Genetics in life, love and lab

1. Genetics in life, love and lab

7. Spontaneous mutation at low levels is normal

8. Antp Ubx Fly homeotic (Hox) selector gene mutations : cool Antennapedia Ultrabithorax Loss-of-function (lof) Ultrabithorax proboscipedia Mutated gene DNA, modified fly

9. What is DNA, Stephen?

10. 1 m Chromatin open closed 1 µm From: Felsenfeld et al., 2003

11. A A A A a a a a Mitosis: one mother cell becomes two daughter cells 2n 4n 2 x 2n

12. A A a a A A a a A a 2n 4n Meiosis: one mother cell becomes four gametes 2 x ‘2n’ 4 x 1n (gametes)

13. A T A G G G C C T C AC ACA G C A T T A A T A G G G C C T C AC ACAC A G C A T T A T C C C G G A G TG TG TG T C G T A DNA double helix 4 building blocks: A, T, G, C DNA polymerase Mutations e.g. stuttering

14. A A a a A A a 256 x 2n a 2n 4n 2 x 2n 16 x 2n Incomplete mitoses give giant chromosomes

15. Giant chromosomes of Drosophila and cytogenetics

16. We can see rearrangements such as inversion loops

17. Amniocentesis, A pre-natal test for high-risk pregnancies

18. A karyotype for a human cell (e.g. amniocentesis) Trisomy for chromosome 21

19. Protein Gene function

20. A Cystic Fibrosis (mucoviscidose)-bearing family tree I The family tree reveals the recessive nature of the disease The disease appears in the offspring of two apparently healthy individuals II III IV Two sick children

21. A quick detour concerning positional cloning

25. .

27. six genotypes (AA, AO, BB, BO, AB, & OO) & four phenotypes (A, B, AB, O) As a function of which protein form – A, B, A and B, or neither of these – is expressed 

28. O AB

29. A marriage between AB and O parents ABxO O ½ A ½ B O ½ AO (A) ½ BO (B)

30. ABO blood groupsIsoagglutinin locus (I) on Chromosome 9 has three alleles: IA , IB , IOA & B alleles are co-dominant: both are expressed in the blood group phenotypeA & B alleles are dominant to O : AA, AO & BB, BO indistinguishable                    Matings ("marriages") between males & females produce Genetics of ABO phenotypes But in a population… Frequency of I - locus alleles Frequency of ABO blood types

31. Now for a different blood type marker: Frequencies of MN blood types

32. Frequency of MN blood types Product Rule: probability of two events occurring together is the product of their separate probabilites                 So, the probability of ABand N blood types  =  f(AB) x f(NN) = (0.08) x (0.21) = 0.0168(<2%)

34. The Experts… Allele frequency Allele / DNA variant A T A G G G C C T C AC ACA G C A T 0.31 A T A G G G C C T C AC ACAC A G C A T 0.32 A T A G G G C C T C AC ACAC AC A G C A T 0.14 A T A G G G C C T C AC ACAC AC AC A G C A T 0.23

38. The Experts always get their man !

39. Normal instability: Jumping genes

40. Mirabilis jalapa

44. Transposable elements interrupt the chromosome and jump around

47. Bad genes run in families