Biomolecules||Part-IV||Plus One Biology||Zoology||Chapter-9||NEET Biology||K-TET NS Exam||Amino acids

 

#biostripsmedia# #pratheeshpallath#

In this session Bio Strips Media takes through the important topics of Biomolecules. It is one of the most important and scoring topics in Plus One Biology Exam and NEET Exam. 

 

This lecture covers:

·         Amino acids

·         Types of amino acids

·         Peptide bond

·         Neutral, basic and acidic amino acids

·         Zwitter ion

·         Aromatic, heterocyclic and sulphur amino acids

·         Essential and non essential amino acids

·         Functions of amino acids

 

The content being discussed in this video will be helpful for those appearing for the Plus One Biology Exam and NEET Biology Exam.

 

The information in this video is very useful to them and it helps those NEET aspirants to score maximum marks in Biology.

 

The Biology content in this video will be helpful for those candidates appearing for Kerala SET Zoology Exam, Kerala SET Botany Exam, KTET Natural Science Exam and various other Entrance Exams. 

Amino acids

Amino acids are the building blocks of proteins. There are 20 amino acids that are normal components of cell proteins. These are called protein amino acids.

The protein amino acids are composed of carbon, hydrogen, Oxygen and nitrogen, some have sulphur also. Amino acids are organic acids(with carboxyl group) having an amino group generally attached to Alpha carbon.

They have a central four valency carbon atom called Alpha carbon, to which are attached an amino group -NH2  on one side, a carboxyl group -COOH on the other side, a hydrogen atom -H on the third side and a variable group symbolised by -R on the fourth side.  The -R group may be a carbon chain or ring. The carbon chains or rings differ in various amino acids and give the latter their unique properties. The carboxyl group provides an acidic property to the amino acid while the amino group gives basic properties.

Types of amino acids (on the basis of their reaction in solution)

Neutral amino acids

They have one amino group and one Carboxylic group (mono amino mono carboxylic) with a non cyclic hydrocarbon chain. Example: glycine, alanine, Valine.

Acidic amino acids

These amino acids have an extra Carboxylic group (mono Amino di carboxylic). Eg: glutamic acid, aspartic acid

Basic amino acids

They have two amino groups and one carboxyl group per molecule ( di amino monocarboxylic). Eg: lysine, arginine

A particular property of amino acids is the  ionisable nature of 1NH2 and -COOH groups.  Therefore in solutions of different pH structure of amino acid changes.

On the basis of structure

Alcoholic amino acids

These are having alcoholic or hydroxyl group. Eg: serine, threonine.

Heterocyclic amino acids

They have nitrogen in the ring structure.

Eg: Histidine, proline

Sulphur containing amino acids

The amino acid possess sulphur.

Eg: Cysteine, methionine

Aromatic amino acids

They possess  cyclic structure with a straight  side chain bearing Carboxylic and amino group. Eg: Phenylalanine, tryptophan.

Essential and nonessential amino acids

Essential amino acids

They are those amino acids which the human body cannot synthesise from raw materials there are 10 in number. (Leucine, isoleucine, lysine, methionine, phenylalanine, tryptophan and valine, threonine, arginine, histidine,) Essential amino acids are obtained from dietary proteins.

Non essential amino acids

They are amino acids which can be synthesized by the human body from raw materials. They are 10 in number.(alanine, asparagine, aspartic acid, cysteine, glutamine, glutamic acid, glycine, proline, serine, tyrosine). They need not be present in the diet.

Linkage of amino acids

Amino acids link up in such a way that the amino group of 1 amino acid is joined to the carboxyl group of the adjacent one with a loss of water molecule.

The amino group contributes hydrogen and the carboxyl group contributes hydroxyl group to water. The covalent bond joining two amino acids is called peptide Bond.

A combination of few amino acids forms a peptide molecule. A chain of two amino acids is called a dipeptide, of three amino acids a tripeptide, and of many amino acids a polypeptide. 

Functions

·        They are building blocks of proteins and enzymes.

·        Amino acid glycine provides nitrogen and carbon atoms for the synthesis of protoporphyrin  and haem.

·        Tryptophan produces plant hormone indole 3 acetic acid or IAA and vitamin nicotinamide.

·        Amino acid tyrosine gives rise to two hormones thyroxine and adrenaline and skin pigment melanin.

·        Beta alanine, a derivative of aspartate takes part in the formation of coenzyme A and pantothenic acid (a vitamin).

·        Histamine is derived from amino acid histidine through decarboxylation.