CBSE Class 12-science Answered

Every nucleotide pair consists of two nitrogen bases. Since the DNA segment consists of 90 nucleotide pairs, the total number of bases in the DNA segment would be 90 x 2 = 180 bases.

Now, every DNA segment consists of 2 strands of DNA. Hence, every DNA strand will have 90 nucleotides. Each of these strands will get separately transcribed to form mRNA. Since every DNA strand consists of 90 nucleotides, there will be 90 nitrogen bases in every strand. Each of these bases will get transcribed to form mRNA strand. So, there would be 90 nucleotides transcribed from only one DNA strand. Unlike DNA replication, in which both strands are copied, only one strand is transcribed.

Now, once mRNA is formed, it would be translated to form the amino acids. Every amino acid is coded by a codon consisting of 3 bases. Therefore, 90 bases would code for 30 amino acids.