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In haemoglobin, there are four polypeptide chains that make it's structure, 2 (A) chains and 2 (B) chains. Sickle-Cell Anemia is caused by a mutation the (B) chain that makes the haemoglobin molecules stick to each other and form fibres inside the red blood cell (RBC).
Instead of a circular disc shaped RBC we now have a sickle shaped cell. This means transport of oxygen is very innefficient and the disease can cause death.
However, in areas with a high malaria rate, heterozygous sickle-cell anaemics (with some sickle shaped AND normal RBCs) are naturally selected because the protozoan (what causes the disease) is unable to live inside the red blood cell due to the fibres formed from the mutation, the cells are more fragile and they have a shorter life span than normal RBCs. This means that people with heterozygous alleles for sickle-cell anaemia benefit against malaria and will survive to reproduce, which increases the allele frequency of the sickle-cell anaemia allele.
Those with homozygous sickle-cell anaemia and those with homozygous normal haemoglobin are selected against as the first usually die of the sickle-cell anaemia, and the latter contract malaria.
NB. Mutations are rare occurrences. It is even rarer for a mutation to give selective advantage. This mutation for sickle-cell anaemia did not happen to 'cure' or prevent malaria, it was a random occurrence that coincidentally gave a selective advantage against malaria.
Wiki User
∙ 14y ago
Wiki User
∙ 10y agoSickle cell anemia occurs when a person gets two abnormal genes for sickle cell anemia. Having one abnormal gene gives a person the ability to live in areas where malaria is common.So these people with these traits live in sub-Saharan regions. That means in southern Africa.
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∙ 12y agoProvides resistance against malaria
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∙ 9y agointer breeding
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Why are red blood cells sickle shaped in a person with sickle cell disease?
Sickle cell is common in people from tropical areas where malaria is prevalent. Malaria can not survive on blood cells that are sickle shaped, so when populations were being killed off by malaria, those with sickle cell were surviving and passing on the sickle cell gene.
Why is frequency of sickle cell allele so much lower in the US than in Africa?
People with sickle cell anemia are resistant to malaria, which increases their ability to survive and produce offspring. This is evolution in action. Since malaria is a bigger problem in Africa than in America, it is more prevalent in Africa. Many black people in America have inherited this gene from their ancestors
What Sickle cell disease is and which population?
sickle cell occurs in populations more toward africa, just like malaria.
Who has a sickle cell trait?
No. Many people become confused with that because the Sickle Cell trait is most common in Africa where the population is more black than any other race.
Why do people of Mediterranean and African decent have sickle cell anemia?
Sickle cell anemia is a inherited blood disorder. This means everyone who has sickle cell has inherited it from their parents. With this in mind it means there was a key ancestor in Africa or the Mediterranean who had the first sickle cell anemia and passed it on to their descendants.
How prevalent is the disease sickle cell in the population?
its a very rare disease because you have to be heterozygous to have it! I KNOW I'M CLEVER
What groups get sickle cell disease?
A person can only inherit sickle-cell genes if some of their ancestors came from certain regions in Africa where the inhabitants carry sickle-cell genes. A person with one sickle-cell gene has sickle-cell trait, a milder problem. If both father and mother pass on sickle-cell genes, the child, with two genes, will have sickle-cell disease.
Can you explain what evolutionary advantage mean and how it accounts for why sickle cell anaemia is still so widespread in Africa?
evolutionary advantage means that if you have to types of sickle cell anaemia and one is resistant to a drug the the other one is not then the one that is not resistant dies off and the sickle cell anaemia that is resistant becomes dominant and that is why sickle cell anaemia is still so widespread in Africa because the strain that is widespread in Africa is resistant is anti-biotics.
What are people with sickle cell resistant to?
Sickle cell anemia provides resistance to malaria - it is ideal for many people in Africa that live in mosquito rampant areas.
How does balancing selection affect the sickle cell allele in central Africa?
The sickle cell allele can be maintained in the central African population, above the frequency of gene mutation (balancing selection), because the heterozygous sickle cell individuals have an advantage in lifespan, in this malaria stricken region, over the homozygous alternatives. Homozygous sickle-sickle individuals die early from the sickle cell disease. Homozygous nonsickle-nonsickle die early from malaria. The heterozygous sickle-nonsickle have a higher survival against malaria and therefore the sickle cell allele is balanced selected.
Is sickle cell common?
Sickle cell anemia is found in approximately 1 in 5000 people. It is mostly found in people from Sub-Saharan Africa do to the nature of the disease providing resistance to malaria.
Why sickle cell anemia resistance malaria?
Sickle cell anemia comes as the result of having two sickle cell chromosomes. One sickle cell chromosome makes people resistant to malaria. Unfortunately when people have two sickle cell chromosomes they can get sickle cell anemia. That makes it difficult for their blood to carry oxygen and under certain conditions makes their blood clump. The disease can be deadly. Drugs can help. It probably makes that person resistant to malaria. The sickle cell trait evolved in various places around the world where malaria is common such as Africa and Greece.
