Chapter 10

A researcher is assessing the expression of a certain protein in cells. This protein appears as a "web" in the cytoplasm of cells. The protein is likely a component of:

the cytoskeleton.

Which of the following is NOT considered an epithelial tissue?

the interior of the brain

Evidence that cytoskeletal elements have ancient origins comes from the:

;;presence of cytoskeletal elements in both eukaryotes and prokaryotes. ;;ability to form functional hybrid microfilaments from actin monomers taken from distantly related organisms. ;;observation that both prokaryotes and eukaryotes use cytoskeletal elements to assist cell division. ;;sequence similarities of cytoskeletal elements when comparing distantly related organisms.

Evidence that cytoskeletal elements have ancient origins comes from the:

;;sequence similarities of cytoskeletal elements when comparing distantly related organisms. ;;presence of cytoskeletal elements in both eukaryotes and prokaryotes. ;;ability to form functional hybrid microfilaments from actin monomers taken from distantly related organisms. ;;observation that both prokaryotes and eukaryotes use cytoskeletal elements to assist cell division.

Red blood cells are characterized as having an actin cytoskeleton associated with their plasma membrane. The presence of the membrane cytoskeleton most likely accounts for:

;;the shape of the cell. ;;enhanced gas exchange. ;;the ability of these cells to fit through narrow capillaries.

Why do you think the presence of a specific type of keratin, an intermediate filament protein, in the bloodstream or lymph node is an indicator of metastasis of tumor cells?

Keratin is only present if its specific cell type is also present.

Which one of the following statements about intracellular transport is TRUE?

Kinesin and dynein move substances along microtubules.

Which one of the following statements about intracellular transport is TRUE?

Myosin moves substances along microfilaments.

Could an isolated melanin granule move along an actin microfilament?

No, motor proteins are specific for the type of filament they bind.

What would happen to a cell that depends on flagellar movement if it had no actin?

Nothing; the cell would still be able to move.

The epidermis contains several layers and receives its nutrients from the dermis by diffusion. Which of the following explains why the outermost layers of the epidermis consist of dead cells?

One of the major functions of the epidermis is forming a waterproof barrier. Once that barrier is formed, nutrients cannot pass through it and the cells beyond that layer die.

Motor proteins cause movement by: (1) undergoing a conformational change, (2) harnessing energy from ATP, (3) binding to the cytoskeleton.

Statements (1), (2) and (3) are correct.

Which of the following statements about the skin is TRUE?

The epidermis is made up of epithelial tissue whereas the dermis is made up primarily of connective tissue.

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

Which of the following is a FALSE statement about the motor proteins myosin and kinesin?

They both move along microtubules.

Many scientists are working to generate organs in vitro. In some cases, cells are seeded onto a "scaffold" shaped like the desired target organ. Such scaffolds are likely composed of extracellular matrix proteins.

True

Which of the following CORRECTLY lists the sequence in which the plant cell wall is synthesized?

middle lamella → primary cell wall → secondary cell wall

The basal lamina is:

a specialized form of the extracellular matrix found beneath all epithelial tissues.

A decrease in cell adhesion, by the introduction of an experimental substance to a tissue, compromises the structural integrity of the tissue. Which cell junction would MOST likely be affected by this treatment causing a decrease in the strength of the tissue?

adherens junctions

Which of the following cytoskeletal elements is capable of assembling and disassembling in the cell?

both microtubules and microfilaments

Kinesin motor proteins use ATP to:

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

If intermediate filaments were capable of dynamic instability, which of the following outcomes would be most likely?

cell adhesion would be affected

Which of the following is NOT found in the extracellular matrix of animal cells?

cellulose

A researcher is studying a population of cells that are shaped normally, but appear to slide past one another. This is likely the result of mutations in genes encoding:

components of cell junctions.

A pathologist is carrying out an autopsy. Upon opening the chest cavity, the pathologist sees a thick, fibrous tissue surrounding the heart. This is likely:

connective tissue.

In skin, the cells of the epidermis connect to the basal lamina through cellular junctions known as hemidesmosomes. Select the cytoskeletal element that helps maintain the integrity of this connection.

intermediate filaments

The extracellular matrix in animals:

differs from one tissue to the next, affecting the expression of genes in the cells that it surrounds.

Dynamic instability is a:

feature of microtubules.

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

Many scientists use a specific type of mouse cell to coat the surface of petri dishes. These cells form a layer on which other kinds of cells, often of different species, can adhere and grow. The mouse cells used to coat petri dishes are likely:

fibroblasts.

Where would you find a cell adhesion molecule?

in a cell junction

Which of the following could NOT be a part of the extracellular matrix made by an animal cell?

lignin

Which of the following enable(s) the movement of cells?

microtubules and microfilaments

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

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 tip of the cilia or flagella

The property of dynamic instability implies that the individual protein subunits of microtubules are held together by:

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 _____.

plus end; kinesin

How do cells connect to the extracellular matrix?

through integrins