Substitution is a type mutation ( permanent change in the genetic material of the organism) that is caused by the exchange of one base with another.
This can occur during the process of DNA replication when an incorrect base is added in the new DNA molecule and thus replacing the original base pair. This can result in formation of new amino acid ( that result in different protein) or it may form a truncated protein ( when stop codon is produced due to substitution).
The role of the nucleolus is to make the monomer of of ribosomes, and ribosomes are used in mRNA to make protein. Therefore the nucleolus plays a major role in the process of making proteins for our body. <span />
