Gene Expression

Let´s review what we have learnt so far. We learnt a bit about the cellular components: the membrane, the cytoplasm with ribosomes, the Golgi vesicles, the cytoskeleton, mitochondria and the nucleus containing the chromosomes that consist of DNA and proteins. Next we will have a closer look how these components are integrated into the cell´s life cycle in normal cells and how the regulation is changed in cancer cells.

For a cell to survive and to grow gene expression is necessary to produce proteins. They are the major working power and the structure forming parts of the cell followed by the nucleic acid RNA (Ribonucleic acid), which is related chemically to DNA (Desoxyribonucleic acid). The first two chapters will, therefore, deal with the Genetic Code and with changes in the code by Mutations. Then we will look at how the information in the DNA is converted to a protein. The first process on the way to the synthesis of proteins is the reading of pieces of DNA from chromosomes encoding single genes thereby synthesizing an RNA species called Messenger RNA. The important point here is that a messenger RNA or abbreviated ´mRNA´ encodes only one polypeptide (remember: all proteins are polypeptides) and is mobile. Chromosomes are rigid and cannot leave the nucleus. Further, RNA is chemically slightly different, which is important for protein synthesis. The synthesis of the mRNA is called Transcription and the enzyme producing mRNA is called RNA polymerase. Once the mRNA is synthesized it has to be processed, which we will discuss in the chapter ´Processing RNA´. Again as pointed out earlier I will present only a very simplified scheme of transcription and processing of RNA showing the basic concept, which is necessary to understand the difference between normal and cancer cells.

What comes next? First we have to get familiar with the genetic code to understand gene expression. So let´s have a closer look at DNA and unravel the secret of the genetic code.

Gene Expression

Overview