Mitosis and the cell cycle (4.1.2.2) — AQA GCSE Biology Revision Notes

Revision notes for AQA GCSE Biology specification point 4.1.2.2, Mitosis and the cell cycle.

The Cell Cycle: Creating New Cells

  • To help an organism grow, develop and repair, the body needs to make new cells.
  • This is done through the CELL CYCLE, which is a series of events that cells go through to grow and DIVIDE. The end result is the formation of 2 cells that are IDENTICAL to the original cell.
  • The two cells formed are known as DAUGHTER CELLS.

 

There are 3 main stages to the cell cycle:

 Cell Cycle

1. Growth and DNA Replication

  • The cell increases the number of SUBCELLULAR STRUCTURES it has, including their MITOCHONDRIA and RIBOSOMES.
  • The nucleus of the cell REPLICATES their DNA, forming two identical X-SHAPED CHROMOSOMES.

X shaped chromsome

2. Mitosis

  • The MEMBRANE of the nucleus breaks down.
  • The chromosomes align in the CENTRE of the cell and are then pulled apart to opposite ends of the cell by structures known as CELL FIBRES.

 3. Cell Division

  • New membranes form around each set of chromosomes to form TWO NUCLEI.
  • The cytoplasm and cell membrane SPLIT to form TWO IDENTICAL DAUGHTER CELLS.

 

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