Question

The following is a DNA sequencing gel where the different dideoxynucleotides have fluorescent labels that cause them to emit a different colour. In this case A = red/triangle, T = green, G = purple/circle and C = black. Based on the image of the gel, what was the sequence of synthesized strand? (The top of the gel is where the DNA was loaded - the negatively charged end) IDOL O III ODDITIO

Answer 1

Option b

DNA sequencing is the procedure of determining the sequence of the nucleic acid. A method or technique that determines the order of the four bases: adenine, guanine, cytosine, and thymine. The major sequencing methods employed are- Maxam Gilbert sequencing and Sanger sequencing/chain termination method (Here dideoxynucleotides are incorporated by the DNA polymerase during the process of replication in vitro.). Nowadays, automated sequencing is used.

In the given gel the base A is denoted by red/triangle

G=purple/circle

C=Black

T=Green

The direction of electrophoresis will be from negative electrode (as DNA is negatively charged) to the positive electrode, i.e, from top of the gel to the bottom of the gel. The resulting sequence will be read from bottom to top direction or 5’ to 3’ direction.

The sequence will be as given in option b.