MENDELIAN GENETICS

Unit Four

Gregor Mendel•Discovered principals of genetics

•Used peas to prove his inheritance theory

•Before Mendel, people thought you were a blend of you parents (blending theory)

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VocabularyALLELE- an alternate form of the same geneGENOTYPE-A letter for the alleleDOMINANT ALLELE- Capital letter, “masks” a recessive alleleRECESSIVE ALLELE- lower case letter, only expressed if both are recessivePHENOTYPE- Physical characteristics

Hair Color (trait)

Hair Color (trait)Brown hair(allele)

Blonde hair(allele)

T t

GenotypeT t t tT T

Homozygous Dominant

Heterozygous Homozygous Recessive

T t t tT T

Blonde Hair Blonde Hair Red Hair

Phenotype

Types of Inheritance 1. Dominant and Recessive

•Monohybrid cross•Dihybrid cross

2. Sex linked inheritance3. Codominance 4. Incomplete dominance

Dominant and Recessive• Inheriting genes on chromosome 1-22-called autosomes• Use upper case and lower case letters• Monohybrid and dihybrid crosses• AA, Aa, aa (monohybrid)• AABb (dihybrid)

Sex-Linked Inheritance• Inheriting genes through sex chromosome X• Y chromosomes does not contain many Alleles• XAXa, XaY