Human Genetics: Concepts and Applications (Lewis), 9th Edition

Chapter 12: Gene Mutation

Thymine Dimers Formation and Repair

View the animation below, then complete the quiz to test your knowledge of the concept.



1.

UV light damages DNA by causing
A)covalent bonds to form between two cytosines next to each other on the same DNA strand
B)covalent bonds to form between thymine nucleotides next to each other on the same DNA strand
C)covalent bonds to form between two thymine nucleotides on opposing DNA strands
D)covalent bonds to form between a thymine and an adenine on the same DNA strand
2.

When DNA is damaged by UV light and is not repaired
A)DNA replication can proceed as normal but transcription is prevented
B)transcription can proceed as normal but replication is prevented
C)neither DNA replication nor transcription can occur and the organism will probably die
D)the damaged part will be excised and allow DNA replication to proceed
3.

In light repair
A)the covalent bonds between the thymine dimers are broken
B)a single thymine is excised
C)the damaged segment of DNA is excised by DNA polymerase
D)the damaged segment of DNA is excised by DNA ligase
4.

Excision repair takes place only in the presence of light.
A)True
B)False
5.

In dark repair, the final phosphodiester bond is formed by DNA ligase.
A)True
B)False
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