If a woman is a carrier for colorblindness (xcx) has a child with a man who is colorblind (xcy) can they have a colorblind female? show your work.

Ans.

Colorblindness is a sex-linked, recessive genetic disorder that results in inaccurate and limited color perception in affected people.

Females carry two X chromosomes and presence of one normal X chromosome can hide the effect of other mutated X chromosome (Xc) as it is a recessive trait.

So, females with both mutated X chromosomes (Xc) are diseased, while females with one normal and one mutated chromosome are unaffected and carrier for the disease.

Males carry only one X chromosome, so, all males with mutated X chromosomes (Xc) are diseased. Cross between a carrier woman and a colorblind man will give following progeny:

Parents:                   XcX  (female)              x             XcY (male)

                                                                  ↓

Gametes:                       Xc    &    X                         Xc      &     Y

                                                                  ↓

Progeny:                         XcXc       XXc                  XcY         XY

Normal (carrier) female: 25% (XXc)

Colorblind female: 25%   (XcXc)

Normal male: 25% (XY)

Colorblind male: 25% (XcY)

Thus, 'a carrier women and a colorblind man can have a colorblind female.'

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: