Biology · MU Sofia

27. Cell cycle. Mitosis. Cell cycle control.

Walks through the cell cycle from G1 through S, G2 and the M phase, then the stages of mitosis from prophase to telophase, including spindle microtubule types and motor proteins. Covers the three checkpoints, the cyclin-Cdk activation sequence and the role of the Rb protein in controlling the restriction point. Three mnemonics are included to help recall the phase order, mitotic stages and cyclin-Cdk sequence.

Inside: 11 sections · 4 labelled pictures · 14 flashcards · 5 min

Topic 28 of 105 in the MU Sofia syllabus for Biology (Medicine, Year 1). The free AceMed note covers it in 11 sections, about 735 words (5 min of reading), with 14 flashcards.

In this note

  1. Cell cycle. Mitosis. Cell cycle control.
  2. Cell Cycle
  3. Phases of the Cell Cycle:
  4. Mitosis
  5. Phases of Mitosis:
  6. Other Features of Mitosis:
  7. Cell Cycle Control
  8. Checkpoints in the Cell Cycle:
  9. Regulatory Proteins and Mechanisms:
  10. Role of Rb Protein:
  11. MNEMONICS

Cell Cycle

  • The cell cycle is the entire process through which a cell grows, prepares for division, and divides into two daughter cells.
  • It is composed of two main phases: interphase (when the cell prepares for division) and the M phase (when division actually occurs).

Phases of the Cell Cycle:

  1. 1. G1 phase (Gap 1)
  • The cell undergoes metabolic activity and grows in size.
  • It checks for internal and external signals to decide whether to proceed.
  • A key moment is the restriction point, after which the cell is committed to division.
  1. 2. S phase (Synthesis)
  • DNA replication occurs in this phase.
  • Each chromosome becomes two sister chromatids after replication.
  1. 3. G2 phase (Gap 2)
  • The cell continues growing and prepares all materials necessary for mitosis and cytokinesis.
  1. 4. M phase (Mitotic phase)
  • This includes mitosis (division of the nucleus) and cytokinesis (division of the cell itself).

Mitosis

  • Mitosis is a part of the M phase where the cell divides its nucleus, ensuring each daughter cell gets an identical set of chromosomes.
  • Although DNA replication happens in the S phase, mitosis ensures those replicated chromosomes are correctly distributed.

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