Q: Which equation best represents the triple helix structure of type I collagen, where three polypeptide chains are wound together?

$$\text{Collagen triple helix} = \text{Chain}_1 + \text{Chain}_2 + \text{Chain}_3$$

Question 1

Which type of cell junction is primarily responsible for forming a waterproof barrier between adjacent epithelial cells, preventing the passage of molecules between them?

Accepted Answer

Tight junctions

Question 2

In the classic sponge cell adhesion experiment, what was the key finding regarding the behavior of dissociated sponge cells when mixed together?

Accepted Answer

Cells sorted themselves and re-formed their original tissue types

Question 3

Which protein family is responsible for connecting the actin cytoskeleton of one cell to the actin cytoskeleton of another cell at adherens junctions?

Accepted Answer

Cadherins

Question 4

Desmosomes are crucial for providing strong adhesion between adjacent cells in tissues that experience significant mechanical stress. Which cytoskeletal element do desmosomes connect between cells?

Accepted Answer

Intermediate filaments

Question 5

Which cell junction allows for the direct passage of ions and small signaling molecules between adjacent animal cells, enabling coordinated cellular activity?

Accepted Answer

Gap junctions

Question 6

Integrins are transmembrane proteins that connect cells to the extracellular matrix (ECM). Which cytoskeletal elements do integrins typically link to inside the cell?

Accepted Answer

Intermediate filaments and microfilaments

Question 7

Which of the following best describes the structural role of collagen in the extracellular matrix of animal tissues?

Accepted Answer

Provides tensile strength and structural support

Question 8

Columnar epithelial cells maintain their elongated shape primarily due to which of the following cellular features?

Accepted Answer

Organization of cell junctions and cytoskeletal elements

Question 9

Which type of cell junction anchors epithelial cells to the underlying extracellular matrix, providing structural stability to the tissue?

Accepted Answer

Hemidesmosomes

Question 10

A mutation in the gene encoding claudin proteins would most likely disrupt which cellular function?

Accepted Answer

Formation of a selective barrier preventing paracellular transport

Question 11

Which of the following best explains why tissues such as skin and heart muscle are rich in desmosomes?

Accepted Answer

They experience frequent stretching and mechanical stress

Question 12

Elastin is a major component of the extracellular matrix. What is its primary function in connective tissues?

Accepted Answer

Allowing tissues to stretch and recoil

Question 13

Which equation best represents the triple helix structure of type I collagen, where three polypeptide chains are wound together?

Accepted Answer

$$	ext{Collagen triple helix} = 	ext{Chain}_1 + 	ext{Chain}_2 + 	ext{Chain}_3$$

Question 14

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

Accepted Answer

Anchoring cells to the extracellular matrix

Question 15

Which of the following is a real-world consequence of defective cadherin proteins in epithelial tissues?

Accepted Answer

Weak cell-cell adhesion leading to tissue fragility and blistering

Question 16

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

Accepted Answer

Adherens junctions connect actin filaments, while desmosomes connect intermediate filaments

Question 17

Which of the following molecules is most abundant in the extracellular matrix of animal tissues and provides structural support?

Accepted Answer

Collagen

Question 18

Gap junctions are formed by which type of protein, allowing for the passage of ions and small molecules between cells?

Accepted Answer

Connexins

Question 19

Which of the following best explains the importance of the extracellular matrix (ECM) in animal tissues?

Accepted Answer

It provides structural support, influences cell shape, and mediates cell signaling

Question 20

A researcher observes that cells in a tissue are unable to communicate and coordinate their activity. Which cell junction is most likely defective?

Accepted Answer

Gap junctions

Cell-Cell Junctions and the Extracellular Matrix: Structure and Function in Animal Tissues

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