Video Transcript
The factors that initiate the
clotting of blood are coded for by particular genes, but sometimes these genes can
mutate. An example of a condition caused by
these mutations is hemophilia. What symptom would you expect
someone with hemophilia to have? (A) Inability to bleed from wounds,
(B) formation of an excessive amount of scabs, (C) excessive or uncontrolled
bleeding from wounds, or (D) frequent formation of clots within blood vessels.
Because the process of clotting
requires a cascade of biochemical reactions to occur, there are many steps in the
process where clotting can go wrong. Mutations in any of the genes that
produce the enzymes and other proteins involved in clotting can result in a clotting
disorder. An example of this is hemophilia, a
genetic disease that prevents normal blood clotting in a person. Specifically, hemophilia affects
the production of fibrin, which is needed to create the net of fibers important for
a strong clot. So a person with hemophilia will
continue to bleed in situations where another person’s blood would normally
clot.
(A), (B), and (D) describe
situations where blood is clotting too easily, which is opposite the symptoms of
hemophilia. So we can eliminate those
choices. (C), on the other hand, describes a
situation where the blood won’t clot normally, so that should be our answer.
The symptom we would expect someone
with hemophilia to have is excessive or uncontrolled bleeding from wounds.
