Task

A double-stranded DNA fragment contains 1500 nucleotides, 20 % of which are adenine nucleotides. The fragment has no introns; one strand fully encodes a protein and its last triplet is a stop codon. The distance between adjacent base pairs is 0.34 nm, the mean nucleotide mass is 345 Da and an amino acid 110 Da (ignore water released on peptide-bond formation). 1) Using Chargaff’s rules, complementarity and the properties of the genetic code, describe the method of solution. 2) Find the number of nucleotides of each kind in the fragment. 3) Calculate the number of hydrogen bonds between nucleotides and the length of the fragment (nm). 4) Calculate the molecular mass of the fragment, the number of amino acids in the encoded protein and the protein’s mass. For each part, write out the law or method used (cross scheme, formulas, reasoning) and all calculations step by step.