What is the Difference Between Base Excision Repair and Nucleotide Excision Repair?

Base excision repair (BER) and nucleotide excision repair (NER) are two mechanisms used to repair damaged DNA. The main differences between them are:

1. Mechanism of repair: In base excision repair, only the damaged base is removed, while in nucleotide excision repair, a patch of nucleotides is removed.
2. Type of DNA damage repaired: Base excision repair is used to repair small damages caused endogenously, such as those caused by deamination or alkylation. In contrast, nucleotide excision repair is used to repair large lesions and damage caused by exogenous factors, such as UV radiation or chemical mutagens.
3. DNA polymerase involved: Nucleotide excision repair uses delta or epsilon DNA polymerase for the resynthesis of the DNA, whereas base excision repair uses beta DNA polymerase for the same purpose.
4. When repair occurs: Base excision repair occurs throughout the cell cycle, repairing DNA that is damaged by endogenous mutagens. Nucleotide excision repair is activated when the DNA is constantly damaging due to UV rays, radiation, and mutagens.

In summary, base excision repair is a simpler mechanism that fixes minor damages in DNA, while nucleotide excision repair is a more complex process that repairs larger lesions and damage caused by external factors.

Comparative Table: Base Excision Repair vs Nucleotide Excision Repair

Here is a table comparing the differences between base excision repair (BER) and nucleotide excision repair (NER):

BER and NER are two major DNA excision repair pathways found in cells, and they follow a complex repair pathway in eukaryotes, while a prototype system exists in prokaryotes. Both pathways have four steps: recognition of damaged DNA, excision of damaged DNA, DNA synthesis to fill the nucleotide gap, and sealing of nicks in the DNA.