The modified base can be repaired before replication by DNA glycosylase via the base excision pathway. If replication occurs before the oxoG is removed, resulting in the misincorporation of an A, then a fail-safe glycosylase can remove the A, allowing it to be replaced by aC. This provides a second opportunity for the DNA glycosylase to remove the modified base.

TLS Online TPP Program

#Id: 650

#Unit 3. Fundamental Processes

Two major products of UV absorption by pyrimidines (thymine and cytosine) are pyrimidine hydrates and pyrimidine dimers.

TLS Online TPP Program

#Id: 651

#Unit 3. Fundamental Processes

Ames Test is used to measure carcinogenicity and mutagenicity of any chemical mutagen.

TLS Online TPP Program

#Id: 652

#Unit 3. Fundamental Processes

The Ames test uses a strain of S. typhimurium that is mutant for the operon responsible for the biosynthesis of the amino acid histidine.

TLS Online TPP Program

#Id: 653

#Unit 3. Fundamental Processes

A more potent mutagen translates into a greater number of revertant colonies.

TLS Online TPP Program

#Id: 654

#Unit 3. Fundamental Processes

Reversal of the mutation can only be done by same mutagen which created forward mutation.

TLS Online TPP Program

#Id: 655

#Unit 3. Fundamental Processes

The telomere is absolutely required for the stability of the chromosome end.