DNA polymerase transcript DS

DNA Polymerase

An enzyme that synthesizes new DNA strands by adding deoxynucleotides (dNTPs) to the 3' end of an existing primer strand. It is highly processive, capable of adding thousands of nucleotides without dissociating from the template.

Generic DNA Polymerase Structure, regions

Comprises three key domains: the Fingers, Thumb, and Palm. These regions together form the active site responsible for the catalytic addition of new nucleotides.

Palm, Fingers, and Thumb Domains, what do regions do

The three primary structural domains of DNA polymerase.

The Palm is the catalytic core,

the Fingers help bind the incoming dNTP,

and the Thumb holds the DNA template, contributing to the enzyme's high processivity.

3' to 5' Exonuclease Activity

A proofreading function located in a separate domain of DNA polymerase. It can remove misincorporated nucleotides from the newly synthesized 3' end of the DNA strand, ensuring high fidelity in replication.

DNA Polymerase Reaction

The enzymatic reaction where DNA polymerase adds a dNTP to the 3' hydroxyl end of a primer strand. It catalyzes the formation of a phosphodiester bond, incorporating one phosphate into the backbone and releasing the other two as pyrophosphate.

Template Strand

The single strand of DNA that serves as the guide for synthesizing a new, complementary strand. The polymerase reads this strand in the 3' to 5' direction.

Primer Strand

The pre-existing nucleic acid strand (typically a short segment of RNA or DNA) to which DNA polymerase adds new nucleotides. It has a free 3' hydroxyl group that is essential for the polymerase to initiate synthesis.

Anti-parallel Strands

The orientation of the two DNA strands, where the template strand runs in one direction (e.g., 3' to 5') and the newly synthesized primer strand runs in the opposite direction (5' to 3').

dNTP (Deoxynucleoside Triphosphate)

The substrate for DNA polymerase. It consists of a deoxyribose sugar, a nitrogenous base, and three phosphate groups. During incorporation, the alpha phosphate is joined to the primer, and the beta and gamma phosphates are released as pyrophosphate.

Direction of Synthesis

DNA polymerase always synthesizes DNA in the 5' to 3' direction. It adds new nucleotides only to the 3' end of the growing strand.

Direction of Template Reading

As DNA polymerase synthesizes the new strand in the 5' to 3' direction, it moves along the template strand in the 3' to 5' direction.

Processivity

A key characteristic of DNA polymerase referring to its ability to catalyze many consecutive nucleotide addition reactions without releasing the DNA template strand. This allows for the efficient synthesis of long DNA strands.

Active Site

The region of the DNA polymerase (encompassed by the fingers, thumb, and palm domains) where the catalytic addition of nucleotides occurs. The 3' end of the primer strand is always positioned here for the next reaction.