3. Section 23-1 Protein Structure Proteins are organic polymers made of amino acids linked together in a specific order, not just random chains of amino acids.Proteins Amino acids are organic molecules that have both an amino group and an acidic carboxyl group.Amino acids

4. Section 23-1 Protein Structure (cont.) The amide bond that joins the two amino acids is called a peptide bond.peptide bond

5. Section 23-1 Protein Structure (cont.) When a chain reaches 50 or more amino acids, it is called a protein. Only 20 different amino acids exist.

6. Section 23-1 Protein Structure (cont.) Denaturation is the process in which a protein’s natural three-dimensional structure is disrupted.Denaturation

7. Section 23-1 The Many Functions of Proteins An enzyme is a biological catalyst.enzyme A substrate refers to the reactant in an enzyme-catalyzed reaction.substrate The spot to which the substrates bind is called the active site.active site

8. End of Section 23-1

9. Section 23-2 Kinds of Carbohydrates Carbohydrates are compounds that contain multiple hydroxyl groups as well as carbonyl groups.Carbohydrates Monosaccharides are the simple sugars, composed of five or six carbon atoms.Monosaccharides

10. Section 23-2 Kinds of Carbohydrates (cont.) Disaccharides are formed when two monosaccharides are bonded together.Disaccharides

11. Section 23-2 Kinds of Carbohydrates (cont.) Polysaccharides are polymers of simple sugars made up of 12 or more monomers.Polysaccharides

12. End of Section 23-2

13. Section 23-3 What is a lipid? A lipid is a large, nonpolar biological molecule.lipid Fatty acids, the building blocks of lipids, are long-chain carboxylic acids.Fatty acids Fatty acids are placed in two groups: saturated and unsaturated.

14. Section 23-3 What is a lipid? (cont.) Saturated fats contain only single bonds. Unsaturated fats contain one or more double bonds.

15. Section 23-3 What is a lipid? (cont.) Triglycerides are formed when three fatty acids are bonded to a glycerol backbone.Triglycerides

16. Section 23-3 What is a lipid? (cont.) Saponification is the hydrolysis of a triglyceride using an aqueous solution of a strong base to form carboxylate salts and glycerol.Saponification

17. Section 23-3 What is a lipid? (cont.) Phospholipids are triglycerides in which one fatty acid is replaced by a polar phosphate group.Phospholipids

18. Section 23-3 What is a lipid? (cont.) Waxes are lipids formed by combining a fatty acid with a long-chain alcohol.Waxes Steroids are lipids that have multiple cyclic rings in their structures.Steroids

19. End of Section 23-3

20. Section 23-4 Structure of Nucleic Acids A nucleic acid is a nitrogen-containing biological polymer that is involved in the storage and transmission of genetic information.nucleic acid The monomer that makes up a nucleic acid is called a nucleotide.nucleotide

21. Section 23-4 Structure of Nucleic Acids (cont.) Each nucleotide has three parts: −Inorganic phosphate group −Five-carbon monosaccharide −Nitrogenous base

22. Section 23-4 DNA: The Double Helix (cont.) DNA contains four different nitrogenous bases. −Adenine −Thymine −Cytosine −Guanine

23. Section 23-4 DNA: The Double Helix (cont.) Watson and Crick used their model to predict how DNA’s chemical structure enables it to function.

24. Section 23-4 RNA RNA is also a nucleic acid. The structure of RNA differs from DNA in three ways. −RNA contains adenine, cytosine, guanine, and uracil (but never thymine). −RNA contains sugar ribose instead of sugar deoxyribose. −DNA is a double helix while RNA is a single strand.

25. End of Section 23-4

26. Section 23-5 Anabolism and Catabolism The set of chemical reactions carried out within an organism is its metabolism.metabolism Catabolism refers to the metabolic processes that break down complex biological molecules such as proteins, polysaccharides, triglycerides, and nucleic acids for the purpose of forming smaller building blocks and extracting energy.Catabolism

27. Section 23-5 Anabolism and Catabolism (cont.) Anabolism refers to the metabolic reactions that use energy and small building blocks to synthesize complex molecules needed by an organism.Anabolism

28. Section 23-5 Anabolism and Catabolism (cont.) ATP is a nucleotide that functions as the universal energy-storage molecule in living cells.ATP

29. Section 23-5 Photosynthesis The process that converts energy from sunlight to chemical energy in the bonds of carbohydrates is called photosynthesis.photosynthesis

30. Section 23-5 Cellular Respiration Oxygen produced during photosynthesis is used by living things during cellular respiration, the process in which glucose is broken down to form carbon dioxide, water, and large amounts of energy.cellular respiration

31. Section 23-5 Fermentation Cells can extract energy from glucose in the absence of oxygen. Cellular respiration produces 38 mol of ATP per 1 mol glucose. Fermentation produces 2 mol ATP per 1 mol of glucose.

32. Section 23-5 Fermentation (cont.) Fermentation is the process by which glucose is broken down in the absence of oxygen.Fermentation There two common kinds of fermentation Alcoholic fermentation Lactic acid fermentation