Final answer:
Most DNA mutations in coding regions remain unnoticed because they're either harmful or have no impact on the protein's structure. Only a small percentage of mutations are beneficial, while many can lead to various disorders or even cancer.Option 2 is the correct answer.
Step-by-step explanation:
Most mutations within DNA in coding regions go unnoticed because they are deleterious or have no effect on protein structure. Mutations can have a range of effects on proteins, such as silent mutations, which do not change the amino acid sequence of a protein, to missense mutations, which change one amino acid for another, potentially affecting function depending upon the importance of the amino acid replaced.
Nonsense mutations introduce a premature stop codon, generally leading to a nonfunctional protein. Finally, frameshift mutations change the reading frame and usually result in nonfunctional proteins.
Contrary to beneficial changes in protein structure, mutations are often harmful and can lead to genetic disorders or cancer. Harmful mutations usually produce a protein that does not function normally, if at all. Repairs do take place in the cell, but they are not always quick or efficient, and some mutations persist and may be passed on to the next generation.