DNA Photolyase and Pyrimidine Dimers

The video tutorial explains photoreactivation, a DNA repair mechanism where the enzyme DNA photolyase removes pyrimidine dimers caused by UV radiation. This process is crucial for cell survival as these dimers can halt DNA replication and transcription. The enzyme binds to the dimers in the absence of light, but light is required to activate the enzyme and catalyze the repair process.

What is the primary function of photoreactivation?

• To repair DNA by removing pyrimidine dimers

• To synthesize new DNA strands

• To prevent DNA from binding with proteins

• To enhance the replication speed of DNA

How does UV radiation affect prokaryotic DNA?

• It has no effect on prokaryotic DNA

• It strengthens the DNA structure

• It induces the formation of pyrimidine dimers

• It causes the DNA to replicate faster

Why is it crucial for cells to remove pyrimidine dimers?

• To promote cell division

• To increase cell membrane stability

• To ensure proper DNA replication and transcription

• To enhance protein synthesis

Which enzyme is responsible for removing pyrimidine dimers?

• Helicase

• DNA photolyase

• RNA ligase

• DNA polymerase

What gene produces the enzyme DNA photolyase?

• his gene

• trp gene

• lac gene

• phr gene

What happens to DNA photolyase in the absence of light?

• It binds to pyrimidine dimers

• It becomes inactive

• It catalyzes the formation of new dimers

• It breaks down into amino acids

What is required for the activation of DNA photolyase?

• High temperature

• Darkness

• Light

• Low pH