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

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

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

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

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

Gene Encodes Protein

Protein Synthesis inside the cell

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

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

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)

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

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

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

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

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

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)

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

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

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