bio lecture 23 pedigrees and sex linked inheritance + lecture 24 dominance and environment

“family tree”

pedigree

autosomal recessive

cannot be dominant as unaffected parents could have an affected offspring, parents must be heterozygous

loss of function alleles are usually —— to wildtype

recessive

gain of function of alleles are usually —- to wildtype

dominant

autosomal dominant

cannot be recessive as affected parents couldn’t have an unaffected offspring

XY

male

XX

female

sex-linked genes

genes found on one sex chromosome but not the other

hemizygous

individual with only one copy of a particular gene

in a XY male, the x is inherited from the —— and y is inherited by the ——-

x inherited by mother, y inherited by father

XX female inhales an X from…

each parent

x - linked dominant

never passed from father to sons, all daughter of an affected father will have the disorder

x-linked recessive

can be hidden in heterozygous XX females, more frequent in XY males, never passed from father to sons

mendelian inheritance

phenotype determine by a single gene, two variants with one dominant and one recessive, dominant allele is completely dominant

incomplete dominance

phenotype of heterozygote displays phenotype between homozygous dominant and homozygous recessive

incomplete dominance occurs because…

neither allele is dominant over the other

codominance

two dominant alleles, both affect phenotype

multiple alleles

3 or more variants in gene

norm of reaction

phenotype range individuals with a particular genotype exhibit under differing environmental conditions