University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

66

Pages:

2
Author:

Mariam A. A.

Fertilisation ✓ Each chromatid begins segregating in Anaphase II and be completely segregated into a different gamete after Telophase II. ✓ This occurs for all 23 pairs of homologous chromosome (one pair being sex chromosomes, XX or XY). ✓ That is, the zygote has 46 chromosomes (23 homologous pairs). That means that during meiosis, the process of crossing over effectively creates the genetic variation in the gametes due to their difference in alleles for various genes. Also, the random process of fertilisation between the egg and sperm increases the chance of genetic variation in the zygote because: _________________________________________________________________________________________ _________________________________________________________________________________________ _________________________________________________________________________________________ _____________________________________________________________ ✓ Due to meiosis, each gamete will have one allele that codes for a particular gene. Upon fertilisation where the female and male gametes fuse together to form a zygote, the zygote will then two alleles that code for each gene (e.g., gene for eye colour). ✓ Therefore, the process of fertilisation creates new genotypes for the offspring that are, for the most part, different from each individual parent. ✓ However, if both parents have homozygous dominant alleles for a trait, then the offspring will have genotype that is exactly the same as the parent (homozygous dominant too) though ONLY for that particular gene. Independent assortment and random segregation both facilitate in increasing the genetic variation in offspring of the new generations. Although they do not create new allele combinations, they do introduce variations in the way which alleles that specifies different genes on non-homologous chromosomes are assorted independently relative to each other (independent assortment) and eventually different chromatids that carries different alleles for certain genes can be segregated into different gametes (random segregation). This means that these two independent assortment and random segregation introduce (genetic) variation into the alleles that each gamete inherit after Cytokinesis II in Telophase II.