Question 1

How is contraction regulated in smooth muscle?

Accepted Answer

An increase in cytosolic calcium promote

Question 2

Both colchicine and colcemid

Accepted Answer

A)  block microtubule organizing centers. 
B)  block microtubule disassembly by binding to microtubule ends. 
C)  block microtubule assembly by binding to free tubulin. 
D)  accelerate microtubule disassembly by binding to tubulin in microtubules, causing those molecules to exit the microtubule more quickly. 
A)  block microtubule organizing centers. 
B)  block microtubule disassembly by binding to microtubule ends. 
C)  block microtubule assembly by binding to free tubulin. 
D)  accelerate microtubule disassembly by binding to tubulin in microtubules, causing those molecules to exit the microtubule more quickly.

Question 3

Myosin II is found in skeletal muscle and the contractile ring. It is a two-headed myosin with tails that can form thick filaments. Other myosins, such as myosin I or myosin V, do not form thick filaments and yet are still capable of producing movement along actin filaments. To what do the tail(s) of myosin I and myosin V bind?

Accepted Answer

A)  Cargo such as membrane vesicles or intermediate filaments 
B)  Centrosomes 
C)  Chromosomes 
D)  Tubulin 
A)  Cargo such as membrane vesicles or intermediate filaments 
B)  Centrosomes 
C)  Chromosomes 
D)  Tubulin

Question 4

The positioning of various organelles-for example, the Golgi apparatus in cells-is the outcome of a balance between dynein and kinesin. What is the expected distribution of the Golgi apparatus in cells in which the dynein function is inhibited?

Accepted Answer

Disruption of activity would mean there

Question 5

The microtubules that overlap in the center of the mitotic spindle are called _______ microtubules.

Accepted Answer

A)  astral 
B)  minus-end 
C)  kinetochore 
D)  interpolar 
A)  astral 
B)  minus-end 
C)  kinetochore 
D)  interpolar

Question 6

Actin filaments are anchored at junctions called

Accepted Answer

A)  adherens junctions. 
B)  tight junctions. 
C)  desmosomes. 
D)  gap junctions. 
A)  adherens junctions. 
B)  tight junctions. 
C)  desmosomes. 
D)  gap junctions.

Question 7

Actin filaments are a major element of the cytoskeleton. The cytoskeleton provides a framework for the cell and acts as a scaffold that both determines cell shape and positions organelles within cells. For example, the cytoskeleton provides the tracks along which organelles move. At the same time, the cytoskeleton is subject to cleavage by proteins like cofilin. What is the apparent function of cofilin in creating a dynamic cytoskeleton?

Accepted Answer

Cofilin is an actin-binding protein, and

Question 8

Formation of actin filaments requires energy in the form of ATP.

Accepted Answer

A) True 
 B)False

Question 9

The intermediate filaments in the nucleus are made of

Accepted Answer

A)  keratins. 
B)  lamins. 
C)  desmin. 
D)  vimentin. 
A)  keratins. 
B)  lamins. 
C)  desmin. 
D)  vimentin.

Question 10

A human hereditary disease has two seemingly unrelated symptoms: an inability to clear mucus from the respiratory system and male sterility. What could be the cause of this disease?

Accepted Answer

The failure of cilia to beat would disab

Question 11

Cofilin plays a role in the

Accepted Answer

A)  disassembly of actin filaments. 
B)  stimulation of actin filament formation. 
C)  nucleation of microfilaments. 
D)  disassembly of microtubules. 
A)  disassembly of actin filaments. 
B)  stimulation of actin filament formation. 
C)  nucleation of microfilaments. 
D)  disassembly of microtubules.

Question 12

In actin filament assembly, the process in which ATP-actin monomers are added to the barbed end of the filament while ADP-actin monomers are concurrently dissociating from the pointed end of the filament is referred to as

Accepted Answer

A)  equilibrium. 
B)  dynamic instability. 
C)  treadmilling. 
D)  recycling. 
A)  equilibrium. 
B)  dynamic instability. 
C)  treadmilling. 
D)  recycling.

Question 13

Which of the following is not true of the assembly of actin filaments?

Accepted Answer

A)  It begins with the formation of an aggregate of three actin monomers. 
B)  It requires ATP. 
C)  Polymerization occurs from both the plus and minus ends. 
D)  Polymerization is faster from the plus end than from the minus end. 
A)  It begins with the formation of an aggregate of three actin monomers. 
B)  It requires ATP. 
C)  Polymerization occurs from both the plus and minus ends. 
D)  Polymerization is faster from the plus end than from the minus end.

Question 14

Actin exists in two forms, a globular G form and a filamentous F form.

Accepted Answer

A) True 
 B)False

Question 15

Which statement about myosin I is true?

Accepted Answer

A)  It is involved in muscle contraction. 
B)  It has a long $\alpha$-helical tail through which it forms homodimers. 
C)  It does not act as a molecular motor. 
D)  It links the actin bundles to the plasma membrane in the microvilli of intestinal cells. 
A)  It is involved in muscle contraction. 
B)  It has a long $\alpha$-helical tail through which it forms homodimers. 
C)  It does not act as a molecular motor. 
D)  It links the actin bundles to the plasma membrane in the microvilli of intestinal cells.

Question 16

The major cation responsible for regulating actin-myosin contraction is

Accepted Answer

A)  Ca2+. 
B)  H+. 
C)  K+. 
D)  Na+. 
A)  Ca2+. 
B)  H+. 
C)  K+. 
D)  Na+.

Question 17

In a motile cilium or flagellum, _______ microtubules are arranged _______.

Accepted Answer

A)  13; in a circle 
B)  9 triplet; in a circle 
C)  9 doublet; in a circle around a central pair of microtubules 
D)  2 microtubules; perpendicular to each other 
A)  13; in a circle 
B)  9 triplet; in a circle 
C)  9 doublet; in a circle around a central pair of microtubules 
D)  2 microtubules; perpendicular to each other

Question 18

In which directions do kinesin and dynein transport vesicles in an axon?

Accepted Answer

Dynein moves vesicles inward (

Question 19

Whether a microtubule shrinks or grows is determined by the

Accepted Answer

A)  rate of GTP-bound tubulin addition relative to the rate of tubulin GTP hydrolysis. 
B)  phosphorylation state of $\beta$-tubulin. 
C)  rate of ATP hydrolysis relative to the rate of ATP-bound tubulin addition. 
D)  presence or absence of $\gamma$-tubulin. 
A)  rate of GTP-bound tubulin addition relative to the rate of tubulin GTP hydrolysis. 
B)  phosphorylation state of $\beta$-tubulin. 
C)  rate of ATP hydrolysis relative to the rate of ATP-bound tubulin addition. 
D)  presence or absence of $\gamma$-tubulin.

Question 20

At the end of interphase, the part of the microtubule farthest from the centrosome is the _______ end.

Accepted Answer

A)  capped 
B)  barbed 
C)  minus 
D)  plus 
A)  capped 
B)  barbed 
C)  minus 
D)  plus

How is contraction regulated in smooth muscle?

Both colchicine and colcemid

The positioning of various organelles-for example, the Golgi apparatus in cells-is the outcome of a balance between dynein and kinesin. What is the expected distribution of the Golgi apparatus in cells in which the dynein function is inhibited?

The microtubules that overlap in the center of the mitotic spindle are called _______ microtubules.

Actin filaments are anchored at junctions called

Formation of actin filaments requires energy in the form of ATP.

The intermediate filaments in the nucleus are made of

A human hereditary disease has two seemingly unrelated symptoms: an inability to clear mucus from the respiratory system and male sterility. What could be the cause of this disease?

Cofilin plays a role in the

In actin filament assembly, the process in which ATP-actin monomers are added to the barbed end of the filament while ADP-actin monomers are concurrently dissociating from the pointed end of the filament is referred to as

Which of the following is not true of the assembly of actin filaments?

Actin exists in two forms, a globular G form and a filamentous F form.

Which statement about myosin I is true?

The major cation responsible for regulating actin-myosin contraction is

In a motile cilium or flagellum, _ microtubules are arranged _.

In which directions do kinesin and dynein transport vesicles in an axon?

Whether a microtubule shrinks or grows is determined by the

At the end of interphase, the part of the microtubule farthest from the centrosome is the _______ end.

An Overview of Cells and Cell Research

Molecules and Membranes

Bioenergetics and Metabolism

Fundamentals of Molecular Biology

Genomics, Proteomics, and Systems Biology

Genes and Genomes

Replication, Maintenance, and Rearrangements of Genomic Dna

RNA Synthesis and Processing

Transcriptional Regulation and Epigenetics

Protein Synthesis, Processing, and Regulation

The Nucleus

Protein Sorting and Transport

Mitochondria, Chloroplasts, and Peroxisomes

The Plasma Membrane

Cell Walls, the Extracellular Matrix, and Cell Interactions

Cell Signaling

The Cell Cycle

Cell Death and Cell Renewal

Cancer

Filters

Exam 14: The Cytoskeleton and Cell Movement

How is contraction regulated in smooth muscle?

Both colchicine and colcemid

The positioning of various organelles-for example, the Golgi apparatus in cells-is the outcome of a balance between dynein and kinesin. What is the expected distribution of the Golgi apparatus in cells in which the dynein function is inhibited?

The microtubules that overlap in the center of the mitotic spindle are called _______ microtubules.

Actin filaments are anchored at junctions called

Formation of actin filaments requires energy in the form of ATP.

The intermediate filaments in the nucleus are made of

A human hereditary disease has two seemingly unrelated symptoms: an inability to clear mucus from the respiratory system and male sterility. What could be the cause of this disease?

Cofilin plays a role in the

In actin filament assembly, the process in which ATP-actin monomers are added to the barbed end of the filament while ADP-actin monomers are concurrently dissociating from the pointed end of the filament is referred to as

Which of the following is not true of the assembly of actin filaments?

Actin exists in two forms, a globular G form and a filamentous F form.

Which statement about myosin I is true?

The major cation responsible for regulating actin-myosin contraction is

In a motile cilium or flagellum, _______ microtubules are arranged _______.

In which directions do kinesin and dynein transport vesicles in an axon?

Whether a microtubule shrinks or grows is determined by the

At the end of interphase, the part of the microtubule farthest from the centrosome is the _______ end.

An Overview of Cells and Cell Research

Molecules and Membranes

Bioenergetics and Metabolism

Fundamentals of Molecular Biology

Genomics, Proteomics, and Systems Biology

Genes and Genomes

Replication, Maintenance, and Rearrangements of Genomic Dna

RNA Synthesis and Processing

Transcriptional Regulation and Epigenetics

Protein Synthesis, Processing, and Regulation

The Nucleus

Protein Sorting and Transport

Mitochondria, Chloroplasts, and Peroxisomes

The Plasma Membrane

Cell Walls, the Extracellular Matrix, and Cell Interactions

Cell Signaling

The Cell Cycle

Cell Death and Cell Renewal

Cancer

Filters

In a motile cilium or flagellum, _ microtubules are arranged _.