Location via proxy:   [ UP ]  
[Report a bug]   [Manage cookies]                
SlideShare a Scribd company logo

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

•
•
J
j3di79

This document discusses different concepts related to genetics including complete and incomplete dominance, codominance, multiple alleles, and sex determination. It provides snapdragons with red, white, and pink flowers as an example of codominance, where the alleles for red (R) and white (r) both influence the phenotype and result in pink (Rr) flowers. It also gives human blood types as an example of multiple alleles, where the IA, IB, and Io alleles determine blood type A, B, AB, or O. The document then provides a genetics problem asking for the possible blood groups of children from a mother with blood type A and a father with blood type B. It works through the

1 of 17
Complete vs Incomplete dominance (Codominance)
Is it possible? X White snapdragon Red snapdragon Pink snapdragon
A situation where neither allele dominates the other and both exercise an influence on the individual Example: Snapdragon cross RR = Red flowers rr = White flowers Rr = pink flowers Incomplete dominance/Codominance
Phenotypic ratio for Codominance
 
Parental phenotype: Parental genotype: Gametes: Random fertilisation: (using the Punnett Square) F 1 genotype: F 1 phenotype: 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
F 1 phenotype: F 1 genotype: Gametes: Random fertilisation: (using the Punnett Square) F 2 genotype: F 2 phenotype: Phenotypic ratio: 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
Another example roan White cow Red cow X
Multiple alleles
Traits regulated by more than two alleles Example: Human Blood Types Three alleles: I A , I B , and I o I A , I B both dominant over I o ; I o is recessive A and B are codominant with each other Codominance = displaying two dominant phenotypes at the same time Thus: I A I A or I A I o = Type A I B I B or I B I o = Type B I A I B = Type AB I o I o = Type O Multiple alleles
Question: 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?
Parental phenotype: Parental genotype: Gametes: Random fertilisation: (using the Punnett Square) F 1 genotype: F 1 phenotype: 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
Am I legitimate? Project task : Collect information regarding the blood group of your parents and siblings. Based on this information, derive the possible genotypes of your parents.
Sex Determination
Sex determination Humans have 23 pairs of chromosomes (46 chromosomes) i) 22 pairs are autosomal chromosomes ii) 1 pair of sex chromosomes Males have the genotype XY Females have the genotype XX
 
Sex determination

More Related Content

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

  • 1. Complete vs Incomplete dominance (Codominance)
  • 2. Is it possible? X White snapdragon Red snapdragon Pink snapdragon
  • 3. A situation where neither allele dominates the other and both exercise an influence on the individual Example: Snapdragon cross RR = Red flowers rr = White flowers Rr = pink flowers Incomplete dominance/Codominance
  • 4. Phenotypic ratio for Codominance
  • 5.  
  • 6. Parental phenotype: Parental genotype: Gametes: Random fertilisation: (using the Punnett Square) F 1 genotype: F 1 phenotype: 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
  • 7. F 1 phenotype: F 1 genotype: Gametes: Random fertilisation: (using the Punnett Square) F 2 genotype: F 2 phenotype: Phenotypic ratio: 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
  • 8. Another example roan White cow Red cow X
  • 10. Traits regulated by more than two alleles Example: Human Blood Types Three alleles: I A , I B , and I o I A , I B both dominant over I o ; I o is recessive A and B are codominant with each other Codominance = displaying two dominant phenotypes at the same time Thus: I A I A or I A I o = Type A I B I B or I B I o = Type B I A I B = Type AB I o I o = Type O Multiple alleles
  • 11. Question: 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?
  • 12. Parental phenotype: Parental genotype: Gametes: Random fertilisation: (using the Punnett Square) F 1 genotype: F 1 phenotype: 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
  • 13. Am I legitimate? Project task : Collect information regarding the blood group of your parents and siblings. Based on this information, derive the possible genotypes of your parents.
  • 15. Sex determination Humans have 23 pairs of chromosomes (46 chromosomes) i) 22 pairs are autosomal chromosomes ii) 1 pair of sex chromosomes Males have the genotype XY Females have the genotype XX
  • 16.