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22 terms

genetics terminology

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gene
section of DNA that codes for a protein and determines a trait
trait
specific characteristic that varies from one individual to another
alleles
alternative forms of a gene
dominant
trait that will show up in an organism's phenotype if gene is present
recessive
trait that will only appear in the phenotype if organism inherits two of them; covered up by the dominant gene
segregation
separation of alleles during meiosis or gamete formation
gamete
sex cell; sperm or egg
hybrid
offspring of a cross between parents with different traits; heterozygous
true-breeding
inherited two identical alleles for a trait; homozygous or purebred
probability
likelihood an event will occur
phenotype
physical characteristics of an organism, observable or measurable
Punnett square
diagram that shows the possible results of a genetic cross; parents' gametes on top and left, offsprings' genotypes inside
genotype
genetic makeup of an organism
homozygous
has two identical alleles for a particular trait; true-breeding or purebred, ex. PP or pp
heterozygous
has two different alleles for a particular trait; hybrid, ex. Pp
independent assortment
principle that genes do not influence each other's inheritance because they are separated independently during meiosis
multiple alleles
three or more alleles exist for a particular trait
incomplete dominance
creates a blended phenotype; one allele is not completely dominant over the other
polygenic trait
trait controlled by two or more genes; shows a wide variety of phenotypes
codominance
both genes contribute to the phenotype of the organism, ex. spotted or striped
nondisjunction
error in meiosis in which homologous chromosomes don't separate; gametes end up with wrong number of chromosomes
sex-linked trait
trait related to a gene that is found on the X or Y chromosomes