Why the Structure and Function of Proteins is Essential to Living Organisms

Why the Structure and Function of Proteins is Essential to Living Organisms

Proteins, along with carbohydrates, lipids and nucleic acid make up

all life on earth, and without any one of these macromolecules, life

on earth would not be able to continue.

Proteins consist of amino acids joined together via peptide bonds to

form polypeptides. There are 20 natural amino acids without which

proteins couldn't exist.

COOH

|

H-C-R

|

NH 2

Above is the general structure of an amino acid, the R represents the

variable group, which varies with each amino acid, and affects the

properties and behaviour of each amino acid. To form a protein the

amino acid must bond with at least one other amino acid, forming a

peptide bond.

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As shown in the diagram Amino acids bond to form proteins which can

bond with other amino acids or other proteins to form new proteins,

therefore there is an infinite number of proteins which can be formed,

each one having its own structure and function within living

organisms.

(1)

(2)

(3)

There are four levels of construction within proteins and which level

the protein is at determines the structure and function of that

particular protein. The four levels are: Primary, Secondary, Tertiary

and Quaternary.

Primary structure makes up the most simple proteins, These fibrous

proteins are made up of simple polymers of amino acids and are

generally very long. They consist a polypeptide backbone running down

the peptide bonds with the variable groups jutting out to the sides,

as demonstrated in the diagram below.

diagram of a polypept...

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...at, pressure and acidity. If the temperature rises

excessively or the globular protein is put under immense pressure

kinetic energy within the molecule will increase causing vibrations

within the molecule to increase also. Eventually the hydrogen bonds

holding protein in its 3D shape break irrevocably causing the molecule

to 'unfold' and lose its shape. Also excess acidity causes the

hydrogen bonds to break and has the same effect as excess heat. This

is known as de-naturation of the protein.

When this happens the proteins can no longer perform their functions

because they no longer have the structure to do so; the key no longer

fits the lock. This further proves a direct link between structure and

function in that when the structure is proved even minutely, the

protein can no longer carry out its metabolic function.