Food Issues Consumer Awareness By Jennifer Turley and Joan Thompson © 2013 Cengage.
Proteins: From Foods to Cells in the Body By Jennifer Turley and Joan Thompson © 2013 Cengage.
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Transcript of Proteins: From Foods to Cells in the Body By Jennifer Turley and Joan Thompson © 2013 Cengage.
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Proteins: Proteins: From Foods to Cells in the BodyFrom Foods to Cells in the Body
By Jennifer Turley and Joan ThompsonBy Jennifer Turley and Joan Thompson
© 2013 Cengage© 2013 Cengage
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Presentation Overview
• Denaturation vs. Digestion
• Synthesis
• Character & Types
• Functions
• Quality
• Needs (Recommended Intake)
• Deficiency vs. Excess
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Protein Denaturation
• Causes the protein to change shape or conformation.
• The protein and the amino acids are still intact.
• Can be caused by heat, alkali or acid treatments, or metals.
• Is required before the protein can be digested.
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Protein Digestion• The protein strand is broken and
the amino acids are released.• Occurs by the protease enzymes
secreted by the pancreas and GI mucosal cells.
• Amino acids are absorbed, transported to cells and then used to build proteins.
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Protein Denaturation to Digestion
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Protein Synthesis• We eat protein, denature &
digest the protein, absorb & transport the amino acids to the cells, then within each cell, protein is made (synthesized) according to the DNA.
• Protein is synthesized in a process of converting DNA to RNA & then protein.
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The Gene Encodes Proteins
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Protein Synthesis inside the Cell
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Protein Character
• Protein Character is determined by: – How the 20 amino
acids are combined together (the sequence).
– The polypeptide strand folding & interacting.
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Types of Protein
Fibrous • Uniform in structure. • Either exclusively
helical or sheet formation.
• Examples are the proteins found in hair, muscle fibers & finger nails.
Globular • Have variation in structure. • Are part helical, part sheet,
part random, or completely random.
• Examples of globular proteins include blood, mucous, milk protein and egg white.
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Low & high quality dietary proteins support these
Protein Functions1. Growth & tissue maintenance (replace, repair &
possibly add LBM).2. Enzymes (catalysts). 3. Antibodies, complement proteins, circulating
components of immunity.4. Fluid & electrolyte balance (free proteins).5. Acid - base balance (H donors & acceptors).6. Energy (4 Cals/gm, requires N removal).7. Protein hormones like insulin & glucagon, secretin &
cholecystokinin.8. Transportation of nutrients (lipoproteins).
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Adult Protein Need (DRI & AMDR)
Sample Calculations
• Eric weighs 90 Kg and ate 88 g of protein and 3000 Calories in one day.
• What is his DRI for protein? – 90 Kg x 0.8 gm/Kg = 72 gm protein
• What % of his DRI for protein did he consume?– 88 gm ÷ 72 gm x 100 = 122%
• What % of Calories in his diet came from protein?– 88 g protein x 4 Cal/gm = 352 Cals from protein– 352 Cals ÷ 3000 Cals x 100 = 11.7%
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Protein Deficiency• Protein deficiency is called
Kwashiorkor. The individual has peripheral edema and may not look undernourished.
• Protein-Energy deficiency is called Marasmus. The individual looks undernourished (skin & bones, starvation).
• Both conditions occur primarily in 3rd world countries.
• In the U.S. individuals who are on starvation diets, poor, abused, or in hypermetabolic states can experience Kwashiorkor or Marasmus.
MarasmusMarasmus
KwashiorkorKwashiorkor
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Protein Excess
• Is most common in athletes & fad dieters.
• Increases risk of: – Dehydration.– Liver & spleen enlargement. – Accelerated kidney aging.– Metabolic acidosis (with low carbohydrate
intake)– Vitamin B6 deficiency, Ca & Zn loss.– Heart disease & cancer.
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Body Builders sample diet
• Meal 1: Cooked cereal, 12 egg whites, banana, 1 piece whole wheat toast, coffee, water, vitamin/mineral & amino acid supplements.
• Meal 2 (Pre-workout): Protein powder, carbohydrate powder, amino acids.
• Meal 3 (Post-workout): 8 oz poultry, rice, sweet potato, corn, non-starchy vegetable, amino acids.
• Meal 4: 7 oz fish, rice, salad, potato, water, amino acids.
• Meal 5: 8 oz beef, potato, mixed vegetable, water, amino acids.
• Meal 6: Cooked cereal, 10 egg whites, amino acids.
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Body Builders sample diet analysis results
• 5500 Calories
• 36% Calories from protein, 49% carbohydrate, 15% fat
• Inadequate in vitamin E (83% DRI) and Calcium (75% DRI)
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What it takes to gain muscle
• One pound muscle is: 75% water, 20% protein, 5% other material like fat, glycogen, minerals, enzymes.
• One pound muscle equals 105 grams protein.
• To gain one pound muscle in 2 weeks an athlete would need an extra 7-8 g protein/day intake. – 1 oz meat, 1 cup milk, 3 slices bread.
3 gm/slice3 gm/slice
7 gm/oz7 gm/oz
7 gm/white7 gm/white
2 gm/0.5 c2 gm/0.5 c3 gm/0.5 c3 gm/0.5 c
3 gm/0.5 c3 gm/0.5 c
7 gm/oz7 gm/oz
4 gm/0.5 c4 gm/0.5 c
7 gm/oz7 gm/oz
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Summary
• Dietary protein is denatured then digested.
• The amino acids from dietary intake are used by cells to make proteins by converting DNA to RNA to protein.
• Protein character is determined by amino acid sequence.
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Summary
• Proteins types: fibrous & globular.
• Proteins have many functions in the body.
• Protein deficiency is called kwashiorkor.
• Protein excess can led to negative health affects.
References for this
presentation are the same as those for
this topic found in
module 3 of the textbook