Biochemistry
Dna Repair
Compiled By Simon Mwangi
Edition: 2024/25
, Science | Biochemistry I of IV pages
1. What is depurination?
Loss of urine bases (adenine and guanine)
- Occurs spontaneously thousands of times per day
2. what nucleotide is most commonly affected by deamination (loss of amine group)?
Cytosine
3. What does cytidine become after deamination?
Uracil
4. What do free radiacls or radation damage on the nucleotide?
Base rings
5. What are possible damage will free radicals so to the base rings?
Oxidative damage
Methylation
Hydrolysis
6. What are the single strand repair mechanisms?
Base excision
NT excision
Mismatch repair
7. What are the double strand repair mechanisms?
Homologous end joining
- Non-homologous end joining
8. What is the pathway for damaged DNA repair called?
Base excision repair
- Recognises specific base errors
9. What is the function of a DNA glycosylase?
Remove damaged bases
- Creates a baseless NT
10. What can a baseless NT be known as?
Apurinic or apyrimidic
11. What is the function of an AP endonuclease?
Recognises NTs w/o a base
Attacks 5 phosphate end of DNA strand
Nicks damaged DNA upstream of AP site
Create a 3-OH end adjacent to the AP site
12. What is the function of an AP lyase?
Some DNA glycosylases also possess AP lyase activity
- Attack the 3 hydroxyl end of ribose sugar
Biochemistry 2024/25 Edition
Dna Repair
Compiled By Simon Mwangi
Edition: 2024/25
, Science | Biochemistry I of IV pages
1. What is depurination?
Loss of urine bases (adenine and guanine)
- Occurs spontaneously thousands of times per day
2. what nucleotide is most commonly affected by deamination (loss of amine group)?
Cytosine
3. What does cytidine become after deamination?
Uracil
4. What do free radiacls or radation damage on the nucleotide?
Base rings
5. What are possible damage will free radicals so to the base rings?
Oxidative damage
Methylation
Hydrolysis
6. What are the single strand repair mechanisms?
Base excision
NT excision
Mismatch repair
7. What are the double strand repair mechanisms?
Homologous end joining
- Non-homologous end joining
8. What is the pathway for damaged DNA repair called?
Base excision repair
- Recognises specific base errors
9. What is the function of a DNA glycosylase?
Remove damaged bases
- Creates a baseless NT
10. What can a baseless NT be known as?
Apurinic or apyrimidic
11. What is the function of an AP endonuclease?
Recognises NTs w/o a base
Attacks 5 phosphate end of DNA strand
Nicks damaged DNA upstream of AP site
Create a 3-OH end adjacent to the AP site
12. What is the function of an AP lyase?
Some DNA glycosylases also possess AP lyase activity
- Attack the 3 hydroxyl end of ribose sugar
Biochemistry 2024/25 Edition
