What are common methods of DNA damage?

What are common methods of DNA damage?

DNA bases can be damaged by: (1) oxidative processes, (2) alkylation of bases, (3) base loss caused by the hydrolysis of bases, (4) bulky adduct formation, (5) DNA crosslinking, and (6) DNA strand breaks, including single and double stranded breaks.

Which DNA damage can be repaired by photoreactivation?

Figure 5.21. Direct repair of thymine dimers. UV-induced thymine dimers can be repaired by photoreactivation, in which energy from visible light is used to split the bonds forming the cyclobutane ring. Another form of direct repair deals with damage resulting from the reaction between alkylating agents and DNA.

Can DNA damage occur during transcription?

In a non-replicating cell, a single-strand break or other type of damage in the transcribed strand of DNA can block RNA polymerase II-catalysed transcription. This would interfere with the synthesis of the protein coded for by the gene in which the blockage occurred.

How do you test for DNA damage?

The comet assay or single-cell gel (SCG) test is a microgel electrophoresis technique that measures DNA damage at the level of single cells. A small number of cells suspended in a thin agarose gel on a microscope slide is lysed, electrophoresed, and stained with a fluorescent DNA binding dye.

What happens if DNA gets damaged?

DNA damage can affect normal cell replicative function and impact rates of apoptosis (programmed cell death, often referred to as ‘cellular senescence’). Alternatively, damage to genetic material can result in impaired cellular function, cell loss, or the transformation of healthy cells to cancers.

What is a TT dimer?

Cyclobuthane thymine dimer is a photolesion produced by UV radiation in sunlight and is considered as a potential factor causing skin cancer. It is formed as a covalently bonded complex of two adjacent thymines on a single strand of DNA.

How do you induce DNA damage to cells?

Ionizing Radiation and Oxidative Stress. In cells, following exposure to ionizing radiation, DNA lesions can be produced directly or indirectly. The direct effect induces a one-electron oxidation of DNA, the indirect effect generates ROS through water radiolysis that can subsequently damage DNA.

How is DNA RNA damage measured?

The Comet Assay is a well-published method to detect various types of DNA damage in intact cells by electrophoresis. Damaged DNA is easily distinguished from healthy DNA by light microscopy; the damaged DNA moves farther when current is applied, creating a “comet” shape (see below).