Amino acids : Definition, structure, classification with mnemonics

All proteins are polymers of amino acids. Proteins are  composed of a number of amino acids linked by peptide bonds.

Although about 300 amino acids occur in nature, only

20 of them are seen in human body. Most of the amino acids (except proline) are alpha amino acids, which means that  the amino group is attached to the same carbon atom to which  carboxyl group is attached 

Answers to Practice Questions

1. Based on Nutritional Requirements

A. Essential or indispensable: The amino acids may

further be classified according to their essential nature

for growth. Thus, Isoleucine, Leucine, Threonine,

Lysine, Methionine, Phenylalanine, Tryptophan,

and Valine are essential amino acids. Their carbon

skeleton cannot be synthesized by human beings and

so preformed amino acids are to be taken in food for

normal growth. Normal growth and optimal health

will not occur, if one such amino acid is deficient in

the diet.

B. Partially essential or Semiessential: Histidine

and Arginine are semi-indispensable amino acids.

Growing children require them in food. But they are

not essential for the adult individual.

 C. Non-essential or Dispensable: The remaining 10

amino acids are non-essential, because their carbon

skeleton can be synthesized by the body. So we

need not have to ingest these amino acids as such.

However, they are also required for normal protein

synthesis. The non-essential amino acids are Alanine,

Asparagine, Aspartic acid, Cysteine, Glutamine,

Glutamic Acid, Glycine, Proline, Serine and Tyrosine.

2. Proline causes bending or Kinking in protein structure

3. The answer is in the video

4. 

Wanna suggest a video topic for me click here