Genetic Structure - Page 5

Proteins

Proteins are compounds assembled from amino acids using information contained in genes - genes make proteins.

Each protein has its own unique amino acid sequence that is specified by the nucleotide sequence of the gene coding (making) this protein. The genetic code is a set of threenucleotide sets called codons and each three-nucleotide combination designates an amino acid.

For example these three bases: <A-T, AT, G-C> code for the amino acid lysine.

Image Courtesy of U.S. Department of Energy Genomes to Life Program Roadmap, April 2001, DOE/SC-0036, U.S. Department of Energy Office of Science, http://genomicsgtl.energy.gov/.

In Summary; When a cell needs to make a specific protein, a gene for that protein in the nucleus "switches on"; it reads the DNA bases that make up the gene for that protein then transcribes a copy of RNA for that protein.

This RNA is then moved out of the nucleus into the cytoplasm. In the cytoplasm mRNA is translated into an intermediary molecule called amino acid. Several amino acids connected to each other from a protein. The genetic code carried by DNA is what specifies the order and number of amino acids and, therefore, the shape and function of the proteins produced.