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ADVANCED GENE INTERACTIONS

ADVANCED GENE INTERACTIONS. Genes interact in more complex ways than SIMPLE dominant / recessive ways Dom./Recess. Only 2 phenotypes Incomplete Dom. At least 3 pheno . / 3 rd is a blend Codominance at least 3 pheno . that are all shown separately. red. pink. white. H. W. T.

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ADVANCED GENE INTERACTIONS

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  1. ADVANCED GENE INTERACTIONS

  2. Genes interact in more complex ways than SIMPLE dominant / recessive ways Dom./Recess. Only 2 phenotypes Incomplete Dom. At least 3 pheno. / 3rd is a blend Codominance at least 3 pheno. that are all shown separately red pink white H W T I E

  3. 2. INCOMPLETE DOMINANCE: -active dominant allele does NOT fully compensate for inactive recessive allele -phenotype = a visual “blend” of dom. and recess. alleles Ex: R= red r = white Homozygous dom. mom X homo. recess. dad

  4. 3. CODOMINANCE: -both alleles are equally active and displayed in phenotype (dominant together) -written differently: both letters capital, since both dominant R = Red B = brown RB = roan Mom=Purebred red Dad = roan

  5. Practice ROAN PINK R = red r = white B = brown Rr = RB = What are phenotype % for the following crosses: 1. red mom & pink dad (incomplete dominance) 2. roan mom with a roan dad (codominance) 3. What would be the best mom genotype to cross with a ROAN dad, if you wanted to eliminate purebred red from the offspring phenotype %? 4. What would be the best mom genotype to cross with a pink dad, if you wanted the largest variety of phenotype % in offspring?

  6. 4. SICKLE CELL ANEMIA -A = normal hemoglobin -a = sickle hemoglobin -incomplete dominance -oxygen depravation causes hemoglobin to crystalize, making cells into sickle cells -being hetero. is good if malaria is common

  7. 5. Multiple Alleles: -some ALLELES exist in more than 2 forms (each organism still has ONLY 2 forms of each gene, regardless of how many are in the genome)

  8. Human Blood Types IA = A IB = B i = O GENOTYPE PHENOTYPE GENOTYPE PHENOTYPE

  9.     TYPES     DISTRIBUTION RATIOS O + 1 person in 3 38.4%      O - 1 person in 15 7.7%      A + 1 person in 3 32.3%      A - 1 person in 16 6.5%      B + 1 person in 12 9.4%      B - 1 person in 67 1.7%     AB + 1 person in 29 3.2%     AB - 1 person in 167 0.7%

  10. Practice 1. What are the GENOTYPE and PHENOTYPE % of a type AB mom crossed with a heterozygous type B dad? 2. What are phenotype % for a cross between: heterozygous type A mom and a heterozygous type B dad?

  11. 6. Sex Linked Traits = If a gene exists ONLY on the X chromosome, it is considered a SEX LINKED TRAIT

  12. Practice: A ) hemophilia H= non-hemo. h=hemo. Mom = XH Xh Dad = Xh Y Mom = Dad =

  13. B) XL = long wings Xl = short wings Mom = Heterozygous (short wing carrier) Dad = long wings 1. What are phenotype ratios for cross? 2. What percentage of females are carriers for short wings?

  14. C) colorvision XB = normal color vision Xb = color blindness Mom = carrier for color blindness Dad = color blind a. What % of offspring are colorblind? B. What % of offspring are carriers? C. In any sex linked situation, what % of MALES will be carriers for a recessive gene?

  15. two or more genes are LINKED if: a) they are on same chromosome b) they are close enough to stay together through almost all crossing over

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