17 D CSF

Chapter 1: Introduction

• Microtubules: Shown in red, facilitate the positioning of golgi vesicles for delivery of cell wall components.
• Asymmetric Cell Division: One cell may be larger than the other due to how the spindle aligns during cell division.
  • Example: Seen in Caenorhabditis elegans where one side of the cell divides asymmetrically, creating a larger cell that becomes the germ cell while the smaller cell becomes a somatic cell.
• Mitosis Without Cytokinesis:
  • Cells may undergo nuclear division without separating cytoplasmic contents, resulting in a syncytium with multiple nuclei in one cytoplasm.

Chapter 2: Development of Different Cells

• Nuclear Migration: During embryo development, nuclei migrate to corners and cell boundaries form, leading to cellular compartmentalization.
• Mycogens: Trigger cell division and influence the restriction point decisions for cell progression.
  • They include growth factors that promote cell size increase and division.

Chapter 3: Growth and Cell

• Cell Growth vs. Proliferation:
  • Cell Growth: Involves increase in volume.
  • Proliferation: Refers to cell division and the cell cycle.
• Survival Factors: Promote cell survival and play roles in stimulating division.
• Platelet-Derived Growth Factor (PDGF): Acts as a mycogen; triggers signaling pathways leading to cell cycle progression.

Chapter 4: Cyclins and Cyclins

• cylins: Ensure progression through the cell cycle by activating corresponding cyclin-dependent kinases (CDKs).
• Retinoblastoma (Rb): A key protein in cell cycle regulation that, when mutated, leads to cancer.
  • Phosphorylation of Rb by active CDK leads to its inactivation and release of E2F, a transcription factor promoting cyclin synthesis and cell cycle progression.
• Positive Feedback Loop: E2F activation leads to further activation of itself and other cyclins to maintain progression through G1 to S phase.

Chapter 5: Main Checkpoint Proteins

• Checkpoint Proteins: Regulate cell cycle checkpoints during genomic stress (e.g., DNA damage).
  • p53: A tumor suppressor that activates in response to DNA damage; often mutated in human cancers.
  • Mechanism of Action:
  • Activation of p53: Induces transcription of p21, an inhibitor of CDK, then halting cell cycle progression.

Chapter 6: Stopping the Cells

• Checkpoint Pathways: Prevent cell cycle progression in response to DNA damage. Can trigger cellular repair pathways or apoptosis if damage is too severe.
• Key Proteins:
  • P53: Can induce apoptosis or halt cell division through transcriptional regulation.
  • Checkpoint Kinase 1 (CHK1): Inhibits CDC25 phosphatase, further halting the cell cycle.

Chapter 7: The DNA Damage Response

• Cells ascertain the extent of DNA damage to manage repair or cell death.
• Damage Repair Mechanisms: Cells may activate pathways to fix damage or trigger apoptosis if damage is irreparable.

Chapter 8: External Growth Factors

• Growth Factors and Nutrients: Stimulate cell growth and protein synthesis.
• mTORC1Signaling: Implicated in activating protein synthesis, lipid synthesis, and cellular turnover processes.

Chapter 9: Overlapping Functions of Factors

• Mitogens vs. Growth Factors: Often have overlapping roles in stimulating growth and division.
  • Possible to find a single factor acting as a growth factor, mitogen, or both.

Chapter 10: Conclusion

• Summarizes key points of the cell cycle, the roles of checkpoints, growth factors, and highlights areas not covered (meiosis).