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BMS 612 Exam 3 > Chapter 15 - Cell Communication Part 1: Nuclear Receptors & GPCRs > Flashcards

Chapter 15 - Cell Communication Part 1: Nuclear Receptors & GPCRs Flashcards

1
Q

What are intracellular signals?

A

Signals originating within the cell for rapid metabolic regulation.

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2
Q

What are extracellular signals?

A

Signals between cells, such as hormones, for metabolic integration.

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3
Q

Give examples of intracellular signals.

A

Fe metabolism, substrate availability, misfolded proteins.

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4
Q

Name examples of extracellular signals.

A

Hormones, neurotransmitters, growth factors.

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5
Q

What is autocrine signaling?

A

Cells responding to signals they release themselves.

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6
Q

Define paracrine signaling.

A

Signals acting locally between nearby cells.

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7
Q

What is endocrine signaling?

A

Hormones traveling through the bloodstream to distant cells.

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8
Q

How is signal specificity achieved in cell signaling?

A

Through ligand-receptor interactions.

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9
Q

Name three families of cell surface receptors.

A

GPCRs, receptor tyrosine kinases, ligand-gated ion channels.

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10
Q

Describe G-protein coupled receptors (GPCRs).

A

Receptors with seven transmembrane domains activating G proteins.

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11
Q

What is the role of receptor tyrosine kinases (RTKs)?

A

They phosphorylate tyrosine residues on signaling proteins.

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12
Q

What are nuclear receptors?

A

Intracellular receptors acting as transcription factors.

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13
Q

How does GPCR activation affect intracellular pathways?

A

It activates G proteins, triggering secondary messengers.

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14
Q

Name a second messenger produced by GPCRs.

A

Cyclic AMP (cAMP).

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15
Q

How is cAMP generated?

A

By adenylyl cyclase activated by G-proteins.

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16
Q

What is IP₃ and what does it do?

A

A second messenger that releases Ca²⁺ from the ER.

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17
Q

Describe the role of diacylglycerol (DAG) in signaling.

A

It activates protein kinase C (PKC).

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18
Q

What enzyme produces IP₃ and DAG?

A

Phospholipase C (PLC).

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19
Q

What role does Ca²⁺ play in signal transduction?

A

It acts as a messenger activating various kinases.

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20
Q

Define calmodulin.

A

A Ca²⁺-binding protein activating enzymes like CaM-kinase.

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21
Q

What is the function of CaM-kinase?

A

It mediates Ca²⁺-dependent signaling, critical for learning and memory.

22
Q

Explain positive feedback in cell signaling.

A

It amplifies the response, leading to an all-or-none effect.

23
Q

What is negative feedback in signaling?

A

A mechanism that reduces the response, aiding in signal desensitization.

24
Q

What is receptor desensitization?

A

Reduction of receptor response after prolonged stimulation.

25
Q

Give an example of a disease caused by disrupted RTK signaling.

A

Cancer, due to overactive receptor tyrosine kinases.

26
Q

Name a drug class that targets GPCRs.

A

Beta-blockers, used in heart disease treatment.

27
Q

How does receptor internalization affect signaling?

A

It removes receptors from the surface, reducing sensitivity.

28
Q

What is adenylyl cyclase’s role in the cAMP pathway?

A

It converts ATP to cAMP, initiating signal transduction.

29
Q

How does Ca²⁺ signaling affect muscle contraction?

A

It triggers contractions by activating contractile proteins.

30
Q

Explain the fight-or-flight response at the molecular level.

A

Adrenaline activates GPCRs, raising cAMP, and triggering responses.

31
Q

What does cholera toxin do to G-protein signaling?

A

Locks G-protein in active state, causing excessive cAMP production.

32
Q

How do GPCRs influence heart rate?

A

They regulate K⁺ channels, altering the pace of cardiac contraction.

33
Q

What type of receptor is the glucocorticoid receptor?

A

A nuclear receptor that binds cortisol and regulates gene transcription.

34
Q

Define signal transduction.

A

The process by which a cell responds to extracellular signals via receptors.

35
Q

What is the role of CREB in the cAMP pathway?

A

A transcription factor activated by PKA to regulate gene expression.

36
Q

How does phosphorylation affect signaling proteins?

A

It activates or inactivates proteins, modifying cellular responses.

37
Q

What is a ‘second messenger’ in cellular signaling?

A

A small molecule that relays signals inside the cell.

38
Q

Why is Ca²⁺ considered a ubiquitous messenger?

A

It participates in numerous cellular processes across cell types.

39
Q

What is the effect of IP₃ binding to its receptor?

A

It releases Ca²⁺ from intracellular stores, modulating cellular activities.

40
Q

Describe the importance of signal amplification.

A

Ensures a strong response from a small signal input.

41
Q

How does nitric oxide (NO) act as a signaling molecule?

A

It diffuses across membranes to activate guanylyl cyclase.

42
Q

How do muscarinic Ach receptors affect cardiac cells?

A

They reduce heart rate by opening K⁺ channels via GPCR signaling.

43
Q

What is the Wnt signaling pathway’s role in cell fate?

A

Regulates cell proliferation and differentiation through gene expression.

44
Q

Name the three major classes of secondary messengers.

A

Cyclic nucleotides, IP₃/DAG, and Ca²⁺ ions.

45
Q

How is cGMP different from cAMP in signaling?

A

cGMP often mediates visual and smooth muscle responses.

46
Q

What is the function of arrestins in GPCR signaling?

A

They desensitize GPCRs, facilitating receptor internalization.

47
Q

Describe Ras protein’s role in cell signaling.

A

A GTPase involved in cell growth signaling via RTKs.

48
Q

How does receptor clustering influence signaling?

A

Increases the efficiency of signal transduction.

49
Q

What are coincidence detectors in signaling?

A

Proteins that require two signals to initiate a response.

50
Q

What is the physiological significance of GPCR diversity?

A

Allows cells to respond to a variety of ligands and signals.

BMS 612 Exam 3 (6 decks)

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