4.3 TheoreticalGenetics

1. 4.3 TheoreticalGenetics • To be able to define the key terms of theoretical genetics • To describe inheritance patterns using inheritance diagrams • To be able to explain sex linkage

2. Definitions Genotype: the alleles of an organism Phenotype: The characteristics of an organism Dominant allele: the allele that gets expressed in heterozygous condition Recessive allele; the allele that has an effect on the phenotype when present in the homozygous state. Codominant alleles: pairs of alleles that are both expressed when present Locus: specific position of a gene in a chromosome Homozygous; having two copies of the same allele. Heterozygous: having two different alleles of a gene Carrier: a person with one recessive faulty allele for a genetic disorder Test cross: testing a suspected heterozygote by crossing with the homozygous recessive

3. Monohybrid Crosses Complete Dominance Incomplete Dominance Codominance

4. #1 - Complete Dominance P: RR  rr F1:Genotype Phenotype Type of Genotype Rr red heterozygous F1 Cross: Rr  Rr Punnett Square: F2:Genotype Phenotype Type of Genotype RR red homozygous Rr red heterozygous Rr red heterozygous rr white homozygous R r F2 Genotypic Ratio: 1 RR : 2 Rr : 1 rr F2 Phenotypic Ratio: 3 red: 1 white R r

5. #4 - Incomplete Dominance P: RR  rr F1:Genotype Phenotype Type of Genotype Rr pink heterozygous F1 Cross: Rr  Rr Punnett Square: F2:Genotype Phenotype Type of Genotype RR red homozygous Rr pink heterozygous Rr pink heterozygous rr white homozygous R r F2 Genotypic Ratio: 1 RR : 2 Rr : 1 rr F2 Phenotypic Ratio: 1 red: 2 pink : 1 white R r

6. #7 - Codominance P: RR  WW F1:Genotype Phenotype Type of Genotype RW red & white heterozygous F1 Cross: RW  RW Punnett Square: F2:Genotype Phenotype Type of Genotype RR red homozygous RW red & white heterozygous RW red & white heterozygous WW white homozygous R W F2 Genotypic Ratio: 1 RR : 2 RW : 1 WW F2 Phenotypic Ratio: 1 red : 2 red & white : 1 white R W

7. ABO Blood Typing

8. ABO Blood Typing

9. ABO Blood Typing

10. ABO Blood Typing RECIPIENT D O N O R

11. #15 - Blood Typing P: IAi  IBi Punnett Square: F1:Genotype Phenotype IAIBAB IAi A IBi B ii O IB i IA i

12. Additional Crosses Sex Determination Sex Linkage ABO Blood Typing

13. #12 - Sex Linkage- Haemophilia P: XHY  XHXh Punnett Square: F1:Genotype Phenotype Sex Type of Genotype XHXHnormal F homozygous XHXhcarrier F heterozygous XHY normal M hemizygous XhY hemophilia M hemizygous XH Xh XH Y

14. #11 - Sex Determination P: XY  XX X X X Ratio: 1 XX : 1 XY Y

15. Dihybrid Crosses Complete Dominance

16. #8 - Complete Dominance P: yyrr  YYRR F1:Genotype Phenotype Type of Genotype YyRr yellow/round heterozygous F1 Cross: YyRr  YyRr Punnett Square: F2:Genotype Phenotype 9 Y_R_ yellow/round 3 Y_rr yellow/wrinkled 3 yyR_ green/round 1 yyrr green/wrinkled YR Yr yR yr YR Yr yR yr

17. Pedigrees

18. Pedigrees Normal Affected Carrier

19. XHXh XHY XhY XHY XHXH You! Pedigrees Example: You are a normal female (homozygous). Both of your parents are normal. Your younger brother is normal and your older brother has hemophilia.

20. XCXC XcY XCY XCXc XCY XCXC XCXc XcY XCY #18 - Pedigrees You!