SC.912.L.16.1-SC.912.L.16.2 Intro to Genetics; Inheritance and Mendelian Genetics

P generation

Parental generation, the first two individuals that mate in a genetic cross

F1 generation

the first generation of offspring obtained from an experimental cross of two organisms (the results of a P generation)

F2 generation

Offspring resulting from interbreeding of the hybrid F1 generation.

Punnet Square

A chart that shows all the possible combinations of alleles that can result from a genetic cross

law of segregation

Mendel's law that states that the pairs of homologous chromosomes separate in meiosis so that only one chromosome from each pair is present in each gamete

law of independent assortment

the law that states that genes separate independently of one another during meiosis

allele

An alternative form of a gene. (ex. a gene can code for blue or brown, each would be an allele of a gene)

dominant

Describes a trait that covers over, or dominates, another form of that trait.

recessive

An allele that is masked when a dominant allele is present, it can only be seen in a homozygous state

homozygous

An organism that has two identical alleles for a trait

heterozygous

An organism that has two different alleles for a trait

codominance

A condition in which neither of two alleles of a gene is dominant or recessive. They both show up evenly.

incomplete dominance

Situation in which one allele is not completely dominant over another allele, instead, they mix their alleles

multiple allele

A gene that has more than two alleles (for example, hair color: brown, red, black, blonde, etc)

polygenic

trait controlled by two or more genes

sex-linked

gene located on the X or Y chromosome

Gregor Mendel

Father of genetics

genotype

genetic makeup of an organism (the code)

phenotype

An organism's physical appearance, or visible traits determined by its genotype

genetics

The scientific study of heredity

carrier

A person whose genotype includes a gene that is not expressed in the phenotype. (a person who has an invisible recessive allele)

inbreeding

Continued breeding of individuals with similar characteristics

pedigree

A diagram that shows the occurrence of a genetic trait in several generations of a family.

dihybrid cross

Cross or mating between organisms involving two pairs of contrasting traits

trihybrid cross

a cross involving three traits

probability

A number that describes how likely it is that a certain genotype or phenotype will occur