Question

Which one of the following is a wrong statement regarding mutations?
A.Cancer cells commonly show chromosomal aberrations.
B.UV and - Gamma rays are mutagens
C.Change in single base pairs of DNA does not cause mutation.
D.Deletion and insertion of base pairs cause frameshift mutations.

Answer 1

Any change happening to the DNA or RNA sequences are known as mutations. In other words, any change or alteration happening to the nucleotide sequence in the genome of any organism or even to any extrachromosomal DNA that is heritable. It can also happen in viral cells.

Complete answer: A change in a single base pair of a DNA does cause mutation. This phenomenon is known as Point-mutation. Here a single nucleotide base is changed. It can be either insertion or deletion of a base pair to the genome. Based on the effects produced, the two types of point mutations are synonymous mutations where no effects are produced, to frameshift mutations which can cause deleterious effects. They have an effect on protein production, also on its composition and function.

Figure: Types of point mutations caused by changes in single base pair

Considering the other options:
Chromosomal aberrations are known as a change in chromosome numbers. Cancer cells normally develop different types of chromosomal aberrations, in various phases such as tumor progression. They can include duplication, deletion, or rearrangements.
UV and rays are mutagens as they have the potential of inducing mutations in specific cells. The main mechanism of UV rays is by the process of forming dimers between the adjacently located pyrimidine bases on the DNA strand. They mostly affect the genome on the skin cells causing skin cancers. Gamma rays cause a mutation by causing oxidative damages, causing strand breaks.
Frameshift mutations can be caused either by insertion, deletion, or even duplications. Diseases such as Chron’s diseases, cystic fibrosis, and certain types of cancers are caused due to frameshift mutations.
Thus considering all the options given above, the wrong statement given is C since even a change in a single DNA base pair has the ability to cause mutations, known as Point mutations.

Note: There are mainly three types of DNA mutations, which are base substitutions, insertions, or deletions. And many diseases are caused due to these abnormalities. Sickle-cell anemia which is a hematological disorder is caused due to the point mutation, where the base-pair coding for glutamic acid is replaced or substituted with the one coding for Valine amino acid. This producing deformed RBCs.