Wednesday, November 27, 2013

The Central Dogma of Molecular Biology

The idea that genetic information is stored as DNA, copied into RNA, and then used to build proteins is considered the central dogma of molecular biology.

The instructions in DNA determine the structure and function of all living
things. Every time a cell reproduces, it must make a copy of these instructions for the new cell. When cells need to build a functional molecule (usually a protein), they copy the information in the genes into an RNA molecule instead of using the DNA blueprint directly.

Here’s an outline of the process:
  1. Cells use transcription to copy the information in DNA into newly synthesized RNA molecules.
  2. The information to build proteins is copied into a special type of RNA called messenger RNA (mRNA), which carries the blueprint for the protein from the nucleus to the cytoplasm where it can be used to build the protein.
  3.  In a process called translation, proteins are build from the information carried in mRNA molecules.
Transcription is the process by which the information contained in a section of DNA is transferred to a newly assembled piece of messenger RNA (mRNA). An essential enzyme called RNA polymerase finds the genes within the DNA it needs to copy with the help of proteins called transcription factors. Transcription occurs in the nucleus.

Messenger RNA is the only kind of RNA that carries a protein-building message. By the process of translation, the protein-building information in an mRNA is decoded (translated) into a sequence of amino acids. The result is a polypeptide chain that twists and folds into a protein. Simply, Translation is the process where ribosomes (a type of cellular machinery needed for holding the mRNA when translating) synthesize proteins using the mature mRNA transcript produced during transcription. Translation occurs in the cytoplasm.