Download Proteins

NUTRİTİON
PROTEİNS :
Proteins are complex organic molecules containing :
Carbon – hydrogen – oxygen –nitrogen
Usually sulfur , sometimes : ıron – phosphorous – ıodine and copper
AMİNOA ACİDS are the chemical compounds which make up
PROTEİNS.
The amino acids are often called building bloks
body tissue
because no
can be built without their nitrogen. There are more than 25 a.a
Those which the body can not synthesize are called :
ESSENTİAL AMİNO ACIDS and must be supplied by food.
There are 8 essential amino acids for human adults are :








ısoleucine
leucine
lysine
methionine
phenylalanine
threonine
tryptophan
valine
in addition , histidine is essential
for growing children.
- 1–
Proteins can be denaturated by :
heat – acıd – alcohol – salts of heavy metals.
Amino Acids link in to long strands together that fold or coil to make
wide variety of different proteins.
COMPLETE AND INCOMPLETE PROTEİNS
When the E.a.a are present in a protein in sufficient quantity
to meet the growth needs , that protein is said to have
high biological value .
Proteins that contains all the E.a.a in sufficient quantity and in the
ratio known are called COMPLETE PROTEİNS :
such as ovalbumin
in egg
casein
in milk
other coplete proteins are those in meat – fish and poultry
Proteins that do not supply all the E.a.a in appropriate amounts
are called INCOMPLETE PROTEİNS such as :
vegetables -- grains—seeds
EGG
B.V : 100
RİCE
B.V : 86
- 2-
THE ROLE OF PROTEİNS ( THE FUCTİONS )
1 . growth and maintanance
2 . formation of enzymes and hormones
Enzymes : are organic catalyst they help the chemical reactions
Hormones : organic substance, they are discharged directly in to
the blood stream for specific regulatory action on the other
organs and gives signals to approprite enzymes to start work.
Regulation functions :
Eg.
blood glucose level by
Metabollic rate by
INSULİN
TYROXİNE
3 . formation of antibodies requires proteins.
Antibodies are spesific substance which protects us from
diseases and foreign substance. Important for ımmun system.
4 . regulates fluid balance : blood PH - osmotic pressure – water
balance
5 . proteins produce energy
-3-
THE BODY’S USE OF PROTEİNS
FOOD
PROTEİNS seperated from
other nutrients
uncoiled by stomach acids
broken in to smaller pieces in
the intestine by enzymes
release them in to the blood
they go to the liver
lıver acts as a distribution
and disposal center
-4-
The diet should supply all E.a.a simultaneously.
If an E.a.a is missing at the time of protein
synthesis
synthesis STOPS.
If we consume proteins more than we need
these proteins covered as fat- glucose - glycogen
than energy .
A . Acids in the cell can be used to :
 mainly in the protein synthesis
 convert to glucose
 provide energy
proteins
a.a
by digestion a.acids
protein synthesis
a.a
fat
fat synthesis
a.a
glucose
energy brain cells
-5 -
Factors that must be supplied in the diet for the body
to be able to synthesis PROTEİN include :
1 . all E.a.a consume simultaneously and in proper amount
2 . an adequate total amount of protein to supply amine
groups to synthesis non – E.a.a
3 . adequate of CHO & FAT to spare protein being
used to yiaeld energy
R D A ( RECOMMENDED DAİLY ALLOWANCE )
1 gram / kg
0.8 gram / kg
2.2 gram / kg
for adolesant
for adults
for newborn
1.2 gram / kg
for childhood
% 12 –15 of the total energy should come from proteins.
-6 -