Dominant – expression that is always expressed when its gene
recessive - An expression that is expressed only when its allele is the only form of the gene present in the genotype.
incomplete dominance - Neither allele is dominant to the other, thus each is expressed in the heterozygous genotype producing an intermediate phenotype. EX. Red (RR) and White (R’R’) snapdragons produce pink (RR’).
epistasis - A condition in which one gene pair has the ability to mask or prevent the expression of another gene pair. EX. Coat color and pigment deposition in mice.
co-dominance - Inheritance characterized by full expression of both alleles in the heterozygote. Ex. Short HornCattle. Red (RR), Roan (RR’), White (R’R’)
homozygous – condition where both genes are the same (AA or aa)
heterozygous – condition where genes are different (Aa)
alleles – different forms of the same gene (Aa)
mutation – a change in the nucleotide sequence of an organism’s DNA or in the DNA or RNA of a virus
locus – location of the gene on the chromosome
gene - The unit of DNA along a chromosome that codes for a single characteristic, unit of dna that codes for a specific polypeptide
synapsis - Pairing of homologous chromosomes called
cross-over - The exchange or mixing of similar genetic material (genes) is called
chiasmata - There is a criss-crossing of the non-sister chromatids called
gene – unit of dna that codes for a specific polyeptide or characteristic
karyotype - A display of metaphase chromosomes in which homologues are paired together and photographed.
non-disjunction – an error in meiosis or mitosis in which members of a pair of homologous chromosomes or a pair of sister chromatids fail to separate properly from eachother
pleiotrophy - The ability of a single gene pair to have multiple effects. EX. Gene for Sickle-cell Anemia.
Polyploidy – a chromosomal