Protein Part-1 sources function clasification

protein

1. Principles of Food Science Principles of Food Science
and Nutritionand Nutrition
Dr. Nahlaa Khalifa
PROTEIN PART I

2. Protein
Tofu
Nuts
Beans
Meat

3. What is the Nitrogen Cycle?What is the Nitrogen Cycle?
The nitrogen cycle represents one of the most important
nutrient cycles found in terrestrial ecosystems. Nitrogen is
used by living organisms to produce a number of
complex organic molecules like amino acids, proteins, and
nucleic acids.
Despite its abundance in the atmosphere, nitrogen is often
the most limiting nutrient for plant growth.
This problem occurs because most plants can only take up
nitrogen in two solid forms: ammonium ion (NH4+ ) and
the ion nitrate (NO3- ).
Ammonium is used less by plants for uptake because in
large concentrations it is extremely toxic.

4. Why is Nitrogen Needed?Why is Nitrogen Needed?
All life requires nitrogen.
In a never ending “nitrogen cycle” Plants use the
nitrogen take up the nitrates to form their own
amino acids and convert them to proteins. Animals
eat the plants and use the amino acid for tissues
Human eat animals and plants for their amino acids
and rearrange the nitrogen to make the pattern of
amino acids required . Finally everybody dies,
organic molecules are degraded by microorganisms
, nitrogen goes back into the soil to be used by
nitrogen fixed bacteria , and the cycle start again.

5. The Nitrogen Cycle The Nitrogen Cycle
Nitrogen is the most
abundant element in the
atmosphere, but most
organisms cannot use it in
that form.
Rhizobium bacteria in soil ,
cyanobacteria in in fresh
water, and blue – green algea
in sea water have the ability to
utilize inorganic nitrogen and
“fix” it into organic ammonia.

6. The Nitrogen Cycle The Nitrogen Cycle
Certain plants, like legumes e.g. soybean rely on a special
type of bacteria to help them obtain the nitrogen they
need.
These plants cannot use nitrogen gases in the atmosphere
nor can they use the nitrogen compounds in the soil.
Nitrogen-fixing bacteria can find a home and moisture in
root nodules (little bumps on the roots of plants).
A symbiotic relationship is formed , in which the bacteria
provide nitrogen , in exchange for sugars and other
nutrients from the plant. This accounts for the high
nitrogen content in legumes such as soya beans and
beans

7. The Nitrogen Cycle The Nitrogen Cycle
•Agricultural practices take advantage of this
phenomenon farmers rotate legume crops with corn
and wheat to provide added nitrogen to the soil
•Whereas plant structure is primarily carbohydrate ,
the structure of humans and animals is built on
protein .
•Deamination is the removal of the amino (nitrogen)
from the amino acid – thus creating urea. The
remaining deaminated carbon compound can be
used to form carbohydrate or fat to produce energy
at the rate of 4 kcal/g
.

8. The Nitrogen Cycle The Nitrogen Cycle
•Protein in muscles and body tissues is in constant
turnover.
•Tissue protein is degraded and nitrogen excreted
in the urine and new protein is required daily to
maintain the body in steady state.
• An energy deficit or an inadequate protein intake
may force the body to use amino acids as fuel
creating a negative nitrogen balance .
• Protein eaten in excess of need is degraded and
stored as body fat.

9. The Nitrogen BalanceThe Nitrogen Balance
1.Zero Nitrogen Balance
2.Positive nitrogen balance.
3.Negative nitrogen balance

10. Zero Nitrogen BalanceZero Nitrogen Balance
Nitrogen intake equals nitrogen excreted or
Protein made = protein broken down
Anabolism = catabolism
Most adults are in zero nitrogen balance

11. Positive nitrogen balancePositive nitrogen balance
exists when nitrogen intake exceeds amount
excreted or Making more protein than
breaking down
Anabolism > catabolism
It occur in
a.Pregnancy
b.Growth periods Infants and children
c.Building muscle Athletes
d.Rebuilding tissue after trauma/illness

12. Negative nitrogen balanceNegative nitrogen balance
Exists when more nitrogen is lost than taken in. or
Breaking down more protein than you are making
Catabolism > anabolism
It occur in
a.Fever
b.Injury
c.Surgery
d.Burns
e.Starvation
f.Immobilization

14. Proteins:Proteins:
The Basis of Body StructureThe Basis of Body Structure
Protein =Proteins are the most structurally
sophisticated molecules known, and all are polymers
constructed from the same set of 20 amino acids.
Polymers of amino acids are called polypeptides
Proteins form key parts of the body’s main structural
components—muscles and bones—and of blood,
enzymes, cell membranes, and some hormones

15. Elementary Composition of Elementary Composition of
ProteinsProteins
Chemical composition:
primarily carbon, hydrogen, oxygen
Additional difference: contain a fairly
constant amount of nitrogen found in
amino groups (17%)
many also contain sulfur, phosphorus and
iron
structure is typically complex, having high
molecular weight

16. Amino acidsAmino acids
•Amino acids are organic molecules possessing
both carboxyl groups and amino
Types of amino acids :
1.Essential amino acids
2. Nonessential amino acids
3.Conditionally Essential amino acids
COOH
2
NH

17. 1.Essential Amino Acids1.Essential Amino Acids
There are 9 amino acids in total
1.Valine
2.Lycin
3.Methionine
4.Phenylalanine
5.Threonine
6.Tryptophan
7.Isoleucine
8.Leucine
9.Histidin (required for children)

18. 1.Essential Amino Acids1.Essential Amino Acids
Called essential because;
i.You must get them from your diet
ii.They are essential for life & growth
iii.The body is NOT able to produce these
nine Amino acids.
Found in animal protein food
sources*except Soy proteins

19. 2. Non - Essential Amino Acids2. Non - Essential Amino Acids
Are the 13 amino acids that can synthesized by
the body in adequate amount and they are as
follow :
7.Alanine
8.Arginine
9.Asparagine
10.Aspartic acid
11.Cysteine
12.Cystine
13.Glutamic acid
1.Glutamin
2. Glycine
3.Hydroxyproline
4.Proline
5.Serine
6.Tyrosine

20. 3. Conditionally Essential Amino Acids3. Conditionally Essential Amino Acids
Sometimes non-essential amino acids
become essential under special
circumstances e.g. the body use essential
amino acids phenylalanine to make tyrosine
(non-essential). If the diet fail to supply
enough phenylalanine or if the body can not
make conversion for some reasons
(inherited disease phenyleketonuria)

21. Complete andComplete and
Incomplete ProteinsIncomplete Proteins
Biological value :
 Is the term describes how well a particular
protein food approximate the amount and
combination of essential amino acids in the body.
Types of protein:
There are tow types of protein
1.Complete protein
2.Incomplete protein

22. Complete andComplete and
Incomplete ProteinsIncomplete Proteins
Complete proteins or higher quality proteins come
from foods containing all of the essential amino acids
in the quantity and correct ratio to maintain nitrogen
balance and allow for tissue growth and repair.
Sources are; Meat, fish, poultry, eggs, milk, cheese, and
soy
Incomplete proteins or lower quality proteins lack ore
or more of the essential amino acid. Incomplete protein
diets will eventually lead to protein
malnutrition. Sources are ; Plants, including legumes,
grains, and nuts

23. Complete andComplete and
Incomplete ProteinsIncomplete Proteins
Generally speaking , animal sources of protein
such as meat, fish, poultry and dairy product
contain complete proteins of high biological
value. Incomplete yet good sources of protein
food that are lacking one or more of the essential
amino acids include plant sources ; whole grains,
legumes , nuts and seeds .

24. Complementary ProteinsComplementary Proteins
Occurs when a combination of sources of
incomplete / low quality proteins are eaten
in the same day to make a complete protein
Examples: corn and beans, rice and beans,
rice and lentils , bread and peanut butter,
bread and split pea soup, bread and cheese,
bread and baked beans, macaroni and
cheese, cereal and milk tortillas and beans

25. Complementary ProteinsComplementary Proteins
Combining incomplete protein foods
over the course of the day can give the
body all of the essential amino acids
needed for adequate protein status .
Therefore , vegetarians can receive
adequate protein without eating meat
if food choices are made wisely

26. Complementary ProteinsComplementary Proteins

27. Complementary ProteinsComplementary Proteins