The Cell Cycle Lecture Notes

Overview

• The cell cycle is the lifespan of a eukaryotic somatic cell (body cell excluding sex cells like sperm and egg).
• It describes the sequence of cell growth and division.
• The cell cycle consists of four main phases:
  • Interphase: G1, S, and G2 phases.
  • Cell Division: M phase.

Interphase

G1 Phase (Growth 1/Gap Phase 1)

• Primary Activities:
  • Cell growth.
  • Performing its specific functions.
• Special Note: Some cells (e.g., muscle and nerve cells) exit the cell cycle after G1 because they do not divide again.

S Phase (Synthesis Phase)

• Main Activity: DNA replication (making a copy of DNA).
• The cell enters this phase once it grows too large to function efficiently and needs to divide.

G2 Phase (Growth 2/Gap Phase 2)

• Function: Further preparations for cell division.

M Phase (Cell Division)

Main Events

• Mitosis: Division of the cell's nucleus.
• Cytokinesis: Division of the cytoplasm.

Outcome

• Results in two daughter cells that are identical to each other and to the original cell.

Summary

• The cell cycle includes four phases: three phases within interphase (G1, S, G2) and one phase of cell division (M phase).
• During G1, most cell growth and function occur.
• The cell replicates its DNA in the S phase to prepare for division.
• G2 involves further preparation for the division.
• M phase includes the processes of mitosis and cytokinesis, leading to the formation of two identical daughter cells.

Next Steps

• Further exploration of the details of mitosis and cytokinesis.