NonMendelian Genetics Mendelian Genetics Dominant Recessive Review v

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Non-Mendelian Genetics

Non-Mendelian Genetics

Mendelian Genetics: Dominant & Recessive Review v One allele is DOMINANT over the other

Mendelian Genetics: Dominant & Recessive Review v One allele is DOMINANT over the other (because the dominant allele can “mask” the recessive allele) genotype: PP genotype: pp genotype: Pp phenotype: purple phenotype: white phenotype: purple

Review Problem: Dominant & Recessive v In pea plants, purple flowers (P) are dominant

Review Problem: Dominant & Recessive v In pea plants, purple flowers (P) are dominant over white flowers (p). Show the cross between two heterozygous plants. GENOTYPES: - PP (25%) Pp (50%) pp (25%) - ratio 1: 2: 1 PHENOTYPES: - purple (75%) white (25%) - ratio 3: 1 P p P PP Pp pp

Non-Mendelian Genetics v. Incomplete Dominance v. Codominance v. Multiple Alleles v. Polygenic Traits v.

Non-Mendelian Genetics v. Incomplete Dominance v. Codominance v. Multiple Alleles v. Polygenic Traits v. Sex-Linked Traits

Incomplete Dominance v a third (new) phenotype appears in the heterozygous condition as a

Incomplete Dominance v a third (new) phenotype appears in the heterozygous condition as a BLEND of the dominant and recessive phenotypes. Ex - Dominant Red (R) + Recessive White (r) = Hybrid Pink (Rr) RR = red rr = white Rr = pink

Problem: Incomplete Dominance v Show the cross between a pink and a white flower.

Problem: Incomplete Dominance v Show the cross between a pink and a white flower. GENOTYPES: - RR (0%) Rr (50%) rr (50%) - ratio 1: 1 R r r Rr rr PHENOTYPES: - pink (50%); white (50%) - ratio 1: 1

Codominance v in the heterozygous condition, both alleles are expressed equally with NO blending!

Codominance v in the heterozygous condition, both alleles are expressed equally with NO blending! Represented by using two DIFFERENT capital letters. v Example: Dominant Black (B) + Dominant White (W) = Speckled Black and White Phenotype (BW) v Sickle Cell Anemia - NN = normal cells SS = sickle cells NS = some of each

Codominance Example: Speckled Chickens v. BB = black feathers v. WW = white feathers

Codominance Example: Speckled Chickens v. BB = black feathers v. WW = white feathers v. BW = black & white speckled feathers v. Notice – NO GRAY! NO BLEND! Each feather is either black or white

Codominance Example: Rhodedendron v R = allele for red flowers v W = allele

Codominance Example: Rhodedendron v R = allele for red flowers v W = allele for white flowers v Cross a homozygous red flower with a homozygous white flower.

Codominance Example: Roan cattle vcattle can be red (RR – all red hairs) white

Codominance Example: Roan cattle vcattle can be red (RR – all red hairs) white (WW – all white hairs) roan (RW – red and white hairs together)

Codominance Example: Appaloosa horses v Gray horses (GG) are codominant to white horses (WW).

Codominance Example: Appaloosa horses v Gray horses (GG) are codominant to white horses (WW). The heterozygous horse (GW) is an Appaloosa (a white horse with gray spots). v Cross a white horse with an appaloosa horse. W W G GW GW W WW WW

Problem: Codominance v. Show the cross between an individual with sickle-cell anemia and another

Problem: Codominance v. Show the cross between an individual with sickle-cell anemia and another who is a carrier but not sick. N S GENOTYPES: - NS (50%) SS (50%) - ratio 1: 1 S NS SS PHENOTYPES: - carrier (50%) sick (50%) - ratio 1: 1 S NS SS

Multiple Alleles vthere are more than two alleles for a gene. Ex – blood

Multiple Alleles vthere are more than two alleles for a gene. Ex – blood type consists of two dominant and one recessive allele options. Allele A and B are dominant over Allele O (i)

Multiple Alleles: Lab Mouse Fur Colors v. Fur colors (determined by 4 alleles): black

Multiple Alleles: Lab Mouse Fur Colors v. Fur colors (determined by 4 alleles): black agouti yellow

Multiple Alleles: Rabbit Fur Colors v. Fur colors (determined by 4 alleles): full, chinchilla,

Multiple Alleles: Rabbit Fur Colors v. Fur colors (determined by 4 alleles): full, chinchilla, himalayan, albino

Multiple Alleles: Blood Types (A, B, AB, O) v. Rules for Blood Types: A

Multiple Alleles: Blood Types (A, B, AB, O) v. Rules for Blood Types: A and B are co-dominant (Both show) AA or IAIA = type A BB or IBIB = type B AB or IAIB = type AB A and B are dominant over O (Regular dom/rec) AO or IAi = type A BO or IBi = type B OO or ii = type O

Multiple Alleles: Blood Types (A, B, AB, O)

Multiple Alleles: Blood Types (A, B, AB, O)

Allele Can (antigen) Donate Receive Possible on RBC Blood Phenotype Genotype(s) surface To From

Allele Can (antigen) Donate Receive Possible on RBC Blood Phenotype Genotype(s) surface To From A I Ai I AI A A A, AB A, O B IB i IB IB B B, AB B, O AB AB A, B, AB, O O AB O I AI B ii

Problem: Multiple Alleles v. Show the cross between a mother who has type O

Problem: Multiple Alleles v. Show the cross between a mother who has type O blood and a father who has type AB blood. GENOTYPES: - Ai (50%) Bi (50%) - ratio 1: 1 PHENOTYPES: - type A (50%) type B (50%) - ratio 1: 1 i i A Ai Ai B Bi Bi

Problem: Multiple Alleles v Show the cross between a mother who is heterozygous for

Problem: Multiple Alleles v Show the cross between a mother who is heterozygous for type B blood and a father who is heterozygous for type A blood. GENOTYPES: -AB (25%); Bi (25%); Ai (25%); ii (25%) - ratio 1: 1: 1: 1 A i B AB Bi PHENOTYPES: i -type AB (25%); type B (25%) type A (25%); type O (25%) - ratio 1: 1: 1: 1 Ai ii

Polygenic Traits vtraits produced by multiple genes vexample: skin color

Polygenic Traits vtraits produced by multiple genes vexample: skin color

Sex-Linked Traits v. Gene is attached to the X chromosome only, not found on

Sex-Linked Traits v. Gene is attached to the X chromosome only, not found on the Y chromosome at all. (women have XX, men have XY chromosomes). These disorders are more common in boys. vexamples: red-green colorblindness, hemophilia

Sex-Linked Traits vin males, there is no second X chromosome to “mask” a recessive

Sex-Linked Traits vin males, there is no second X chromosome to “mask” a recessive gene. If they get an X with the disorder, they have it. Girls must inherit defective X’s from both parents.

Sex-Linked Traits A: 29, B: 45, C: --, D: 26 Normal vision A: 70,

Sex-Linked Traits A: 29, B: 45, C: --, D: 26 Normal vision A: 70, B: --, C: 5, D: - Red-green color blind A: 70, B: --, C: 5, D: 6 Red color blind A: 70, B: --, C: 5, D: 2 Green color blind