Question 1

Which of the following best describes the main function of tight junctions in epithelial tissue?

Accepted Answer

They seal the space between cells, preventing the movement of solutes through the paracellular pathway.

Question 2

A mutation in the gene encoding β-catenin would most directly disrupt which cellular structure?

Accepted Answer

Adherens junctions

Question 3

Which of the following molecules is primarily responsible for the tensile strength of the extracellular matrix in connective tissue?

Accepted Answer

Collagen

Question 4

Gap junctions are composed of which protein subunits, and what is the diameter of the channel they form?

Accepted Answer

Connexins; 1.4 nm

Question 5

Which of the following best explains why cells expressing different types or levels of cadherins sort into distinct tissues during development?

Accepted Answer

Cadherins mediate homophilic binding, so cells with the same type or amount of cadherin preferentially adhere to each other.

Question 6

A patient presents with blistering of the skin due to a genetic defect in desmoglein. Which cellular structure is most likely compromised?

Accepted Answer

Desmosomes

Question 7

Which of the following statements about proteoglycans in the extracellular matrix is correct?

Accepted Answer

They consist of a core protein with long chains of glycosaminoglycans (GAGs) attached.

Question 8

Which of the following best describes the role of fibronectin in the extracellular matrix?

Accepted Answer

It acts as a bridging molecule, connecting cells to the extracellular matrix and facilitating cell migration.

Question 9

Which of the following is a unique property of hyaluronate compared to other glycosaminoglycans (GAGs) in the extracellular matrix?

Accepted Answer

It exists both as a free molecule and as a backbone for proteoglycan aggregates.

Question 10

Which of the following best explains why tight junctions are essential in the epithelial lining of the intestine?

Accepted Answer

They prevent the leakage of digestive enzymes and pathogens between cells, maintaining a selective barrier.

Question 11

Which of the following is true regarding the assembly of collagen fibers in the extracellular matrix?

Accepted Answer

Collagen is secreted as procollagen, which is then processed and assembled into fibrils and fibers extracellularly.

Question 12

Which of the following cell junctions is most directly involved in the rapid spread of electrical signals in cardiac muscle?

Accepted Answer

Gap junctions

Question 13

Which of the following statements about integrins is correct?

Accepted Answer

They are transmembrane receptors that connect the cytoskeleton to the extracellular matrix.

Question 14

A researcher observes that cells in a tissue sample are unable to transmit mechanical stress efficiently from cell to cell. Which structure is most likely defective?

Accepted Answer

Adherens junctions

Question 15

Which of the following best describes the difference between adherens junctions and desmosomes?

Accepted Answer

Adherens junctions form continuous bands around cells, while desmosomes form button-like points of contact.

Question 16

Which of the following is a function of matrix metalloproteinases (MMPs) in the extracellular matrix?

Accepted Answer

They degrade extracellular matrix components, allowing cell migration.

Question 17

Which of the following molecules is most abundant in the basal lamina and is critical for connecting epithelial cells to the underlying connective tissue?

Accepted Answer

Laminin

Question 18

Which of the following best explains why elastin is important in tissues such as the lungs and arteries?

Accepted Answer

It forms a network that allows tissues to stretch and then return to their original shape.

Question 19

Which of the following statements about gap junctions is correct?

Accepted Answer

They are composed of connexons, each made of six connexin subunits.

Question 20

A tissue sample is found to have a high concentration of glycosaminoglycans (GAGs) and proteoglycan aggregates. Which tissue is this most likely to be?

Accepted Answer

Cartilage

Cell Junctions and the Extracellular Matrix: Structure, Function, and Molecular Components

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