Mendelian Genetics Gregor Mendel Austrian monk and scientist

Gregor Mendel Austrian monk and scientist called the “Father of Genetics” Did work in

Sexual reproduction Gene = small piece of DNA located on the chromosome that codes

What type of alleles can parents pass on? Dominant Allele = an allele that

Alleles Homozygous = “Pure Breed” 2 alleles are the same for the trait •

Phenotype = Physical appearance of offspring EX: Tall Genotype = The genetic make up

PHENOTYPE TALL pea plant X SHORT pea plant ALL TALL Pea plants 3 TALL

PUNNETT SQUARES GENOTYPE T PHENOTYPE T ______TALL PLANTS t ______SHORT PLANTS t Ratio=

GENOTYPE T PHENOTYPE t ______TALL PLANTS T ______SHORT PLANTS t

TEST CROSS: When an unknown genotype crosses with a known homologous recessive individual.

INCOMPLETE DOMINANCE: • Trait is not dominant or recessive Trait is expressed mid-way

CO-DOMINANCE: both alleles or traits are fully expressed, if present • Examples: 1.

Multiple Alleles Genes with more than two alleles (options) • Example--Blood Type (A, B,

PEDIGREE PEDIGREE= chart of the genetic history of a family over several generations •

Slides: 17

Download presentation

Mendelian Genetics

Gregor Mendel Austrian monk and scientist called the “Father of Genetics” Did work in the 1860’s on pea plants Used math to tackle questions of genetics He did not get recognition until after his death

Sexual reproduction Gene = small piece of DNA located on the chromosome that codes for the trait EX: Hair color gene Allele = Possible version of a gene EX: Blond hair or brown hair In sexual reproduction, each parent gives ONE allele for each trait. Therefore, offspring have TWO alleles for the trait.

What type of alleles can parents pass on? Dominant Allele = an allele that is expressed, if present • upper case T Recessive Allele = an allele that is not expressed when with a dominant allele • lower-case t

Alleles Homozygous = “Pure Breed” 2 alleles are the same for the trait • Ex: AA or aa Heterozygous = “Hybrid” 2 alleles are different for a trait • Ex: Aa

Phenotype = Physical appearance of offspring EX: Tall Genotype = The genetic make up of the offspring, the alleles involved Ex: T t

PHENOTYPE TALL pea plant X SHORT pea plant ALL TALL Pea plants 3 TALL pea plants & 1 SHORT pea plant

PUNNETT SQUARES GENOTYPE T PHENOTYPE T ______TALL PLANTS t ______SHORT PLANTS t Ratio=

GENOTYPE T PHENOTYPE t ______TALL PLANTS T ______SHORT PLANTS t

TEST CROSS: When an unknown genotype crosses with a known homologous recessive individual. ? Rr = Round = 50% rr = Wrinkled = 50% r r ?

INCOMPLETE DOMINANCE: • Trait is not dominant or recessive Trait is expressed mid-way • Heterozygous individuals show a phenotype that is in between that of the 2 alleles White parent X Red parent Pink offspring! W R R W

CO-DOMINANCE: both alleles or traits are fully expressed, if present • Examples: 1. Red cow X White bull Roan offspring (Roan = Red and White) R W W R

Multiple Alleles Genes with more than two alleles (options) • Example--Blood Type (A, B, O, AB) (4 alleles) IAi (OR) IAIA =TYPE A IBi (OR) IBIB =TYPE B IAIB =TYPE AB ii =TYPE O

Blood Type i IA IB IB i IA i i

PEDIGREE PEDIGREE= chart of the genetic history of a family over several generations • Used to determine who has a specific trait or disorder • Can help figure out the genotype of family A= Normal Skin Pigment a = Albino

PEDIGREE