Unit 4 Flashcards
homozygous
an organism with two identical alleles
examples: AA; aa
heterozygous
an organism with two different alleles
examples: Aa; Ba
karyotype
the complete set of chromosomes in a cell/organism
(see cut & paste worksheet)
recessive trait
the weaker, non-expressed trait that is only represented when there is no dominant trait present
(little letters)
blood type chart
Type A AA, AO
Type B BB, BO
Type AB AB
Type O OO
allele
matching genes, one from mom one from dad; organisms have two copies of every gene
genotype
genetic makeup of an organism; an organism’s combination of alleles
example: Aa
phenotype
an organism’s physical appearance/visible traits
example: hair color
codominance
when neither allele dominates over the other; both are expressed equally
result: both traits are shown separately without mixing together
dominant trait
an allele that blocks another allele because it is more “powerful.”
example: Aa
(usually a capital letter)
incomplete dominance
when one allele is not completely dominant over the other, resulting in both traits blending/mixing.
example:
B = black fur
W = white fur
so together, BW = gray fur
sex-linked traits
a trait determined by a gene that was transferred to the offspring by the mother or father
punnent square
a chart showing all possible combinations of alleles that can be the result of a genetic cross of two parents
hemophilia
a hereditary disease where bleeding is extremely hard to stop
carrier of hemophilia has a small “h” allele, homozygous for hemophilia has two small “h” alleles
examples:
male = XhY
female = XhXh (homozygous); XHXh (carrier)
a hemophiliac woman has a phenotypically normal mother. what are the genotypes of the woman’s mother and father?
mother: XHXH
father: XhY
