checkpoint 2 Flashcards
What is genetic drift
The change in allele frequency due to chance
Genetic drift is particularly important if the population is small because in large populations the frequency of alleles tends to remain stable.
Genetic biodiversaty
Individuals living in a population share a gene pool, which is the number, type and variety of all the alleles present in a population.
Genetic biodiversity is a measure of the different genetic combinations within a gene pool.
The amount of genetic biodiversity, or genetic variation within a population may affect the likelihood of survival of that population.
Natural selection
Natural is a process whereby organisms better adapted to their environment tend to survive and produce more offspring.
Migration/gene flow
Migration occurs when individuals move into (immigration) or out of (emigration) a population.
When the migrating individuals interbreed with the population, they contribute their alleles to the genepool of the local population, distribute favourable mutations and reduce genetic variation between populations.
A high rate of migration can have a significant effect on the allele frequencies of both the population they leave, and the population they enter. In small populations, migration can have a major effect on allele frequency.
Founder effect
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
bottleneck effect
Population bottleneck is an event that drastically reduces the size of a population causing a decrease in the genetic diversity
COmplete dominace
A dominat allele can fully mask a recessive alle
INcomplete dominace
Alleles are expressed equally and together as an intermediate
co-domimance
both alleles are equally dominat and therfore express at the same time individually
linked genes independent assortsment
Independetn assortment does not affect linked genes as it only results in a random combination of chormosomes not qalleses
Independent assortment
When homologous pairs of chromosomes line up randomly along the quator of the cell during metapahse I
crossing over
Crossing over happens during prohpahse I when nonsister chormotifs of homologous paris form a chaisma. This is where genetic information is swapped
Segregation
Segregation is the process when allels are seperated into different gametes duering sexual reproduction
how many chromosomes do we have
46
how many chromosones do gametes have
23
Sex linkage
X-linked recessive: Males are more likely to express X-linked recessive traits because they only have one X chromosome, so a single copy of the recessive allele is sufficient for expression.
X-linked dominant: X-linked dominant traits can affect both males and females, but females are more likely to be affected because they have two X chromosomes.
Y-linked: Y-linked traits are passed down from fathers to sons, as only males have a Y chromosom
