is common knowledge that relatively few offspring of any species survive to reproduce. Charles Darwin (biologist, 1859) formed the idea of natural selection: the idea that some individuals will have a higher probability of survival than others, and on average such individuals will then leave more descendants than other less well adapted individuals. We will use Darwin's, Mendel's and Watson and Crick's and other information to investigate our concern - the role of pollutants in natural selection. It has been shown many times that pollutants can exert powerful selective forces, and we need therefore to understand something of the mechanisms of inheritance and how natural selection acts on populations.For the purpose of this assignment I will outline/review all the general findings of important works that proved significant in understanding the concepts of genetics. A good place to start would be with an outline of some of Mendel's results obtained when breeding peas (Pisum sativum). "A" indicates the dominate gene for yellow seed, "a" the recessive gene for green seed.However, genes do not always fall into this simple dominant/recessive pattern. Some may be incompletely dominant in the heterozygote, showing a transition stage between the phenotypes of the homozygous dominant and recessive conditions. Later workers also found that there are often more than two alternative forms of a gene. One such worker was Avery (1944) who showed that the genetic material in a bacterium consists of the nucleic acid DNA (deoxyribonucleic acid), and in 1953 Watson and Crick first suggested the three-dimensional structure of DNA from which has developed all the subsequent work on the genetic code. The essential feature of this code is that: genes are arranged along chromosomes, which in essence may be regarded as giant molecules of DNA. The DNA molecule consists of two intertwined helical chains of many nucleotides, with ten nucleotides in both chains for...
