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AQA GCSE · Question 05.6 · Cell Biology
Describe the process of cell division by mitosis.
Describe the process of cell division by mitosis.
How to approach this question
Describe the key stages of mitosis in a logical order.
1. What happens to the DNA/chromosomes before division starts?
2. Where do the chromosomes move to in the middle of the process?
3. What happens to the copies of the chromosomes?
4. How does the cell finally split into two?
Full Answer
First, the cell grows and replicates its DNA, so each chromosome consists of two sister chromatids. The chromosomes then condense and line up at the centre of the cell. Spindle fibres pull the sister chromatids apart to opposite poles of the cell. Finally, new membranes form around the two sets of chromosomes, and the cytoplasm divides to form two genetically identical daughter cells.
Mitosis is a type of cell division used for growth, repair, and asexual reproduction. The process can be described in stages:
1. **Interphase (before mitosis):** The cell grows, and importantly, it replicates its DNA. Each chromosome is copied, so it consists of two identical "sister" chromatids joined together.
2. **Prophase/Metaphase:** The chromosomes condense (become shorter and fatter) and become visible. They then line up along the equator (the centre) of the cell.
3. **Anaphase:** Cell fibres (spindle fibres) attach to the chromosomes and pull the sister chromatids apart. One chromatid from each pair is pulled to opposite ends (poles) of the cell.
4. **Telophase/Cytokinesis:** A new nuclear membrane forms around each set of chromosomes at the poles. The cytoplasm then divides in two.
The result is two new daughter cells that are genetically identical to each other and to the original parent cell.
Common mistakes
✗ Getting the stages in the wrong order.
✗ Forgetting the initial DNA replication step.
✗ Confusing mitosis with meiosis (e.g., mentioning homologous pairs or reduction division).
Practice the full AQA GCSE Biology Higher Tier Paper 1
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