A gene = a length of DNA that helps code for a protein’s primary-structure polypeptide sequence

A locus = the chromosomal position where a particular gene can be found (always the same per gene)

An allele = a particular variant of a specific gene that can be dominant, recessive, or co-dominant

A dominant allele = an allele that affects heterozygous and homozygous phenotypes equally (ie. only one copy of it is required in the genotype)

A recessive allele = an allele that only affects homozygous phenotypes without a dominant allele in them (ie. two copies of it are required in the genotype)

Two co-dominant alleles = alleles that both affect heterozygous phenotypes equally

Linkage = when two genes are on the same chromosome so they can be inherited together instead of being independently assorted

Test crosses = genetic crosses where organisms with dominant allele-produced phenotypes are crossed with homozygous recessive-phenotype ones to produce offspring that can help determine if the organism w/ the dominant allele’s heterozygous or homozygous dominant

F1 = the resultant offspring of a cross between a homozygous dominant-phenotype organism and a homozygous recessive-phenotype one

F2 = the resultant offspring of a cross between two heterozygous F1 organisms

A phenotype = a set of organismal characteristics often caused by genotype-environment interactions

A genotype = a set of alleles possessed by an organism

Homozygosity = when two identical alleles of a gene are present in an organism

Heterozygosity = when two different alleles of a gene are present in an organism