Proteins

Miss_Naqvi · #1 Sunday, December 17, 2006

Proteins

Proteins are made up of chains of amino acids. Amino acids are organic compounds that contain an amine group (-NH2) bonded to a carbon atom that is bonded to a carboxylic acid group (-COOH) as seen below. Remember you saw the carboxylic acid group in fatty acids.

For glycine the R group is a hydrogen, H. Other side chains or R groups make up other amino acids. There are about 20 amino acids that naturally form in nature. We can classify amino acids into four major groups, each characterized by its type of side chain: non-polar, polar but neutral, acidic, and basic.

Amino acids can bond together forming what is called a peptide bond (which is also called a amide linkage) . The amine group (-NH2) of one amino acid bonds to the carboxylic acid group (-COOH) of another amino acid as seen below for the general case, where the R groups are different.

Peptide bonds are formed by loosing an (-OH) and a (-H).

Two amino acids bonded together produce a dipeptide. Di means two, therefore if three are bonded together the product is a tripeptide. If many amino acids are bonded together the product would be a polypeptide. Notice that there is still an amine group and a carboxylic acid group in the final product.

When many amino acids bond together they form a protein, which is used in many functions in living organism.

Proteins are the tools of the living organism

Proteins are composed of amino acids and have a defined three-dimensional structure. This form dictates the function. Proteins are responsible for all the reactions and activities of the cell. The structure of the individual proteins is encoded in DNA in the cell nucleus. Cytoskeletal proteins control the shape and movement of the cell.

Proteins are synthesized on ribosomes. Mitochondrial proteins are responsible for cell respiration and the synthesis of ATP that provides cellular energy. Enzymes in the cell catalyze chemical reactions. Storage vesicles contin, and release, hormones and neurotransmittors. They act on receptors and control ion channels. In this way cells can communicate with each other and order proteins in the cell to work in concert with the entire organism.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Solved Everyday Science Papers	Dilrauf	General Science & Ability	4	Friday, April 08, 2011 06:10 PM
Balanced Diet and the function of essential Constituents	Lord AvaLon	General Science Notes	0	Thursday, June 04, 2009 01:44 AM
All about Science	Sureshlasi	General Science Notes	6	Sunday, August 17, 2008 02:04 AM
Plant cell	Last Island	General Science Notes	0	Monday, August 06, 2007 09:40 PM