This document provides information about protein, amino acids, and nucleic acids. It defines proteins as complex organic compounds that contain carbon, hydrogen, oxygen, and nitrogen. It notes that proteins are found in cells and are involved in many biological processes. It classifies proteins into simple, conjugated, and derived proteins and describes their structures. It also defines amino acids as components of proteins and lists their essential functions. It provides classifications of amino acids and describes their properties. Finally, it discusses nucleic acids and their roles in storing genetic information.

1. BOBY BASNET
ASSISTANT PROF. (ANIMAL SCIENCE)
ILAM COMMUNITY AGRICULTURE CAMPUS
PURBANCHAL UNIVERSITY
bobybasnet666@gmail.com
ANIMAL NUTRITION AND FEEDING
PRACTICES (ANS 224)

2. PROTEIN
Proteins are complex organic compounds of high molecular weight.
50% dry weight of cells (70% water of total cell weight and 30% of
protein)
In common with carbohydrates and fats they contain carbon,
hydrogen and oxygen, but in addition they all contain nitrogen and
generally Sulphur.
Proteins are found in all living cells, where they are intimately
connected with all phases of activity that constitute the life of the
cell.
Each species has its own specific proteins, and a single organism has
many different proteins in its cells and tissues.
Protein is made up of amino acids. 20 amino acids. 9 are essential, 11
essential

3. FUNCTIONS OF PROTEINS
➢ Forms muscles and tissues.
➢ Maintaining the loss of body tissues and muscles.
➢ Essential for the growth and development of the body.
➢ Formation of the enzymes, hormones and digestive juices of the body.
➢ Helps for the proper functioning of the enzymes and hormones.
➢ Repair of body cells as well as for the production of new cells.
➢ Supply energy to the body.
➢ Formation of egg and development of the embryo inside the egg.
➢ Helps for the formation of wools and hairs .
➢ Supplies essential amino acid to the body.
➢ Provides the basic cellular matrix.
➢ Regulation of the osmotic pressure.
➢ Regulation of acid base balance.
➢ Formation of the antigen and antibody.

4. CLASSIFICATION OF PROTEINS
A. Classification on the basis of structure of protein
➢Proteins may be classified into three main groups: simple proteins, conjugated proteins and
derived proteins.
1. SIMPLE PROTEINS
➢These proteins produce only amino acids on hydrolysis.
➢They are subdivided into two groups, globular proteins, and fibrous (scleroprotein) according
to shape, solubility and chemical composition.
a. Fibrous protein/scleroprotein
➢These proteins, which in most cases have structural roles in animal cells and tissues, are
insoluble and are very resistant to animal digestive enzymes.
➢They are composed of elongated filamentous chains joined together by cross-linkages.
➢The group includes collagens, elastin and keratins.

5. ➢Collagens are the main proteins of connective tissues and constitute about 30
per cent of the total proteins in the mammalian body.
➢Elastin is the protein found in elastic tissues such as tendons and arteries.
➢Keratins are classified into two types.
a.The α-keratins are the main proteins of wool and hair.
b.The β-keratins occur in feathers, skin, beaks and scales of most birds and reptiles.
➢These proteins are very rich in the sulphur-containing amino acid cysteine; wool
protein, for example, contains about 4 per cent of sulphur.

6. b. Globular proteins
➢Globular proteins are so called because their polypeptide chains are folded into compact
structures.
➢The group includes all the enzymes, antigens and those hormones that are proteins.
➢Albumins are water-soluble and heat-coagulable and occur in milk, the blood, eggs and many
plants.
➢Histones occur in cell nuclei are not heat coagulated and on hydrolysis they yield large quantity
of arginine and lysine.
➢ Protamines are associated with nucleic acids. Globulin, occur in milk, eggs and blood as well as
reserve protein in many seeds.

7. 2. CONJUGATED PROTEINS
➢Conjugated proteins contain, in addition to amino acids, a non-protein group termed a prosthetic group.
➢Some important examples of conjugated proteins are glycoproteins, lipoproteins, phosphoproteins and
chromoproteins.
➢Glycoproteins are components of mucous secretions, which act as lubricants in many parts of the body.
➢The storage protein in egg white, albumin, is a glycoprotein.
➢Chromoprotein: Protein +pigment= Haemoglobin
➢Lipoprotein: Protein +lipid= serum lipoprotein (lipids are transported in the blood stream to tissue for oxidation
or for storage. Chylomicrons,VLDL, LDL, and HDL).
➢Nucleoprotein: Protein + Nucleic acid= RNA
➢Glycoprotein: Protein + CHO= muicin (component of mucous secretions).
➢Phosphoprotein: Protein + Phosphorus= caesin in milk and phosvitin in egg yolk.
➢Metalloprotein: Protein + Metal= ceruloprotein

8. 3. DERIVED PROTEINS
➢This class of proteins are formed from simple and conjugated proteins.
➢Proteins which are produced by degradation of natural occurring protein by action of heat,
enzyme or chemical agents is called derived protein. eg. Proteoses, peptones, peptides.
➢Derived proteins are subdivided into primary derived and secondary derived proteins.
1. Primary derived proteins:These proteins derivatives are formed by the process which causes
only slight changes in the protein molecules. Such as metaoproteins and coagulated proteins.
2. Secondary derived proteins: Proteases are hydrolytic products of proteins which are soluble in
water, are not coagulated by heat and are precipted by saturated ammonium sulphate.They are
precipated by phospotungstic acid.The examples are proteoses, peptones and peptides.

9. STRUCTURE OF PROTEIN
Primary structure: The simplest level of
protein structure, primary structure, is simply the
sequence of amino acids in a polypeptide chain.
Secondary structure: The peptide chain exists
in the form of the right handed alpha helix.
Tertiary structure: Three-dimensional folding
pattern due to side chain reactions.
Quaternary structure: Protein consisting of
more than one amino acid chain.

10. NUCLEIC ACIDS
❑Nucleic acids are high-molecular-weight compounds that play a
fundamental role in living organisms as a store of genetic
information; they are the means by which this information is
utilised in the synthesis of proteins.
❑On hydrolysis, nucleic acids yield a mixture of basic nitrogenous
compounds (purines and pyrimidines), a pentose (ribose or
deoxyribose) and phosphoric acid. Nucleotide containing ribose
are termed as ribonucleic acid (RNA) while those containing
deoxyribose are termed as deoxyribonucleic acid(DNA).
❑The main pyrimidines found in nucleic acids are cytosine,
thymine and uracil.
❑Adenine and guanine are derivatives of purine base.

11. AMINO ACIDS
• Amino acids are produced when proteins are hydrolyzed by enzymes, acids or alkalis.
• Although over 200 amino acids have been isolated from biological materials, only 20 of these
are commonly found as components of proteins.
• Amino acids are characterized by having a basic nitrogenous group, generally an amino group (–
NH2), and an acidic carboxyl unit (–COOH).
• Most amino acids occurring naturally in proteins are of having the amino group attached to the
carbon atom adjacent to the carboxyl group, and can be represented by the general formula:

12. FUNCTIONS OF AMINO ACID
❑Amino acids plays a important role in cellular metabolism
since almost all biochemical reactions are catalyzed by
enzymes composed of amino acid residues.
❑Amino acids are essential for Carbohydrate and lipid
metabolism,for synthesis of tissue proteins and many
important compounds (i.e. adrenalin, thyroxine, melanin,
histamines, porphyrins, haemoglobin, pyrimidines and
purines-nucleic acids, choline, folic acid and nicotinic acid-
Vitamins, Taurine-bile salts etc.) and as a metabolic source
of energy or fuel.

13. CLASSIFICATION OF AMINO ACIDS
Mono amino-monocarboxylic acids
• Glycine
• Alanine
• Serine
• Threonine
• Valine
• Leucine
• Isoleucine

14. MONO AMINO-DICARBOXYLIC ACIDS
• Aspartic
• Glutamic acid

15. SULPHUR CONTAINING AMINO ACIDS
• Cysteine
• Methionine

16. BASIC AMINO ACIDS
• The basic amino acid contains more than one amino group.
❑Lysine
❑Arginine
❑Histidine

17. AROMATIC AMINO ACIDS
• Aromatic amino acids (AAAs) are amino acids that include
an aromatic ring.
❑Phenyl alanine
❑Tyrosine
❑Trytophane

18. HETEROCYCLIC AMINO ACIDS
Referring to any organic compound forming a ring
made up of carbon atoms and at least one atom
other than carbon.
❑Proline
❑Hydroxypropline
❑Tryptophan

19. ESSENTIAL AMINO ACIDS
• Arginine
• Methionine
• Histidine
• Phenylalanine
• Isoleucine
• Threonine
• Leucine
• Tryptophan
• Lysine
• Valine

20. ESSENTIAL AMINO ACIDS
➢Amino acids can be produced from others by a process known as transamination , but the
carbon skeletons of a number of amino acids cannot be synthesized in the animal body; these
are referred to as essential or indispensable amino acids.
➢Plants and many microorganisms are able to synthesize proteins from simple nitrogenous
compounds such as nitrates.
➢Animals cannot synthesize the amino group, and in order to build up body proteins they must
have a dietary source of amino acids. In poultry, glycine is also essential dietary source.
➢Ruminants do not require the essential amino acids to be supplied in the diet as the
microorganisms present in the rumen can synthesize all the amino acids and when they are
digested in the lower gastro-intestinal tract these amino acids are available to the host animals.
➢However, the supply of amino acids from microbial protein is limiting in quantity and quality for
maximum rates of growth in young animals and for maxi-mum milk production.

21. NON- ESSENTIAL AMINO ACIDS
❑ Alanine
❑ Aspartic Acid
❑Citrulline
❑Cystine
❑Glutamic acid
❑Glycine
❑Proline
❑Hydroxyproline
❑Serine
❑Tyrosine
Nonessential amino
acids are synthesized by
by animal body.
Non-essential amino
acids are mainly
synthesized from
glucose.

23. LIMITING AMINO ACIDS
❑Certain proteins are deficient with one or more essential amino acids. These amino acids are called limiting amino
acids.The essential amino acids are required by livestock in definite proportions. While the proportion may differ
for different functions. The limiting amino acid is the essential amino acid found in the smallest quantity in the
foodstuff. The amino acid which is present in a protein in the least amount in relation to the animal’s need for that
particular amino acid is referred to as the limiting amino acids.
❑Lysine, threonine, methionine, and tryptophan are the major limiting amino acids.
❑The first-limiting amino acid is the essential amino acid that first become deficient in the diet.
❑Lysine is typically the first-limiting amino acid in most swine diets because the requirement of lysine is greater
relative to the amount provided in the diet.

24. PROPERTIES OF AMINO ACIDS
❖Because of the presence of an amino group and a carboxyl group, acids are amphoteric, i.e. they have both
basic and acidic properties.
❖Amino acids in aqueous solution exist as dipolar. In a strongly acid solution an amino acid exists largely as a
cation, while in alkaline solution it occurs mainly as an anion.
❖There is a pH value for a given amino acid at which it is electrically neutral; this value is known as the
isoelectric point. Because of their amphoteric nature, amino acids act as buffers, resisting changes in pH.
❖All proteins have colloidal properties; they differ in their solubility in water ranging from insoluble keratin to
albumins, which are highly soluble.
❖ Like amino acids, proteins are amphoteric in nature.
❖All proteins can be denatured or changed from their natural state( by heat ,acid, alkali, alcohol, urea and salts
of heavy metals).
❖Susceptibility of proteins to heat damage is increased in the presence of various carbohydrate, owing to
occurrence of Millard-type reactions.(condensation between the carbonyl group of a reducing sugar with
free amino group of an amino acid or protein).

25. DEFICIENCY SYMPTOMS OF PROTEIN
Protein deficiencies usually shows the following symptoms in
animals:
❑Reduced appetite in young animals.
❑hypoproteinemia
❑Lowered feed intake.
❑Lack of muscle development.
❑A prolonged time to reach maturity.
❑In mature animals there is loss of weight and decreased
milk production.
❑Kwashiorkor in human
❑lowered appetite, weight loss, poor growth, depressed
reproductive performance, and reduced milk production.

26. SOURCES OF PROTEIN
❖Animal-based foods (meat, poultry, fish, eggs, and dairy
foods) tend to be good sources of complete protein, while
plant-based foods (fruits, vegetables, grains, nuts, and seeds)
often lack one or more essential amino acid.
❖Oil cakes- Mustard, Soyabean Meal
❖Meat and bone meal, feather meal, blood meal, fish meal

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