Lecture Notes: Cell Cycle

Introduction

• Presenter: Andy from Med School EU
• Topic: Cell Cycle

Cell Cycle in Prokaryotic Organisms

• Process Name: Binary Fission
• Phases of Binary Fission:
  1. B Period
     • Characterized by cell growth
     • Ends when DNA replication begins
  2. C Period
     • DNA replication occurs
     • Chromosomes are doubled
     • Ends when chromosomes are separated
  3. D Period
     • Cytoplasm division (cell membrane pinching)
     • Ends with full separation of the cell
• Special Conditions:
  • In nutrient-rich environments, cells may skip or accelerate through the B Period.
  • Bacteria like E. coli can double every 20 minutes under optimal conditions.

Cell Cycle in Eukaryotic Organisms

• Stages of Cell Cycle:
  1. Interphase
     • Comprises of G1, S, and G2 phases
     • G1 Phase
       • Cell carries out its function and grows
       • Cells may enter G0 phase (non-dividing state)
     • G1-S Checkpoint
       • Checks for cell size, nutrients, growth factors, and DNA damage
     • S Phase
       • DNA replication begins
       • Chromosomes and chromosomal proteins are duplicated
     • G2 Phase
       • Preparation for mitosis
       • Continues to grow and synthesize proteins
     • G2 Checkpoint
       • Ensures DNA replication is complete and correct
       • May lead to apoptosis if irreparable errors exist
  2. Mitosis (M Phase)
     • Involves cell division
     • Includes spindle checkpoint (details to be discussed in the next lecture)
  3. Cytokinesis
     • Division of cytoplasm
     • Results in two daughter cells
     • Sometimes considered part of mitosis

Conclusion

• Next topic will focus on cell division and the process of mitosis.