The Forces of Evolution

mutation, 

genetic drift

gene flow or migration

selection.

TLS Online TPP Program

#Id: 6103

#Unit 3. Fundamental Processes

EMS causes ethylation of the bases in DNA at the 7-N and the 6-O positions. When 7-ethylguanine is produced, it base-pairs with thymine to cause G:C → A:T transitions.

TLS Online TPP Program

#Id: 6104

#Unit 3. Fundamental Processes

Base alkylation products activate error-prone DNA repair processes that introduce transitions, transversions, and frameshift mutations during the repair process

TLS Online TPP Program

#Id: 6105

#Unit 3. Fundamental Processes

In contrast to most alkylating agents, the hydroxylating agent hydroxylamine (NH2OH) has a specific mutagenic effect. It induces only G:C → A:T transitions.

TLS Online TPP Program

#Id: 6106

#Unit 3. Fundamental Processes

Thymine dimers cause mutations in two ways. (1) Dimers perturb the structure of DNA double helices and interfere with accurate DNA replication. (2) Errors occur during the cellular processes that repair defects in DNA, such as UV-induced thymine dimers To identify chemicals that are converted into mutagens in the liver, the Ames test treats potential indirect mutagens with a mixture of liver extract

TLS Online TPP Program

#Id: 6107

#Unit 3. Fundamental Processes

TLS Online TPP Program

#Id: 6108

#Unit 3. Fundamental Processes

In ames test reversal mutants are formed by same mutagen which caused forward mutation.

A more potent mutagen translates

into a greater number of revertant colonies