Question

Your friend is interning in a research lab at CERN in Switzerland. The lab they are working in is studying a family of mice named the Quarks. The family consists of parents named Up and Down, monozygotic twins Charm and Strange, and their third child Bottom. In other words, Bottom is Charm and Strange’s little brother (and all three mice are the offspring of Up and Down). At the immunoglobulin heavy chain locus Up is homozygous for y3^a and Down is heterozygous, having both y3^a and y3^b (note: in mice the different alleles are named with letter superscripts).

c). Bottom suffers from Higgs Syndrome, a condition characterized by extreme weight gain due to the presence of an anti-leptin IgG3 auto-antibody. Should your friend be able to guess which of the other family members will also develop this syndrome (i.e. have the same anti-leptin IgG3 antibody)? Explain your reasoning. (1 point)

d). Bottom has just discovered his long-lost evil twin Top. Top has a component in his serum called W particles. The W particles appear to be immunolglobulins and have been found to bind to IgG3 antibodies from Down. Using this information determine Top’s genotype for y3. (1 point)

Answer 1

Given,

Up X Down (Parents)

Monozygotic twins Charm and Strange

Third child bottom

Up is homozygous for y3a, Down is heterozygous, having both y3^a and y3^b

y3^a y3^a X y3^a y3^b

y3^a y3^a, y3^a y3^a, y3^a y3^b, y3^a y3^b

So, there is a probability of 50% child being infected with Higgs syndrome as Higgs syndrome is recessive disorder, so need to be homozygous.

Bottom is already having Higgs syndrome.

So probability of other child with this syndrome = 1/3

So, there is 1/3 chance of getting syndrome.

d. Top has W particle, from down,

So the genotype should be y3^a y3^b