Cellular Information System (CIS v.1.1b)

Ribonucleic acid (RNA)

RNA is very similar in chemical structure to DNA (DeoxyRiboNucleic acid) but has very different functions in the cell.
There are 3 types of RNA, each with a unique role.

Messenger RNA (mRNA)

• In the process of transcription, the information in DNA is copied (transcribed) into a new molecule, mRNA.
• The enzyme RNA polymerase is responsible for making this mRNA molecule from the information encoded in the DNA.
• The mRNA then moves to the cytoplasm where the information in the mRNA is translated into instructions to make a protein.
• This shuttling of information is necessary as protein synthesis occurs outside the nucleus in the cytoplasm.

Ribosomal RNA

• Is a component of the ribosome (along with ribosomal proteins)

Transfer RNA

• Proteins are made up of chains of subunits called amino acids.
• Transfer RNA acts as a shuttle, picking up a specific amino acid and transferring it to the ribosome for protein synthesis.
• Each of the different amino acids can only bind to specific transfer RNAs.

The information in the mRNA determines what the next correct amino acid should be to make the forming protein. Only the correct transfer RNA (with its correct amino acid) as specified by the information in the mRNA can bind to the ribosome. The transfer RNA therefore ensures that the correct amino acid is attached to the growing protein chain.