MIMM 413 Lecture : feb 15 2012- dr. rorbach.docx

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magentacricket108

15 May 2012

School

McGill University

Department

Microbiology and Immun (Sci)

Course

MIMM 413

Professor

Various

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Document Summary

The number of cases is probably too low. Almost everyone who lives in africa has a low level of parasites in the blood (so the numbers can go up to a billion). The children are mainly affected, as are the women (with maternal malaria). Facts about malaria (2: malariae and p. ovale are not very common. P. vivax is more in southern asia, and p. falciparum is the lethal malaria and the problem in africa. Everything we will discuss will be about p. falciparum, because this is where most of the research is done. P. malariae and p. ovale are not very well studied because we do not have lab strains of them, the same with p. vivax (but it is getting better here). 35% of the world"s population live in regions where there is a risk of acquiring malaria. Studies are being done to see what would happen because of climate change.

Related Questions

For African populations in malaria infested areas, the S alleleprovides some immunity to malaria. However, two S alleles causesthe debilitating illness sickle cell anemia. If the S allele didnot have the beneficial role of decreasing malarial symptoms, whatwould likely happen to the S allele?

A) The allele would continue to be maintained in thepopulation

B) The allele would become fixed in the population

C) Hardy-Weinburg equilibrium would be maintained

D) The allele would likely become more rare in the populationbecause of the anemia it causes in a homozygote condition

lemonox668

Imagine a population living in part of the world where malaria is very common. In that population, most people are homozygous for normal globin genes; they are vulnerable to Malaria, so their relative fitness is close to, but below 1. People that are homozygous for a mutated globin gene have a relative fitness is much lower than 1 because of anemia.

What is the name for this fitness scenario?

Sickle-cell anemia is an interesting genetic disease. Normal homozygous individuals (SS) have normal blood cells that are easily infected with the malarial parasite. Thus, many of these individuals become very ill from the parasite and many die. Individuals homozygous for the sickle-cell trait (ss) have red blood cells that readily collapse when deoxygenated. Although malaria cannot grow in these red blood cells, individuals often die because of the genetic defect. However, individuals with the heterozygous condition (Ss) have some sickling of red blood cells, but generally not enough to cause mortality. In addition, malaria cannot survive well within these "partially defective" red blood cells. Thus, heterozygotes tend to survive better than either of the homozygous conditions. Assuming an African-American child were born each day of the year, statistically, one of these children per year would have a severe form of sickle-cell anemia (ss). Assuming Hardy-Weinberg equilibrium of these alleles, what is the percentage of the African-American population that are sickle-cell carriers? (Note that these carriers will turn out to be more resistant to malaria, should they decide to visit a malaria-infested part of the world; sometimes there are bizarre perks to being a carrier of a horrible disease!). Enter a percentage number (round up to whole number) without percent sign (%)

MIMM 413 Lecture : feb 15 2012- dr. rorbach.docx

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