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

What is the role of a protein kinase in a signal transduction pathway?

It acts as a secondary messenger to relay signals within the cell.

It adds phosphate groups to specific proteins, altering their activity.

It removes phosphate groups from proteins, deactivating them.

It binds directly to DNA to regulate gene expression.

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Verified step by step guidance

Understand the role of protein kinases in cellular processes: Protein kinases are enzymes that catalyze the transfer of phosphate groups from ATP to specific amino acid residues (usually serine, threonine, or tyrosine) on target proteins. This process is called phosphorylation.

Recognize the importance of phosphorylation: Phosphorylation can alter the activity, localization, or interaction of a protein with other molecules, thereby playing a critical role in regulating cellular processes such as signal transduction, cell division, and metabolism.

Differentiate protein kinases from other enzymes: Protein kinases specifically add phosphate groups to proteins, whereas other enzymes, such as phosphatases, remove phosphate groups. This distinction is crucial for understanding their opposing roles in regulating protein activity.

Relate protein kinases to signal transduction pathways: In signal transduction, protein kinases often act as intermediaries that propagate and amplify signals by phosphorylating downstream proteins in a signaling cascade. This ensures that the signal is transmitted effectively within the cell.

Clarify misconceptions: Protein kinases do not act as secondary messengers (e.g., cAMP or calcium ions), nor do they directly bind to DNA to regulate gene expression. Their primary role is to modify proteins through phosphorylation, which can indirectly influence gene expression by activating or deactivating transcription factors.