Slide 1
Protein NTN 1232Learning objectivesList down the essential and
nonessential AADescribe the different sources of proteinsExplain
the methods of measuring protein qualityExplain the health effects
of protein
Introduction Involve in body structure formation Eg : Muscles,
cell plasma membrane, nailsContain C,H,N,OProvide 4 kcal/gAmino
acids (AA) link together by peptide bonds to form proteinsTwo types
of AA two types Essential & non essential
Functions of proteinsStructure formation muscle, nails,
hairHereditary function Histone in DNARegulatory functions -
hormonesCatalytic functions - enzymesAcid base balanceFluid
balanceImmune functions Antibodies Provide energy 4 kcal at
starvation
Protein digestion and absorptionStart in stomach Complete in
Small intestine Trypsin, pepsisn, EndopeptidaseExopeptidase, di
& tri peptidasesEnd products AA, small peptidesFinal digestion
in SI cellsAA travels to liver Produce proteins, glucose, fat, or
enter to blood Protein denaturationDestruction of protein
structureBy HCL in stomachImportant for protein digestionAccessible
to photolytic enzymes Caused by acids, base, heatCooking is
important for protein digestion
Essential AAEssential AA: - AA that can not be synthesized in
the body in sufficient amount to meet physiological requirements.
IsoleucineLeucineLysineMethioninePhenylalanineThreonineTryptophaneValine
Histidine For small children AA that can be synthesized in the body
in sufficient amount to meet physiological requirements
GlutamineGlycineProlineSerineArginineAlanineAspartic acidsGlutamic
acidNon essential AAConditionally essential AASome AA become
essential when there are conditions in the body that prevent the
biochemical conversion of one amino acid into another Glutamine (at
ill condition) Tyrosine (from Phenylalanine)
Type of proteins Animal proteinsPlant proteins Animal proteins
High in qualityComplete proteinsProvide all essential AAEg : Fish,
meat, eggs, milkAbsorption is high
Plant proteins Lower in qualityIncompleteNot having all
essential AANeed to combine food items to make the diet completeEg:
- Pulses, nuts, legumesLess absorption
Protein quality Food proteins that provide an unbalanced
combination of amino acids are poor quality proteins. Limiting
amino acids An essential amino acids supplied in less than the
amount needed to support protein synthesis is called limiting amino
acids Complete proteins Protein contain all the essential amino
acids in relatively the same amount as human being require. (except
gelatin lack tryptophan) Eg animal protein, but soy proteins are
completeMeasurements of protein quality Biological value amount of
protein nitrogen that is retained for growth and maintenance, as a
percentage of the protein nitrogen that has been digested and
absorbed.
Amino acids scoring Comparison of a protein with reference
protein Digestibility A measure of the amount of AA absorbed from a
given protein intakeNitrogen balanceBody maintain same amount of
protein in tissues for day today works N balance = N intake N
lossesLosses = Urine + feces + skinN balance = +ve, -ve, Zero + ve
= Growth, among children, pregnant mothers, recovering from
illness- ve = starving, burns, injuries, infections, wasting (body
protein breakdown for energy) 1 g N = 6.25 g protein
Protein turnover Constant degradation and synthesis of body
proteins are known as protein turnover Protein in tissues
constantly made and break downFree AA comes to circulationSome
recycled for other proteins Some use for energy productionHealth
effect of proteins Heart diseases - AA homocystein - Saturated fats
Cancers colon, breast, kidneyOsteoporosis - increase Ca excretion
Obesity protein rich foods are rich in fats Protein energy
malnutrition Marasmus - Result from sever deprivation or impaired
absorption of energy, protein, vitamins and minerals
Kwashiorkor result ether from inadequate protein intake or from
infections Proteins that maintain fluid balance diminish
Activity List down the consequences of Kwashiorkor and
Marasmus
