Answer
ddNTP is known as dideoxynucleotide triphosphates and is a chain terminating sequence used in Sanger sequencing method. Sanger sequencing is a DNA sequencing method in which DNA is denatured and annealed to an oligonucleotide primer. ddNTP is used as a chain terminating sequence because it lacks the 3'OH group without which no more nucleotide can be added and the DNA polymerase falls off. Chain termination occurs when a ddNTP is incorporated instead of deoxynucleotide because there will be a 3'H instead of a 3' OH. a) when too little ddNTP is added the chances of chain termination to occur is very less and we will get longer products away from the primer. b) when too much ddNTP is added we will get shorter products more close to the primer.
Work Step by Step
ddNTP is known as dideoxynucleotide triphosphates and is a chain terminating sequence used in Sanger sequencing method. Sanger sequencing is a DNA sequencing method in which DNA is denatured and annealed to an oligonucleotide primer. ddNTP is used as a chain terminating sequence because it lacks the 3'OH group without which no more nucleotide can be added and the DNA polymerase falls off. Chain termination occurs when a ddNTP is incorporated instead of deoxynucleotide because there will be a 3'H instead of a 3' OH. a) when too little ddNTP is added the chances of chain termination to occur is very less and we will get longer products away from the primer. b) when too much ddNTP is added we will get shorter products more close to the primer.
