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PROTEIN - PowerPoint PPT Presentation

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PROTEIN. Protein Structure. Polymer of amino acids amine group (N) acid group side chain. Protein Structure. Proteins are unique among energy nutrients They contain NITROGEN Composed of 20 different amino acids 9 amino acids are essential, other 11 are not essential

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protein structure
Protein Structure
  • Polymer of amino acids
    • amine group (N)
    • acid group
    • side chain
protein structure3
Protein Structure

Proteins are unique among energy nutrients

They contain NITROGEN

Composed of 20 different amino acids

9 amino acids are essential, other 11 are not essential

Proteins are strands of amino acids

linked by a peptide bond with next amino acid




protein structure6
Protein Structure

Primary Structure

Amino acid sequence or strand

like a strand of pop-beads or pearls

Secondary Structure

coiling of the strand

like a slinky: positive and negative parts attract each other

protein structure7
Protein Structure

Tertiary or third level of structure

Folding back of coil

The slinky gets messed up

Quaternary or fourth level of structure

Subunits fit together

Hemoglobin has four subunits to make the functional molecule

protein structure8
Protein Structure


The shape of the protein molecule determines if the molecule is functional

the shape of the lipase molecule determines if it will actually help breakdown a lipid

protein structure9
Protein Structure

Change of shape is called DENATURATION

What causes change of shape?

acid (like the stomach low pH) or base(high pH)


mechanical agitation(beating an egg white)

heat(heat an egg white) or heavy metals(mercury)

cellular protein synthesis
Cellular Protein Synthesis

DNA: in nucleus: acts as a template for mRNA

mRNA moves out of nucleus to cytoplasm

Carries instruction for an amino acid sequence for a specific protein to a ribosome

Ribosome ‘reads’ the mRNA which dictates which amino acid is next

tRNA carries the correct amino acid to the mRNA

cellular protein synthesis12
Cellular Protein Synthesis

tRNA’s line up one after the other with amino acids

Amino acids form peptide bonds to make the primary sequence of the protein

Protein then coils to form the secondary and tertiary structure


heredity factor
Heredity Factor
  • Cystic fibrosis
  • Hypercholesterolemia
    • LDL-receptor
  • Sickle cell anemia
protein digestion
Protein Digestion



Pepsin induced breakdown into shorter ‘peptides’

Small Intestines

duodenum: peptidases or proteases enter from pancreas thru the common bile duct

breakdown proteins to aa’s, dipeptides and tripeptides

protein digestion18
Protein Digestion

Cells of small intestine

complete digestion of proteins so that only amino acids remain

cells of S.I. absorb amino acids and a few larger peptides and release them into the blood for circulation

protein function
Protein Function
  • Structure proteins
    • Muscle fiber protein
    • Connective proteins
    • others
protein function21
Protein: Function

Supporting Growth and Maintenance

body needs amino acids to grow new cells and replace cells that are worn out

protein function22
Protein: Function

Building Enzymes, Hormones, and other Compounds

amino acids used to make enzymes (e.g.. lipases for digestion)

amino acids used to make some hormones(e.g.. insulin for glucose metabolism)

protein function24
Protein: Function

Building Antibodies

antibodies are formed from amino acids to defend against foreign proteins and substances in the body

Maintaining fluid and electrolyte balance

Proteins act like magnets and hold water in the blood vessels and also electrolytes like sodium

transport proteins
Transport Proteins

Cellular content differ from the contents of the surrounding environment: fluids and electrolytes

Protein Membrane carriers provide a ‘pump’ to maintain this difference

Sodium-Potassium Pump

Animation of the Sodium-Potassium Pump

protein function26
Protein: Function

Maintain acid-base balance

proteins buffer the blood against big changes in pH so body remains pretty neutral


protein function27
Protein: Function

Providing Energy

When insufficient CHO and Fat are eaten, the body takes apart Protein for energy

Nitrogen portion removed from A.A. and the rest is oxidized for energy. Nitrogen ends up in the urine as urea

amino acid possibilities
Amino Acid Possibilities

Can be added to other A.A.’s to make a protein

Can have Nitrogen removed

then it can be oxidized for energy or

made into glucose (glucogenesis) or

made into fat (lipogenesis)

The diet needs to supply the 9 essential amino acids and 0.8 grams protein/kg wt.

protein quality use and need
Protein Quality, Use and Need

Protein Quality

the amino acid assortment greatly influences a protein’s usefulness to the body

protein quality use and need30
Protein Quality, Use and Need

Measuring Protein Quality

the amount of the essential amino acids present in the protein

If all are well represented, the protein will support growth and maintenance: COMPLETE PROTEIN

If not, it won’t support growth: POOR QUALITY PROTEIN

protein quality
Protein quality

Complete or good quality proteins

soy beans, milk protein, animal flesh

Poor quality proteins

grains (missing lysine, an essential amino acid)

many legumes(beans, missing methionine)

Mutual Supplementation or complementing proteins

mix grain and legume and get a good quality protein eg: corn tortilla and refried beans


Vegetarian Diets-Reasons






types of vegetarian diets
Types of Vegetarian Diets

Non-red meat vegetarian

poultry, fish, dairy, eggs O.K

no special nutritional problems, may be high in fat, saturated fat

Lacto-ovo vegetarian

milk and eggs O.K.

no special nutritional problems

may be high in fat, saturated fat

vegetarian diets types
Vegetarian Diets: Types

Strict Vegetarian: Vegan

no animal products

protein quality-complement



vitamin B 12

Top Stories - The Olympian - Olympia, Washington

vegetarian vs meat eaters

reduced risk




heart disease

digestive disorders


Meat eaters


support during critical times.

Vegetarian vs Meat eaters
protein rda 0 8 grams kg
Protein RDA: 0.8 grams/kg

Nitrogen balance

negative balance= more out in urine than coming in from the diet

protein is being broken down faster than it is replaced

who is in this predicament? elderly, bedridden

protein rda 0 8 grams kg38
Protein RDA: 0.8 grams/kg

positive balance=more in the diet than going out in the urine

protein is being made into tissue faster than it is taken apart

protein rich foods
Protein Rich Foods

Animal products

also high in vitamin B12, iron, and zinc

lacking in vitamins C and folate

often high in fat


soy protein almost “complete”

high in fiber, many B vitamins, iron, calcium

low in vitamins A, C and B12

protein needs
Protein Needs

154# (70 kg)

RDA = 70 x .8g/kg = 56 grams

Athlete 1 to 1.5 g/kg (ADA)=

70 to 105 grams Protein/day

too little protein
Too little Protein

Kwashiorkor: Protein deficiency

true definition: what happens to the first child when the second child is born

symptoms: edema, ascites(swollen belly)

immune system failure so many infections

loss of pigmentation

Phenylalanine to Tyrosine to Melanin is blocked

Fatty Liver

no lipoproteins to carry fats and accumulate in liver

too much protein
Too Much Protein


100 Cal of extra protein takes 350 grams(12 oz) of water to clear( this is how many grams of protein?)

100 Cal of extra CHO or Fat only takes 50 grams of water to clear

Coupled with heavy workouts may result in dehydration

protein needs of athletes
Protein needs of Athletes

May be up to 1.7 for power athletes

May be up to 1.4 grams/kg for endurance athletes

Tour de France, marathoners, triathletes

They may need every available source of energy they can get their hands on