Presentation Transcript
Radiolysis of water :Radiolysis of water Presented by:
Michael Mallo
NMT 1312
How does indirect interaction occur? :How does indirect interaction occur? As the human body is approximately 80% water, it is theorized that most radiation action with humans are indirect.
Indirect interactions with DNA occur mainly because of the “Radiolysis of Water”.
What is Radiolysis of Water :What is Radiolysis of Water Exposure of cells to ionizing radiation induces high-energy radiolysis of H20 water molecules into H+ and OH- radicals, which are themselves chemically reactive. These in turn recombine to produce a variety of highly reactive radicals such as superoxide (H02) and peroxide (H202), which produce oxidative damage within the cell.
Free Radicals :Free Radicals A free radical is an unstable molecule that loses one of its electrons and therefore becomes unbalanced and highly reactive.
Free radicals have an estimated life of less than 1 millisecond.
They have excess energy which can be moved to other molecules and interfere with bonds at sites distant from the original ionizing incident.
Slide 5:The end result of the radiolysis of water is the development of an ion pair, H+ and OH- , and two free radicals, H* and OH*
Ions can recombine and form a normal water molecule, or they can react chemically and damage cell macromolecules.
References :References Forshier, Steve. Essentials of Radiation Biology and Protection. Canada: Delmar, 2002.
Gateways, Material. Materials Research Society. 23 8 1996-2008. 1 10 2008 .
Researchsoft, ISI. IOP Electronic Journals. 6 12 2008. 1 10 2008 .
Questions :Questions T/F. Indirect interaction takes place if the process of the radiolysis of water fails to occur.
T/F. Only 20% of the human body is water.
T/F. When an atom of water is irradiated, this ionizes the water, and produces a free radical.
T/F. Radiolysis of water occur every time macromolecule is exposed to radiation.
Name two highly reactive radicals that can cause damage to a cell.
T/F. Direct interaction between an (α,γ ray) and water atoms will result in Radiolysis of water.
T/F. Multiple ionizations is shown to be responsible for creation of a large amount of HO2/O2-radicals and O2 molecules.
T/F. The formula for water is H2O (a hydrogen and two oxygen).
T/F. In radiolysis, an electron is attenuated by the gamma ray when the water molecule is irradiated.
T/F. The atom of water duplicates when irradiated.