1. Proteins: from foods to cells in the body
Module 3.2
Proteins: from foods to cells in the body
By Jennifer Turley and Joan Thompson
© 2013 Cengage

2. Presentation Overview
Denaturation vs. digestion
Synthesis
Character & types
Function
Quality
Needs (recommended intake)
Deficiency vs. excess

3. Protein Denaturation Causes protein to change shape or conformation
protein & amino acids are still intact
Can be caused by heat, alkali or acid treatments, or metals
Is required before the protein can be digested

4. Protein Denaturation
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

5. Protein Synthesis
Eat protein  denature & digest protein  absorb and transport amino acids to cells  protein is made (i.e. synthesized) inside cells according to DNA
Protein is synthesized in a process of converting DNA to RNA to protein

6. Gene Encodes Protein

7. Protein Synthesis inside the cell

8. Protein Character Protein Character is determined by:
How the 20 amino acids are combined together
The polypeptide strand folding & interacting with itself

9. 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

10. Protein Functions- both low & high quality proteins
Growth & tissue maintenance (replace, repair & possibly add)
Enzymes (catalysts)
Antibodies, complement proteins, circulating components of immunity
Fluid & electrolyte balance (free proteins)
Acid - base balance (H donors & acceptors)
Energy (4 Cals/gm, requires N removal)
Protein hormones like insulin & glucagon, secretin & cholecystokinin
Transportation of nutrients (lipoproteins)

11. Eric weighs 90 Kg and ate 88g of protein and 3000 Calories in one day
Recommended Intake
Eric weighs 90 Kg and ate 88g of protein and 3000 Calories in one day
What is his DRI for protein?
90Kg x 0.8g/Kg = 72g protein
What % of his DRI for protein did he consume?
(88g ÷ 72g) 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%
Adult DRI is 0.8 gm/Kg

12. Protein Deficiency Protein deficiency is called
Kwashiorkor. The individual has
peripheral edema and may not
look undernourished
Severe 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 hyper-metabolic states can experience Kwashiorkor or Marasmus
Kwashiorkor

13. Protein Deficiency Protein deficiency is called
Kwashiorkor. The individual has
peripheral edema and may not
look undernourished
Severe 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 hyper-metabolic states can experience Kwashiorkor or Marasmus
Marasmus

14. Excess Protein 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

15. 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): 8oz poultry, rice, sweet potato, corn, non-starchy vegetable, amino acids
Meal 4: 7oz fish, rice, salad, potato, water, amino acids
Meal 5: 8oz beef, potato, mixed vegetable, water, amino acids
Meal 6: Cooked cereal, 10 egg whites, amino acids

16. Body Builders- Sample Diet Analysis
5500 Calories
36% Calories from protein,
49% carbohydrate & 15% fat
Inadequate in vitamin E (83% DRI)
and Calcium (75% DRI)

17. What it takes to build muscle
One pound of muscle is: 75% water, 20% protein & 5% other material like fat, glycogen, minerals and enzymes
One pound of muscle equals 105 grams protein
To gain one pound muscle in 2 weeks an athlete would need an extra 7-8g protein/day intake
1oz meat, 1 cup milk, 3 slices bread

18. 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
Proteins types: fibrous & globular
Proteins have many functions in the body

19. Summary 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