Biology - Genetic Variation Flashcards
Punnett Square
A prediction in the phenotypes of an organism from known/possible genotypes
Homologous Chromosomes
Pairs of chromosomes containing the same genes at the same loci
Genome
All of an organism’s genes
Bottleneck effect
Reduction of genetic diversity
A population is suddenly reduced to few individuals
Speciation
A species diverging into 2 or more species over time
Independent assortment
Homologous chromosomes line up at a random order at the equator cell in meiosis
How does independent assortment lead to genetic variation?
Increased number of unique gametes/sex cells, maternal & paternal chromosomes are seperated
How does the bottleneck effect affect genetic diversity?
Gene pool decreases, less individuals to breed with, decreasing genetic variation
Segregation
One allele goes into each gamete. Seperation of homologous chromosomes
How does segregation affect genetic variation?
The dominant and recessive traits are split up, ensuring that the recessive is able to be shown. Each gamete has a different combo of alleles.
Gene flow
Exchanging of alleles between different populations of a species
Founder effect
Few individuals within a larger population move away, starting a smaller population
How does the founder effect affect genetic diversity?
Smaller gene pool, fewer allele frequencies
Genetic drift
Random changes in allele frequencies within a gene pool
How do linked genes decrease genetic variation?
(Independent assortment, crossing over, segregation)
- Can’t independently assort and will be inherited together
- Crossing over can seperate linked genes due to large distance between loci
- Segregation doesn’t seperate linked genes, so will both end up in the same gamete
How does a gametic mutation lead to a new allele?
A mutation has to occur in the gametes to be passed down, not the somatic cells, as those mutations don’t get passed down to offspring.
When a population is facing hardships & humans intervine (translocation)
The species will continue facing hardship, with inbreeding, etc.
Genetic variation
Variety of alleles present in a gene pool
What does natural selection lead to?
Increased frequencies of favourable alleles, decreased frequencies of unfavourable alleles.
Variation in gametes
New alleles aren’t being produced from parent cells (no new genetic info) but the combinations are different.
Why are mutations the ultimate source of gen variation?
They introduce entirely new alleles into a population
Different phenotypes in different environments
One is favourable in one climate, where the other one is favourable in the other
Impacts that death, migration, have on small/big populations
Death has a bigger impact on small populations, but has little effect of large pops. This leads to alleles being lost, decreased gen var. Same for immigration
