Biology, Genomics and Why Mutants Matter
Your body is made up of approximately one hundred, million, million cells. Each of these cells has a complete set of instructions about how to make your cells, their components and their components' components. This set of instructions is your genome. Scientists know this DNA consists of only adenine, thymine, guanine and cytosine (shown as red, green, blue and yellow in the schematic to the left).
DNA's code is written using only four chemical compounds or 'letters', labeled A, C, T and G. The meaning of this code lies in the sequence in the same way that the meaning of a word lies in the sequence of alphabet letters. Your cells read the DNA sequence to make chemicals that your body needs to survive.
A gene is a length of DNA that contains the instructions to make a chemical in your body. The DNA in a gene usually codes for a protein. For instance, if you hear about 'genes for eye color', it means that these genes code for protein pigments in the iris of each of our eyes making them blue, green or another color.
In gene tests, scientists scan a patient's DNA sample for mutated sequences. Some genetic tests include biochemical tests that identify gene products as enzymes and other proteins rather than a specific gene sequence. Some tests may clarify a diagnosis while others may identify people at high risk for conditions. One of the limitations of these susceptibility tests is difficulty in interpreting a positive result because some people who carry a disease-associated mutation never develop the disease. Scientists believe that these mutations may work together with other, unknown mutations or with environmental factors to cause disease.
The DNA code uses groups of three 'letters' to make meaning. This means that when the cell reads the instructions encoded in the DNA sequence to make a protein, it reads it three letters at a time. Most groups of three letters - known as triplets or codons - code for an amino acid the ingredients that make a protein. Sometimes, one of the DNA letters is accidentally swapped for another letter. This mutation might have a very serious effect or none at all. For example, sickle cell disease occurs because of a mutation in the hemoglobin gene. Note the A is changed to a T in the middle codon which results in the production of valine (Val) not glutamic acid (Glu). You can inherit mutations from your parents. Environmental factors such as smoking and sunlight can increase the rate of DNA mutation in your cells.
Genomes: Things to Know
This is a website describing the Microbial genome annotation network that provides undergraduate students research experience with genome science. http://mgan.jgi-psf.org/
This is the The U.S. Department of Energy Joint Genome Institute’s website that provides information related to DOE’s bioenergy projects. http://www.jgi.doe.gov/