What will happen if there was a change in the base pair sequence?

Answer 1

Changing a base pair on a human chromosome (or any organism's chromosome) can range from no effect to catastrophic. The changing of a base pair -- a mutation -- can either result in a nonsense mutation, a missense mutation, or a silent mutation.

A nonsense mutation changes a codon upstream of the normal stop codon into a stop codon, resulting in a truncated protein. Such proteins are non-functional and usually result in a non-viable offspring although some can survive (with serious genetic disorders).

A missense mutation is just like a nonsense mutation, except the codon isn't changed into a stop codon and the protein does not terminate early. The only difference between the normal protein and the affected protein is that the affected protein will have one amino acid along the polypeptide chain that is different. The affects of such a change can change the shape of the protein entirely, seen with sickle-cell anemia.

A silent mutation has no effect on the protein produced. There are only 20 amino acids, but 43 variations of four bases arranged three at a time (in other words, there are 64 different codons possible). Accordingly, more than one codon can code for the same amino acid. For example, both UAU and UAC code for the amino acid tyrosine. Imagine a point mutation replaced the U in UAU with a C making it UAC. Either way, the amino acid that will be used will be tyrosine, in no way changing the structure of the protein. For that reason, these mutations are "silent" or having no effect.

Answer 2

A change in the base pair sequence, known as a mutation, can lead to changes in the protein produced by the affected gene. This can result in altered gene function, potentially leading to genetic disorders or diseases. The impact of the mutation can vary depending on its location and the specific changes to the DNA sequence.

Answer 3

A point mutation might occur, or it may have no effect.