Lecture 7: Sources of Genetic Variation: Sex Flashcards
Sources of Allelic Variation
mutation
Sources of Genotypic Variation
Sex (Meiosis)
In Sex: No new alleles, only new __
genotypes
What process introduces genetic variation during sexual reproduction?
meiosis (crossing over and independent assortment)
the exchange of genetic material between homologous chromosomes during meiosis.
crossing over (a form of recombination)
changes the composition along chromosome arms, creating new combinations of alleles on chromosomes.
crossing over
refers to mating that occurs without regard to the genotypes of individuals.
random mating
How does random mating contribute to genetic variation?
increases the likelihood of different genotypes coming together during reproduction, leading to the formation of new combinations of alleles in offspring.
produces gametes
meiosis
shuffling of gametes
random mating
meiosis generate genotypic diversity through two main mechanisms: What is the first mechanism?
The physical exchange of homologous chromosomal regions by homologous recombination.
What does homologous recombination result in?
New combinations of DNA within chromosomes.
meiosis generate genotypic diversity through two main mechanisms: What is the second mechanism?
The separation of homologous chromosome pairs.
What does the separation of homologous chromosome pairs allow?
random and independent shuffling of haploid chromosomes (gametes) during random mating.
a process by which a molecule of nucleic acid (usually DNA, but can also be RNA) is broken and then joined to a different one.
Genetic recombination
What is the outcome of the crossover process during eukaryotic recombination?
Offspring have different combinations of alleles along the chromosomes compared to their parents.
What is the consequence of random mating?
increases genotypic variation
Mixing up combinations of alleles at a given locus during reproduction, leading to the formation of new genotypes in the offspring.
This process can also help break up LD on different chromatids by further mixing alleles from different chromosomes.
Random mating
What is the consequence of genetic recombination during sexual reproduction?
reduces Linkage Disequilibrium (LD)
How does genetic recombination achieve this reduction in LD?
by breaking up associations of alleles along a chromosome.
- the non-random association of alleles at two or more loci, not necessarily on the same chromosome.
- It occurs when certain combinations of alleles or genetic markers are more or less frequent than expected based on random formation of haplotypes from allele frequencies.
Linkage Disequilibrium (LD)
What can cause Linkage Disequilibrium?
Evolutionary forces such as natural selection and genetic drift
__ breaks down LD on the same chromosome by shuffling genetic material between homologous chromosomes, leading to the creation of new combinations of alleles.
Recombination
Linkage Disequilibrium (LD)
__ will break down linkage disequilibrium on the same chromosome, and __ __ on different chromosomes
- Recombination
- random mating