3.9 Carbohydrates. Provide building materials and energy storage. Are molecules that contain carbon, hydrogen and oxygen in a 1:2:1 ratio

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2 3.9 Carbohydrates Provide building materials and energy storage Are molecules that contain carbon, hydrogen and oxygen in a 1:2:1 ratio Are of two main types Simple carbohydrates Complex carbohydrates

3 Simple Carbohydrates 1. Monosaccharides Consist of one subunit Fig Glucose Chemical formula: C 6 H 12 O 6 glucose, "blood sugar", the immediate source of energy for cellular respiration galactose, a sugar in milk (and yogurt), and fructose, a sugar found in honey.

4 Simple Carbohydrates 2. Disaccharides Consist of two subunits Formed by a dehydration reaction Fig Sucrose sucrose - common table sugar = glucose + fructose lactose - major sugar in milk = glucose + galactose maltose - product of starch digestion = glucose + glucose

5 Complex Carbohydrates Consist of long polymers of sugar subunits Also termed polysaccharides Examples: Starch provides energy storage in plants Glycogen provides energy storage in animals Cellulose is found in the cell walls of plants Chitinis found in the cell walls of fungi

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7 Because its linking bonds are flipped, and there are no side chains, cellulose molecules lie close together with lots of hydrogen bonds. Cellulose (your T-shirt and textbook) is long, rigid polymer of glucose that is not sweet.

8 All sugars are very soluble in water because of their many hydroxyl groups. Carbohydrates provide the bulk of the calories in most diets, and starches provide the bulk of that.

9 Hydrogen bonds are weak (only 5% the strength of a covalent bond) but important hold water molecules together hold proteins together hold the two strands of the DNA double helix together

10 3.10 Lipids Large nonpolar molecules that are insoluble in water Lipids are hydrocarbons hydrogen + carbon Three major types Fats are energy-storage molecules Phospholipids are a major component of cell membranes Steroids are often hormones

11 Fats Used for long-term energy storage Also termed triglycerides or triacylglycerol Composed of three fatty acid chains linked to glycerol Fig. 3.33

12 Fats Fatty acids can be saturated or unsaturated Fig Most animal fats Most plant fats solid at room temperature liquid at room temperature

13 Monounsaturated fats have one double bond in the fatty acid chains. olive, peanut, and canola oil. Polyunsaturated fats have two or more double bonds in their fatty acid chains. corn, soy bean, cottonseed, sunflower, and safflower oils.

14 5g total - 1 g saturated fat g polyunsaturated fat -1.5 g monounsaturated fat =2 g trans fat Trans Fats have been partially hydrogenated may be worse for your health than saturated fats Read the label!

15 Why is the food industry sneaking in a bad fat? the most abundant (least expensive) source of fat is from liquid plant oils many cooking applications, particularly baked products, need solid fats the food industry uses hydrogenated oils for things like shortening and margarine.` -fewer double bonds -remaining converted from cis to trans -straightened so they get closer and -become solid

16 Fats are bad for you. True or False or?

17 The relationship between fat in the diet and cardiovascular disease is not proven, but the evidence seems to indicate that: -A diet high in fat is harmful. -Mono and polyunsaturated fats are less harmful

18 Have you heard of omega-3 fatty acids? Omega-3 unsaturated fats may be GOOD for you (protective against cardiovascular disease) A DRI of 1.1 grams/day for women and 1.6 grams/day for men was established in September These fats have at least one double bond three carbon atoms in from the end of the fatty acid chain. Fish oils are a rich source of omega-3 fats.

19 How are fats good for you? Fat are our most concentrated form of energy. Fat =9 kcal/gram Carbohydrates =4 kcal/gram The fats we eat give us the building material for our own fat as well as cholesterol and various phospholipids. Our bodies make fat from carbohydrates (as I know all too well!) Three essential fatty acids must be in our diet. linoleic acid, linolenic acid, arachidonic acid.

20 Phospholipids A modified fat One of the three fatty acids is replaced by a phosphate and a small polar functional group Fig. 3.34a In water, phospholipids aggregate to form a lipid bilayer more later when we talk about cell membranes

21 Steroids Composed of four carbon rings Examples: Cholesterol Found in most animal cell membranes Fig. 3.34b Male and female sex hormones are made of cholesterol

22 All forms of life have common features All are made of cells. All have carbohydrates, lipids, and proteins. All forms of life have DNA as their genetic blueprint. Each species has its own DNA sequence