, in this
case the receptors for acetylcholine at the neuromuscular junction. Which of
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