It's something to do with the fact that having sickle cell anaemia reduces the chances of contracting malaria, obviously a very common disease in Africa. I'm not quite sure what the link is but hopefully this helps a little bit?
        
             
        
        
        
Plant cells have walls that arent very flexible, so a plate forms in between the cells, and the cell splits in half.
        
             
        
        
        
Answer:
its the midline, or the middle of the pig 
Explanation:
 
        
             
        
        
        
No, the sickle-cell anemia allele won't be eliminated by natural selection.
Sickle-cell anemia trait is controlled by a single gene and the allele (S) for sickle-cell anemia is a harmful autosomal recessive. 
It is caused by a mutation in the normal allele (A) for hemoglobin (a protein on red blood cells).
Heterozygotes (AS) with the sickle-cell allele are resistant to malaria, a deadly tropical disease. It is common in many African populations.
In these areas, (S) carriers have been naturally selected, because their red blood cells, containing some abnormal hemoglobin, tend to be in sickle shape when they are infected by the malarial parasite.
Therefore, they are more likely to survive and reproduce. This keeps the S allele in the gene pool.
Learn more about Sickle-cell anemia on
brainly.com/question/14505007
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<span>The answer is cysteine. This is a half essential proteinogenic amino acid with the formulation of HO₂CCHCH₂SH. It is prearranged by the codons UGU and UGC. The thiol side chain in cysteine frequently partakes in enzymatic responses, as a nucleophile.</span>