DNA Mistakes and Repairs Flashcards
How often does DNA polymerase make mistakes?
Every 10^5 nucleotides
What are the three types of mutations? Define each
- Substitution- change in nucleotide pair (most common)
- Insertion- addition of nucleotide pair
- Deletion- loss of nucleotide pair
The final molecule will have errors every what?
10^7 to 10^10 molecule
What is the role of exonuclease in the body?
Proofread the DNA strand for errors and remove the mispaired bases
What is mismatch repair?
enzymes correct errors in base pairing following replication
What is the group of enzymes that is a part of the mismatch repair system? What does each do?
- Exonuclease- remove the sequence
- DNA polymerase III- Add required nucleotide
- DNA ligase- fix the backbone
What are some other causes for errors in DNA
Cigarette smoke, oxygen radicals, ionizing and non-ionizing radiation (UV and X-rays)
What does the nucleotide excision repair?
Damage from external sources
Energy emission from atomic activities and dispersed at _____ _______ through matter or space.
high velocity
What does radition cause?
Abnormal bonding
What is a thymine dimer?
Bonding between two thymine bases instead of the normal A-T bonding
What enzyme will cut the damaged thymine dimer?
Nuclease
What enzyme will create the new DNA strand?
DNA Polymerase
What enzyme will fix the knick left behind after DNA polymerase?
DNA ligase
What is the significance of altered DNA nucleotides?
Impact protein structure
- changes can become permanent if not fixed and passed to next generation
- Source of genetic variation in populations
