Mechanisms of Mutation: Spontaneous Mutation

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What is the main cause of spontaneous mutation?

Enzymatic removal of distortions in the helix

Tautomeric forms of the bases (correct)

Errors in the replication of DNA

Thermodynamically unfavored base-pairing

Which base pairing is allowed in DNA replication?

A–C and G–T

A–T and G–C (correct)

A–G and C–T

A–G and T–C

What is the frequency of the alternative tautomeric forms of the bases at any one point in time?

1 in 100 –200 molecules

1 in 10 –20 molecules

1 in 104 –105 molecules (correct)

1 in 1000 –5000 molecules

Why will the imino form of adenine base-pair with cytosine rather than thymine?

Tautomeric form of adenine Signup and view all the answers

What is the observed frequency of mutation compared to the frequency of alternative tautomeric forms?

Many orders of magnitude lower Signup and view all the answers

What does the text suggest as the problem with the explanation for spontaneous mutation?

The observed frequency of mutation is lower than expected Signup and view all the answers

What is one of the mechanisms for repair of damaged or altered DNA?

Proofreading mechanism Signup and view all the answers

Which type of strain may have mutation rates many thousand times higher than normal?

Mutator strains Signup and view all the answers

What type of conversion can nitrous acid cause in DNA?

Oxidative deamination Signup and view all the answers

Which alkylating agent acts by introducing alkyl groups onto the nucleotides at various positions?

Ethyl methane sulphonate (EMS) Signup and view all the answers

What type of mutation can intercalating agents like ethidium bromide cause?

Frameshift mutation Signup and view all the answers

Which type of agent acts only against growing cells?

Base analogues Signup and view all the answers

What can replace thymine in DNA and lead to base pair formation?

5-bromouracil Signup and view all the answers

What can uracil pair with in DNA, leading to a change from a C–G pair to U–A and ultimately T–A?

Adenine Signup and view all the answers

Mechanisms of Mutation: Spontaneous Mutation

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