Mendel inheritance Flashcards
genetic character
heritable feature such as flower color that varies among individuals
genetic trait
variant for a character such as purple or white flower color
mendel hybridization
crossing of two true breeding varieties of traits
True breeding generations
P generation is parental generation; F1 generation is first generation which is hybrid
character inheritance
an organism inherits two alleles; one from each parent
law of segregation
two alleles for a heritable character separate during gamete formation and end up in different gametes
testcross
breeding of a recessive homozygote with a dominant phenotype but unknown genotype
monohybrids
heterozygous for one character
dihybrid
heterozygous for two characters
dihybrid cross
a cross between F1 hybrids to determine assortment
law of independent assortment
each pair of alleles segregate independently of other pairs of alleles during gamete formation
complete dominance
F1 plants always looked like one of the two parental varieties of one allele over another
codominance
two alleles both affect the phenotype in separate distinguishable ways
incomplete dominance
alleles for some characters fall in the middle of the spectrum of dominance
blood transfusion
if a type A person receives blood from a type B or type AB donor, the recipients immune system recognizes the foreign B substance and attacks them
peiotropy
most genes have multiple phenotypic character effects
epistasis
gene at one locus alters the phenotypic expression of a gene at a second locus
polygenic inheritance
additive effect of two or more genes on a single phenotypic character; skin pigmentation in humans is controlled by at least 3 separately inherited genes
segragation stage
alleles segregate from each other during anaphase I of meiosis
linked genes
genes located on the same chromosome that tend to be inherited together in genetic crosses
recombinants
offspring have new combinations of traits that produce a different phenotype from the parent
genetic map
ordered list of genetic loci along a particular chromosome
centimorgans
originally map units; distance between genes; one map unit equals 1% recombination frequency
cytogenetic maps
locate genes on chromosomoes by comparing features such as stained bands
X chromosome mosaicism
some cells have active X from the father and others have active X from the mother
Barr body
the inactive X in each cell of a female condenses into a compact object
tortoiseshell cat
only females can have this fur coloration because of the X inactivation
nondisjunction
members of a pair of homologous chromosomes do not move apart properly during meiosis I or sister chromatids fail to separate during meiosis II
aneuploidy
an aberrant gamete unites with a normal one at fertilization, offspring will have an abnormal number of a particular chromosome
