The Functions of Proteins in Plants and Animals

The Functions of Proteins in Plants and Animals

Proteins are polymers of monomers called amino acids. Amino acids

contain hydrogen, carbon, oxygen and nitrogen. When amino acids are

linked together, they form polypeptide chains and bonded together by

peptide bonds. There are different structures of polypeptides primary,

secondary, tertiary and quaternary. The primary structure is a

straight chain of polypeptides. Secondary structure is the polypeptide

chain coiling to form an α helix or the polypeptide chain linking

together to form a β pleated strand. In an α helix hydrogen bonding

forms in the secondary structure between the NH group of one amino

acid and the CO group of another amino acid. In a β pleated strand

hydrogen bonding occurs between the CO and NH groups of one amino acid

residue of one chain and the NH and CO group of another chain. The

further folding of the polypeptide chain is known as the tertiary

structure. In this structure the folding and coiling of the chain is

irregular. This causes the types of bonding between the amino acid

residues to vary. The quaternary structure consists of more than one

polypeptide chain this structure is found in haemoglobin. The bonding

between different groups in this case can vary depending upon the

functional groups present. If hydrogen and oxygen bind to another

hydrogen and oxygen of another R group the hydrogen bonding is

present. If not then ionic bonding occurs. If the amino acid residues

contain sulphur then disulphide bridges are formed. There are two

types of protein fibrous which is insoluble in water and globular

which is soluble in water. Fibrous proteins are found in p...

... middle of paper ...

...tractible such as myosin and

actin which are found in the skeletal muscles. They also make up some

of the pigments found in plants and animals. In animals, opsin is

found in both rodopsin and iodopsin which allows animals to see

objects in colour or black and white and is found only in the eye.

Melanin found in mammals is a pigment which gives the skin colour.

Phytochrome is found in plants. This protein allows the conversion of

P730 into P660 or vice versa depending on the amount of far-red or red

light present. This results in the stimulation or inhibition of

flowering.

Many proteins are required in plants and animals to ensure that they

function efficiently. Proteins are needed for many vital processes.

Every protein has its own function within plants and animals varying

from structural to homeostatic control.