Molecular biology chapter 10

Which one of the following is a major difference between integrins and cadherins? Integrins are integral membrane proteins, whereas cadherins are not. Cadherins are found in cellular junctions, whereas integrins are not. Integrins allow cells to adhere to extracellular matrix, whereas cadherins do not. Cadherins associate with intermediate filaments, whereas integrins do not.

Integrins allow cells to adhere to extracellular matrix, whereas cadherins do not.

Which one of the following statements about intracellular transport is true? Kinesin and myosin move substances toward the "plus end" of microtubules and microfilaments, respectively. Kinesin and myosin move substances toward the "minus end" of microtubules and microfilaments, respectively. Myosin and kinesin move substances toward the "plus end" of microtubules and microfilaments, respectively. Myosin and kinesin move substances toward the "minus end" of microtubules and microfilaments, respectively.

Kinesin and myosin move substances toward the "plus end" of microtubules and microfilaments, respectively.

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 of the following would you expect to observe as a result of this mutation? The integrin would be unable to signal the cytoplasm when it had bound to laminin. The integrin would function normally because the cytoplasmic domain is not responsible for binding to laminin. The strength of tissues would be decreased because the integrin could no longer associate with microfilaments in adherens junctions. Cell adhesion to laminin would decrease, but laminin-meditated gene expression would remain the same.

The integrin would be unable to signal the cytoplasm when it had bound to laminin.

how does an adherens junction differ from a desmosome? Adherens junctions connect a cell to neighboring cells, and desmosomes connect a cell to the extracellular matrix. Adherens junctions connect cells using adherin proteins, and desmosomes connect cells with cadherin proteins. While both adherens junctions and desmosomes connect cells by using cadherin proteins, only adherens junctions connect to the cytoskeleton. While both adherens junctions and desmosomes connect cells by using cadherin proteins, adherens junctions connect to microfilaments while desmosomes connect to intermediate filaments inside the cell. These two types of junctions only differ in their band-like versus button-like architecture in the plasma membrane.

While both adherens junctions and desmosomes connect cells by using cadherin proteins, adherens junctions connect to microfilaments while desmosomes connect to intermediate filaments inside the cell.

A decrease in cell adhesion by the introduction of cytochalasin to a tissue compromises the structural integrity of the tissue. Which junctional complexes would be affected by this treatment to cause the decrease in the strength of the tissue? adherens junctions desmosomes hemidesmosomes tight junctions

adherens junctions

Cell shapes are largely determined by: cytoskeletal protein networks in the cytoplasm. adhesion proteins that assemble at cell surfaces. a mesh of proteins and polysaccharides in the extracellular matrix. cytosolic proteins that assemble into structures called cellular junctions. all of these choices are correct.

all of these choices are correct.

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

cellulose fibers

Which one of the following pairs includes junctional complexes that perform similar functions? tight junctions and adherens junctions tight junctions and desmosomes desmosomes and adherens junctions desmosomes and plasmodesmata

desmosomes and adherens junctions

Which one of the following properly groups a junctional complex with a cytoskeletal structure and cell adhesion molecule? adherens junction, microfilament, integrin hemidesmosome, intermediate filament, integrin desmosome, intermediate filament, integrin hemidesmosome, intermediate filament, cadherin

hemidesmosome, intermediate filament, integrin

Match each description below with the type of cell junction it characterizes: 1. A band-like attachment where cadherins attach to microfilaments inside the cell and to the extracellular domain of an adjacent cell's cadherin proteins on the outside of the cells. 2. A button-like point of attachment where cadherins attach to intermediate filaments inside the cell and to the extracellular domain of an adjacent cell's cadherin proteins on the outside of the cells. 3. A button-like point of attachment where integrins attach to intermediate filaments inside the cell and to a protein of the extracellular matrix on the outside of the cells. 4. 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. 5. Transmembrane proteins on the plasma membrane arranged in a ring that bind to a similar protein ring on an adjacent cell to allow transfer of materials between the cells

1. adherens junction 2. desmosome 3. hemidesmosome 4. tight junction 5. gap junction

Complete the following exercise by matching the terms with one of the following descriptions: an extracellular matrix component, a cell adhesion molecule, part of the cytoskeleton 1. lignin 2. collagen 3. integrin 4. actin 5. microtubule 6. cellulose 7. middle lamella 8. cadherin 9. tubulin 10. keratin 11. pectin 12. intermediate filament 13. microfilmament

1. an extracellular matrix component 2. an extracellular matrix component. 3. a cell adhesion molecule. 4. part of the cytoskeleton. 5. part of the cytoskeleton. 6. an extracellular matrix component. 7. an extracellular matrix component. 8. a cell adhesion molecule. 9. part of the cytoskeleton. 10. part of the cytoskeleton. 11. an extracellular matrix component. 12. part of the cytoskeleton. 13. part of the cytoskeleton.

For each function described below, choose the cytoskeletal element it best characterizes (some of the functions listed are carried out by more than one cytoskeletal element): 1. provide structural support for epithelial cell shape (keratins) 2. enable movement of cells 3. enable movement of substances within cells 4. provide structural support for fibroblast cell shape (vimentins) 5. arrange and tether organelles within the cytoplasm 6. provide cellular movement as a component of cilia and flagella 7. provide structural support for nuclear envelopes (lamins) 8. attach to the cytoplasmic surfaces of desmosomes 9. provide structural support to cells and layers of cells through attachment to adherens junctions 10. help cells to withstand compression when organized into a spokelike array by the centrosome 11. separate chromosomes during cell division when organized in a spindle apparatus 12. provide a contractile ring to separate cells during cell division 13. support the plasma membrane and organize membrane proteins 14. shorten cell shapes during contraction

1: intermediate filaments 2. microtubules, microfilaments 3. microtubules, microfilaments 4. intermediate filaments 5. microtubules 6. microtubules 7. intermediate filaments 8. intermediate filaments 9. microfilaments 10. microtubules 11. microtubules 12. microfilaments 13. microfilaments 14. microfilaments

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

All of these choices are correct.

The extracellular matrix (ECM) affects a cell that it surrounds in which ways? (Select all correct choices.) The ECM affects the shape that the cell takes, depending on the structure and composition of the extracellular matrix. The ECM affects the genes that the cell expresses, depending on the types of fibrous proteins in the extracellular matrix. The ECM affects the size that the cell grows to, depending on the polysaccharides in the extracellular matrix. The ECM has no effect on the cells that it surrounds.

The ECM affects the shape that the cell takes, depending on the structure and composition of the extracellular matrix. The ECM affects the genes that the cell expresses, depending on the types of fibrous proteins in the extracellular matrix

Cells that have a crawling movement include: (select all correct choices) amoebas foraging for food. white blood cells in pursuit of invading pathogens. migrating embryonic cells. nerve cells transporting neurotransmitters. contracting muscle cells.

amoebas foraging for food. white blood cells in pursuit of invading pathogens. migrating embryonic cells.

Metastatic cancer cells: are able to leave the tumor where they originated and travel to distant locations to set up new tumors at distant sites. have lost their adhesion to the extracellular matrix, freeing them from being confined to the original tumor. become malignant when they cross the capillary basal lamina. only need to cross a single layer of capillary endothelial cells to form tumors at distant sites. All of these choices are correct.

are able to leave the tumor where they originated and travel to distant locations to set up new tumors at distant sites.

Cilla and flagella: (select all correct choices) are specialized cells that move by rotary motion. are specialized organelles that move by rotary motion. are specialized organelles that propel some plant, algae, and anima cells. contain microfilaments arranged in nine pairs around the periphery and two microfilaments in the center. contain microtubules arranged in nine pairs around the periphery and two microfilaments in the center.

are specialized organelles that propel some plant, algae, and anima cells.

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. by kinesin motor proteins moving pigment granules outward from the center of the cell. by dynein motor proteins moving pigment granules inward toward the center of the cell. by kinesin motor proteins moving pigment granules inward toward the center of the cell. by dynein motor proteins moving pigment granules inward toward the plus end of microtubules.

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

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

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

Microtubules and microfilaments are said to be "dynamic" elements of the cytoskeleton. In this case, dynamic means that: once individual microfilaments and microtubules have formed they can change shape and move around inside the cell. they are constantly changing and are never in the same place for very long. microtubules and microfilaments are assembled and disassembled and then reassembled again in a regulated manner.

microtubules and microfilaments are assembled and disassembled and then reassembled again in a regulated manner.

Which one of the following correctly lists the sequence in which the plant cell wall is synthesized? primary cell wall → secondary cell wall → middle lamella secondary cell wall → middle lamella → primary cell wall secondary cell wall → primary cell wall → middle lamella middle lamella → primary cell wall → secondary cell wall middle lamella → secondary cell wall → primary cell wall

middle lamella → primary cell wall → secondary cell wall

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

of a keratin gene that disrupts intermediate filaments, weakening epidermal cell connections.