Below are diagrams of double stranded DNA molecules some of

Below are diagrams of double stranded DNA molecules some of which have mis-matches (“P” represents a 5’ phosphate group) and single strand breaks. Indicate which single strand breaks could efficiently be closed by DNA.

OH P T-c-A-T-G-T-G-G-A A-c-T-A G-T-C-C-T-G-G-G-A-C. .A-G-T-A-C-A-C-C-T-G-A-T-C-A-G-G-A-C-C-C-T-G.. OH G-A-C-T-A A-T-C-C-T-G-G-G-A-C. .A-G-T-A-C-A-C-C-T-G-A-T-C-A-G-G-A-C-C-C-T-G.. OH T-C-A-T-G-T-G-G-A-C-T G-T-C-C-T-G-G-G-A-C A-G-T-A-C-A-C-C-T-G-A-T-C-A-G-G-A-C-C-C-T-G. OH OH. L T-C-A-T-G-T-G-G-A-C-T-A GT-C-C-T-G-G-G-A-C A-G-T-A-C-A-C-C-T-G-A-T-C-A-G-G-A-C-C-C-T-G.

Solution

DNA breaks in A, B and C can be closed as they contain a phosphate group and Hydroxyl group which can form bond to seal the gap.