Page 200 - MNU microbiology theoritical 2025
P. 200
General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025
1- UV rays.
• It causes mutation through the formation of
pyrimidine dimers “Thymine dimer” (covalent bond
between adjacent pyrimidine bases on the same
strand of DNA
2- Ionizing radiations.
• For example: X- rays.
➢ X rays cause several types of damage:
- Base damage
- single- and double-strand breaks in DNA
B- Chemical mutagens.
• They could be classified into:
1- Mutagens that modify DNA bases.
A- Alkylating agents.
B- Deaminating agents.
2- Intercalating agents.
3- Base analogues.
General Microbiology & Immunology (PM 401) theoretical handbook Page 189
