In: Biology
Genetic variation are the changes in the sequence of DNA between different individuals resulting in different phenotype.
Sources of genetic variations include -
1. Crossing over is the the exchange of genetic material between non sister chromatids of homologous chromosomes. It occurs during prophase 1 of meiosis 1. It results in the formation of recombinant chromosomes. The chromosomes so formed are different from one another and also from the parental chromosomes.
2. Independent assortment with occurs during metaphase 1 is an other source of genetic variation. It is the separation of alleles of different gene independently of each other so that every gamete receives one allele of a gene. This process ensures that every gamete is a mixture of paternal as well as maternal chromosomes. Although gametes can only contain parental or only maternal chromosomes as well.
3. The third source of genetic variation is random fertilization of gamete. Gamete from two different parents, sperm and egg which are haploid in nature fuse to form diploid zygote.
4. Mutation, which are the most common thoughts of genetic variations. They are heritable changes in the DNA which may or may not affect the phenotype of the organism. They can occur in somatic cell of an individual and also in the germline cell. If they occur in the germline cell, then they are passed on to the next generation.
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