meiosis and genetic variation
- Created by: Margaret Hobart
- Created on: 16-05-21 11:44
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- meiosis and genetic variation
- meiosis
- produces 4 haploid daughter cells that are genetic genetically different from each other
- gametes
- 1. DNA unravels and replicates so there are two copies of each chromosome
- 2. 2 sister chromatids join in the middle at the centromere
- 1st division
- 3. chromosomes orange themselves into homologous pairs
- 4. these separate into 2 daughter cells
- crossing over of alleles
- new genetic combinations, increased diversity
- Independent segregation of homologous chromosomes
- 3. chromosomes orange themselves into homologous pairs
- 2nd division
- 5. pairs of sister chromatids are separated (the centromere divides)
- 6. 4 haploid cells that are genetically different are produced
- 5. pairs of sister chromatids are separated (the centromere divides)
- produces 4 haploid daughter cells that are genetic genetically different from each other
- gene mutations
- change in base sequence of DNA
- doesn't always change sequence of amino acids coded for due to the genetic code being degenerate
- base substitution
- may cause change in one amino acid
- change to structure and folding of a protein
- may cause change in one amino acid
- base deletion
- may cause frameshift
- completely different codons and amino acids, and so a different protein is synthesised
- may cause frameshift
- mutagenic agents increase rate of mutation
- mutations occur spontaneously but some things can increase the rate
- e.g. radiation
- mutations occur spontaneously but some things can increase the rate
- Can arise spontaneously during DNA replication in interphase
- change in base sequence of DNA
- meiosis
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