Functional Genomics is the study of the function of all genes of an organism. The understanding of such function allows understanding the physiology and metabolism of an organism. A major approach is transcriptomics, the study of all genes expressed at a given moment, for example by cDNA microarrays.
From Genes to Proteins
credit: http://ghr.nlm.nih.gov/handbook/illustrations/proteins
In fact genes code for proteins through the intermediate of RNA (see figure above). If more RNAs corresponding to specific genes are present at one point, this means that the cell is making more efforts to produce the type of proteins that are coded by these genes. These genes are then said to be over-expressed.
By comparison of the level of expression of genes in different conditions (stress due to an attack by a pathogen, etc…(see cDNA microarrays), scientists are able to see which kind of protein is being more or less synthesised by the organism. In fact, when an organism is under a certain condition of stress, like high light for instance, it will produce more of one or several kinds of proteins in order to develop a strategy to resist to this stress.
For example, functional genomics is being used for the study of the physiology of the red alga, Chondrus crispus, and especially for the study of the physiological response of the alga to an attack by a pathogen or grazer. In fact, this tool allows scientists identifying all the molecules that are implied in this response.
Comparing the level of expression of genes between the different stages of development can allow understanding which proteins are more particularly needed at which moment. This can be very interesting concerning marine invertebrates because their planktonic larvae often have to undergo metamorphosis in order to become adults that are fixed to the substrate. Functional genomics can allow identifying which proteins are needed for this transformation.
