Question

2. The sequence below represents two DNA strands linked together by hydrogen bonds. The smaller DNA strand has a 3'-OH that will be used by the DNA polymerase to add nucleotides using the longer DNA strand as a template. You add dATP, SCTP, dTTP, and ddGTP (dideoxy-GTP); and incubate at the DNA polymerase optimum temperature to allow the extension of the smaller DNA strand. Using the symbols below, draw the extended DNA strand (you don't need to draw the template DNA strand). Remember what happens when a dideoxynucleotide is at the 3' end of a DNA strand, will the DNA polymerase be able to extend the smaller DNA strand until the end of the DNA template? (20 points) 5'-CG-3' 3'- phosphate deoxyribose dideoxyribose bases GCATCGTTACTAGC-5'

Answer 1

Due lack of 3' OH in ddGTP, DNA Polymerase will

Not able to extend DNA after ddGTP.

For more detail please look into image

DELLATUL Answer: ONA polymerase will not able to extend the smaller DNA. Strand until the end of the DNA template. This is because in a mixture of nucleotide if we add a dideoxyribonucleotide C Analoge of one of nuueotide in misture) into the mise ture, it become Incorporated in growing DNA chain. * Remember danitp ( dideoxyribonucleotide ) lack 3'04 group. 3 In this case we add dd GTP, due to lack of 3 oy in dd GTP, it can not form a Phosphodiester bond with the next nucleotide. Hence the addition of next nucleotide is blocked and DNA chain terminates at that point. =) Sanger of this method of DNA Sequeneing and named it Chaun termination metuod. for more detail please read Chown termination method. a- Chain terminate K-CGTAG Here 3 GCATCGTTACTAG C-5' Primer (Smaller DNA) le - он phodiester Hoy bond. Phosphodiester Khoo Extended DNA 30 >> Chain terminates here due to lack of slo4 group in dd GTP.