BIOS 1700 Chapter 10

Cancer can be characterized by: cells with an enhanced ability to adhere to proteins in the basal lamina. a mass of rapidly dividing cells called a tumor. All of these choices are correct. metastasized tumor cells that leave the tumor and invade distant parts of the body.

All of these choices are correct

Evidence that cytoskeletal elements have ancient origins comes from the: ability to form functional hybrid microfilaments from actin monomers taken from distantly related organisms. presence of cytoskeletal elements in both eukaryotes and prokaryotes. observation that both prokaryotes and eukaryotes use cytoskeletal elements to assist cell division. All of these choices are correct. sequence similarities of cytoskeletal elements when comparing distantly related organisms.

All of these choices are correct

Why are the ends of microfilaments and microtubules called "plus ends" and "minus ends"? Because monomers are added more quickly to one end (the "plus end") than they are to the other end (the "minus end"). Because monomers can be added to one end only (the "plus end"), and can only be removed from the other end (the "minus end"). Because polymerization occurs at one end (the "plus end") and depolymerization occurs at the other end (the "minus end"). Because the actin and tubulin monomers that make up microfilaments and microtubules have evolved more rapidly than most other proteins.

Because monomers are added more quickly to one end (the plus end) than they are to the other end (the minus end)

Which one of the following statements about integrins is CORRECT? Adjacent integrins create channels referred to as gap junctions. Integrins indirectly connect microfilaments with the extracellular matrix. Integrins are the primary cell adhesion molecule in a desmosome. There is a single type of integrin, capable of binding to multiple types of extracellular matrix proteins.

Integrins indirectly connect microfilaments with the extracellular matrix

How does the extracellular matrix affect a cell that it surrounds? (Select all that apply.) The extracellular matrix has no effect on the cells that it surrounds. All of these choices are correct. The cell's shape depends in part on the structure and composition of the extracellular matrix. The genes that the cell expresses depend in part on the types of proteins in the extracellular matrix. The size that the cell grows to depends in part on the polysaccharides in the extracellular matrix.

The cell's shape depends in part on the structure and composition of the extracellular matrix. The genes that the cell expresses depend in part on the types of proteins in the extracellular matrix.

A cell's particular shape is largely determined by: a mesh of proteins and polysaccharides in the extracellular matrix. All of these choices are correct. cytosolic proteins that assemble into structures called cell junctions. cytoskeletal protein networks in the cytoplasm.

all of these choices are correct

In a study of tadpole coloration, you noticed that a certain percentage of tadpoles in a population displayed a decreased ability to shift from dark coloration at night to light coloration during the day. These individuals were studied and found to have the normal number of melanophores and these melanophores produced normal amounts of melanin pigment granules. You remember reading that pigment granule transport in melanophores involves the cytoskeleton. 27. You investigated the cytoskeleton and found that all three elements, including the one you suspected, are completely normal. You then decide to look at the motor proteins to see if the cause of the abnormality might lie with one of them. Which one of the following would be your hypothesis? The melanophores in these tadpoles have partially functional or nonfunctional kinesin that would normally transport organelles along microtubules to the center of the cell. The melanophores in these tadpoles have partially functional or nonfunctional myosin that would normally transport organelles along microfilaments to the center of the cell. The melanophores in these tadpoles have partially functional or nonfunctional kinesin that would normally transport organelles along microfilaments to the center of the cell. The melanophores in these tadpoles have partially functional or nonfunctional dynein that would normally transport organelles along microfilaments to the center of the cell. The melanophores in these tadpoles have partially functional or nonfunctional dynein that would normally transport organelles along microtubules to the center of the cell.

The melanophores in these tadpoles have partially functional or nonfunctional dynein that would normally transport organelles along microtubules to the center of the cell.

Suppose there is a mutation in a laminin-binding integrin gene that causes a loss of function in the cytoplasmic domains of the integrin. Which one of the following would you expect to observe as a result of this mutation? The integrin would function normally because the cytoplasmic domain is not responsible for binding to laminin. Cell adhesion to laminin would decrease, but laminin-meditated gene expression would remain the same. The strength of tissues would be decreased because the integrin could no longer associate with intermediate filaments in hemidesmosomes.

The strength of tissues would be decreased because the integrin could no longer associate with intermediate filaments in hemidesmisomes

When tumor cells are about to metastasize, which of the following would you expect to happen? an increase of cadherin expression and a decrease in integrin expression an increase in both cadherin and integrin expression a decrease in cadherin expression and an increase of integrin expression a decrease in both cadherin and integrin expression

a decrease in both cadherin and integrin expression

Epidermolysis bullosa is a set of rare genetic disorders that is caused by: All of these choices are correct. a keratin gene that disrupts microfilaments, weakening epidermal cell connections. a keratin gene that disrupts intermediate filaments, weakening epidermal cell connections. a microfilament gene that disrupts desmosomes, weakening epidermal cell connections. an intermediate filament gene that disrupts hemidesmosomes, weakening epidermal cell connections.

a keratin gene that disrupts desmosomes, weakening epidermal cell connections

Which of the following statements about mammalian skin is INCORRECT? The dermis is the layer below the epidermis containing connective tissue, blood vessels, and nerve endings that provides nutrients to the epidermis and a cushion layer for the body. The epidermis is an outer layer that provides a water-resistant, protective barrier. A specialized form of extracellular matrix, called the basal lamina, underlies the dermis and separates it from tissues below. Fibroblasts in the dermis produce extracellular matrix proteins to make the dermis strong and flexible. Epithelial cells in the epidermis are primarily composed of keratinocytes that protect underlying tissue.

a specialized form of extracellular matrix, called the basal lamina, underlies the dermis and separates it from tissues below

Which one of the following properly groups a cell junction with a cytoskeletal element and cell adhesion molecule? desmosome, microfilament, integrin tight junction, cadherin, intermediate filament adherens junction, microfilament, cadherin desmosome, microtubule, integrin

adherens junction, microfilament, cadherin

Microtubules increase in length: All of these choices are correct. more quickly at one end than the other. in cycles, following rapid depolymerization. if free tubulin dimers are available. by growing outward from the centrosome.

all of these choices

Epithelial tissue is found: All of these choices are correct. lining blood vessels. on the outer surface of the body. lining the lungs. lining the gastrointestinal tract.

all of these choices are correct

Myosin motor proteins use ATP to: carry vesicles along a microfilament within a cell in a plus-to-minus direction. carry vesicles along a microtubule within a cell in a minus-to-plus direction. carry vesicles along a microfilament within a cell in a minus-to-plus direction. carry vesicles along a microtubule within a cell in a plus-to-minus direction. slide along intermediate filaments to contract muscle cells.

carry vesicles along a microfilament within a cell in a minus-to-plus direction

Kinesin motor proteins use ATP to: slide along microfilaments to contract muscle cells. carry vesicles along a microfilament within a cell in a minus-to-plus direction. carry vesicles along a microfilament within a cell in a plus-to-minus direction. carry vesicles along a microtubule within a cell in a plus-to-minus direction. carry vesicles along a microtubule within a cell in a minus-to-plus direction.

carry vesicles along a microtubule within a cell in a minus-to-plus direction

Which of the following is NOT found in the extracellular matrix of animal cells? laminin collagen elastin cellulose polysaccharide

cellulose

Biologists spend a great deal of time studying the cytoskeleton of cells. Some of the tools they use in their research include chemicals that interfere with the structure of the cytoskeletal elements or with the activities of the motor proteins that associate with the cytoskeleton to facilitate movement. For example, a family of compounds called cytochalasins disrupts the normal assembly and disassembly of microfilaments. Another compound called colchicine binds to tubulin and prevents the assembly of microtubules. A compound known as EHNA (erythro-9-[3-2-(hydroxynonyl)] adenine) interferes with the function of dynein, and blebbistatin inhibits the activity of myosin. Where would you predict colchicine to have the greatest effect? the shortening of a muscle cell fibroblast migration sperm cell motility chromosome segregation Colchicine would likely have no effect on any of these cells or processes.

chromosome segregation

Where would you predict cytochalasins to have the greatest effect? sperm cell motility chromosome segregation Cytochalasins would likely have no effect on any of these cells or processes. the shortening of a muscle cell fibroblast migration

fibroblast migration

The dermis of mammalian skin, including that of humans, contains a large amount of extracellular matrix proteins, including collagen and elastin. As a person ages, the amount of elastin in the dermis declines. Which of the following cell types is likely to be the cause of this change in the dermis of the skin? fibroblasts keratinocytes epidermal cells melanocytes

fibroblasts

Which of the following is a button-like point of attachment formed by the linking of integrins to intermediate filaments inside the cell and their binding to a protein of the extracellular matrix on the outside of the cell? tight junction adherens junction hemidesmosome desmosome

hemidesmosome

Which of the following provide structural support for epithelial cells, such as those in the skin (keratinocytes)? intermediate filaments microtubules microtubules and microfilaments microfilaments microfilaments and intermediate filaments

intermediate filaments

Which of the following cytoskeletal elements contribute to the structural integrity and strength of epithelial tissues in animals? intermediate filaments and microfilaments microtubules and microfilaments intermediate filaments and microtubules

intermediate filaments and microfilaments

In many cells, the adhesion to the extracellular matrix through integrins causes the activation of kinases in the cytoplasm. This suggests that: extracellular matrix proteins are receptors and integrins are ligands. integrins promote the activation of signal-transduction pathways. integrins are kinases.

interns promote the activation of signal-transduction pathways

Zebrafish embryos change the color of the melanophore cells in their skin to a darker shade by: dynein motor proteins moving pigment granules outward from the center of the cell. dynein motor proteins moving pigment granules inward toward the center of the cell. kinesin motor proteins moving pigment granules outward from the center of the cell. dynein motor proteins moving pigment granules inward toward the plus end of microtubules. kinesin motor proteins moving pigment granules inward toward the center of the cell.

kinesin motor proteins moving pigment granules outward from the center of the cell

Which part of the cytoskeleton would you suggest investigating as a potential source of the faulty color adjustment in these tadpoles? microtubules intermediate filaments microfilaments

microtubules

Which of the following enable(s) the movement of cells? microfilaments and intermediate filaments microfilaments microtubules and microfilaments microtubules intermediate filaments

microtubules and microfilaments

Which one of the following statements about intracellular transport is TRUE? Microtubules and intermediate filaments facilitate cellular movement, but microfilaments do not. Intermediate filaments, microfilaments, and microtubules all facilitate cellular movement of one kind or another. Microtubules and microfilaments facilitate cellular movement, but intermediate filaments do not. Intermediate filaments and microfilaments facilitate cellular movement, but microtubules do not.

microtubules and microfilaments facilitate cellular movement, but intermediate filaments do not

Which is the correct order of cytoskeletal filaments in DECREASING filament diameter? microfilaments → microtubules → intermediate filaments intermediate filaments → microfilaments → microtubules microtubules → intermediate filaments → microfilaments microtubules → microfilaments → intermediate filaments

microtubules → intermediate filaments → microfilaments

The cytoskeleton of animal cells includes: actin, microtubules, and intermediate filaments. microtubules and microfilaments. microtubules, microfilaments, and intermediate filaments. actin, microfilaments, and intermediate filaments. tubulin, microfilaments, and intermediate filaments.

microtubules, microfilaments, and intermediate filaments

Macrophage cells undergo a process called phagocytosis in which material is brought into a cell in the form of membrane vesicles and then transported along microtubules toward the cell center. Assuming that the centrosome is near the cell center, you can predict that these vesicles are moving to the _____ end of microtubules using the motor protein _____. minus end; dynein minus end; kinesin plus end; kinesin plus end; dynein

minus end; dynein

Microfilaments increase in length: in cycles, following rapid depolymerization. All of these choices are correct. by assembling outward from the centrosome. more quickly at one end than the other. if free tubulin dimers are available.

more quickly at one end than the other

Which one of the following statements about intracellular transport is TRUE? Myosin moves substances along microfilaments. Kinesin and dynein move substances along microfilaments. Myosin and dynein move substances along microfilaments. Kinesin and myosin move substances along microtubules.

myosin moves substances along microfilaments

The internal cytoskeletal structure of cilia and flagella grows out from a structure called a basal body located near the cell surface. Based on this information, where would you predict the plus end of the microtubules to be located? near the basal body at both ends of the cilia or flagella It is not possible to predict from the information provided. near the tip of the cilia or flagella

near the tip of the cilia or flagella

The property of dynamic instability implies that the individual protein subunits of microtubules are held together by: disulfide bonds. All of these choices are correct. covalent bonds. noncovalent interactions.

non covalent interactions

In nerve cells, the centrosome is located near the nucleus. Vesicles move from near the nucleus to the end of long extensions (axons) along microtubules. Based on these two facts, it is possible to conclude that these vesicles are moving in the _____ direction on the microtubule using the motor protein _____. minus end; kinesin plus end; dynein plus end; kinesin minus end; dynein

plus end; kinesis

Where would you predict EHNA to have the greatest effect? fibroblast migration EHNA would likely have no effect on any of these cells or processes. sperm cell motility the shortening of a muscle cell chromosome segregation

sperm cell motility

Which one of the following is a characteristic shared by integrins and cadherins? The cytoplasmic domains of both proteins are connected to the cytoskeleton. Both facilitate the adhesion of cells to extracellular matrix proteins. Both are present in adherens junctions, desmosomes, and hemidesmosomes. Both are peripheral membrane proteins.

the cytoplasmic domains of both proteins are connected to the cytoskeleton

The MOST likely reason(s) a metastatic tumor cell might lose its connection to the basal lamina would be: a change in the type of integrin proteins present on the cell's surface. the loss of integrin proteins from the cell's surface, or a change in the type of integrin proteins present on the cell's surface. the loss of integrin proteins from the cell's surface. a change in the composition of the basal lamina.

the loss of integrin proteins from the cell's surface, or a change in the type of integrin proteins present on the cell's surface

Where would you predict blebbistatin to have the greatest effect? the shortening of a muscle cell fibroblast migration Blebbistatin would likely have no effect on any of these cells or processes. chromosome segregation sperm cell motility

the shortening of a muscle cell

Which of the following is a mesh-like attachment between cells formed by binding of transmembrane proteins of one cell to the same protein type on the adjacent cell, preventing substances from passing between cells?.13 tight junction hemidesmosome adherens junction desmosome

tight junction

Flagella move in a(n): oarlike motion by the motor protein dynein sliding microtubules past each other. whiplike motion by the motor protein dynein sliding microfilaments past each other. oarlike motion by the motor protein kinesin sliding microtubules past each other. whiplike motion by the motor protein kinesin sliding microtubules past each other. whiplike motion by the motor protein dynein sliding microtubules past each other.

whiplike motion by the motor protein dynein sliding microtubules past each other