Question

Question 9 (4 pts) The genetic term “loss of function” is used to describe any mutation in the DNA that leads to a particular protein that cannot function. There are many reasons why a protein may not be functioning any longer…digging into your knowledge on mechanism of gene expression and gene expression regulation, describe a mutation that could lead to a loss of function mutation. Where is the mutation in the gene? What function of gene expression or gene expression regulation is it affecting? How is it leading to a loss of function for the protein encoded for within that gene? But I’m going to restrict your answer…describe a mechanism that DOES NOT include a point mutation leading to missense, nonsense or frameshift – in other words, choose a mutation/mechanism other than a mutation that leads to a change in the protein coding region of a mature mRNA. I want you to think outside of that particular box.

Answer 1

Several mutations are spontaneous in nature which arises due to

a)         Low chemical stability of purine and pyrimidine bases

b)         Errors during DNA replication

c)         Exposure to environmental factors such as ultraviolet light and chemical carcinogens

One of the common causes of spontaneous mutation is deamination of cytosine to uracil in double stranded DNA. During replication, T-A base pair replaces the wild-type C·G base pair

For example – Sickle cell Anemia is caused by spontaneous mutation in which the glutamic acid (at position 6in normal protein) is changed into valine. As a result of this Hemoglobin becomes insoluble in erythrocytes and forms crystalline arrays due to which its transmission through capillaries get blocked thereby leading to severe pain and tissue damage.