Proteins

1. Proteins Chapter 17

2. What is a protein? • Large and complex molecules • Made of hydrogen, carbon, oxygen, nitrogen • Often called macromolecules because of their large size containing many atoms. • Nitrogen is a crucial part of protein, gives proteins their variety and versatility

3. What is a protein? Continued Human body contains 10,000 to 50,000 different proteins Made from chemical compounds called amino acids There are 22 amino acids Our bodies make all but 9 of them

4. Structure of Protein • Made from chains of amino acids • Amino acids consists of two groups • Carboxyl group, carbon bonded to oxygen by a double covalent bond, and to a hydroxyl group with a single bond (-COOH) • Amine group, two atoms of hydrogen and one atom of nitrogen (-NH2) • Glycine – simplest amino acid

5. Structure of Protein Continued • Peptide Bonds, bonds between nitrogen of one amino acid and the carbon of a second amino acid • Polypeptide, a single protein molecule containing ten or more amino acids linked in peptide chains

6. Structure and Function Shape determines the proteins function. Fibrous protein form rope-like fibers, this structure strengthens them to serve as connective tissue in the body such as collagen, hair, skin and nails. Globular proteins form a rounded shape, this structure makes them convenient carriers such as hemoglobin.

7. Structure and Function Continued Denaturation is a process of changing the shape of a protein molecule without breaking its peptide bonds. Coagulation changes a liquid into a soft, semisolid clot or solid mass.

8. Means of Denaturation • Heat – most common • Freezing, pressure, sound waves and addition of certain compounds • Mechanical treatment (beating eggs, kneading dough • Very high or very low pH (adding lemon juice) • Metal ions, (Sodium, potassium, copper and iron)

9. Protein in Foods Eggs – contain almost every vitamin and mineral you need Meat – contains fibrous proteins called actin and myosin. These proteins form bundles of fibers, which are held together by connective tissue made of collagen and elastin, two proteins with long, strong molecules. Cooking meat is more complex due to variations in fat and types of muscle fibers and connective tissue. Fish – contain shorter, segmented muscle fibers that are layered between thin sheets of connective tissue. Takes less time to cook. Nuts and Legumes – carry lots of nutrients, cholesterol free but fat content ranges from zero to very high. Soybean proteins are equal to that in foods from animals.

10. Protein in Cooking • Emulsifiers – keep foods blended together. Ex: salad dressing, mayonnaise • Foams – air bubbles incorporated and trapped in a protein film by whipping. Foam adds volume and lightness to a recipe • Gelatin – animal protein used to set desserts and thicken meat sauces • Gluten – an elastic substance formed by mixing water with the proteins found in wheat, gives baked goods their structure and shape.

11. Function of Body Proteins • Structural protein is needed for every cell in the body. Collagen helps build bones, the ligaments that bind them, the tendons that connect them to muscles, and the muscles themselves. • New Growth – replace and repair cells • Enzymes and hormones that are responsible for body processes. (hormones aid in growth, balance fluid, regulate metabolism) • Transports nutrients in cells. (lipoproteins, oxygen) • Antibody proteins help ward off disease • Stabilize pH levels • Supply energy if needed

12. 9 Essential Amino Acids • Essential Amino Acids you need to eat every day. • They come from animals source. • Soybeans are the only plant source that provides them • Unfortunately these contain saturated fat and cholesterol

13. Two Types of Proteins • Complete Protein – supplies all 9 “essential” amino acids • Meat • Fish • Poultry • Dairy (milk, cheese, yogurt) • Eggs • Soy • Incomplete Protein – lacking one or more essential amino acids • Plant sources, must be eaten in greater variety • Rice with beans • Legumes • Nuts • Seeds • Grains • vegetables

14. How much protein do you need? • Depends on… • Age Gender Body size Activity level • Children, pregnant women, and nursing mothers need higher levels

15. Age 15-18 • Multiply your weight by 0.36 to estimate how many grams of protein do you need each day? • Example if you are 130 lbs. You would need 47 grams (130 X 0.36 =46.8)

16. Protein Deficiencies • Growth Failure • Loss of Muscle Mass • Decreased Immunity • Weakening of the Heart & Respiratory System

17. Protein Excesses • To much protein will mainly cause dehydration • Loss in calcium and vitamin B • Which can lead to other mental and physical conditions

18. Interesting Facts • Brain is made up of 10% protein