The pedigree shows the inheritance of an autosomal recessive disorder. Shown bel

Question

The pedigree shows the inheritance of an autosomal recessive disorder. Shown below the pedigree (and lined up by individual) are the Southern blot data for two different RFLP loci. One locus has alleles of either 7kb or 5kb (revealed by digestion with BamHI and a specific probe A) The second locus gives alleles of size 4kb or 3kb (revealed by digestion with EcoRI and a specific probe B). What is the genotype of the parents? Which RFLP locus (Bam or Eco) is linked to the mutant gene? Which allele of the RFLP segregates with the mutant gene in the affected individuals? In one of the progeny, the disease gene has recombined away from the linked RFLP. Which progeny? The diagram shows a biochemical pathway for flower pigment biosynthesis. Normally. enzymes A, B and C cooperate to produce PURPLE flowers (i.e. PURPLE results from a mixture of RED and BLUE pigments). Assume that the genes for enzymes A, B, and C are unlinked. You have true-breeding RED plants and true breeding BLUE plants. If these are crossed. What is the genotype of the parents? The RED plants = The BLUE plants = What phenotypic ratios do you expect in the F2 when the F1's are self-crossed?

Explanation / Answer

Que 5

Mother is heterozygous carrier and father will be homozygous recessive, as daughter will not be affected until one mutated gene is received from either parent.

Que 6

It is an example of additive gene interaction i.e. more than one gene form one phenotypes.

The parent genotype must have one gene of dominant homozygous and since only one gene expresses that’s why other will be in recessive homozygous condition.

One – AAbb    x   aaBB

In F1 generation all will be identical i.e. purple

F2 generation ratio will be 9:7

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