Lecture Notes: Cell Cycle and Its Regulation

Introduction

• Concept of cells:
  • All living things, including humans, are made of cells.
  • Cells form tissues, tissues form organs, organs form organ systems.
  • Various cell types include skin, stomach, and muscle cells.

Cell Cycle Overview

• Purpose:
  • Regulates cell growth and division.
  • Cells grow in number, not size, as organisms grow.
• Processes:
  • Mitosis and cytokinesis are key for creating new body cells.

Importance of Cell Regulation

• Cancer:
  • Results from uncontrolled cell division.
  • Cancer cells may not communicate or function properly.
  • Can secrete growth hormones, diverting nutrients from healthy cells.
• Risk factors for cancer:
  • Genetic links, toxins, radiation, UV exposure.

Cell Cycle Phases

• Interphase:
  • Majority of cell’s life; involves cell growth and DNA replication.
  • Includes G1, S (DNA synthesis), and G2 phases.
• M Phase (Mitosis and Cytokinesis):
  • Actual division of the cell into two new cells.

Checkpoints in the Cell Cycle

• G1 Checkpoint:
  • Checks for cell growth adequacy, DNA damage, and resource availability.
• G2 Checkpoint:
  • Ensures correct DNA replication and sufficient resources.
• M Phase Checkpoint:
  • Ensures chromosomes are properly aligned and attached.

Regulation of the Cell Cycle

• Regulatory Proteins:
  • Positive regulators promote cycle progression.
  • Negative regulators, like p53, can trigger apoptosis.
• Cyclin and CDK:
  • Cyclin-dependent kinases (CDKs) bind different cyclins.
  • Levels of cyclins rise and fall, signaling cycle progression.

Apoptosis and Beyond

• Apoptosis:
  • Cell self-destructs if irreparable damage is detected.
  • Acts as a safeguard against passing on faulty cells.

G0 Phase

• Resting Phase:
  • Cells perform functions but do not prepare to divide.
  • Some cells, like neurons, may remain permanently in G0.

Conclusion

• Ongoing Research:
  • Continuous development in understanding cell cycle and cancer.
  • Encouragement to explore topics like cyclins, CDKs, and apoptosis further.

Note: The lecture emphasized staying curious and exploring beyond the basic concepts discussed.