The role of deoxyribonucleic acid or DNA in protein synthesis is that of a blueprint. It is a guide to the structure of the proteins being produced. Without DNA, the ribosomes in any given cell would not know what order to put amino acids in. DNA has the same function in both prokaryotic and eukaryotic cells, although there are subtle differences.
DNA is a chain of nucleic acids arranged into two polymers or strands. Each strand has one set of amino acids that connects to an opposite amino acid on the other polymer to produce a structure that looks like a window cleaner’s ladder. The order of amino acids is a genetic map of information that tells the cell how it is to be structured and tells the cells how to combine to form a larger organism. The information is used directly to build cell components such as ribonucleic acid (RNA) and protein.
The presence of DNA in protein synthesis is vital. Protein synthesis is the act of creating a new protein within a cell. The entire process takes place within a ribosome, a kind of protein factory, within a cell. Free ribosomes in eukaryotic cells and all ribosomes in prokaryotic cells synthesize proteins in the cytoplasm.
There are many steps to the protein synthesis process. The use of DNA during protein synthesis takes place in the first stage called amino acid synthesis. The second stage is called transcription, and the final phase is where the ribosome translates the information into protein.
A protein called helicase splits apart both polymers of DNA in protein synthesis. One of the strands will contain the protein blueprint the cell requires. This strand will be copied into messenger RNA (mRNA) when the mRNA is organized so that it is made up of the opposite amino acids to those present in the DNA section being copied.
The mRNA then takes the information to the ribosome. The ribosome will process the mRNA so that it translates the amino acid code using the opposites of those in the mRNA, therefore returning the chain back to its original form. From this, the ribosome makes proteins.
Organisms are not capable of synthesizing all amino acids. There are around 20 known amino acids in the world, and humans can synthesize around 12 of them. The rest are ingested through food and sometimes drink.
The prokaryotic cell will convert DNA in protein synthesis directly into mRNA. Eukaryotic cells, however, first transcribe the DNA into heterophil nuclear RNA (hnRNA). This hnRNA is created when the polymer section is capped with 7-methyl-guanosine and a poly A tail. The cell then converts hnRNA into mRNA.