Deck 6: Cellular Movement and Muscles

Question 1

Which of the following types of movement may NOT require use of a motor protein?

A)muscle contraction
B)flagellar movement
C)vesicle transport
D)amoeboid movement

Answer 1

D

Question 2

Microtubule growth will stop if

A)concentration of tubulin drops below a critical point.
B)cholchicine binds to free tubulin.
C)GTP on the β-tubulin is hydrolyzed.
D)all of the above

Answer 2

D

Question 3

The main component in __________ of a muscle cell is polymerized actin.

A)thin filaments
B)thick filaments
C)A-bands
D)Z-disks

Answer 3

A

Question 4

Kinesin-associated proteins have the ability to do all of the following EXCEPT

A)affect kinetics of movement.
B)affect the type of cargo binding to kinesin.
C)affect the isoforms used to build kinesin.
D)affect the ATP hydrolysis rate.

Question 5

Actin and myosin work together to allow

A)movement of vesicles throughout the cell.
B)movement of muscle.
C)movement of the cell itself.
D)all of the above

Question 6

Which of the following is a motor protein?

A)myosin
B)microtubules
C)microfilaments
D)intermediate filaments

Question 7

The unitary displacement of the myosin refers to

A)how many actins are displaced by myosin.
B)how far along the actin filament the myosin can move in one cycle.
C)how many units of time pass during one cross-bridge cycle.
D)how much time the myosin stays bound to the actin before it is displaced.

Question 8

What is the function of capping proteins?

A)to prevent increased growth of microfilaments
B)to stabilize the microfilament,allowing for increases in length
C)to attach microfilaments together at a common point
D)to allow the microfilament to bind to the cell membrane

Question 9

__________ vesicles are transported to the membrane by the motor protein __________.

A)Filled;kinesin
B)Filled;dynein
C)Empty;kinesin
D)Empty;dynein

Question 10

The thin filaments are stabilized by being capped by __________ at one end and CapZ at the other.

A)troponin
B)tropomodulin
C)tropomyosin
D)a polymer of all three

Question 11

Which of the following statements about movement via actin polymerization is true?

A)Movement can be generated using actin polymerization by itself (no motor proteins).
B)Movement occurs only when motor proteins move across actin polymers.
C)Actin polymerization prevents growth of filapodia.
D)During cell movement there is always a net growth of actin polymer length.

Question 12

Filapodia

A)are rodlike extensions of cells formed by myosin fibers.
B)are used by nerve cells to make physical contact with neighboring cells.
C)resemble pseudopodia found in protists.
D)arise from sheetlike networks of microfilaments.

Question 13

Dyneins generate movement in cilia and flagella by

A)the dynein moving along its own microtubule,pulling the cell membrane with it.
B)the dynein on one side of the flagella moving along its neighbor's tubule.
C)all dyneins moving along their neighbors' tubules in a synchronized fashion.
D)the dynein pushing on the neighboring tubules,generating movement.

Question 14

When myosin moves along the actin,it goes through cycles of binding and releasing (duty cycle).How does myosin keep from losing its place on the actin when it releases?

A)The time of the duty cycle is large (.99)so that it is only unattached a short time.
B)The myosin is still attracted to the actin by weak electrostatic forces that prevent it from moving too far away during release.
C)The myosin is attached to the actin by another protein that it uses as a safety line to prevent it from slipping too far back.
D)The myosin is arranged in dimers so that when one releases,the other is bound.

Question 15

The __________ of the myosin is where ATP is broken down,providing energy for movement.

A)tail
B)neck
C)head
D)light chains

Question 16

In the cross-bridge cycle,the power stroke of myosin is immediately preceded by which of the following events?

A)the hydrolysis of ATP
B)binding the actin
C)releasing Pᵢ
D)binding new ATP

Question 17

The microtubule disruptor,vinblastine

A)is derived from the autumn crocus.
B)kills dividing tumor cells by disrupting the mitotic spindle.
C)kills cells that line blood vessels,thus cutting off blood flow to tumors.
D)B and C

Question 18

Microtubules are strings of tubulin proteins that are formed from a

A)dimer of α-tubulin.
B)single string of α-tubulin.
C)dimer of one α-tubulin and one β-tubulin.
D)hexamer of α-tubulins and β-tubulins twisted together.

Question 19

The microfilament __________ is commonly used with its motor protein,__________.

A)actin;dynein
B)nexin;dynein
C)actin;myosin
D)nexin;kinesin

Question 20

The sarcomere,or contractile unit of striated muscle,extends from one __________ to the next.

A)Z-disk
B)M-line
C)A-band
D)I-band

Question 21

During which phase of an excitation-contraction cycle does depolarization occur?

A)excitation
B)inhibition
C)contraction
D)relaxation

Question 22

Skeletal muscle may be used in a __________ contraction.

A)shortening
B)isometric
C)lengthening
D)both A and B
E) all of the above

Question 23

When Ca²⁺ is present at high levels in the sarcoplasm of striated muscles,then

A)TnI has a strong interaction with actin.
B)TnC has a strong interaction with TnI.
C)TnT has a strong interaction with myosin.
D)TnT has a weak interaction with Ca²⁺.

Question 24

Smooth and striated muscle share many common features,including

A)organization of filaments into sarcomeres.
B)use of actin and myosin in contraction.
C)a ratio of 2:1 thin to thick filaments.
D)dependence on T-tubules for spread of depolarization.

Question 25

In what ways is muscle myosin II the same as the myosin used in vesicle travel?

A)They have the same unitary displacement.
B)They have the same length of duty cycle.
C)Myosin attaches to actin.
D)There is a chance myosin can drift away from actin.

Question 26

Which myosin isoform is found in fast-twitch muscle?

A)perinatal
B)extraoccular
C)type I
D)type IIb

Question 27

Cardiomyocytes have a much longer repolarization period than skeletal muscles due to their

A)voltage-sensitive Na⁺ channels.
B)voltage-sensitive Ca²⁺ channels.
C)voltage-sensitive K⁺ channels.
D)voltage-sensitive Cl⁻ channels.

Question 28

Muscle fiber types may be termed glycolytic or oxidative in reference to

A)the amount of myoglobin.
B)the speed of contraction.
C)the metabolic processes.
D)the myosin heavy chain isoforms used.

Question 29

Contraction of striated muscle is regulated by

A)TnC's affinity for Ca²⁺ (and nothing else).
B)alternating the two available isoforms of myosin.
C)utilizing different combinations of muscle protein isoforms.
D)the rate at which Ca²⁺ is able to bind to actin.

Question 30

What is the underlying mechanism that allows striated muscles to contract more rapidly when very little force is required?

A)The muscle is shortening so rapidly that some myosin heads are moved to their new position without actually generating any force.
B)Fewer myosin heads actually attach to the actin,increasing the rate of shortening.
C)Lighter loads stimulate only a very high speed,low tension isoform of myosin.
D)Lighter loads stimulate a myosin isoform with a very long unitary displacement.

Question 31

Action potentials can be conducted into the muscle along invaginations of the sarcolemma,or __________.

A)sarcoplasmic reticulum
B)T-tubules
C)terminal cisternae
D)sarcotubes

Question 32

Motor neurons release __________ into the neuromuscular synapse,which may generate depolarization at the motor end plate.

A)acetylcholine
B)adenosine
C)catecholamines
D)GABA

Question 33

Muscle contraction kinetics can be affected by

A)affinity of troponin for Ca²⁺.
B)pH.
C)temperature.
D)all of the above

Question 34

A single skeletal muscle cell is referred to as a

A)cardiomyocyte.
B)sarcomyocyte.
C)myofibril.
D)myofiber.

Question 35

Which of the following pumps is specifically used to return Ca²⁺ to the sarcoplasmic reticulum?

A)Ca²⁺ATPase
B)NaCaX
C)parvalbumin
D)SERCA

Question 36

Muscle fiber types can be changed in response to

A)activity levels.
B)temperature.
C)thyroid hormone levels.
D)all of the above

Question 37

Dihydropyridine receptors (DHPR)are also called __________ because of their large Ca²⁺ conductance.

A)T-type Ca²⁺ channels
B)N-type Ca²⁺ channels
C)L-type Ca²⁺ channels
D)Na+/ Ca²⁺ exchangers (NaCaX)

Question 38

Most of the Ca²⁺ stored in the sarcoplasmic reticulum is bound to

A)parvalbumin.
B)troponin.
C)calsequestrin.
D)ryanodine.

Question 39

Factors such as adenosine and catecholamines alter heart rate by affecting the kinetics of

A)voltage-sensitive Cl⁻ channels.
B)voltage-sensitive Na⁺ channels.
C)funny channels.
D)voltage-independent K⁺ channels.

Question 40

Invertebrate muscle,like vertebrate muscle,

A)has two major forms of muscle (striated and smooth).
B)utilizes thick and thin filaments in contraction.
C)makes use of obliquely striated muscle.
D)both A and C

Question 41

In skeletal muscle,the dihydropyridine and ryanodine receptors are linked to allow for __________ Ca²⁺ release that is independent of local Ca²⁺ concentrations.

Question 42

The __________ explains how the myosin head moves down the actin polymer,generating movement.

Question 43

Microtubule-associated proteins that stabilize the tubules are called __________.

Question 44

Vertebrate striated muscles composed of twitch fibers are able to produce a graded contraction by

A)recruiting different numbers of motor units.
B)summing EPSPs in the motor end-plate region.
C)having excitatory and inhibitory input to a single muscle.
D)Vertebrate muscles are unable to produce graded contractions.

Question 45

Mollusc catch muscles are able to generate tension for long periods of time without consuming much energy.We do not understand everything about how this is accomplished,but there are unique proteins,such as __________,that seem to play a role.

A)twitchin
B)myosin
C)titin
D)all of the above

Question 46

Which of the following statements is inaccurate with respect to sonic muscles?

A)Rattlesnakes,cicadas,and toadfish are examples of animals with sonic muscles.
B)Animals can modify their muscles to operate some 10 times faster than the fastest locomotor muscles in that animal.
C)The fast speed can be attributed to some muscles being able to lengthen sarcomeres.
D)Sonic muscles must have fast Ca²⁺ transport.

Question 47

Which of the following statements is true concerning sonic muscles?

A)They contract at much higher frequencies than the locomotor muscles found in the same organism.
B)They utilize completely different muscle proteins.
C)They have a very slow rate of cross-bridge cycling.
D)They are able to contract rapidly while producing large amounts of force.

Question 48

An increase in surface area of a membrane,or contact with another cell,can be achieved by generating __________,thin,rodlike extensions produced by polymerizing actin fibers.

Question 49

Specialized animal cells that have contractile properties are called __________,or muscle cells.

Question 50

Asynchronous flight muscles in insects are able to achieve contractions in the range of 250-1000 Hz because

A)they have very fast Ca²⁺ ATPase pumps.
B)they have muscles that don't depend on Ca²⁺ regulation at all.
C)they have very high amounts of parvalbumin in the cytosol.
D)the TnC can rapidly change its affinity for Ca²⁺,leading to rapid contraction/relaxation cycles.

Question 51

The term ______________ refers to the time in each cross-bridge cycle that myosin is attached to actin.

Question 52

__________ muscle cells can depolarize and contract on their own,as opposed to neurogenic muscle cells which require neuronal innervation.

Question 53

Microtubules are organized in cells with the ends near the nucleus in a region known as the __________,or MTOC for short.

Question 54

When microfilaments remain the same size by increasing length on one end and decreasing their length on the other,we say they are __________.

Question 55

The thick filament of striated muscle is indirectly connected to the Z-disk by the compressible protein __________.

Question 56

The Pacific yew tree produces the microtubule disrupter known as ___________.

Question 57

An __________ contraction is one in which the length of the muscle does not change significantly.

Question 58

Animals are capable of movement because they have a unique type of cell,the __________.

Question 59

The axon termini of motor neurons are found in the __________ of the sarcolemma of vertebrate skeletal muscles.

Question 60

How does the heater organ of a swordfish produce heat?

A)The muscle contracts very rapidly,producing large quantities of heat.
B)The myosin binds very weakly to the actin,utilizing large amounts of ATP that ultimately produces heat,but no tension.
C)The sarcoplasmic reticulum releases and recovers large amounts of Ca²⁺,releasing heat as a by-product of these processes.
D)The muscle fibers are rapidly generated and degraded,which produces large quantities of heat as a by-product.

Question 61

Sonic muscles are able to shorten even more than most muscles because of perforations in their __________ that allow the thick filaments to pass into adjacent sarcomeres.

Question 62

Insect flight muscles contract at frequencies much higher than the stimulation rates they receive from the nerves that innervate them.For this reason,they are termed __________ flight muscles.

Question 63

In striated muscle,Ca²⁺ regulates contraction by interacting with troponin and tropomyosin.Explain how Ca²⁺ is able to regulate the timing of contraction as well as affecting the kinetics of contraction.

Question 64

Contractions can occur in striated muscle as long as Ca²⁺ is present in the cytosol.As cytosolic levels of free Ca²⁺ decrease,so does the ability for myosin to form cross-bridges with actin.This leads to relaxation of the muscle.You have found a novel muscle and are trying to determine if its relaxation processes are regulated in a manner analogous to vertebrate striated muscle.Describe some of the features of Ca²⁺ regulation that you would expect to see in this novel muscle.

Question 65

Actin and myosin interactions are utilized in many types of movement,including the movement generated by muscles.Explain how the movement of myosin down an actin filament can generate contraction of a muscle.

Question 66

Skeletal and cardiac muscle are both types of striated muscle.You have been given one type of each sample,but the identifying labels have come off.You know that these muscles have some similarities and some differences in terms of their rate of depolarization,rate of repolarization,and length of action potential.Which of these features would not be useful in identifying the two types of muscle? Which of these features will you use to correctly label the samples? Explain what you would expect to see for skeletal and cardiac muscles for each feature that you use.

Question 67

In smooth muscle,the actin is bound by __________,a functional parallel to troponin C because it prevents myosin from binding actin.

Question 68

In smooth muscle,bundles of filaments attach to the plasma membrane at points referred to as __________.

Question 69

Some muscle tissues undergo trans-differentiation during development,causing them to have novel properties that are not typically associated with muscles,like the billfish __________,for example.

Question 70

The tension that a sarcomere can produce is related to its length.The same is true for a skeletal muscle,as it is composed of sarcomeres arranged end to end.Explain how the structure of a sarcomere allows the most tension to be generated at an intermediate length,while the longest and shortest lengths will produce very little tension.

Question 71

Discuss some of the important factors responsible for the diversity of muscle types.

Question 72

Compare smooth and striated muscles in terms of thick and thin filaments,calcium trigger,sarcoplasmic reticulum,regulation of contraction,and rate of contraction.

Question 73

Microtubules are important as structural proteins.They may be used to support the cell,as pathways for the movement of motor proteins,and to ensure the even division of chromosomal material during mitosis.Thus,having the ability to regulate the growth of these proteins is necessary for survival.Discuss some of the ways in which microtubule growth can be regulated.

Question 74

Smooth muscle,like striated muscle,utilizes Ca²⁺ as a signal molecule that can allow contraction to occur.However,smooth muscle does not have troponin.Therefore,Ca²⁺ must interact with other proteins.Describe these relationships and then comment on how this alternate control system affects the rate and duration of smooth muscle contraction.