Consider the following segment of DNA:
       5'-...ATGCCAGTCACTGACTTG...-3'
       3'-...TACGGTCAGTGACTGAAC...-5'

If the lower strand of DNA serves as the template transcribed into mRNA, how many peptide bonds are present in the polypeptide fragment into which the mRNA is translated?

Key Concepts

Transcription

Transcription is the process by which the genetic information in DNA is copied into messenger RNA (mRNA). During transcription, RNA polymerase binds to the DNA template strand and synthesizes a complementary RNA strand. In this case, the lower strand of DNA serves as the template, leading to the formation of mRNA that carries the code for protein synthesis.

Translation

Translation is the process by which the sequence of nucleotides in mRNA is decoded to produce a polypeptide chain, which will fold into a functional protein. This process occurs in the ribosome, where transfer RNA (tRNA) molecules bring amino acids to the growing polypeptide chain based on the codon sequence of the mRNA. Each codon corresponds to a specific amino acid, and the number of peptide bonds formed is one less than the number of amino acids in the polypeptide.

Peptide Bonds

Peptide bonds are the chemical bonds that link amino acids together in a polypeptide chain. Each peptide bond forms between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of water in a dehydration reaction. The number of peptide bonds in a polypeptide is always one less than the total number of amino acids, which is crucial for determining the length of the resulting protein.