Biology Questions and Answers

Biology Questions and Answers

XhY. Concerning the phenotypes, factor

VIII is produced in every individual withat least one nonaffected X chromosome. (^)
So the women XX and X Xh and the
men XY are normal. Oand men XhY have the disease.nly women XhXh

14. Why is it rare to find
    hemophilic women?

There are more hemophilic mehemophilic women because womenn than

need to have two X chromaffected to develop the disease wosomeshile in (^)
men the disease manifests when the
single X chromosome is affected.

15. Is it possible for any son
    of a couple formed by a
    hemophilic man (XhY) and a
    nonhemophilic noncarrier
    (XX) woman to be hemophilic?

If mothers are not affected by the
disease annot have an Xh alleled noncarrie) it is impossiblers of the gene (do
for their sons to be hemophilic since the
X chromosome from the mother. Hemophilic sons arof males always comese
only possible when the mother is

hemophilic (homozyghemophilic gene, a very rarous for thee situation) (^)
or carriers of an affected X chromosome
(XXh).

16. What is the clinical
    manifestation of the disease
    known as daltonism?

The X-linked daltonism is a disease in

which the red color as graffected individeen or confounds theseual sees the (^)
two colours.

17. What is the type of genetic
    inheritance of daltonism? Is
    daltonism more frequent in
    men or in women? What is the
    physiological explanation for
    the daltonism?
    Daltonism is a recessive X-linkeinheritance (gene situated in thed
    nonhomologous portion of the X
    chromosome).
    Daltonism is more frequent in men since

in them only the single X cneeds to be affected for the disease tohromosome (^)
manifest. In women it is necessary for
both X chthe disease to comromosomes to e out.be affected for
The disease the gene that coappears ddifies a ue to a defect inretinal pigment (^)
sensitive to red.

18. Are sex-linked diseases
    associated only to genes of
    the X chromosome?
    There are many X-linked diseases, like
    hemophilia A, hadrenoleukodystropemophilia B anhy, but known Y-d
    linked diseases are few and very rare.

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