topic 6.1.2: patterns of inheritance Flashcards
what causes phenotypic variation
genetics and environment
what causes genetic variation
sexual reproduction
crossing over (prophase 1) independent assortment of homologous chromosomes (metaphase 1) random fusion of gametes
what is monohybrid inheritance
characteristics determined by one gene
what is dihybrid inheritance
characteristics determined by two genes
what is codominance
both alleles expressed in heterozygote resulting in different phenotype
what is multiple alleles inheritance
more than two alleles for a single gene
what is sex linkage
genes with locus on x or y chromosome
what is autosomal linkage
genes with locus on same chromosome
what is epistasis
one gene modifies or masks the expression of another at a different locus
what is directional selection
an extreme is selected, occurs due to change in env
what is stabilising selection
modal trait selected, reduces sd
what is speciation
reproductive isolation of members of an original population
what is allopatric speciation
geographical separation, both pops select beneficial mutations
what is sympatric speciation
isolation due to behavioural differences eg diffs in courtship behaviour
what is genetic drift
random mutation causes change in allele frequency, causing natural selection
what is a genetic bottleneck
large pop suffers dramatic fall in numbers causing small gene pool
what is the founder effect
few individuals relocate to isolated area causing small gene pool
what affects allele frequency
mutations, sexual selection, gene flow, genetic drift
what is artificial selection
humans select organisms with desirable characteristics and breed them, manipulating gene pool
what are the risks of inbreeding
increases chance of recessive genetic disorders, decreases genetic diversity
