Genetics

Created by mrsj147 Teacher

22 terms · Genetics Terms for FMS 8th Grade Science

gene

section of DNA that codes for a protein and determines a trait

trait

specific characteristic that varies from one individual to another

allele

form 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

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

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