Proteins

1. Proteins

2. What FOODS contain Proteins??

3. Protein • A nutrient that gives us energy (4kcal/g) • Composed of carbon, hydrogen, oxygen and NITROGEN • Found in beef, poultry, dairy, nuts, seeds, beans and eggs

4. 6 Basic FUNCTIONS: • Build & Maintain Tissues • Ex: skin, blood, hair, nails • 18-20% of your body maintained daily consumption of calories.

5. Functions… • Make Important Compounds Ex: enzymes, hormones and antibodies

6. Functions… • Regulate Mineral & Fluid Balance • Proteins help carry the minerals sodium and potassium from one side of the cell membrane to the other; (controls the flow of water through membranes) • FLUID BALANCE is important for the functioning of ALL cells!

7. Functions… • Maintain Acid-Base balance – correct acidity level of body fluids. • Proteins in the blood act as chemical buffers (counteract an excess of acid or base in a fluid)

8. Functions • Carry Vital Substances • Many different proteins are used in the blood stream for transport, ex: hemoglobin • Some proteins link with fats to make lipoproteins – these are how fats travel in the blood.

9. Functions • Provide Energy (4kcal/g) • Used when fats and carbs are lacking, or when there is an excess of protein in the diet.

10. What makes up proteins? • AMINO ACIDS are the building blocks of protein molecules • Most proteins are made up of different patterns and combinations of 20 amino acids (which are linked in strands)

11. Structure of an amino acid

12. Making Proteins • The body probably has at least 30,000 types of protein, each performing a special job. • The number of amino acids and the order that they are linked determines the type of protein. (unlimited combinations) • DNA in the nucleus provides the instructions for how the amino acids will be linked to form the proteins in the body

13. Do protein molecules ever change? • YES! The process is called DENATURATION • Heats, acids, bases, and alcohol can denature proteins • Ex: When you cook an egg heat changes it from a runny fluid to a solid. Once denatured it cannot go back to its original state, (the egg will never go back and hatch a chick!)

14. TYPES OF AMINO ACIDS • You need all 20 amino acids for good health • Your body makes 12 of them (nonessential amino acids) • Your body cannot make the other 8 (essential aa’s), so you need to get them from your DIET. • Animal protein (ex: meat & milk) are COMPLETE sources of protein – they provide the 8 essentials • Vegetable protein (ex: legumes, grains and nuts) are considered INCOMPLETE because they lack one or more of the essential aa’s.

15. Complementary Proteins • Two incomplete protein sources when eaten together become one complete source of protein • Copy Table from page 117 in textbook.

16. PROTEIN DIGESTION • HCL in the stomach uncoils protein to smaller polypeptides (chains of amino acids) • Pancreatic and small intestinal enzymes split polypeptides further into tripeptides, dipeptides, and amino acids • Once broken down fully into amino acids they are absorbed through intestinal cells

17. What happens to “Extra” protein? • The EXTRA amino acids may be used for energy OR changed into fat for later use • When amino acids are broken down, Nitrogen is lost. It is set to the liver and converted to urea • High Protein diets can tax the kidneys and increase calcium excretion = osteo, etc…

18. Vegetarianism • The practice of eating a diet consisting of entirely or largely of plant foods. Some vegetarians will also eat milk products, but no meat. • Some reasons: religious, health, socioeconomic, environmental and humanitarian • Why is protein such a concern for vegetarians?

19. PRO’s & CON’s of VEGETARIANISM • Pros – Better health (low fat/no cholesterol) • Decrease in obesity • Decrease in heart disease, cancer rates • Decrease in Type II diabetes • CONS – Plants don’t contain all of the essential aa’s. • Low protein and caloric intake can be an issue for children • B12 and iron deficiencies are a concern