Proteins, Amino Acid, Peptide, Peptide bond, Polypeptide??? IM CONFUSED?

[iniloy]

Hey guys, im studying for my bio exam and im just so confused between all of the stuffs mentioned in the questions. Like I am having a hard time understanding which one is which ones part. I would REALLY APPRECIATE if you guys help me understanding this stuff.....its just so vague and confusing...so please explain in a way that is crystal clear....pls help

[Kunal Pandya]

Amino acid :- Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids Nh2-CH(R)-COOH [ Where R is side chain).Their were 20 natural occuring amino acid and they are polymerize to give Peptide,Polypeptide and protein.

Peptide Bond :-A peptide bond is a covalent bond that is formed between two amino acid when the carboxyl group of one amino acid reacts with the amino group of the another amino acid. Simply [O=C-NH ], while amide bond is [O=C-NH2]

Peptide :- Peptides are short polymers of amino acids linked by peptide bonds. Here is confusion about no. of amino acid but mostly till 50 amino acid they were called peptide or polypeptide and if no. of amino acid is more then 50 it's called protien.

Polypeptide is same as peptide which use by some of the chemist to define peptide haviny amino acid more then 2 but less then 50 .

Protein :- Having amino acid more then 50 which were linked by peptide bond

go for this link for more details.

http://en.wikipedia.org/wiki/Protein