3.1 Nutrients - Macronutrients

1. 3.1 Nutrients - Macronutrients Nutrients: substances in foods that provide structural materials or energy Macronutrients: nutrients that are required in large amounts (vs. micronutrients) Water Adults need about 3 liters per day Too little leads to dehydration Maintains blood pressure Involved in all cellular activities Dilutes waste products Cooling by evaporation

2. Now we will talk about Macronutrients: • Carbs (carbohydrates) • Proteins • Fats

3. Carbohydrates: main energy source Simple sugars (glucose) enter our system quickly Complex carbohydrates (branching chains of simple sugars) are digested more slowly Starch: complex carbohydrate from plants Glycogen: complex carbohydrate from animals

4. Processed food Food that has undergone processing that has stripped it of its nutritional value side effects of its preservation Whole foods Foods that have not been stripped of their nutrition Fiber: indigestible complex carbohydrates Essential for large intestine function Lowers cholesterol (by binding and preventing reabsorption of bile salts) and reduces cancer risk

5. Proteins Polymers of amino acids Essential amino acids: we cannot make these ourselves; must obtain them from food Complete proteins: contain all the essential amino acids we need Plant proteins can be combined to make them complete.

6. Fats Energy storage molecules Acts as a cushion and insulator Consist of a glycerol attached to fatty acid tails Essential fatty acids: we cannot make these ourselves (e.g., omega-3 and omega-6) Necessary for proper immune function Omega-6: initiate inflammation when necessary Omega-3: attenuate excessive inflammation (brain, eyes, hair, degenerative diseases)

7. Fats Saturated fats: fatty acid carbons are bound to as much hydrogen as possible – maximum energy stored Lack C=C double bonds Solid at room temperature Most animal fats are saturated shortening, lard (pigs), butter (from milk fat)

8. Fats Unsaturated fats are not bound to as much hydrogen as possible Contain double bonds which give kinks in the tails Liquid at room temperature (oils) Most plant fats are unsaturated or polyunsaturated (corn oil, olive oil, avocado oil, etc.)

9. Fats Polyunsaturated fats Have many double bonds preventing it from tightly packing – needed for immune function Hydrogenation Process that adds hydrogen atoms to unsaturated fats to make it a solid (sticks and more stable) Our body only makes and uses cis fats Transfats are chemically produced by incomplete hydrogenation and not beneficial May be linked to an increased risk of heart disease and diabetes Margarine made from vegetable (commonly) or butter (less commonly)

10. Count the number of hydrogen atoms in the oil and in the margarine. Which has more? Vegetable oil Margarine Cis fatty acid High pressure Saturated fatty acid Hydrogenation Hydrogen gas Liquid Solid Trans fatty acid

11. (a) Structural Proteins ATP Steak Protein Amino acids Structural proteins, enzymesand energy (b) Carbohydrate breakdown Structural components ATP Apple Carbohydrates Energy production (c) Fat breakdown Build membranes Fat droplet Butter Fat Glycerol and fatty acids ATP Stored energy

12. What serves as the major source of energy for cells? water molecules carbohydrates dietary fiber proteins

13. What serves as the major source of energy for cells? water molecules carbohydrates dietary fiber proteins

14. Which of the following describes a processed food? foods that have been stripped of most of their nutritional value foods that have not been stripped of their nutritional value foods that are also called roughage and cannot be digested foods that have additional vitamins and minerals added

15. Which of the following describes a processed food? foods that have been stripped of most of their nutritional value foods that have not been stripped of their nutritional value foods that are also called roughage and cannot be digested foods that have additional vitamins and minerals added

16. Now we will talk about micronutrients: • Vitamins • Minerals • antioxidants

17. Micronutrients: nutrients that are needed in small quantities Vitamins: Table 3.1 lists the various vitamins organic substances which usually function as coenzymes Vitamin D the only one we can synthesize Sunlight is required for synthesis Water-soluble vitamins Not stored in the body and typically the cause of nutritional-based deficiencies Fat-soluble vitamins Stored in fat and can cause problems in excess

18. Minerals: inorganic substances Do not contain carbon but essential for cell functions Must be supplied through diet and are water soluble Calcium is a very important mineral that plays a role in bones, clotting, muscle contraction and nerve impulses Iron is involved in oxygen binding and transport to cells of the body from the lungs Table 3.2 lists the various minerals and their functions

19. Antioxidants Found in whole foods Most important one: Vitamin C Protect cells from damage by free radicals Many come from activation of the immune system Free radicals can damage DNA and cell membranes Table 3.3 describes food sources of antioxidants (fun to know; do not memorize for exam)

20. Membrane Transport • All of these nutrients have to enter the cell THROUGH THE MEMBRANE in order to be used • The cell membrane is composed of phospholipids

21. Membrane Transport • The cell membrane is semipermeable • Carbon dioxide, oxygen and water move freely across the membrane • Larger molecules and charged molecules cannot pass through membranes without help • Larger molecules and charged molecules can only enter the cell by moving through protein channels embedded in the membrane

22. All molecules want to be in a state of equilibrium • By moving randomly, all molecules tend to move from an area of high concentration to an area of low concentration • Think of a drop of food coloring in water • Biology promotes two modes of molecular movement: • Passive Transport • Active Transport

23. Passive Transport • Moving molecules across the membrane from an area of high concentration to an area of low concentration • Requires no energy; used to remove wastes (CO2, amines)

24. Active Transport • Moving molecules from an area of low concentration to high concentration (going against where they “want” to go, “pushing” them (think of the time and effort involved in cleaning a mess vs. making the mess in the first place) • Requires energy • We need some ions in higher concentrations inside or out of the cells • Critical to bring in foodstuffs, vitamins, and minerals into cells from the blood for cellular function and life!

25. 3.3 Body Fat and Health • Difficult to define “overweight” precisely • Women need more body fat to maintain fertility than men do (lipoproteins transports steroids through body) • Healthy body fat percentages: • Women: 22% • Men: 14%

26. Body Mass Index (BMI): correlates amount of body fat with risk of illness and death, using both height and weight • Not perfect! (e.g., muscle is heavier than fat, and will give deceptively higher BMI for athletes) • Healthy range of BMI = 20 - 25 • Obesity: BMI of 30 or higher (do not memorize formula) weight in lbs. x 703 weight in kg BMI = = (height in inches)2 (height in cm)2

27. Risk of obesity is influenced by both lifestyle (diet, exercise) and genetics • Obesity increases risks of all of the following: • Diabetes • Hypertension • Heart disease • Stroke • Joint problems

28. Diabetes: disease of improper carbohydrate metabolism or uptake by cells • Insulin: hormone that triggers cells throughout the body to take up glucose; produced by beta cells of the pancreas Liver Pancreas 4 2 When blood sugaris high, a healthypancreas secretes insulininto the bloodstream. Excess glucose isstored in the liveras glycogen. Insulin Blood sugar ishigher followinga meal. 3 Capillary Insulin triggers allthe body’s cells totake up glucose. 1 Figure 3.16

29. Type 1 (insulin-dependent): not associated with obesity • Usually arises in childhood • Cannot produce insulin • Immune system mistakenly destroys beta cells • Treated with daily insulin injections • Type 2 (non-insulin-dependent): associated with obesity • Usually arises in adults • Body does not process glucose properly • May be controlled by diet and exercise

30. Hypertension: high blood pressure (the force exerted on blood vessels by the blood) • Systolic: highest blood pressure as the heart contracts and blood is pushed into the arteries • Diastolic: lowest blood pressure while heart is refilling and arteries slowly release the blood into the capillaries

31. Hypertension: high blood pressure (the force exerted on blood vessels by the blood) • Normal blood pressure is about 120 systolic and 80 diastolic (120/80) • Hypertension: persistently over 140/90 • clogged or constricted arteries increase resistance to blood flow; both numbers increase

32. Cholesterol: a lipid that builds up with fats in the arteries (atherosclerosis), eventually blocking them. • The heart has to beat harder to push blood through tighter arteries • Clots form and are eventually thrown off, clogging elsewhere

33. Heart attack: a sudden loss of blood to the heart because of blocked arteries • Stroke: a sudden loss of blood to the brain because of blocked arteries

34. Cholesterol is carried in the blood by lipoproteins • Low-density lipoproteins (LDLs): carry cholesterol made in the liver and from foods • High-density lipoproteins (HDLs): contain more protein than cholesterol. They scavenge excess cholesterol from body and take it to the liver, for excretion as bile • Saturated fats may raise cholesterol levels • High cholesterol is defined as total cholesterol level over 200, or LDL levels over 100

35. Not all cholesterol is bad! • Some cholesterol is needed to build plasma membranes and steroid hormones Cholesterol Testosterone Estrogen Figure 3.17

36. Anorexia: self-starvation • Can starve heart muscles, producing altered rhythms, increased illness, decreased mental function • Amenorrhea: cessation of menstruation • can be permanent and result in sterility • Increases risk of osteoporosis • Destabilized bones break more easily

37. Bulimia: binge-eating followed by purging • Many of the same health effects as anorexia • May lead to stomach rupture • Dental and gum problems from stomach acid • Dehydration (sometimes fatal)

38. Fitness may be more important than weight • Fit but overweight people are healthier than unfit slender people • Very low levels of fat in the body correlate with increased health problems and decreased ability to fight infections (ultra-athletes, elderly, anorexics) • Key is healthy diet and exercise

39. Now let’s do some review questions

40. What serves as the major source of energy for cells? • Water molecules • Carbohydrates • Dietary fiber • Proteins

41. What is the only vitamin our cells can synthesize? • Vitamin A • Vitamin B • Vitamin C • Vitamin D

42. Which of the following statements is incorrect? • Enzymes raise the activation energy of a reaction. • Enzymes speed up the rate of a reaction. • Substrates bind to an enzyme’s active site. • Enzymes change shape when they bind to a substrate.

43. Charged amino acids enter the cell through _____. • passive diffusion • osmosis • facilitated diffusion • exocytosis

44. True or False: Type 2 diabetes usually arises in childhood. • True • False

45. Which of the following statements is incorrect? • Low-density lipoproteins have a high proportion of cholesterol. • Cholesterol maintains fluidity in cell membranes. • High levels of cholesterol increase the risk of heart disease and stroke. • LDLs return excess cholesterol to the liver where it is used to make bile.

46. Which of the following statements is correct? • K+ will move from high concentration to low concentration; ATP is used. • K+ will move from low concentration to high concentration; ATP is used. • K+ will move from high concentration to low concentration; ATP is not used. • K+ will move from low concentration to high concentration; ATP is not used.