GS-1 Biological Sciences Question 34

[judyfranks6280]

Why sickle cell protazoa don't survive in Ss genotype people

My Question regarding CBT 1, question 34:

If the malaria protazoa can't live in abnormal hemoglobin and therefore lives in normal hemoglobin, why can't it live in the other 60% of normal hemoglobin cells in a person with sickle cell traits and the genotype Ss?

<<<CBT 1, Q 34:
Regarding sickle cell anemia question: In parts of the world where malaria is endemic, individuals with sickle-cell trait cannot contract the disease. Which of the following is the most likely explanation for this?>>>

<<<Answer to question:
we are left with the plausible explanation in answer choice C. which suggests that the organism cannot procreate in an environment where 40% of the hemoglobin is abnormal (P1, S6).>>>

[admin]

To begin with, the protozoa in question do not live in Hb (= hemoglobin, which is a protein complex which is certainly far too small for cells to live in), rather they live in RBC's (red blood cells). Also, all the cells contain the same abnormal genetic information for Hb (thus it is not the case that 60% of the RBC's contain completely normal Hb; ALL the cells contain some, on average 40%, abnormal Hb).

Though the precise mechanism by which sickle cell trait imparts resistance to malaria is unknown, it is clear that once an RBC has a certain percentage of abnormal Hb (ie 40%), this is sufficient to interfere with the activity of the protozoa. Using the process of elimination, as described in the Explanation, is useful to help deduce the correct response for this question.

[admin]

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