Why heterozygous for sickled cell anemia are resistant to malaria?

Answer 1

Because individuals who inherit the gene from only one parent produce red blood cells which are distorted. This distortion makes the cells unpalatable to malaria parasites, without seriously harming the individual. This tends to protect against malaria and that protection causes selection for this allele. Individuals who get the sickle cell gene from both parents suffer serious distortion of the red blood cells. This protects against malaria, but also reduces the oxygen-carrying capacity of the red cells to a dangerous degree. This causes a disease called sickle-cell anaemia, which causes selection against the gene. In malarial regions a balance is established. When a population with sickle cell alleles moves to an area with effectively no malaria present, the sickle cell alleles are steadily selected against. This shifts the balance steadily towards low levels.

Answer 2

People who have a sickle cell allele are immune to malaria, so the people with the one sickle cell allele have a greater chance of surviving malaria than people who do not have the allele. Through natural selection the frequency of people with the sickle cell allele will increase because they survive and are able to pass on their gene. More people will die who do not have the allele, so they are unable to pass on their genes.

Answer 3

Because people who have sickle cell have abnormal blood cell which blocks the path where the blood flows therefore mosquito can't enter the abnormal red blood cell

Hope this helps!!

Answer 4

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