2. Proteins are organic compounds with higher
molecular weight (macro-molecules).
They are polymers of L-α amino acids, more
than 50 amino acids linked together by peptide
bonds.
3. Protein
Contains carbon, hydrogen, oxygen and nitrogen
Protein regulates and maintains body functions;
structural (skeleton, connective tissues), protective
(antibodies ), transport (plasma proteins and
hormones) and enzymatic (digestive enzyme).
4. Functions of protien
1-Structural eg: collagen in connective tissue
2-Hormones eg: Insulin
3-Defense molecule eg antibodies
4-Transport of
=molecules - albumin
=Oxygen – hemoglobin
5-Enzymes eg: digestive enzymes
6-Movement and contraction eg: muscle proteins (actin and
myosin)
7- immunoglobulin
8- clotting factors
9- buffers
10- neurotransmitters.
5. • metalloproteins
Transport of oxygen(hemoglobin)
Electron transport (cytochromes)
Photosynthesis (Chlorophyll)
9. Protein are made up of 20 different amino
acids bonded together in different sequences
to form may specific proteins
Twenty amino acids are important in nutrition
10. • Sources and fate of amino acids pool:
• Sources:
1- Dietary proteins
2- Hydrolysis of body proteins
3- Synthesis of nonessential amino acids.
11. 1- Dietary sources of proteins:
A- Animal sources:
- milk and dairy products
- meat
- fish
- liver
- eggs
13. - Maize (deficient in lysine& tryptophan)
- Wheat (deficient in lysine)
- Beans (some beans deficient in methionine)
14. • Proteins biological value:
1- First class (high biological value: contain
all essential a.as eg. Meat & milk).
2- Second class (low biological value:
deficient in one or more of essential a.as
eg. Maize & wheat).
15. • Nitrogen Balance:
Nitrogen balance occurs when the amount
of nitrogen consumed equals that of the
nitrogen excreted in the urine ,sweat ,and
feces. Most healthy adults are normally in
nitrogen balance.
16. NITROGEN BALANCE
Nitrogen balance = nitrogen ingested - nitrogen excreted
(primarily as protein) (primarily as urea)
Nitrogen balance = 0
Positive nitrogen balance
Negative nitrogen balance.
Nitrogen in = nitrogen out
300 g 300 g
Nitrogen in < nitrogen out
250 g 300 g
Nitrogen in > nitrogen out
310 g 300 g
17. • Positive Nitrogen Balance:
Occurs when nitrogen intake exceeds nitrogen
excretion. It is observed in situations in which
tissue growth occurs (e.g. In children, pregnancy,
or during recovery from illness).
18. • Negative Nitrogen Balance:
Occur when nitrogen losses are greater than
nitrogen intake. It is associated with inadequate
dietary protein, lack of an essential a.as, or
during physiologic stresses such as trauma,
burns, illness.
19. BIOMEDICAL IMPORTANCE
All 20 of the amino acids present in
proteins are essential for health.
amino acid deficiency states are endemic in
certain regions of West Africa where the
diet depend on grains that are poor
sources of amino acids such as tryptophan
and lysine.
20. These disorders include kwashiorkor,
which results when a child is weaned
onto a starchy diet poor in protein; and
marasmus, in which both caloric intake
and specific amino acids are deficient.
