DNA synthesis, repair and recombination 1 of 2

Question 1

list the possible mutagens-3

Answer 1

Mutagens:

1. chemicals
   
   1. by cell
   2. from enviornment
2. Radiation
   
   1. x ray
   2. UV light

carcingogens

• can be passed to next cell after division and lead to tcancer

Question 2

Describe the rate of DNA mutation

Answer 2

500000 DNA modification per cell per day.

Question 3

describe how the results of a deaminated C and depurinated A

Answer 3

• deaminated C
  
  • one mutant and one unchanged
• Depurinated A
  
  • one mutated (frameshift) and one unchanged

Question 4

Explain the difference between DNA damage

1. direct
2. indirect

Answer 4

DNA damage can be caused by radiation and chemicals

1. directly
   
   1. cigarette smoke- contain benzoapyrene
      
      1. when oxidized in the body, forms adducts with G residues
2. indirect
   
   1. Xrays produce from radicals from H2O
3. UV light forms covalent dimer between adjacent thymines

Question 6

describe what happens in the deaminated C

Answer 6

a cytosine is deaminated into a uricil