protein in human health and nutrition ppt

protein in human health and nutrition ppt

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

2. Classification of proteinsClassification of proteins
Classification of protein is based on solubility and
characteristic physical properties and partly on chemical
composition .They are grouped into

1.simple proteins: essentially pure proteins, when
hydrolyzed, produce individual amino acids (e.g., egg
albumin)
2.conjugated: protein unit linked to another non-protein
unit (e.g., casein, the protein component of milk with
phosphorus esterified to it via the AA serine (ser)
3.derived: modified proteins such as peptides, modified by
heat, acidification,etc.

3. Classification of proteinsClassification of proteins
1. Simple proteins: are those which yield only
amino acids upon hydrolysis . They include:
a.Albumins: soluble in water , coagulated by heat
b.Globulins : insoluble in water , soluble in dilute
salt solution, coagulated by heat .
c.Glutelins: insoluble in neutral solvents but soluble
in dilute acids and alkalis , coagulated by heat .
d. Prolamins: soluble in 70 to 80 per cent alcohol,
insoluble in absolute alcohol, water and salt
solution.

4. Classification of proteinsClassification of proteins
e. Albuminoids: insoluble in all neutral
solvents and in dilute acids and alkalis
f. Histones and protamines: basic
polypeptides , soluble in water , not
coagulable by heat. They are found in
nuclei of cells

5. Classification of proteinsClassification of proteins
2. Conjugated proteins : are combination of simple protein
and some other non- protein substance , called prosthetic
group, attach to the molecule. They include:
a.Nucleoproteins ; protein + nucleic acid (DNA) are the
principle constituents of the genes and (RNA) are
necessary for the synthesis of proteins in cytoplasm (e.g.,
seed germs)
b.Mucoproteins and Glycoproteins: protein + COH group
(e.g., mucus)
combination of protein and large quantities of complex
polysaccharides such as that found in secretions from
gastric mucous membranes

6. Classification of proteinsClassification of proteins
c. Lipoproteins: compound of protein and triglycerides or
phospholipids or cholesterol found in cell and organelle
membrane
d. Phospholipids : protein+ P-containing compound (e.g.,
casein). Phosphoric acid joined in ester linkage to
protein found in casein of milk .
e. Chromoproteins: compounds of proteins and a non-
protein pigments found in flavoproteins , hemoglobin
and cytochromes
f.Metalloproteins : compounds of metals attached to
protein found in ferritin, hemosiderin
g.lecithoproteins: protein + lecithin (e.g., fibrinogen)
3.Derived proteins: are products formed in the various
stages of hydrolysis of the protein molecules

7. ProteinsProteins structure structure

8. Functions of proteinFunctions of protein
The nitrogen founds in protein is what sets protein apart from
the other macronutrients . Nitrogen gives protein its unique
functions as follows:

1. Growth, maintenance, and repair of body tissue
It is essential for growth , supplying materials for tissues
building. muscles, skin, hair, blood vessels how ? By supplying
amino acids building blocks. This is reason for an increased
protein needs during periods of rapid growth , as
infancy ,childhood and pregnancy
It is essential for life , supplying materials to repair or replace
worn-out tissues. No other nutrients can do it because the amino
acid building blocks of tissues are available only from protein .
Replace lining of GI tract every 3 days (maintenance example)

9. Proteins within Cell WallProteins within Cell Wall

10. Functions of proteinFunctions of protein
2. Enzymes
•Protein supplies certain essential substances for
the construction and proper functioning of
important compounds like (enzymes,
hormones .hemoglobin, antibodies , blood
protein and glandular secretions
•Enzymes are proteins that catalyze (speed up)
chemical reactions
•Every reaction in the body requires a specific
enzyme

11. Functions of proteinFunctions of protein
3. Hormones
•Hormones are chemical messengers
•Travel to target cells/organs and illicit a
response
•Examples:
•Insulin and glucagon
•Growth hormone
•Thyroxin – regulates metabolic rate

12. Functions of proteinFunctions of protein
4. Antibodies
•Protein play a large role in the
resistance of the body to disease .
Antibodies to specific disease are found
in part of the plasma globulin.
Antibodies are;
•Component of immune system
•Attack foreign substances in the body

13. Functions of proteinFunctions of protein
5. Transportation of Substances
•Proteins are needed to transport lipids in the
blood
•Proteins are needed to transport substances
across cell membranes
•Need for nerve and muscle contraction
•Proteins are needed to absorb calcium and
iron

14. Functions of proteinFunctions of protein
6. Fluid Balance
• Protein are important in the maintenance of
normal osmotic relations among the various
body fluids .The plasma protein of the blood
play important role in these relations. Indeed
one of the main signs of the hypoproteinemia is
the appearance of edema (excessive tissue fluid)
as a result of osmotic balance

15. Functions of proteinFunctions of protein
6.Fluid Balance
•Proteins attract water
•3 major fluid compartments – each
contain proteins
•Inside cells
•Plasma in the blood
•Fluid bathing cells (least fluid, least
protein)

16. Functions of proteinFunctions of protein
6. Fluid Balance
Generally proteins do not leave their
compartments
Fluids can move among compartments
Fluids are drawn to the proteins
Need enough protein in the blood and inside
cells to hold water in these compartments and
prevent edema

17. Functions of proteinFunctions of protein
6. Fluid Balance
Edema occurs when there are inadequate
plasma proteins
This occurs when:
Liver disease
Inadequate protein/food intake
Kidney disease  blood proteins excreted
Injury breaks open cells

18. Functions of proteinFunctions of protein
7. Acid Base Balance
•Proteins can act as acids and bases
•Help keep body fluids at a safe pH
•Serve as buffers in the body

19. Functions of proteinFunctions of protein
8. Energy
•Use as a source of energy when
glucose/glycogen stores are empty
•It supplies some heat and energy 4 kilocalories
per gram but is not as well equipped for this
purpose as are carbohydrate and fat .Explain.

20. Functions of proteinFunctions of protein
Explanation
i.It is more expensive source of energy to by and eat
carbohydrate is cheap .
ii.Protein has a greater specific dynamic action (SDA) than
carbohydrate which adds to the total energy expended by
the body. (SDA of food may be defined as the stimulus
given to metabolism which is exhibited to a notable degree
by protein and to a lesser degree by carbohydrate and fat .
iii.One of the end products of protein metabolism is nitrogen
which has to be excreted by the body , a function that
involves a cost in work by the body . Carbohydrate on the
other hand is burns completely to CO2 and H2O

21. Functions of proteinFunctions of protein
9. Dietary protein furnish the amino acids
for a variety of metabolic functions. They
are components or precursors of many
non-protein nitrogen –containing
substances

22. Problems caused by excess protein intakeProblems caused by excess protein intake
The normal kidneys can handle large amounts of nitrogenous waste
without difficulty .
High protein intake is harmful for persons with renal insufficiency , like
chronic kidney disease with nitrogen retention .The damaged kidney
cannot excrete nitrogenous wastes and giving excess protein only adds
to the burden of a kidney that cannot do it’s normal work.
Excess protein is generally a problem for end –stage liver disease
because excess nitrogen from food protein that must be excreted can be
place a burden on the liver.
Excess protein can lead to an excess intake of fat which promote obesity
, cardiovascular disease and cancer.

23. Problems caused by inadequate protein Problems caused by inadequate protein
intake intake
Excess protein also limits the body’s ability to use
calcium
 In low protein intake , the urinary nitrogen falls
drastically , which indicates an adaptation process
going on within the body to compensate for the low
protein intake
If the protein in the diet is suddenly decreased , a
negative nitrogen balance will exist for a few days .
Eventually , equilibrium is reestablished at the lower
level , unless the decreased intake of protein is below
the critical point .

24. Protein DeficiencyProtein Deficiency
Protein deficiencies, along with energy
deficiencies, are the world’s leading
form of malnutrition

25. Protein Energy Malnutrition (PEM)Protein Energy Malnutrition (PEM)
Lack protein and energy-rich foods.
Prevalent in Africa, central and South
America, the Middle East, East and Southeast
Asia
Stunted growth and mental retardation may
occur.
Includes marasmus and kwashiorkor

26. MarasmusMarasmus
Affects very young children.
Results from severe malnutrition (lack of protein,
vitamins, and minerals).
Emaciated, no edema
Characterized by thinness, dry wrinkled and thin
skin
 Poor muscle development, and retarded growth.
Hair is dull and dry

27. KwashiorkorKwashiorkor
Sudden or recent lack of protein-containing
food; affects children and adults.
Fat accumulates in liver, and lack of
protein and hormones results in edema,
Swollen belly painful skin lesions, and
changes in pigmentation of skin and hair.
High mortality rate

28. Differentiate between marasmus Differentiate between marasmus
and kwashiorkorand kwashiorkor
Marasmus Kwashiorkor
Weight decreased
Weight within normal
limits
Visceral proteins
within normal limits
Visceral proteins
decreased
Immune function
within normal limits
Immune function
decreased
Dull, dry hair
Reddish color hair
Emaciated, wrinkled
appearance
Edema, puffy
appearance

29. Kwashiorkor
Marasmus