Question

The following figure shows a simplified diagram of part of a DNA molecule. a. Identify the parts of the DNA molecule labelled A to C in the figure above. (3 marks) b. The table below shows the results of an analysis of the base composition for each strand of a DNA molecule. Complete the table by adding the missing values for strands 1 and 2. (5 marks) Percentage of each base DNA strand А Тc TG Strand 1 3522 Strand 2 18 c. Hydrogen bonding is central to the function of nucleic acids. Explain how hydrogen bonding contributes to the process of semi-conservative replication of DNA. (3 marks)

Answer 1

4) A B c nitrogenous base: Purine (&g A 89) Ribose Sugar phosphate backbone (Phosphate Group) No. of À in Strand 1 No. of a in strand = No. of T in Strand 2 = No. of c in strand 2 & Vice-versa & Vico Vesse Strand 1 t- EEE Strand 2. A G C 1 llle Hydrogen bond. C G a T 22 18 35 25 ul Strand1 | 25 35 Stranda | 18 22 c) Semi- Conservative replication of DIVA means both strands of DNA replicate to from a topies of DNA, each containing one original strand & one replicated newly synthesize Strand. Hydrogen bond plays an important role in semi- Conservative mode of replication. The Hydrogen bonds between the DNA helix breaks and the two strands separated. Both the strands form complementary base pairing through Hydrogen bond with the Nucleic acid to synthesize a new stand on each. Two Hydrogen bend formed between A&T and three H-bond formed between G&C.