NonMendelian Genetics Mendelian Genetics Dominant Recessive Review v
- Slides: 25
Non-Mendelian Genetics
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 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. Sex-Linked Traits
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. 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! 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 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 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 (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). 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 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 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 agouti yellow
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 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)
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 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 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
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 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, 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
- Nonmendelian traits
- Family resemblance test
- Example of sex linked pedigree
- Mendelian genetics
- Extension of mendelian genetics
- Extending mendelian genetics
- Mendelian genetics concept map
- Codominance
- Section 11-3 exploring mendelian genetics answers
- Mendelian genetics vocab
- Dominant
- Multiple alleles
- Section 11-3 exploring mendelian genetics
- Section 11-3 exploring mendelian genetics
- Chapter 7 extending mendelian genetics vocabulary practice
- Mendel's three laws
- 11-3 exploring mendelian genetics answers
- Codominance
- Section 11-4 meiosis answer key
- Chapter 7 vocabulary practice extending mendelian genetics
- Chapter 10 section 2 mendelian genetics answer key
- 11-3 exploring mendelian genetics
- Mendelian genetics
- Karyotype
- Color blindness punnett square
- Heterozygous for blood type a