Question 1

Which of the following cell junctions is primarily responsible for preventing the passage of molecules between adjacent epithelial cells, thereby maintaining the polarity of the tissue?

Accepted Answer

Tight junction

Question 2

A patient presents with woolly hair and progressive heart disease. Genetic analysis reveals mutations in plakoglobin and desmoplakin. Which cell structure is most likely affected?

Accepted Answer

Desmosome

Question 3

Which of the following extracellular matrix proteins is most directly responsible for providing tensile strength to connective tissues?

Accepted Answer

Collagen

Question 4

Which cell adhesion molecule is a member of the immunoglobulin superfamily and is involved in neuronal development and growth?

Accepted Answer

NCAM

Question 5

Which of the following best describes the role of integrins in cell biology?

Accepted Answer

They connect the extracellular matrix to the cytoskeleton.

Question 6

A mutation in which protein would most likely result in Ehlers-Danlos syndrome, characterized by hyperflexible skin and joints?

Accepted Answer

Collagen I or III

Question 7

Which of the following is a key feature of selectins that distinguishes them from other cell adhesion molecules?

Accepted Answer

They bind to glycosylated ligands on other cells.

Question 8

Which of the following best explains why claudins are essential for tight junction function?

Accepted Answer

They form the selective barrier that regulates paracellular transport.

Question 9

Listeria monocytogenes can invade host cells by interacting with which host cell adhesion molecule?

Accepted Answer

E-cadherin

Question 10

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

Accepted Answer

Mediates cell attachment, movement, and blood clotting

Question 11

Which of the following cell junctions is most likely to be disrupted in a patient with a blistering skin disease due to autoantibodies against hemidesmosomal proteins?

Accepted Answer

Hemidesmosome

Question 12

Which of the following statements about cadherins is correct?

Accepted Answer

They mediate homophilic cell-cell adhesion and require Ca$$^{2+}.$$

Question 13

A researcher observes that a certain cell junction allows the passage of ions and small molecules between adjacent cells. Which junction is being described?

Accepted Answer

Gap junction

Question 14

Which of the following best explains why collagen fibers become less flexible with age?

Accepted Answer

Increased crosslinking of collagen fibers

Question 15

Which of the following is a real-world consequence of a laminin defect?

Accepted Answer

Muscular dystrophy

Question 16

Which of the following best describes the difference between homotypic and heterotypic cell adhesion?

Accepted Answer

Homotypic adhesion involves the same adhesion molecule on both cells, while heterotypic involves different molecules.

Question 17

Which of the following best explains the role of focal adhesions in cell biology?

Accepted Answer

They connect the actin cytoskeleton to the extracellular matrix via integrins.

Question 18

Which of the following is a likely outcome if claudin proteins are mutated in the intestinal epithelium?

Accepted Answer

Increased paracellular permeability and loss of selective ion transport

Question 19

Which of the following best describes the mechanism by which adenovirus enters host cells?

Accepted Answer

Receptor-mediated endocytosis after binding to cell adhesion molecules

Question 20

Which of the following best explains why elastin is important for skin and blood vessels?

Accepted Answer

It allows tissues to stretch and recoil.

Cell Junctions and Extracellular Structures: Structure, Function, and Clinical Relevance

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