Proteins classification, source, function & RDA

Objectives
 Introduction to Protein Nutrient
 Attributes of Protein
 Classification of Protein
 Source of Protein
 Functions of Protein
 RDA for Protein
 Excess and Deficiency of proteins

Protein
After water, protein is the most plentiful
substance in the body. Proteins grow,
maintain, and replace the tissues in our
bodies. Therefore our muscles, organs, and
immune systems are mostly made of
protein. Once protein is digested it is
broken down into its amino acid.
You'll find protein in lots of yummy foods
like eggs, nuts, beans, fish, meat, and milk.

PROTEIN
 It is an organic compound contain C,H,O,N,S
 Protein is the 50% dry weight of cells (total
cell weight = 70% of water + 30% of protein
 Protein is made up of amino acids
 There are 20 amino acids in our body. Out of
20 amino acids 9 are essential that need to
take everyday from food and 11 are non
essential that body can make themselves

ATTRIBUTES OF PROTEIN
1) Protein is a long chain-like molecule that is made up of small units known as
amino acids, joined together by peptide bonds.
2) The word protein is derived from the Greek word 'proteios' which means
"primary" or "in the lead".
3) Like carbohydrates and fats, proteins are considered a major nutrient for the
body due to the energy (calories) they provide.
4) Protein is essential for life, it is crucial to all cells in the body playing a key role
as enzymes in a cell. After water, protein is the most plentiful substance in the
body.
5) Proteins grow, maintain, and replace the tissues in our bodies. Therefore our
muscles, organs, and immune systems are mostly made of protein.
6) Once protein is digested it is broken down into its amino acids. These amino
acids can then be reused to make the proteins your body needs to maintain
muscles, bones, blood, and body organs.
7) There are over 20 slightly differing amino acids. Our bodies can produce around
13 of these, but there are 9 amino acids that our body cannot make itself. These
are called essential amino acids and we obtain these by eating certain
protein-rich foods.

ATTRIBUTES OF PROTEIN
8 Complete protein that has all amino acids including essential ones are meat,
poultry, fish, dairy products, eggs, and soy. Incomplete protein sources
include nuts, grains, fruits, and vegetables. Therefore it is important for
vegetarians to pair meals wisely in order to get all essential amino acids in
their daily diet.
9 Keratin is a type of protein that our hair, nails and outer skin is made off.
10 Taking on too much protein can be dangerous to the body, it is a strain on
the liver and kidneys causing them to work extra hard to get rid of the extra
protein.
11 Like the other energy sources, carbohydrates and fat, too much protein can
also lead to weight gain.
12 The protein contained in eggs is considered to be the highest quality protein
out of all foods.
13 Insects actually contain quite high levels of protein, more than some normal
protein foods.
14 Proteins in some food can cause allergies as the structure of a protein can
cause a reaction in the immune system. A lot of people are allergic to gluten
for example, which is a protein in wheat and grains.

Proteins classification, source, function & RDA

CLASSIFICATIONS OF PROTEIN
PROTEIN CAN BE CLASSIFIED BY:
 Structure
 Biological Function
Composition

Biological Function of protein
Proteins depending upon their physical and chemical structure and
location inside the cell, they perform various functions. Proteins are
grouped as follows, based on their metabolic function they perform
1. Enzymic Proteins- They are the most varied & highly specialized
proteins with catalytic activity. Enzymes catalyze a variety of
reactions
2. Structural Proteins- These proteins aid in strengthening or
protecting biological structures. Example: KERATIN
3. Transport or Carrier Proteins- These proteins help in transport of
ions or molecules in the body. Example: Hemoglobin
4. Nutrient and Storage Proteins - These proteins provide nutrition
to growing embryos and store ions
5. Contractile or Motile Proteins- These proteins function in the co
ntractile system. Example: Actin
6. Defense Proteins- These proteins defend against other organisms.
Example: Antibodies
7. Regulatory Proteins- They regulate cellular or metabolic activities.
Example: Hormones:- Insulin
8. Toxic Proteins - These proteins hydrolyze or degrade enzymes. Exa
mple: snake venom

CLASSIFICATIONS OF PROTEIN
COMPOSITION
1. SIMPLE PROTEINS- are those which on hydrolysis yield
only amino acids and no other major organic or
inorganic hydrolysis products.
They usually contain about 50% carbon,7% hydrogen, 2%
oxygen, 16% nitrogen and 0–3% sulphur.
o Example: -Egg (albumin) -Serum (globulins) –Wheat (Glu
telin) -Rice (Coryzenin)
2. CONJUGATED PROTEINS- are those which on hydrolysis
yield not only amino acids but also organic or inorganic c
omponents. The non-amino acid part of a conjugated pr
otein is called prosthetic group.

1. Growth and Maintenance- Your body needs protein for growth and maintenance
of tissues.
2. Causes Biochemical Reactions- Bodily functions that depend on protein enzymes
include: Digestion, Energy production, Blood clotting, Muscle contraction
3. Acts as a Messenger- Amino acid chains of various lengths form protein and
peptides, which make up several of your body’s hormones and transmit
information between your cells, tissues and organs.
4. Provides Structure- A class of proteins known as fibrous proteins provide various
parts of your body with structure, strength and elasticity.
FUNCTIONS OF PROTEIN

FUNCTIONS OF PROTEIN
5. Maintains Proper ph.- Proteins act as a buffer system,
helping your body maintain proper pH values of the
blood and other bodily fluids.
6. Balances Fluids- Proteins in your blood maintain the
fluid balance between your blood and the surroundin
g tissues.
7. Strength Immune Health- Proteins form antibodies to
protect your body from foreign invaders, such as
disease-causing bacteria and viruses.
8. Transports and Stores Nutrients- Some proteins trans
port nutrients throughout your entire body, while
others store them.
9. Provides Energy- Protein can serve as a valuable
energy source but only in situations of fasting,
exhaustive exercise or inadequate calorie intake.

RDA OF PROTEIN
The DRI (Dietary Reference Intake) is 0.8 grams
of protein per kilogram of body weight, or 0.36
grams per pound. This amounts to: 56 grams
per day for the average sedentary man. 46
grams per day for the average sedentary
woman.

DEFICIENCY & EXCESS OF PROTEIN
Protein-deficiency symptoms are always observed when
either protein or energy is deficient
Extreme food energy deficiency is marasmus
Extreme protein deficiency is kwashiorkor
The two diseases overlap most of the time and together
are called PEM
Protein-energy malnutrition (PEM)– World’s most
widespread malnutrition problem. It includes both
marasmus and kwashiorkor and states of overlap
Hunger– Physiological craving for food– Progressive
discomfort, illness, and pain resulting from the lack of food

DEFICIENCY & EXCESS OF PROTEIN
Overconsumption of protein-rich foods can make Possib
le health risks such as:
Heart disease
Homocysteine
Kidney disease
Adult bone loss
Cancer

Quiz Time
Q. Men need more protein than women
 TRUE
FALSE
Q. How many of your calories should come from protein?
 10% to 35%
 5% to 15%
 35% to 50%
 50% to 60%
Q. Why do we need protein?
a. For energy
b. To build cells
c. To repair bones and muscles
d. All of the above
Q. Our bodies are good at storing protein to use later.
TRUE
FALSE

Home Assignment
Q. Prepare the chart that includes rich source of protein veg. &
non veg. food both
Q. Write 5 major functions of protein in our body
Q. Classify protein on the basis of structure composition,
biological function?
Q. Write daily requirement of protein for average age male
and women?

Proteins classification, source, function & RDA

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