Meiosis & Genetic Diversity
Biology: Cambridge International A Level, topic 16.1.3
Genetic Variation
Meiosis produces four genetically different daughter cells. Genetic variation is generated in each daughter cell in two ways. These are:
Crossing over
- The chromosomes of a homologous pair are arranged down the middle of the cell before the first cell division in meiosis I.
- Sections of DNA are swapped between the chromosomes in a pair in a process called crossing over.
- Crossing over produces new combinations of alleles.
- This increases genetic variation.
Independent assortment
- The chromosomes in a homologous pair are separated in meiosis I in a random formation to produce two genetically different daughter cells.
- The combination of chromosomes in the two daughter cells is random.
- The process of separating chromosomes into random combinations is called independent assortment.
- Independent assortment increases genetic variation.
- This process also ensures each haploid gamete receives a haploid set of chromosomes that contains both maternal and paternal chromosomes.
Random fertilization
- Sexual reproduction involves the random fusion between gametes.
- Any two gametes could fuse together to produce a random combination of chromosomes.
- Meiosis and random fertilization further increase genetic diversity in this way.
Test yourself on Meiosis & Genetic Diversity
Which of the following statements about genetic variation in meiosis are true?
Which of these is NOT a process that increases genetic variation in meiosis?
Crossing over and independent assortment occur during which process?