1698 is the minimum number of nucleotides required in the coding region of the LDS2B mRNA molecule to produce and terminate the 565-amino acid polypeptide.
TWO reasons why the number of nucleotides in the mature RNA may differ from the number of base pairs in the gene are:
i) because gene contains non coding sequence also called as introns +exons while mature mRNA contains only exons.
ii) genes have promoter region while mature mRNA does not have so.
Explanation:
The minimum number of nucleotides in the coding region of a mRNA sequence or molecule is number of amino acids multiplied by three. There are triplet codon or 3 nucleotides which code for an amino acid.
number of nucleotides = number of amino acids x 3
number of nucleotides = 565 x 3
number of nucleotides= 1695 nucleotides
The stop codon would also be added as it is a part of mature RNA so
1695 + 3 = 1698
The coding region or exons carry only the nucleotides which code for amino acid polypeptide chain.
The two reasons why number of nucleotides in mature RNA and gene is different:
1) Because the gene carries both introns (non-coding regions) and exons (coding region) and mature mRNA after spicing removes the introns and has only exons which are read by the tRNA to carry amino acids in translation.
2) Genes consist of promoter region which are not transcribed hence not transferred to mRNA. Although mRNA is transcribed using the promoter region.
