DNA Repair Mechanisms and Photo Reactivation

The video explains photo reactivation, a DNA repair mechanism that reverses UV-induced damage. It details how UV radiation causes thymine dimers, disrupting DNA symmetry. The process involves light-dependent reactions using enzymes and cofactors like FAD and MTHF to repair the damage. Photo reactivation occurs in both prokaryotes and eukaryotes, restoring DNA integrity.

What is the primary purpose of photo reactivation in cells?

• To inhibit protein synthesis

• To reverse DNA damage caused by UV radiation

• To promote cell division

• To enhance DNA replication

What type of bond formation occurs between adjacent pyrimidines due to UV radiation?

• Covalent bond

• Ionic bond

• Hydrogen bond

• Metallic bond

What is the result of thymine dimer formation in DNA?

• Increased DNA stability

• Loss of DNA symmetry

• Enhanced protein synthesis

• Improved DNA replication

Which spectrum of light is involved in the photo reactivation process?

• Ultraviolet light

• Infrared light

• Visible light

• X-ray light

What is the role of photolyase enzymes in photo reactivation?

• To initiate cell division

• To break down proteins

• To repair damage caused by UV radiation

• To synthesize new DNA strands

Which cofactor absorbs visible light in the photo reactivation process?

• ATP

• MTHF (methenyltetrahydrofolate)

• NADH

• Coenzyme A

What happens to FAD during the photo reactivation process?

• It is converted to ATP

• It is reduced to FADH2

• It is oxidized to FADH2

• It is broken down into amino acids

What is the final outcome of the photo reactivation process on thymine dimers?

• They are broken down into monomers

• They are converted into adenine dimers

• They are stabilized in the DNA

• They are replicated into new DNA strands

In which organisms does photo reactivation occur?

• Only in viruses

• Only in eukaryotes

• Only in prokaryotes

• In both prokaryotes and eukaryotes

What is the significance of photo reactivation in DNA repair?

• It prevents DNA replication

• It enhances protein synthesis

• It restores DNA integrity after UV damage

• It inhibits cell growth