Q: Which of the following is a correct sequence for the GPCR-cAMP second messenger pathway?

$\text{Ligand} \rightarrow \text{GPCR} \rightarrow \text{G-protein} \rightarrow \text{Adenylyl cyclase} \rightarrow \text{cAMP} \rightarrow \text{PKA} \rightarrow \text{Target phosphorylation}$

Question 1

Which of the following is TRUE regarding electrical signals in cell-to-cell communication?

Accepted Answer

They are created by the distribution of ions such as $\mathrm{Na^+}$, $\mathrm{K^+}$, and $\mathrm{Cl^-}$ across the plasma membrane.

Question 2

A water-soluble (hydrophilic) ligand will most likely bind to which type of receptor?

Accepted Answer

Membrane receptor, initiating signal transduction to the inside of the cell.

Question 3

Which receptor type is responsible for the fastest signaling response?

Accepted Answer

Ligand-gated ion channel

Question 4

Which of the following is a correct sequence for the GPCR-cAMP second messenger pathway?

Accepted Answer

$	ext{Ligand} ightarrow 	ext{GPCR} ightarrow 	ext{G-protein} ightarrow 	ext{Adenylyl cyclase} ightarrow 	ext{cAMP} ightarrow 	ext{PKA} ightarrow 	ext{Target phosphorylation}$

Question 5

Which of the following is NOT a function of cytokines?

Accepted Answer

Directly generating action potentials in neurons

Question 6

During skeletal muscle contraction, which band remains constant in length?

Accepted Answer

A band

Question 7

Which protein provides elastic recoil in the sarcomere?

Accepted Answer

Titin

Question 8

A patient is given a drug that blocks the release of $\mathrm{Ca^{2+}}$ from the sarcoplasmic reticulum. Which step in the sliding filament theory will be directly affected?

Accepted Answer

Troponin will not move tropomyosin off actin binding sites.

Question 9

Which of the following best describes the role of integrin receptors?

Accepted Answer

They connect the extracellular matrix to the cytoskeleton, influencing cell shape and motility.

Question 10

Which muscle type is striated and involuntary?

Accepted Answer

Cardiac muscle

Question 11

Which of the following is a local communication mechanism that requires physical contact between cells?

Accepted Answer

Contact-dependent signaling

Question 12

Which of the following is the correct order of events in the sliding filament theory?

Accepted Answer

Ca$^{2+}$ released $\rightarrow$ troponin moves tropomyosin $\rightarrow$ myosin binds actin $\rightarrow$ sarcomere shortens $\rightarrow$ ATP detaches myosin

Question 13

Which of the following is a correct example of a long-distance chemical signal?

Accepted Answer

Hormones released into the bloodstream

Question 14

Which of the following is a function of the sarcoplasmic reticulum in skeletal muscle?

Accepted Answer

Stores and releases $\mathrm{Ca^{2+}}$ ions to trigger contraction

Question 15

Which of the following statements about antagonistic muscle pairs is correct?

Accepted Answer

Flexors bring bones together, while extensors move them apart.

Question 16

Which of the following is a regulatory protein found on the thin filament of the sarcomere?

Accepted Answer

Troponin

Question 17

A mutation causes a muscle cell to lack functional T-tubules. Which process will be directly impaired?

Accepted Answer

Conducting the action potential deep into the muscle fiber to trigger $\mathrm{Ca^{2+}}$ release

Question 18

Which of the following is a common second messenger used in GPCR pathways?

Accepted Answer

$\mathrm{cAMP}$ (cyclic adenosine monophosphate)

Question 19

Which of the following best explains why chemical signals such as hormones are suited for long-distance communication?

Accepted Answer

They are stable and can travel through the bloodstream to reach distant targets.

Cell-to-Cell Communication and Skeletal Muscle: Key Concepts and Exam Prep

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