Sexual Sources Of Genetic Variation
Independent Assortment of Chromosomes
- Occurs during Metaphase I
- There is a 50-50 chance that a chromosome will pair with another paternal/maternal chromosome.
- Sometimes the linkage seemed to break, but only between homologous pairs of chromosomes.
- This genetic recombination is called crossover.
- The farther apart genes are the greater the chance of crossover.
- By examining frequency of crossover, the relative distance of genes was mapped.
- The that sperm actually fertilizes an ovum is a random selection.
- A human ovum can have one of 8 million chromosome combinations.
- An individual human sperm can have of 8 million different chromosome combinations.
- This yields 64 trillion possible combinations minimum.