Human Genetics Unit 2 pt. 1

Chapter 4-5

autosomal dominant

the mode of inheritance in which one autosomal allele causes a phenotype. Such a trait can affect males and females and does not skip generations

autosomal recessive

the mode of inheritance in which two autosomal alleles are required to cause a phenotype. Such a trait can affect males and females and can skip generations

compound heterozygous

an individual w/ two different recessive alleles in the same gene

consanguinity

blood relatives having children together

dihybrid cross

breeding individuals heterozygous for two traits

heterozygous

having two different alleles of a gene

homozygous

having identical alleles of a gene

mode of inheritance

pattern in which a gene variant passes from generation to generation. It may be dominant or recessive, autosomal, or X- or Y-linked

monogenic

a trait caused by mutations in a single gene

monohybrid cross

a cross of two individuals who are heterozygous for a single gene

mutant

an allele that differs from the most common allele in a population and alters the phenotype

punnett square

a diagram that follows and combines parental gene contributions to offspring

segregation

mendels first law, which states that the alleles of a gene are distributed into separate gametes during meiosis

test cross

breeding an individual of unknown genotype with a homozygous recessive individual to deduce the unknown genotype from observing the traits of the offspring

wild type

the most common phenotype in a population for a particular gene

antigen

a molecule that elicits an immune response

centimorgan

a unit that indicates percent recombination between two loci linked on a chromosome, serving as a measure of relative distance

codominant

form of gene expression where both alleles are fully expressed in heterozygous

epistasis

a gene masking or affecting the expression of another

expressivity

severity or degree of a phenotype

genetic heterogeneity

a phenotype that can be caused by variants of any of several genes

genetic marker

a DNA sequence near a gene of interest that is co-inherited unless separated by a crossover

haplotype

a series of genes linked on a chromosome that do not separate by crossing over

heteroplasmy

mitochondria in the same cell with different allels of a gene

incomplete dominance

a form of gene expression that results in a heterozygous intermediate in phenotype between either homozygote

linkage

genes on the same chromosome

linkage disequilibrium

a consequence of extremely tight linkage between DNA sequences in which two genes or DNA sequences are nearly always inherited together

linkage maps

diagrams that show gene order on chromosome, determined from crossover frequencies between pairs of genes

penetrance

percentage of individuals with a genotype who have an associated phenotype

phenocopy

an environmentally caused caused trait that occurs in a familial pattern, mimicking inheritance

pleiotropic

a single gene disease w/ several sypmtoms or a gene that controls several functions or has more than one effect, causing different sypmtom subsets in different individuals

recombinant

a series of alleles on a chromosome that differs from the series of either parent