This document discusses amino acids and proteins. It defines amino acids as organic compounds that contain both amino and carboxyl groups, and notes that they are the building blocks of proteins and polypeptides. It identifies 10 essential amino acids that must be obtained through diet as humans cannot synthesize them. The document outlines different types of amino acid structures and discusses how amino acids link together through peptide bonds to form polypeptide chains and proteins.

1. E. Elavarasi,
III B.Sc. Chemistry,
BON SECOURS COLLEGE FOR WOMEN,
THANJAVUR.

2. • Organic compounds that contain
both amino group and acid group.
-NH2, -COOH
• Building blocks of proteins and
polypeptides
• Biologicaly significant.

3. 25 amino acids
ESSENTIAL
AMIN0 ACIDS
NON
ESSENTIAL
AMINO ACIDS
AMINO
ACIDS

4. • Deficiency in any one of the essential
amino acid
 prevents growth in young
animals
 cause death
• Cannot be synthesized by
themselves.
• Must be supplied in their original form.

5. Leucine Tryptophane
Isoleucine Arginine
Valine Methionine
Threonine Phenylalanine
Lysine Histidine

6. The amino acids that can be
synthesised from other compounds
by the tissues of the body

7. H2NCH2COOH -aminoacid
CH3CH(NH2)COOH -aminoacid
CH2(NH2)CH2COOH -aminoacid
CH2(NH2)CH2CH2COOH -aminoacid

8. • Due to the presence of an acidic and a basic group in the
same molecule, amino acids exist in an ionic form called a
Zwitter ion where
the proton of –COOH group is transferred to the –NH2
group.

9. The pH at which the amino acid
shows no tendency to migrate when
placed in an electric field is known
as isoelectric point.

10. • The bond formed between two amino acids
by the elimination of a water molecule is
called a peptide linkage or bond.

11. The product formed by linking amino
acid molecules through peptide
linkages, – CO – NH –, is
called a peptide.

12. Complex nitrogenous organic
compounds.
Contain C, H, N, O & occasionally S
and halogens.
Polymeric amides.
monomer – amino acids.

13. Protein

Polypeptides

Peptides

Amino acids

14. 1. Fibrous Proteins – skin, hair, nails,
wool, muscles.
2. Globular Proteins – enzymes,
harmones, haemoglobin, albumin.
3. Conjugated Proteins –
nucleoproteins, haemoproteins.

15. 1. Structural proteins – skin, bone
2. Contractile proteins – skeletal
muscle
3. Enzymes – amylase, pepsin
4. Harmones – adrenaline, insulin
5. Antibodies – gamma globulins
6. Blood proteins - fibrinogen

16. Primary structure
 sequence of amino acid present in
the molecule.
N – terminal ends with amino
group
C – terminal  ends with acid group

17. • Isolated in a pure state.
• Whether it consists of single peptide chain
or no. of sub-units.
• Hydrolysed into constituent amino acids,
their nature and amounts are determined.
• Molecular weight is determined.
• End group analysis.
• Amino acid sequence is determined.

18. • Conformation of the polypeptide is
called the secondary structure.
• Protein chain is coiled.

19. 1. Peptide group is planar.
2. H – bonding stabilises the
conformation.

20. • 3.7 amino acid residues per turn.
• Each H bond is formed between CO
group of one residue and NH group of
fourth residue
• H bonding prevents rotation. So helix
is rigid.
• Right handed helix – more stable.