Ch 5 Extensions and Modifications of Basic Principles Flashcards
heterozygote has the same phenotype as one homozygote
complete dominance
heterozygote has phenotype intermediate between those of two parental homozygotes
incomplete dominance
heterozygote exhibits traits of both parental homozygotes simultaneously
codominance
phenomenon where the genotype does not always produce the expected phenotype
incomplete penetrance
the percentage of individual organisms having a particular genotype that express the expected phenotype
penetrance
the degree to which a trait is expressed
expressivity
allele that causes death at an early stage of development
lethal allele
what ratio is produced by a recessive lethal allele
2:1 ratio (heterozygote:homozygous recessive)
loci where more than two alleles are present
multiple alleles
how do you determine the number of possible genotypes in a locus with multiple alleles
[n(n+1)/2]; n = # of different alleles at a locus
what is gene interaction?
interaction between effects of genes at different loci
interaction of gene that hides the effect of another gene at a different locus
epistasis
the gene who does the masking
epistatic gene
the gene whose effect is masked
hypostatic gene
describe recessive epistasis; what’s the ratio?
recessive allele at a second locus masks the effect of alleles at the first locus; two recessive alleles must be present
9:3:4
describe dominant epistasis; what’s the ratio?
dominant allele at a second locus masks the effect of alleles at the first locus; only one allele required to be present
describe duplicate recessive epistasis; what’s the ratio?
two recessive alleles at either of two different loci are capable of suppressing a phenotype
9:7
what is the ratio for duplicate dominant epistasis?
15:1
what is the ratio for duplicate interaction epistasis?
9:6:1
characteristics determined by autosomal genes, but are expressed differently in males and females
sex-influenced characteristics
characteristics encoded by autosomal genes but expressed only in one sex
sex-limited characteristics
characteristics encoded by genes located in the cytoplasm
cytoplasmic inheritance
how are cytoplasmic inherited traits usually passed down
they are usually passed from mother to offspring
describe the genetic maternal effect
the phenotype of offspring are determined by the genotype of the mother
what is genomic imprinting
differential expression of genetic material depending on whether it is inherited from the male or female parent
describe anticipation
a genetic trait becomes more strongly expressed or expressed earlier as it is passed down from generation to generation
an allele whose product is functional only at certain temperatures
temperature-sensitive allele
