Please explain in detail how to obtain the answers below. Thanks! 19. (16 points
ID: 212228 • Letter: P
Question
Please explain in detail how to obtain the answers below. Thanks!
19. (16 points) The human gene for hemophilia is on the X chromosome. Below is a pedigree from a family afflicted with hemophilia. The man with blackened symbol (III-1) has hemophilia. To help with genetic diagnosis, a probe that detects an RFLP (restriction fragment length polymorphism) on the X chromosome is used. This probe detects either a 7 kb restriction enzyme fragment or 3 kb and 4 kb restriction enzyme fragments. The RFLP pattern for all the members of the pedigree is shown. The recombination distance between the RFLP and the hemophilia locus is 40%. Show your work and circle your answer. a. Draw X-chromosomes indicating the linkage relationship between hemophilia alleles and the RFLP morphs in II-1 7kb 4 kb 3 kb 7kbA/ (4,3kb)a (4 points) b. What is the chance that III-2 is a carrier? (3 points) p(111-2 is Aa)-0.4-40% c. What is the chance that III-3 is not a carrier? (3 points) p(111-5 is AA)-0.4-40% d. What is the chance that their unborn child (III-7) is affected? (4 points) p(111-7 is affected) pda from mom) x p(Y from dad)-.4 x S-.2-20% e. If there are any abnormalities in the RFLP result, please briefly explain. (2 points) III-5 must have XO genotype (Turner syndrome). The nondisjunction must happen in II-2 (her father) during either meiosis I or II.Explanation / Answer
Explanation for the answers
a. In the first generation Female (circle symbol) is carrier and phenotype is AA, where as Male (square symbol) is affected and phenotype is Aa. As recombination locus distance is 40% II-1 female have the chance of 60% carrier and 40% non carrier.
b. In progeny III-2 phenotype is AA (one A from father and one A from mother) having chance of 40% carrier and 60% affected, hence having haemophilia.
c. In progeny III-3 phenotype is Aa (one A from father and one ‘a’ from mother) having chance of 60% carrier and 40% affected, hence does not have haemophilia.
d. As III-7 gender is not known and recombination locus distance is 40% hence theoretically 40/2 = 20% chance of getting affected. If the gender is known as male and having 60% chance of getting affected and 40% not, if female 60% chance as a carrier and 40% chance as getting affected.
e. As III-5 is female and having other 4kb, 3kb RFLP DNA fragments and no 7kb fragment, its phenotype can be ‘aO’ or XO, no contribution of X chromosome from father, hence turners syndrome not haemophilic