Unit 4- Extensions and Mods of Basic Principles Flashcards
complete dominance
phenotypes of heterozygotes is same as phenotypes of 1 of the homozygotes
(red or white flowers)
incomplete dominance
phenotypes of heterozygotes is intermediate (fall in range) between 2 phenotypes of 2 homozygotes
(pink flowers)
codominance
phenotype of heterozygotes has both phenotypes of both homozygotes
(red and white speckled flowers)
CFTR
channel in the membrane that regulated chloride levels
- mutated in cystic fibrosis
- mutated channel stays closed, so chloride ions build up
- in heterozygotes, enough functional CFTR is made to prevent cystic fibrosis
penetrance
the % of indiv having a particular genotype that express the expected phenotype
expressivity
the degree to which a trait is expressed
multiple alleles
for a given locus, more than 2 alleles are present w/in a group of indiv
gene interaction
effects of genes at 1 locus depend on the presence of genes at other loci
- exhibit indep assortment, but do not act indep in their pheno expression
- the product of genes at diff loci interact to produce new pheno
(red pepper + cream pepper yield red, peach, orange, and yellow peppers)
epistasis
one gene masks the effect of another
recessive epistasis
9:3:4 F2
dominant epistasis
12:3:1 F2
duplicate recessive epistasis
9:7 F2
duplicate dominant epistasis
15:1 F2
complementation
determine whether mutations are at the same locus or at diff loci
test
parents homozygous for diff mutations are crossed; offspring are heterozygous
allelic
occur at same locus
if mutations are allelic:
heterozygous offspring have only mutant alleles. exhibit mutant pheno
if mutations occur at diff loci
heterozygous offspring inherit a mutant allele and a wild-type allele. Exhibit wild-type pheno
sex-influenced characteristics
pheno determined by autosomal genes that are more readily expressed in one sex (ex: beards in goats)
sex-limited characteristics
pheno determined by autosomal genes whose expression is limited to 1 sex
(ex: only sons have precocious puberty)
cytoplasmic inheritance
-present in males and females
- typically inherited from mom
- reciprocal crosses = diff results
- exhibit extensive phenotypic variation, even w/in family
(ex: mitochondrial DNA)
Genetic maternal effect
pheno affected by nuclear genotype of the maternal parent
epigenetics
phenomenon due to alteration to DNA that do not include changes in the base sequence; often affect the way in which the DNA sequences are expressed
genomic imprinting
- type of epigenetics
- differential expression of genetic material depending on whether it is inherited from the male or female parent
anticipation
a genetic trait becomes more strongly expressed or is expressed at an earlier stage as it is passed from gen to gen
- due to expansion of unstable region of DNA
temp-sensitive allele
an allele whose product is functional only at certain temp
discontinuous characteristics
relatively few phenotypes (ex: peas, fur color, etc)
continuous characteristics
continuous distribution of pheno; occurs when genes at many loci interact (ex: human height)
polygenetic characteristics
characteristics encoded by genes at many loci
pleiotropy
1 gene affects multiple characteristics
