Carbohydrates & Lipids

1. Carbohydrates & Lipids September 10th, 2012

2. What are Carbohydrates? Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen that serve as energy sources and structural materials for cells of all organisms

3. Structure of carbohydrates • Carbohydrates consist of carbon, hydrogen, and oxygen • They may be monomers or polymers

4. What Are Monomers? • Monomers are molecules that can be bonded to other identical molecules to form polymers • The monomer form of carbohydrates are known as monosaccharides • Glucose is an example of a monosaccharide

5. Disaccharides • Disaccharides: consist of two monosaccharides. Ex: maltose & sucrose • Disaccharides form by dehydration synthesis – where a molecular of water is split out as the bond is formed • Disaccharides are broken down into monomers by hydrolysis

6. What are Polymers? • Polymers are substances that have a molecular structure built up chiefly or completely from a large number of similar units bonded together • The polymer form of carbohydrates are polysaccharides • Polysaccharides are large carbohydrate molecules that are polymers of monsaccharides • Ex: starch, glycogen and cellulose

7. Glycogen is a polymer of glucose Glucose Glycogen

8. What is Starch? • Starch is the energy storage molecule in plants and a good source of energy for human cells • Produced by all green plants • It is the most common carbohydrate in the human diet and is contained in large amounts in such staple foods as potatoes, wheat, maize (corn), rice and cassava

9. What is Glycogen? • Glycogen is the short-term energy storage molecule in human cells

10. What is Cellulose? • Cellulose is the molecule that makes up plant cell walls in green plants

11. Polysaccharides Continued • Differences between the polysaccharides are caused by differences in their molecular structure • Organisms must break down polysaccharides to obtain usable glucose molecules. For example: our body breaks down starch and glycogen by hydrolysis • However, we cannot break down cellulose into molecules of glucose. Instead, cellulose passes undigested through our digestive system

12. What are Lipids? • Lipids are organic compounds that include: fats, phospholipids, waxes, and steroids • Long-term energy storage • Insoluble in water

13. Fats • In human cells, fats serve as long-term energy storage • Useful long-term energy storage molecules in both plants and animals – because of the many energy containing carbon-hydrogen bonds • Very concentrated source of energy • Stored fat helps cushion and protect important organs such as the kidneys

14. Fats, Continued… • Fats are made up mainly of two types of molecules: fatty acids and glycerol • Fatty acids may be either saturated or unsaturated • Saturated fatty acids have no double bonds between their carbon atoms. They are relatively straight structurally • Unsaturated fatty acids have one or more double bonds between carbons and so are not saturated with hydrogen

15. Saturated vs. Unsaturated fatty acids

16. Saturated vs. Unsaturated fatty acids • When referring to the structure of a fatty acid, wherever you see a double bond, it causes a kink in the molecule • The kinks prevent unsaturated and polyunsaturated fatty acids (more than one double bond) from packing together tightly – therefore these are liquid at room temperature • The linear saturated fatty acids are able to pack together more tightly and tend to be solids at room temperature

17. Saturated vs. Unsaturated fatty acids • Saturated Fatty Acids = Saturated Fats - found in red meat and dairy products - associated with health problems  usually cardiovascular related • Unsaturated Fatty Acids = Unsaturated Fats - Come from plants like: canola, corn and olives. Also some animals - Some may benefit your health - Linoleic acid is actually essential for your body!

18. Glycerol • Glycerol is an organic molecule with 3 carbons and 3 hydroxyl groups • Bonds with 2 or 3 fatty acids to form a fat • Glycerol bonded to 3 fatty acids  Triglyceride • Triglycerides – long-term energy storage in animals. Stored in adipose tissue • Adipose tissue  body fat

19. Glycerol Continued… • Fat cells usually cannot grow. Therefore we can’t create new fat cells in our body, instead we can just add to the triglycerides existing in our fat cells

21. Phospholipids • Phospholipids are an important part of cell membranes. They help the cell membrane perform its role of monitoring the passage of molecules into and out of the cell • Consist of a hydrophilic phosphate molecule and two hydrophobic fatty acid tails • Hydrophilic – water-loving • Hydrophobic – water-hating

22. Steroids • Steroids is a group of organic compounds that include: cholesterol and the sex hormones – estrogen and testosterone • Cholesterol is necessary for many different functions, including the proper formation of cell membranes. However, too much cholesterol can cause for the onset of cardiovascular disease

23. Steroids Continued… • Estrogen and testosterone are present in both males and females • It is the amount of estrogen and testosterone that vary in males and females • Testosterone – more in males • Estrogen – more in females