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
Proteins are strands of amino acids linked by a peptide bond with next amino acid

Glucose
Triglyceride

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 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 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 Structure
Change of shape is called
DENATURATION
What causes change of shape?
acid (like the stomach low pH) or base(high pH) alcohol mechanical agitation(beating an egg white) heat(heat an egg white) or heavy metals(mercury)

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

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
SHAPE DETERMINES FUNCTION

LDL-receptor

Protein Digestion
Stomach
Denaturation
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 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

Muscle fiber protein
Connective proteins others

Protein: Function
Supporting Growth and
Maintenance body needs amino acids to grow new cells and replace cells that are worn out

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: 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
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: Function
.
Maintain acid-base balance proteins buffer the blood against big changes in pH so body remains pretty neutral

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

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
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

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
Strict Vegetarian: Vegan no animal products protein quality-complement calcium iron vitamin B 12
Top Stories - The Olympian -
Olympia, Washington

Vegetarian reduced risk obesity diabetes hypertension heart disease digestive disorders cancer
Meat eaters growth support during critical times.

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 is being made into tissue faster than it is taken apart

Animal products also high in vitamin B12, iron, and zinc lacking in vitamins C and folate often high in fat
Legumes soy protein almost “complete” high in fiber, many B vitamins, iron, calcium low in vitamins A, C and B12

154# (70 kg)
RDA = 70 x .8g/kg = 56 grams
Athlete 1 to 1.5 g/kg (ADA)=
70 to 105 grams Protein/day

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

Dehydration
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

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