Mendelian Genetics

Chromatin in a Normal Cell (one length from each parent) Allele A version of a gene Dominant Allele that may mask the presence of another Recessive Allele that may be masked by another Heterozygous The 2 alleles are different Homozygous The 2 alleles are identical F Free f Attached Earlobe Gene a Albino Melanin Gene a albino P Extra Fingers Polydactyly Gene ♂ ♀

Chromatin in a Normal Cell (one length from each parent) Genotype The set of alleles an organism possesses Phenotype The genetic outcome resulting from the genotype F Free f attached Earlobe Gene a albino Melanin Gene a albino P Extra Fingers Polydactyly Gene ♂ ♀

Inheritance f F f F F f F f

Exact copies Pure bred parents PP x pp What will the F1 offspring look like? Phenotype = 100% Purple Genotype = 100% Heterozygous P p What will the F2 offspring look like? Phenotype = 75% Purple 25% white Genotype = 100% Homo. Dominant, 50% Hetero., 25% Homo. Recessive

Dihybrid Cross GgYy GY Gy gY gy GY PHENOTYPE G-Y- : 9 G-yy : 3

Law of segregation: two alleles for a trait separate when gametes are formed Law of Independent assortment: Alleles of different genes separate independently of one another during gamete formation

Codominance Both alleles are detectable in a specimen Gene: Cattle coat color Alleles CR = red CW = White Genotypes CRCR = red coat CWCW = white coat CRCW = roan coat

Multiple Alleles More than two alleles exist for a gene Human Blood Type IA = Type A carbs on RBC surface IB = Type B carbs on RBC surface i = Neither type on RBC surface

Multiple Alleles Blood Type Genotype Antibodies Universal Acceptor Universal Donor

Linked Genes

Human Genetics

Dominance Brown over Blue over Green Polygenic Chrom.15 Chrom.19

Sex linked: traits are tied to X or Y Xr XR Y XR Y XR XR Xr XR Y XR XR XR XR Xr Y XR Xr Xr XR Xr XR Y

Sex linked: traits are tied to X or Y Color blindness:males Recessive x linked Abnormal production of pigment(protein) Does not absorb red green light Y Xr XR Y XR Y XR XR Xr XR Y XR XR XR XR Xr Y XR Xr Xr XR Xr XR Y

Sex influenced Trait not tied to sex chromosome Autosomal chromosome produces protein which affects the production of other proteins. Testosterone affects the production and location of hair in males.

Patterns of Inheritance Polygenic: Eye color, skin color, height Complex characters: Skin color=sun, Multiple alleles: Blood type Incomplete Dominance: Red x White= Pink X-linked: Color blindness, fruit fly eyes Sex influenced: Male pattern baldness Single alleles: Huntington’s disease,