6.1.5 - Causes of Genetic Variation

Question 1

Mutations as cause of genetic variation

Answer 1

Mutations

• Increase the number of alleles for a trait
• Chromosomal mutations: typically arise from errors during crossing-over, which leads to deletion, duplication, inversion, or translocation mutations (structural abnormalities). Non-disjunction during anaphase causes an abnormal distribution of chromsomes in daughter cells, leading to numerical abnormalities like monosomy, trisomy, and polyploidy and aneuploidy.
• These chromosomal disorders often result in many physicial and intelletcual symptoms –> more traits.

Question 2

Mechanisms of sexual reproduction as causes of genetic variation

Answer 2

Mechanisms of sexual reproduction

• Meiosis: recombination of chromatids and their segregation during anaphase lead to the formation of genetically unique daughter cells, each with a different permutation of maternal and paternal chromosomes
• Fertilisation: the syngamy of two genetically different gametes recombines genetic material to form a diploid zygote that has a unique combination of chromosomes inherited from its two parents. This promotes genetic variation between individuals