Question

5. The recognition sites for two restriction enzymes are: Xbal: 5'-T^CTAGA-3' Nhel: 5'-G^CTAGC-3 If you digest a DNA sample with A and B separately and then mix the digested products from the two reactions with DNA ligase and ATP. Show the DNA sequences of the (a) cut products (also indicate the - OH and-Pi groups on each cut product) and (b) newly ligated products at the ligation site (Give 4 but EXCLUDE the self-relegated products). (1+3)

I drew out the cut products but I can't figure out 4 new possible ligated products, I'm only seeing two ones not counting the self-relegated products.

** Two Restriction sites are given, the "^" indicates where the sequence will be cut. So if these two sequences are cut with restriction enzymes, give 4 unique ways that they can be ligated together NOT counting they're initially ligated. Draw out the complimentary strand to the site to make it easier to visualize.

Answer 1

Answer-

a)Xbal and Nhel restriction enzymes cleaves palindrome sequence of DNA to produce cohesive ended products.

b) when these digested DNA products are ligated using enzyme DNA ligase in presence of ATP, four different ligation products can be observed as both enzymes recognition sequence has central tetra nucleotide same, 5'-CTAG-3'. The ligated products are-

5-T-OH 3 + 5-6-CTAGA-3 3- AGATC-5 T 3 Ho-T5 5.G-OH3' 5--CTAGC-3 B-CGATC-05 340-G-5 DNA ligaset I ATP 5-TCT AGC-3, 3- AGATCG-5 Ligated product 1 5-GCTAGA-3 3'-CGATC T-51 [Ligated product-2 5-TCT AGC-3 3 - AGATCG-5 Ligated product 4 S-TCTAGC-3 3-A GATCG-5 Ligated product 3