Like it or not, you cannot make a serious study of any aspect of Life Science nowadays without an elementrary understanding of molecular biology. Even if your interest lies far from molecules themselves, and focuses instead on, say, the function of the brain, the anatomy of a developing foetus, or the evolution of the human species, you will find that many of the key papers of your field now rely on molecular techniques. These include the ability to identify individuals by their DNA sequence, the generation of mutant animals with specific 'tailor-made' defects, and the comparison of the genomes of different species. The purpose of this course is to teach you enough molecular biology to allow you to read papers without feeling overwhelmed by technical details, and to give you a starting point from which to find out more when you have to. There are about 150,000 different genes in the mammalian genome .
Genes encode the sequence of amino acids of a particular protein.
There are also usually enhancers either further upstream or sometimes downstream of the promoter. When the appropriate number of transcription factors binds to the promoter and enhancer elements, a transcriptional complex is formed and transcription begins. Translation takes place in the cytoplasm, and begins at an AUG codon. If the nascent polypeptide contains a leader sequence, it and its ribosome are targetted to the endoplasmic reticulum and the protein enters the secretory pathway. Once a polypeptide is complete, it folds up into the three-dimensional structure of the mature protein, either spontaneously or with the help of 'chaperone' proteins.