Question 1

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

Accepted Answer

They seal adjacent cells together, preventing the passage of molecules between them.

Question 2

A mutation in the gene encoding E-cadherin would most likely disrupt which of the following cellular structures?

Accepted Answer

Adherens junctions

Question 3

Which of the following statements about integrins is CORRECT?

Accepted Answer

Integrins bind to ECM proteins such as fibronectin and laminin, linking the ECM to the cytoskeleton.

Question 4

Which sequence correctly describes the assembly of collagen from smallest to largest structure?

Accepted Answer

$$\alpha$$ chain polypeptide, procollagen, collagen molecule, collagen fibril, collagen fiber

Question 5

A patient with a genetic defect in claudin proteins would most likely experience which of the following symptoms?

Accepted Answer

Increased permeability of epithelial barriers, leading to leaky tissues

Question 6

Which of the following is a key difference between desmosomes and hemidesmosomes?

Accepted Answer

Desmosomes connect adjacent cells via cadherins, while hemidesmosomes connect cells to the basal lamina via integrins.

Question 7

Which of the following best explains why cancer cells that lack fibronectin are more likely to metastasize?

Accepted Answer

Fibronectin anchors cells to the ECM, so its absence allows cells to detach and migrate.

Question 8

Which of the following is TRUE regarding gap junctions?

Accepted Answer

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

Question 9

Which of the following ECM components is primarily responsible for providing elasticity to tissues such as skin and blood vessels?

Accepted Answer

Elastin

Question 10

A researcher observes that a certain cell type cannot grow unless attached to a substrate. This phenomenon is best explained by which of the following?

Accepted Answer

Anchorage-dependent growth, which requires integrin-mediated signaling

Question 11

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

Accepted Answer

They form a hydrated gel that resists compression.

Question 12

Which of the following statements about the basal lamina is CORRECT?

Accepted Answer

It separates epithelial cells from underlying connective tissue and acts as a permeability barrier.

Question 13

Which of the following best explains why plant cells do not require structures analogous to desmosomes?

Accepted Answer

Plant cells are surrounded by rigid cell walls that provide structural support.

Question 14

Which of the following is a function of the RGD sequence found in fibronectin?

Accepted Answer

It is recognized by integrins, facilitating cell-ECM adhesion.

Question 15

Which of the following best describes the function of matrix metalloproteases (MMPs) in tissue remodeling?

Accepted Answer

They degrade components of the basal lamina, allowing cells to migrate.

Question 16

Which of the following is TRUE regarding the epithelial-mesenchymal transition (EMT)?

Accepted Answer

It is associated with cancer metastasis and involves changes in cadherin expression.

Question 17

Which of the following best explains why gap junctions are important in cardiac muscle?

Accepted Answer

They allow rapid electrical and chemical communication between adjacent cells.

Question 18

Which of the following statements about plasmodesmata is CORRECT?

Accepted Answer

They are cytoplasmic channels in plant cells that allow direct communication between adjacent cells.

Question 19

Which of the following best describes the role of focal adhesions in cell migration?

Accepted Answer

They connect bundles of actin filaments to the ECM via integrins, allowing cells to move.

Question 20

A scientist is studying a tissue sample and observes that the cells are connected by structures containing desmocollins and desmogleins. Which type of junction is being observed?

Accepted Answer

Desmosome

Cell Adhesions, Cell Junctions, and Extracellular Structures: Study Guide

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