Genetics Visual Vocabulary Chromosomes These carry genes that

Genetics Visual Vocabulary

Chromosomes These carry genes that determine the sex of offspring as well as other traits; it is made up of DNA and protein

DNA The directions or blueprints of life; made up of subunits called nucleotides

Gene a string of nucleotides that give the cell information on how to make a specific trait; these are located on chromosomes

Trait • A characteristic that can be passed from parent to offspring. Trait A Trait B

Allele The different forms of a gene.

dominant Kind of trait that always appeared in the offspring produced in Mendel’s first experiment; that trait that appears more often.

recessive Kind of trait that seemed to vanish in the offspring produced in Mendel’s first experiment; the trait that seems to reappear in the second generation; usually indicated by a lower case letter

phenotype An organism’s inherited physical appearance (descriptions)

genotype The combination of alleles (letters) GG, Gg, or gg

heterozygous The combination of two different alleles for an inherited trait

homozygous The combination of two of the same alleles for an inherited trait

probability that mathematical chance that an event will occur Ratio: 3: 1 or percent: 75% or fraction 1/4

Punnett Square A tool used to visualize all the possible combinations of alleles from parents

Mendelian dominance • recessive alleles will always be masked by dominant allele Therefore, a cross between a homozygous dominant and a homozygous recessive will always express the dominant phenotype, while still having a heterozygous genotype.

Incomplete dominance • a form of intermediate inheritance in which one allele for a specific trait is not completely expressed over its paired allele. This results in a third phenotype in which the expressed physical trait is a combination of the phenotypes of both alleles