MUTATION

Subject: Science and tech

Context:  Researchers at Duke University have identified a number of silent mutations in the virus’s genetic code that helped it thrive after it crossed over to humans.

Concept:

Mutations

• The DNA sequence is specific to each organism. It can sometimes undergo changes in its base-pairs sequence. It is termed as a mutation.
• A mutation may lead to changes in proteins translated by the DNA. Usually, the cells can recognize any damage caused by mutation and repair it before it becomes permanent.

Types of Mutations

Silent mutation

• It refers to any change in the sequence of DNA, which has no further impact on the amino acid sequence in a protein or in the functions performed by a protein. There is no phenotypic indicator of mutation.

Nonsense mutation

• When due to a point mutation there is change in the sequence of base pair leading to stop codon. It results in a shortened or non-functional protein.

Missense mutation

• A missense mutation is a result of point mutation leading to change in the codon, which then codes for another amino acid.

Causes:

• Most of the mutations occur when the DNA fails to copy accurately. All these mutations lead to evolution. During cell division, the DNA makes a copy of its own. Sometimes, the copy of the DNA is not perfect and this slight difference is called a mutation.
• When the DNA is exposed to certain chemicals or radiations, it causes the DNA to break down. The ultraviolet radiations cause the thymine dimers to break resulting in a mutated DNA.

Negative effects :

• Genetic disorders can be caused by the mutation of one or more genes. Cystic fibrosis is one such genetic disorder caused by the mutation in one or more genes.
• Cancer is another disease caused by the mutation in genes that regulate the cell cycle.