B.7C Mutations Approaching – 03

This is a diagram showing mutations in an RNA sequence. 

Figure (1) is a normal RNA sequence, consisting of 4 codons.

Figure (2) shows a missense mutation.

Figure (3) shows a deletion of the second base pair in the second codon.

Figure (4) shows an insertion in the third base pair of the second codon.

Both show frameshift mutation.

Figure (5) shows an entire codon duplicated.

A chromosomal mutation involves changes in large pieces of the chromosome. There are many types of chromosomal mutations. They are deletion, duplication, inversion, and translocation. In deletion, large parts of the chromosome are removed. In duplication there is an extra copy of all or parts of the chromosome. In inversion, whole order of the DNA is flipped upside down. In translocation parts of one chromosome are moved to another.

Ethan wanted to know the effect of these mutations. Dr. Wallace said mutations can be spontaneous or induced. Spontaneous mutations can be caused by mistakes during DNA replication. 

Mutations can also be induced by mutagens. Mutagens can be pesticides or radiation or UV rays. Xray can cause changes in the DNA. The DNA then cannot be copied properly, unless they are repaired. DNA can repair and reverse mutations with the help of enzyme. But when these processes fail, it results in a permanent change in the DNA.

Mutations that happen in body cells are not passed on to the next generation. When mutations happen in sex cells, the mutations are passed on to the offspring. This then creates new variations, which might have evolutionary impact. In many cases, they may not have any effect at all.

Mutations may cause diseases. Alkaptonuria is a condition that results in discolored urine. People who have this condition have a high rate of frameshift and missense mutations in the DNA.

Sickle cell disease (SCD)is caused by point mutation which causes structural change in the hemoglobin.

When large parts of the DNA go through mutation, they can cause diseases like Fragile X syndrome.

Dr. Wallace smiled and looked at Ethan and asked, “Does that answer your questions?” “Yes Sir, thank you very much.” As he walked home, he thought to himself that the X Men probably didn’t get their superpowers from mutations, or did they?