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A mutation in one amino acid of one of the subunits making up hemoglobin.
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For sickle-cell disease assume S is the dominant allele and s the recessive allele Which genotypes are possible for offspring of a carrier (Ss) and a person who lacks the sickle-cell allele (SS)?
SS,Ss
Heterozygous persons with one sickle cell allele and one normal allele also show resistance to?
Malaria
Compare the normal allele for hemoglobin with the sickle cell allele How does this difference affect the persons red blood cells?
The amino acid sequence of the sickle cell allele for hemoglobin varies from the normal allele for hemoglobin by one amino acid. The sickle cell allele for hemoglobin has valine instead of glutamic acid. When the oxygen level of the blood decreases, the hemoglobin molecules come out of solution, stick together, and form long chains that cause the red blood cells to become sickle shaped.
Mutation that causes sickle cell anemia?
pooo
What was primarily acting to change the frequency of the sickle-cell allele in the overall U.S. population?
The absence of the selection pressure malaria. Without selection, in the form of the malarial environment, the sickle cell allele will be lost in the overall US population. Even the heterozygous condition is somewhat deleterious and, statistically without malarial selection pressure the allele will be selected out.
What are the pros for SICKLE CELL ANEMIA?
The pro of sickle cell hemoglobin is that if you have only one allele for sickle cell hemoglobin and the other allele is normal, then you are immune to malaria.
What allele for the sickle cell trait is with the normal allele?
codominant
What is the allele for sickle cell trait with the normal allele?
codominant
The allele for the sickle cell trait is what with the normal allele?
codominant
If malaria were eliminated how might the frequency of the sickle-cell allele change over time?
Since people with the sickle cell allele trait are resistent to malaria, if malaria were eliminated there would be no change in the frequncy of sickle cell allele. This is because the presense of malaria does not have an affect on patients with the sickle cell allele trait.
For sickle-cell disease assume S is the dominant allele and s the recessive allele Which genotypes are possible for offspring of a carrier (Ss) and a person who lacks the sickle-cell allele (SS)?
SS,Ss
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.
How would you describe what an allele is?
*An allele is basically the different forms a particular gene can take (describes the various genotypes/phenotypes a gene can take).* For example there is an allele of a gene which codes for haemoglobin in red blood cells, which gives them their characteristic concave shape. But there can also be a mutation in that gene, which causes a different allele to be produced which gives it a sickle-cell shape, which leads to sickle-cell anaemia.
Where is the sickle-cell allele most frequent?
Around the mediterranean sea.
Where is the sickle cell allele most frequent?
Around the Mediterranean Sea.
Where is sickle cell allele most frequent?
Around the Mediterranean Sea.
Which individuals have the greatest fitness in an area where malaria is common?
Individual homozygous for the sickle cell anemia allele
