Question 1

Which of the following best describes the primary function of the extracellular matrix (ECM) in animal tissues?

Accepted Answer

To provide structural support, mediate cell signaling, and regulate cell behavior.

Question 2

Collagen, a major component of the ECM, is synthesized inside the cell as procollagen. Which of the following steps is essential for collagen to become functional outside the cell?

Accepted Answer

Cleavage of procollagen terminal peptides by extracellular enzymes.

Question 3

Integrins are transmembrane proteins that play a crucial role in cell-ECM interactions. What do integrins primarily connect?

Accepted Answer

The ECM to the cytoskeleton inside the cell.

Question 4

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

Accepted Answer

They create a seal that prevents the movement of substances between adjacent cells.

Question 5

A researcher is studying tissue sorting in embryonic development. She finds that cells expressing different cadherins sort into distinct layers. What property of cadherins is responsible for this selective adhesion?

Accepted Answer

Cadherins bind specifically to identical cadherins on adjacent cells.

Question 6

In an experiment to discover the role of cadherins, what was used to block cadherin binding and disrupt cell-cell adhesion?

Accepted Answer

Antibodies specific to cadherins.

Question 7

Which of the following statements correctly differentiates adherens junctions from desmosomes?

Accepted Answer

Adherens junctions connect to actin filaments, while desmosomes connect to intermediate filaments.

Question 8

Gap junctions are specialized for cell-cell communication. Which of the following types of molecules can typically pass through gap junctions?

Accepted Answer

Ions and small signaling molecules such as $\mathrm{Ca^{2+}}$ and cAMP.

Question 9

Which of the following best describes the difference between endocrine and paracrine signaling?

Accepted Answer

Endocrine signals travel through the bloodstream to distant targets, while paracrine signals act locally on nearby cells.

Question 10

Lipid-soluble signaling molecules, such as steroid hormones, can cross the plasma membrane. Why is this possible?

Accepted Answer

They are nonpolar and hydrophobic, allowing them to diffuse through the lipid bilayer.

Question 11

Which of the following is the correct sequence of events in a typical G-protein coupled receptor (GPCR) signaling pathway?

Accepted Answer

Ligand binds receptor → G-protein exchanges GDP for GTP → Effector enzyme activated → Second messenger produced → Cellular response

Question 12

Adenylyl cyclase is a membrane-bound enzyme involved in cell signaling. What is its primary function?

Accepted Answer

To convert ATP into cyclic AMP ($\mathrm{cAMP}$), a second messenger.

Question 13

Which of the following molecules is classified as a second messenger in cell signaling pathways?

Accepted Answer

cAMP, which is a nucleotide derivative.

Question 14

What is the main difference between a second messenger and a kinase in cell signaling?

Accepted Answer

A second messenger is a small molecule that relays signals inside the cell, while a kinase is an enzyme that phosphorylates other proteins.

Question 15

Which amino acids are most commonly phosphorylated by protein kinases during signal transduction, and what type of bond is formed?

Accepted Answer

Serine, threonine, and tyrosine; a covalent phosphate ester bond is formed.

Question 16

A mutation in the Ras protein prevents it from hydrolyzing GTP to GDP. What is the most likely consequence of this mutation?

Accepted Answer

Ras will be constitutively active, potentially leading to uncontrolled cell division and cancer.

Question 17

Which enzyme is responsible for turning off the cAMP signal by converting cAMP to AMP?

Accepted Answer

Phosphodiesterase

Question 18

In the context of enzyme-linked receptors, what does 'autophosphorylation' refer to?

Accepted Answer

A receptor phosphorylating itself on specific amino acid residues after ligand binding.

Question 19

Which of the following best describes the role of phosphatases in cell signaling?

Accepted Answer

They remove phosphate groups from proteins, thereby turning off signaling pathways.

Question 20

A patient is exposed to a toxin that inhibits phospholipase C. Which signaling pathway would be most directly affected?

Accepted Answer

The pathway that generates inositol trisphosphate ($\mathrm{IP_3}$) and diacylglycerol ($\mathrm{DAG}$) as second messengers.

Chapter 11 Study Guide: Cell Communication, ECM, and Signaling Pathways

Study Guide - Practice Questions

Study Guide - Flashcards