Longest stage. DNA is replicated. Just before division the chromosomes replicate- so each consists of 2 chromatids join togehter in centromere
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What happens in prophase?
First stage in mitosis. The chromosomes condense and become visible. Centrioles divide and move to opposite ends of cell. Spindle develops from centriole. Nuclear membrane disappears, chromatids can be seen.
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What happens in metaphase?
Chromosomes arrange themselves at centre and become attached to spindles at centromere
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What happens in anaphase?
Centromere splits and spindle contracts and pull the chromatids to poles and seperate.
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What happens in telophase?
Chromosomes uncil and lengthen. Spindles break down and centrioles replicate.
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What is the significance of mitosis?
Replicates cells- genetically identical so stable. Growth and repair. Asexual reproduction.
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What is meiosis?
Sexual reproduction. Two gametes fuse to form a zygote. For each generation to have a full set of chromosomes (diplod) the chromosomes must be halved (haploid)
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What happens in meiosis 1?
Chromosome number is halved
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What happens in meiosis 2?
Haploid nuclei divide again in a division identical to mitosis
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What does it result in?
4 daughter nuclei, each with half the number of chromosomes of parent cell.
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What is the difference between prophase in meiosis and mitosis?
In meiosis, homologous chromatids wrap around eachother and then partially repel eachother but remain joined at certain points. At these points the chromatids may break and recombine with a different chromatid. This is a source of genetic variation.
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