CH 10

The natural loss of dead cells from the surface of your skin is a result of:

breakdown of adherens junctions.

Which is a component of the extracellular matrix made by a plant cell but not animal cells?

cellulose

Which answer choice correctly lists components of the extracellular matrix found in plants?

cellulose and lignin

Predict what would happen if an embryonic epidermal cell switched from expressing E-cadherin to N-cadherin.

The cell would leave the epidermis and adhere to neural cells.

Evidence that cytoskeletal elements have ancient origins comes from the:

-observation that both prokaryotes and eukaryotes use cytoskeletal elements to assist cell division -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

If intermediate filaments were capable of dynamic instability, what outcome would be most likely?

Cell shape and support would be affected.

__________ is not a cellular function of microfilaments.

Movement of motile cilia

Could melanin granules be moved by dynein and kinesin along an actin microfilament?

No, these motor proteins are specific to microtubules and cannot move along microfilaments.

The epidermis contains several layers and receives its nutrients from the dermis by diffusion. What 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.

Imagine that you are examining a mouse that does not produce basal lamina in the skin. How will this mouse be different from a normal, wild-type mouse?

The cells of the epidermis would not be properly connected to form a water-resistant barrier.

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 outcomes would you expect to observe as a result of this mutation?

The strength of tissues would decrease because the integrin could no longer associate with microfilaments.

A patient in a physician's office has a deep cut, and as it is being stitched up, a sample of tissue is taken for testing. Analysis of the tissue reveals it has few cells, surrounded by a large amount of extracellular matrix proteins with some blood vessels, sweat glands, and nerve cells. What kind of tissue is this?

The tissue is most likely dermis, and should also have some fibroblasts, but few keratinocytes and melanocytes.

Gap junctions and plasmodesmata have what feature in common?

They both allow direct transport of materials between cells

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

Cadherin is an example of:

a cell adhesion molecule

An epithelial tissue is defined as:

a collection of cells that lines cavities or outside surfaces.

Epidermolysis bullosa is a set of rare genetic disorders that is caused by:

a keratin gene that disrupts intermediate filaments, weakening connections between epidermal cell layers

Which one of the choices matches a type of cell junction with its proper cytoskeletal element and cell adhesion molecule?

adherens junction, microfilament, cadherin

A decrease in cell-cell adhesion was caused by the introduction of an experimental substance that compromised the structural integrity of the tissue. Which type of cell junction would most likely be affected by this treatment given that the treatment caused a decrease in the strength of cell-cell adhesion?

adherens junctions

A researcher is studying a population of mutant fibroblasts that fail to flatten and attach to extracellular matrix proteins on a flat surface. This is likely the result of mutations in genes encoding:

components of cell junctions.

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 basal lamina:

is a specialized extracellular matrix found beneath epithelial tissues.

Epithelial tissue is found:

lining the lungs lining blood vessels lining the gastrointestinal tract on the outer surface of the body.

Kinesin is a motor protein found attached to:

microtubules

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

microtubules and microfilaments

Which of the choices correctly lists the sequence in which the plant cell wall is synthesized?

middle lamella → primary cell wall → secondary cell wall

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 grows out from a structure called a basal body located near the base of the cilia. 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)

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

Metastatic cancer cells have a dynamic actin cytoskeleton associated with their plasma membrane. The presence of the membrane cytoskeleton most likely accounts for:

the ability of these cells to move and crawl to new locations in the body.

The extracellular domain of a cadherin protein can only bind to:

the extracellular domain of the same type of cadherin.