Genetics -USBT JWK

Genetics

a field of biology devoted to understanding how characteristics are transmitted from parents to offspring

Heredity

the transmission of characteristics from parents to offspring

Trait

genetically determined variant of a characteristic, such as flower color

Self-Pollination

pollen is transferred from the anthers of a flower of the stigma

True-Breeding

pure for a trait always produce offspring with that trait when they self-pollinate

P Generation

The parental generation in a genetic cross.

F1 Generation

offspring of the P generation, the first full filial generation

F2 Generation

offspring of the F1 generation, the second filial generation

Dominant

factor named because it masked , or dominated, the factor for the other trait in the pair

Recessive

factor that seemingly vanished , or is hidden, the by another factor. Can often reappear in later generations/

Law of Segregation

factors (alleles) separate independently of one another during the formation of gametes if they are located on separate chromosomes.

Law of Independent Assortment

Genes separate independently from one another in meiosis

Allele

each of two or more alternative forms of gene

Genotype

an organisms genetic makeup

Phenotype

an organisms appearance or expression of a characteristic

Homozygous

both alleles of a pair are alike

Heterozygous

when two alleles in the pair are different

Probability

the likelihood that a possible future event will occur in any given instance of the event

Monohybird Cross

a cross in which only one characteristic is tracked

Punnet Square

diagram to aid in predicting the probable distribution of inhered traits in the offspring

recessive allele

represented by a lower case letter

Testcross

an individual of unknown dominant genotype is crossed with a homozygous recessive individual

Genotypic Ratio

the ratio of genotypes that appear in the offspring of a cross

Phenotypic Ratio

the ratio of phenotypes produced by a cross

Complete Dominance

a relationship, one allele was completely dominant over another

Incomplete Dominance

the F1 offspring will have a intermediate (blend) phenotype in between the parents

Codominance

occurs when both alleles for a gene are expressed in a heterozygous offspring

Dihybrid Cross

is a cross in which two characteristics are tracked

Multiple Alleles

genes with 3 or more alleles. i.e. blood type

polygenic

characteristics that are influence by several genes. i.e. skin color.

genetic disorder

diseases or disabling conditions that have a genetic basis.

Pedigree

a diagram used to show how a trait is inherited over several generations.

sex-linked trait

a trait coded for on the sex chromosomes (X or Y)