Genes and Herdity

Herdity

passing of traits from parents to offspring

Gentics

the study of the patterns of inheritance as heredity chracteristics or traits

Gregor Mendel

-the “father of modern genetics”

-an austrian monk

-published his new ideas of inheritance in 1866

Law of Segregation

during gamete formation, the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene

Law of independent assortment

genes for different traits can segregate independently during the formation of gametes

Law of dominance

some alleles are dominant while others are recessive; an organism with at least one dominant allele will display the effect of it

Trait

any characteristic that can be passed from parent to offspring

Alleles

alternate forms of genes which produce contrasting effects for a certain trait

Dominant

-stronger of two genes expressed in a hybrid

-represented by a capital letter

Recessive

-gene that shows up less often in a cross

-represented by a lowercase letter

Genotype

the genetic makeup of an individual

Phenotype

the physical expression of the genes

Purebred (true breding)

an organism having all homozygous gene pairs

Homozygous

having two of the same alleles

Heterozygous

having two different alleles

Monohybrid heterozygous x heterozygous ratio

3:1 (phenotypic)

Monohybrid heterozygous x homozygous recessive ratio

1:1 (phenotypic)

Dihybrid heterozygous x heterozygous ratio

9:3:3:1

Mulitiple alleles

-when traits are determined by more than two alleles

-not just dominant and recessive

Wild type

the most commonly seen trait

Mutant

non-wild-type trait

Incomplete Dominance

when two alleles are equally dominant and interact to produce a new blended phenotype

Codominance

-both alleles are fully expressed in a heterozygous individual

-one of the alleles is turned off in each cell

Sex-linked trait

genes located on the x chromosome