Mutation
a mutation that occurs in a body cell
somatic mutation
gametes have one copy of each _________ and therefore one copy of each gene
chromosome
inheritance pattern where homozygous dominant and heterozygous display the same phenotype
complete dominance
in a dihybrid cross 2 genes found on different chromosomes are called
unlinked genes
environmental factor that causes natural selection to occur (eg drought, temperature change, predators)
selection pressure
the type of cell that carries out meiosis and its ploidy
haploid gamete
example of a gamete
sperm OR egg OR pollen
when a heterozygote has two dominant alleles expressed fully in phenotype
co-dominance
linked genes
when a small population is left behind from an originally larger population due to a catastrophe - making the population vulnerable to genetic drift
bottleneck effect
mutations create new
alleles
which process halves the number of alleles by separating allele pairs into separate chromosomes
segregation
when a heterozygote has a blend or mixture of the two alleles expressed as a new phenotype
incomplete dominance
what type of genes assort independently during meiosis (linked or unlinked)
unlinked genes assort independently - (because they are on independent chromosomes and chromosomes assort independently by independent assortment)
when a small population is randomly blown off course from an original population - making the population vulnerable to genetic drift
founder effect
mutations can create a new allele which results in a new________
phenotype
which process shuffles homologous chromosomes onto either side of the equator so each gamete receives a different mix of maternal and paternal chromosomes and different combinations of alleles
independent assortment
how many alleles constitute multiple alleles
3 or more
what is the expected phenotypic ratio of a dihybrid cross of two heterozygotes when genes are UNLINKED?
9:3:3:1
this stops two populations becoming genetically different from each other by sharing alleles between them
gene flow
How can a new mutation in one individual be lost from a gene pool, even if it's created an advantageous allele
Genetic drift, passing on the new mutation is 50:50 chance
the process where non-sister chromatids of homologous chromosomes touch and swap sections of DNA creating recombinant chromosomes with new combinations of alleles
crossing over
what type of monohybrid inheritance often results in a 2:1 genotypic and phenotypic ratio due to loss of an embryo
lethal alleles
What is the genotype of the gametes that each parent in this cross can make - RrTt X RRtt
RrTt =RT, rT, Rt rt
RRtt = all Rt
Natural selection acts on variation. Why can a new advantageous gene variant be lost from a small population before it is selected for?
Genetic drift acts faster than natural selection, which can take many generations to increase a genes frequency in a population.