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What is the 'cell cycle'?
The period between the formation of a new cell and when it divides to produce two offspring cells
What is interphase?
Briefly describe the different stages
- Interphase: the stage in the cell cycle during which various molecules are synthesised and Dna is replicated
- G1: pre DNA synthesis
- S: DNA synthesis
- G2: post DNA synthesis
- The first stage
- chromosomes begin to condense (shorten and thicken)
- Each chromosome is double stranded (from S phase)
- Nuclear membrane diappears
- network of fibres appear- spindle
- Chromosomes gather on the equator of the spindle
- Centromere of each chromosome attaches to the spindle fibres
- Spindle fibre contracts
- Centromere of each chromosome is pulled in two directions and splits
- Drawn to opposite poles
Nuclear membranes form around each group of chromosomes
What happens during cytokinesis?
- After mitosis
- Separates the 2 daughter nuclei into separate cells
- Cell membrane pinches in dividing the ell into two daughter cells
What is meiosis?
- A reduction division
- Produces gametes
- Involves one replication of DNA and two nuclear divisions
- Results in halving the number of chromosomes of a parent diploid nucleus to 4 haploid daughter nuclei