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Class Notes S3 - Coggle Diagram
Class Notes S3
CHAPTER 7: BIOCHEMICAL EFFECT OF POLLUTANTS
When pollutants enter living organisms; they cause a variety of changes (bio-effects) and can be 2 kinds: 1. Those which serve to protect the organisms against the harmful effects and 2. those which don’t.
Protective responses
When the concentration of a xenobiotic or inorganic ion exceeds a certain level in the cell, it may trigger off responses designed to protect the organism against potential toxic effects.
Monooxigenases
Metallothioneins
Non portective/ repair responses/ homeostatic mechanisms
MOLECULAR MECHAMISMS OF TOXICITY
In studying responses to toxic molecules, it is very important to construct appropriate dose—response curves of the range of exposures that are likely to be experienced. It would be unwise to assume that a dose—response curve is a simple straight-line relationship.
GENOTOXIC COMPOUNDS, Many compounds which act as carcinogens are known to cause damage to DNA, i.e. they are genotoxic, and it is strongly suspected that this is a causal relationship.
The relationship between DNA changes and harm to the organism is complex.
NEUROTOXIC COMPOUNDS
The nervous system of both vertebrates and invertebrates is very sensitive to the toxic effects of chemicals and there are many examples of neurotoxins—both naturally occurring and manmade
MITOCHHONDRIAL POISON, mitochondrial poisons, can inhibit the operation of the electron transport chain of the inner membrane of the mitochondrion, thus preventing the production of the proton gradient referred to above.
VITAMIN K ANAGONISTS
Vitamin K plays an essential role in the synthesis of clotting proteins in the liver. It undergoes a cyclical series of changes (vitamin K cycle) during the course of which the clotting proteins become carboxylated. After carboxylation has occurred, the clotting proteins are released into the blood, where they play a vital role in the process of clotting, which occurs when there is damage to blood vessels.
THYROXINE ANTAGONISTS
The thyroid gland produces two hormones which have marked effects upon metabolic processes in many tissues. One of these, thyroxine (1–3,3,5,5-tetraiodothyronine or T4), binds to the protein transthyretin (TTR) which is part of a transport protein complex found in blood. The other part of the complex consists of a second protein to which is bound retinal (vitamin A).
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