DNA Polymerase
Definition
The enzyme that synthesises new DNA by adding deoxyribonucleoside triphosphates complementary to the template strand. In humans, polymerase delta copies the lagging strand and polymerase epsilon copies the leading strand. Both carry a 3-prime to 5-prime exonuclease proofreading domain.
- Function
- Synthesises new DNA from a template strand
- Lagging strand enzyme
- Polymerase delta
- Leading strand enzyme
- Polymerase epsilon
- Proofreading
- 3' to 5' exonuclease domain on both
Common questions
Why does the proofreading function of DNA polymerase matter for forensic mutation analysis?+
The exonuclease domain removes most misincorporated bases during replication, which keeps the natural mutation rate low and is part of why STR and SNP markers stay stable enough across generations to be forensically useful for identification and kinship work.
Is the DNA polymerase used in PCR the same enzyme active in human cells?+
No, PCR typically uses a heat-stable polymerase from a thermophilic organism, such as Taq polymerase, chosen to survive the repeated high-temperature denaturation steps, unlike the human replicative polymerases which are not heat stable.
Related terms
- Frameshift Mutation
- A change in the reading frame of a coding sequence caused by an insertion or deletion of a number of nucleotides that...
- Okazaki Fragment
- A short segment of DNA (100 to 200 nucleotides in eukaryotes) synthesised on the lagging template strand in the 5-prime to 3-prime...
- Point Mutation
- A change in a single nucleotide in the DNA sequence. A transition substitutes one purine for another or one pyrimidine for another...
- Semi-Conservative Replication
- The mode of DNA copying in which each daughter double helix retains one parental strand and acquires one newly synthesised strand, confirmed...
- Short Tandem Repeat (STR) Slippage
- Replication slippage at a repetitive locus where the template and nascent strands temporarily misalign. If the nascent strand slips forward, one repeat...