Cell Communication

Which of the following best describes the role of a second messenger in a signal transduction pathway?

• It directly activates the target protein.

• It relays the signal from the receptor to the target molecules inside the cell.

• It binds to the ligand outside the cell.

• It degrades the signaling molecule.

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DOK Level 2: Skill/Concept

Explain how G-protein coupled receptors (GPCRs) activate intracellular signaling pathways. Provide an example of a specific pathway.

• GPCRs directly phosphorylate target proteins.

• GPCRs activate G-proteins, which then activate or inhibit other proteins such as adenylyl cyclase.

• GPCRs enter the nucleus to activate gene transcription.

• GPCRs degrade cAMP to stop the signal.

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DOK Level 3: Strategic Thinking

Which type of cell receptor is most likely to be involved in the rapid response to a neurotransmitter?

• Enzyme-linked receptor

• G-protein coupled receptor

• Ion channel-linked receptor

• Intracellular receptor

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DOK Level 2: Skill/Concept

Describe the process of signal amplification in a signal transduction pathway. Why is this process important?

• Signal amplification occurs when a single signaling molecule activates multiple downstream molecules, leading to a large cellular response.

• Signal amplification involves the degradation of the signaling molecule to prevent overactivation.

• Signal amplification is the process of reducing the signal strength to avoid cellular damage.

• Signal amplification is the direct binding of the signaling molecule to multiple receptors.

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DOK Level 3: Strategic Thinking

Which of the following is a common second messenger in signal transduction pathways?

• ATP

• cAMP

• DNA

• RNA

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DOK Level 2: Skill/Concept

How do receptor tyrosine kinases (RTKs) initiate a signaling cascade inside the cell?

• RTKs bind to DNA to initiate transcription.

• RTKs dimerize and autophosphorylate, creating docking sites for downstream signaling proteins.

• RTKs degrade signaling molecules.

• RTKs open ion channels directly.

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DOK Level 3: Strategic Thinking

Which of the following molecules is NOT typically involved in intracellular communication?

• Hormones

• Neurotransmitters

• DNA

• Cytokines

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DOK Level 2: Skill/Concept

Discuss the role of phosphorylation in the regulation of signal transduction pathways. Provide an example of a kinase involved in this process.

• Phosphorylation always deactivates proteins in signal transduction pathways.

• Phosphorylation can either activate or deactivate proteins, depending on the context. An example is Protein Kinase A (PKA).

• Phosphorylation is only involved in the degradation of signaling molecules.

• Phosphorylation is irrelevant to signal transduction pathways.

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DOK Level 3: Strategic Thinking

Which of the following best describes paracrine signaling?

• Signaling molecules are released into the bloodstream to affect distant cells.

• Signaling molecules affect only the cell that released them.

• Signaling molecules affect nearby cells.

• Signaling molecules are transmitted through direct cell-to-cell contact.

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DOK Level 2: Skill/Concept

Explain how ligand-gated ion channels function in cell signaling. Provide an example of a physiological process that involves these channels.

• Ligand-gated ion channels open or close in response to the binding of a signaling molecule, allowing ions to flow across the membrane. An example is the synaptic transmission in neurons.

• Ligand-gated ion channels degrade signaling molecules.

• Ligand-gated ion channels phosphorylate proteins.

• Ligand-gated ion channels bind to DNA to initiate transcription.

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DOK Level 3: Strategic Thinking