9.3 - Meiosis & Genetic Variation Flashcards
The importance of meiosis in living organisms The processes of crossing over and independent segregation (or random assortment) How crossing over and independent segregation (or random assortment) cause variation
What are the two important roles of meiosis?
Production of haploid gametes
What does the fusion of gametes during fertilization lead to?
Genetic variation
Why is meiosis needed in sexual reproduction?
To produce haploid gametes
What happens when two gametes fuse?
They form a zygote
What is the chromosome number of a zygote?
Diploid (2n)
What are the two events in meiosis that lead to genetic variation?
Crossing over and independent segregation
When does crossing over occur?
Prophase I
What happens during crossing over?
Chromatids twist and exchange genetic material
What does crossing over result in?
Different combinations of alleles on chromosomes
When does independent segregation occur?
Metaphase I
What happens during independent segregation?
Homologous chromosomes line up randomly at the equator
What does independent segregation result in?
Different combinations of chromosomes in daughter cells
What is the formula to calculate the number of genetically distinct gametes due to independent segregation?
2^n (where n is the number of chromosome pairs)
What is the formula to calculate the number of genetically different zygotes possible from two parents?
(2^n)^2
