Task

An mRNA fragment used for polypeptide synthesis: 5′-AUG GCU UUC AAA GGC UGG UAA-3′. Part of the genetic code table: AUG — methionine; GCU — alanine; UUC — phenylalanine; AAA and AAG — lysine; GGC — glycine; UGG — tryptophan; UAA, UAG, UGA — stop codons. 1) Describe transcription and translation, the principles of complementarity and antiparallelism and the properties of the genetic code, and outline the method. 2) Write both strands of the DNA fragment from which this mRNA was made (marking 5′ and 3′ ends); calculate the number of hydrogen bonds and the length (nm) of the DNA fragment. 3) Write the anticodons of the tRNAs involved in translation and determine the number of tRNA molecules. 4) Write the amino-acid sequence of the peptide. Determine how the peptide changes if mRNA nucleotide 10 (A) is replaced by U and, separately, if nucleotide 12 (A) is replaced by G. For each part, write out the law or method used (cross scheme, formulas, reasoning) and all calculations step by step.