Complete vs Incomplete dominance (Codominance)
Is it possible? X White snapdragon Red snapdragon Pink snapdragon
  <ul><li>A situation where neither allele dominates the other and both exercise an influence on the individual   </li></u...
Phenotypic ratio for Codominance
 
<ul><li>Parental phenotype: </li></ul><ul><li>Parental genotype: </li></ul><ul><li>Gametes: </li></ul><ul><li>Random ferti...
<ul><li>F 1  phenotype: </li></ul><ul><li>F 1  genotype: </li></ul><ul><li>Gametes: </li></ul><ul><li>Random fertilisation...
Another example roan White cow Red cow X
Multiple alleles
<ul><li>Traits regulated by  more than two alleles </li></ul><ul><li>Example: Human Blood Types </li></ul><ul><li>Three al...
Question: <ul><li>The inheritance of the ABO blood groups in Man is controlled by three alleles ( I A ,  I B , and  I o ),...
<ul><li>Parental phenotype: </li></ul><ul><li>Parental genotype: </li></ul><ul><li>Gametes: </li></ul><ul><li>Random ferti...
Am I legitimate? <ul><li>Project task : </li></ul><ul><li>Collect information regarding the blood group of your parents an...
Sex Determination
Sex determination <ul><li>Humans have 23 pairs of chromosomes (46 chromosomes) </li></ul><ul><li>i) 22 pairs are  autosoma...
 
Sex determination
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Chapter 19 Heredity Lesson 3 - Complete and Incomplete Dominance_Multiple alleles_Sex determination

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Chapter 19 Heredity Lesson 3 - Complete and Incomplete Dominance_Multiple alleles_Sex determination

  1. 1. Complete vs Incomplete dominance (Codominance)
  2. 2. Is it possible? X White snapdragon Red snapdragon Pink snapdragon
  3. 3. <ul><li>A situation where neither allele dominates the other and both exercise an influence on the individual </li></ul><ul><li>Example: Snapdragon cross </li></ul><ul><li>RR = Red flowers </li></ul><ul><li>rr = White flowers </li></ul><ul><li>Rr = pink flowers </li></ul>Incomplete dominance/Codominance
  4. 4. Phenotypic ratio for Codominance
  5. 6. <ul><li>Parental phenotype: </li></ul><ul><li>Parental genotype: </li></ul><ul><li>Gametes: </li></ul><ul><li>Random fertilisation: </li></ul><ul><li>(using the Punnett Square) </li></ul><ul><li>F 1 genotype: </li></ul><ul><li>F 1 phenotype: </li></ul>Red flower x white flower RR x rr All Rr All pink R r R r Let R represent the alleles of the snapdragon with red flower. Let r represent the alleles of the snapdragon with white flower. R R r r Rr Rr Rr Rr
  6. 7. <ul><li>F 1 phenotype: </li></ul><ul><li>F 1 genotype: </li></ul><ul><li>Gametes: </li></ul><ul><li>Random fertilisation: </li></ul><ul><li>(using the Punnett Square) </li></ul><ul><li>F 2 genotype: </li></ul><ul><li>F 2 phenotype: </li></ul><ul><li>Phenotypic ratio: </li></ul>pink x pink Rr x Rr RR, Rr, Rr, rr red, pink, pink, white 1:2:1 (red:pink:white) r r R r R r Rr R R Rr rr RR
  7. 8. Another example roan White cow Red cow X
  8. 9. Multiple alleles
  9. 10. <ul><li>Traits regulated by more than two alleles </li></ul><ul><li>Example: Human Blood Types </li></ul><ul><li>Three alleles: I A , I B , and I o </li></ul><ul><li>I A , I B both dominant over I o ; I o is recessive </li></ul><ul><li>A and B are codominant with each other </li></ul><ul><li>Codominance = displaying two dominant phenotypes at the same time </li></ul><ul><li>Thus: </li></ul><ul><li>I A I A or I A I o = Type A </li></ul><ul><li>I B I B or I B I o = Type B </li></ul><ul><li>I A I B = Type AB </li></ul><ul><li>I o I o = Type O </li></ul>Multiple alleles
  10. 11. Question: <ul><li>The inheritance of the ABO blood groups in Man is controlled by three alleles ( I A , I B , and I o ), only two of which can be present in one individual. I A and I B are of equal dominance but both are dominant to I o . What are the possible blood groups of children born to a homozygous group A woman and heterozygous group B man? </li></ul>
  11. 12. <ul><li>Parental phenotype: </li></ul><ul><li>Parental genotype: </li></ul><ul><li>Gametes: </li></ul><ul><li>Random fertilisation: </li></ul><ul><li>(using the Punnett Square) </li></ul><ul><li>F 1 genotype: </li></ul><ul><li>F 1 phenotype: </li></ul>Blood group A x Blood group B I A I A x I B I o I A I B , I A I B , I A I O , I A I O Blood groups AB, AB, A and A I O I B I O I A I A I B I B I A I A I A I A I B I A I O I A I O
  12. 13. Am I legitimate? <ul><li>Project task : </li></ul><ul><li>Collect information regarding the blood group of your parents and siblings. Based on this information, derive the possible genotypes of your parents. </li></ul>
  13. 14. Sex Determination
  14. 15. Sex determination <ul><li>Humans have 23 pairs of chromosomes (46 chromosomes) </li></ul><ul><li>i) 22 pairs are autosomal chromosomes </li></ul><ul><li>ii) 1 pair of sex chromosomes </li></ul><ul><li>Males have the genotype XY </li></ul><ul><li>Females have the genotype XX </li></ul>
  15. 17. Sex determination

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