Genetic Variation Flashcards
What is the order of Meiosis?
- Cell Replicates 2. Crossing Over 3. Independent Assortment 4. Segregation
What is a chromatid?
One copy of replicated DNA
What is complete dominance?
When one allele is fully dominant over the other e.g. pure black rabbit
What is incomplete dominance?
When both alleles are partially expressed (black + white = grey)
What is co-dominance?
When both allele phenotypes are equally expressed e.g. white with black spots all over
What are homologous chromosomes?
The position of the gene is the same on each chromosome
What is independent assortment?
The way the homologous chromosomes line up at the equator of the cell
What is crossing over?
Occurs during meiosis, when the homologous chromosomes line up at the equator, sometimes they tangle, snap and exchange genetic
information.
What is segregation?
The process that occurs during meiosis where pairs of alleles are separated when the homologous chromosomes split
Describe what multiple alleles are and give an example?
Multiple alleles is when there are more than two alleles exist. E.g. human blood types with 3 alleles although a healthy human only inherits 2
What is natural selection?
The process by which heritable traits increase an organism’s chances of survival and reproduction.
What is allele frequency?
It represents the occurrence of a particular allele within a gene pool and it is a reflection of the genetic diversity of a population
Define Genetic variation
The presence of differences in genetic material between individuals within a species
Define Genetic Drift
The change in the frequency of an existing gene variant (allele) in a population due to random chance alone and not natural selection.
What can cause genetic drift?
Population Bottleneck and Founders effect
What is the bottleneck effect?
Is an event that drastically reduces the size of a population, may be caused by various events, such as an environmental disaster.
How does population bottleneck effect genetic variation?
Genetic variation / allele frequency in a population is affected by genetic bottleneck through loss of alleles.
How does genetic bottleneck affect a small populations?
In a small population, genetic drift can have a larger proportional effect on allele frequencies/ genetic variation
How does genetic bottleneck effect large populations?
In a large population, genetic drift/ bottleneck is less likely to lead to alleles becoming fixed /lost due to the buffer effect of the larger number of individuals.
What are linked genes?
Genes located on the same chromosome that tend to be inherited together
What is a mutation?
A permanent change in the bases on the DNA. It is the only way of creating new alleles
What kinds of mutations are there?
Gametic and Somatic. Gametic can be passed onto offspring. Somatic cannot.
Why might harmful mutations accumulate more in small populations than a larger population?
They might accumulate more due to a small number of individuals breeding. With limited numbers of individuals, the mutation is easily passed on.
What is the founder effect?
Is the loss of genetic variation that occurs when a new population is established by a very small number of individuals from a larger population and/or are reproducibly isolated from the original population and/or subjected to different reproductive pressures
