Although incorporation of the wrong nucleotide is not desirable in either the sy

Question

Although incorporation of the wrong nucleotide is not desirable in either the synthesis of DNA corresponding to a particular gene or in the mRNA transcribed off that DNA-explain why such a mistake is more deleterious at the DNA than RNA level. A single mutation in the beta-globin chain of hemoglobin results in sickle cell anemia, a serious disease in which misshapen red blood cells can clog small blood vessels. The mutation results in the use of a valine rather than a glutamic acid as the seventh amino acid in the beta-globin protein. Do you think the results would be as devastating if the mutation resulted in aspartic acid being substituted for the glutamic acid? Why or why not?

Explanation / Answer

Simple, DNA is the genetic material that inherited through the generations in particular sexually reproducing population. If mutations occur in the DNA that might cause deleterious effects in several generations, unlike, the mutations in mRNA which is not inherited through generations may affect that particular individual.

Aspartic acid substitution for glutamate may not much affect (may not distort the structural conformation of beta-globulin and its active site for binding with O2) the beta-globin chain since, both amino acids under similar group like COOH containing negatively charged (polar) amino acids. Whereas, valine is completely a different group of amino acid that is a branched chain, non-polar (hydrophobic) amino acid affects the polarity of beta-chain to interact with O2 via structural distortion (forms aggregates in HbS by exposing hydrophobic patches).

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