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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
   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
SHAPE DETERMINES
 FUNCTION
 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)
Denaturation
   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 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
SHAPE DETERMINES FUNCTION
How Are Proteins Made?
       Heredity Factor
Cystic fibrosis
Hypercholesterolemia
 LDL-receptor


Sickle cell anemia
Sickle-cell hemoglobin
         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
      Protein Function
Structure proteins
 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
Vegetarian Diets-Reasons
Health
Religion
Ethical
Environmental
Taste
 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 vs Meat eaters
Vegetarian              Meat eaters
reduced risk            growth
  obesity
  diabetes
                        support during
  hypertension          critical times.
  heart disease
  digestive disorders
  cancer
  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/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

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
          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

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

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
   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

								
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