Genetic Variability and Recombination

What is the primary evolutionary advantage of sexual reproduction?

During which phase of meiosis does crossing-over occur?

How many nuclei are produced after the second meiotic division?

What results from independent assortment of chromosomes?

What type of chromosomes are generated through crossing-over?

What is the consequence of having 23 pairs of chromosomes in humans?

Which process can produce new allele combinations within a chromatid?

How do crossing-over and independent assortment differ?

Genetic Variability

Sexual reproduction is the main evolutionary advantage because of genetic variability.
Genetic variability increases the chance of survival and reproduction for offspring in changing environments.

Sources of Variability

Genetic Variability arises from three sources: Crossing-over, independent assortment, and the combination of male and female gametes during fertilization.

Crossing-Over

Exchange of chromosome segments during prophase I of Meiosis.
Crossing over occurs between homologous chromosomes.
If genetic differences exist between homologs, crossing over can produce new allele combinations in a chromatid.
Four nuclei (chromatids) result from the second meiotic division.
Two nuclei receive unaltered chromosomes (parental) and two receive chromosomes with new allele combinations (recombinant chromosomes).
Crossing-over is a mechanism for genetic recombination.

Independent Assortment

Homologous pairs are made up of one maternal and one paternal chromosome.
During Metaphase I, one homologous chromosome is randomly attached to the spindle of each pole..
Humans have 23 pairs of chromosomes, leading to 2^23 different combinations of maternal and paternal chromosomes.

Explore the mechanisms behind genetic variability, including sexual reproduction's role in evolution. This quiz covers topics like crossing-over, independent assortment, and their importance for creating diverse offspring in changing environments.