Question

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6. How can a missense mutation-such as in sickle cell disease-result in a protein that has an abnormal structure? Some of these mutations are lethal or cause serious disease, such as cystic fibrosis and sickle cell disease. Many of these point mutations that cause genetic disorders occur as a result of errors in DNA replication or crossing over. 7. What will be the consequence if a single base is deleted from the coding region of a gene?

Answer 1

Sickle cell anemia is caused due to missense mutation in the beta hemoglobin gene. This converts GAG to GUG. As a result of this mutation, a valine is incorporated in the chain instead of glutamic acid. A protein is formed from several amino acids joined through peptide bonds and the amino acids are encoded by the codons. Any change in the codon will affect the incorporation of amino acids that will directly alter the protein's structure. The occurrence of valine instead of glutamic acids makes the Red blood cells to stick each other and acquire a sickle shape, hence the name. These sickle-shaped red blood cells get stuck in the blood vessels hindering the supply of oxygen to the body.