Table of contents

1. Overview of Cell Biology2h 49m
2. Chemical Components of Cells1h 14m
3. Energy1h 33m
4. DNA, Chromosomes, and Genomes2h 31m
5. DNA to RNA to Protein2h 31m
6. Proteins1h 36m
7. Gene Expression1h 42m
8. Membrane Structure1h 4m
- The Lipid Bilayer
  38m
- Membrane Proteins
  25m
9. Transport Across Membranes1h 52m
10. Anerobic Respiration1h 5m
11. Aerobic Respiration1h 11m
12. Photosynthesis52m
13. Intracellular Protein Transport2h 18m
14. Cell Signaling1h 28m
15. Cytoskeleton and Cell Movement1h 39m
16. Cell Division3h 5m
17. Meiosis and Sexual Reproduction50m
18. Cell Junctions and Tissues48m
19. Stem Cells13m
- Stem Cells
  13m
20. Cancer44m
21. The Immune System1h 6m
22. Techniques in Cell Biology1h 41m

14. Cell Signaling

Overview of Signaling Molecules

Cell Biology

14. Cell Signaling

Overview of Signaling Molecules

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Multiple Choice

Which of the following is a second messenger?

Acetylcholine

Epidermal growth factor (EGF)

Insulin

cAMP

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Verified step by step guidance

Understand the concept of a second messenger: A second messenger is a small intracellular signaling molecule that is produced or released in response to an extracellular signal (first messenger) and helps propagate the signal within the cell.

Review the examples of first messengers: Acetylcholine, Epidermal Growth Factor (EGF), and Insulin are all examples of first messengers. These are signaling molecules that bind to receptors on the cell surface to initiate a signaling cascade.

Identify the role of cAMP: Cyclic adenosine monophosphate (cAMP) is a well-known second messenger. It is synthesized from ATP by the enzyme adenylyl cyclase, which is activated by certain receptors (e.g., G-protein-coupled receptors).

Differentiate between first and second messengers: First messengers (e.g., acetylcholine, EGF, insulin) are extracellular molecules that bind to receptors, while second messengers (e.g., cAMP) are intracellular molecules that relay the signal inside the cell.

Conclude that cAMP is the correct answer: Based on the definitions and roles, cAMP is the second messenger in this context, while the other options are first messengers.