2. La nuova biologia.blu Le cellule e i viventi David Sadava, David M. Hillis, H. Craig Heller, May R. Berenbaum

3. Chemistry’s Life

4. What Kinds of Molecules Characterize Living Things? Isomers: molecules with the same chemical formula, but atoms are arranged differently. Functional groups— groups of atoms with specific chemical properties and consistent behavior.

5. Some Functional Groups Important to Living Systems (part 1) A single macromolecule may contain many different functional groups.

6. Some Functional Groups Important to Living Systems (part 2)

7. What Kinds of Molecules Characterize Living Things? Molecules that make up living organisms: Proteins Carbohydrates Lipids Nucleic acids

8. Condensation and Hydrolysis of Polymers Polymers are formed in condensation reactions. Polymers are broken down into monomers in hydrolysis reactions. Hydrolysis releases energy. Most are polymers of smaller molecules called monomers. Macromolecules: polymers with molecular weights >1,000 Da.

9. What Are the Chemical Structures and Functions of Carbohydrates? Carbohydrates have the general formula C m H 2n O n. They are: sources of stored energy used to transport stored energy carbon skeletons for many other molecules

10. Monosaccharides Are Simple Sugars

11. Monosaccharides bind together in condensation reactions to form glycosidic linkages. Disaccharides: two simple sugars linked by covalent bonds. Oligosaccharides: three to twenty monosaccharides. What Are the Chemical Structures and Functions of Carbohydrates?

12. Disaccharides Form by Glycosidic Linkages

13. Polysaccharides are giant polymers of monosaccharides. Cellulose: very stable, good for structural components. Starch: storage of glucose in plants. Glycogen: storage of glucose in animals. What Are the Chemical Structures and Functions of Carbohydrates?

14. Lipids are non-polar hydrocarbons; insoluble in water. Fats and oils are triglycerides: three fatty acids plus glycerol. Carboxyls bond with hydroxyls of glycerol in an ester linkage. What Are the Chemical Structures and Functions of Lipids? Glycerol: has three –OH groups (an alcohol). Fatty acid: nonpolar hydrocarbon with a polar carboxyl group. They are amphipathic, and they can be saturated or unsaturated.

15. Saturated and Unsaturated Fatty Acids Saturated fatty acid: no double bonds between carbons (it is saturated with H atoms). Unsaturated fatty acid: one or more double bonds in carbon chain.

16. Synthesis of a Triglyceride

17. What Are the Chemical Structures and Functions of Lipids? Phospholipids: fatty acids bound to glycerol; a phosphate group replaces one fatty acid.

18. What Are the Chemical Structures and Functions of Lipids? In water, phospholipids form a bilayer.

19. What Are the Chemical Structures and Functions of Lipids? Carotenoids: light-absorbing pigments Steroids: multiple rings share carbons. Vitamins—small molecules not synthesized by the body; must be acquired in the diet. Waxes—highly nonpolar and impermeable to water.

20. What Are the Chemical Structures and Functions of Proteins? Amino acids have carboxyl and amino groups—they function as both acid and base. Proteins are polymers of 20 different amino acids.

22. What Are the Chemical Structures and Functions of Proteins? These hydrophilic amino acids attract ions of opposite charges.

23. The Twenty Amino Acids

24. Hydrophilic amino acids with polar but uncharged side chains form hydrogen bonds. Hydrophobic amino acids

25. The Twenty Amino Acids The terminal —SH group of cysteine can react with another cysteine side chain to form a disulfide bridge, or disulfide bond (—S—S—). These are important in protein folding.

26. What Are the Chemical Structures and Functions of Proteins? Amino acids bond together covalently in a condensation reaction by peptide linkages (peptide bonds).

27. The Four Levels of Protein Structure

28. Quaternary Structure of a Protein

29. What Are the Chemical Structures and Functions of Proteins? Conditions that affect secondary and tertiary structure: High temperature pH changes High concentrations of polar molecules Non-polar If a protein is heated, is said to be denatured.

30. What Are the Chemical Structures and Functions of Proteins? Proteins bind non-covalently with specific molecules. Specificity is determined by: Shape — there must be a general “fit” between the 3-D shapes of the protein and the other molecule. Chemistry — R groups on the surface interact with other molecules via ionic, hydrophobic, or hydrogen bonds.

31. What Are the Chemical Structures and Functions of Nucleic Acids? Nucleic acids are polymers specialized for the storage, transmission, and use of genetic information.

32. What Are the Chemical Structures and Functions of Nucleic Acids? RNA contains the sugar ribose. DNA contains deoxyribose.

33. What Are the Chemical Structures and Functions of Nucleic Acids? Complementary base pairing: purines pair with pyrimidines by hydrogen bonds.

34. RNA and DNA

35. What Physical Principles Underlie Biological Energy Transformations? Metabolism: the sum total of all chemical reactions occurring in a biological system at a given time. Metabolic reactions involve energy changes. Two types of metabolism: Anabolic reactions: complex molecules are made from simple molecules, and energy input is required. Catabolic reactions: complex molecules are broken down to simpler ones, and energy is released.

36. What Is the Role of ATP in Biochemical Energetics? ATP (adenosine triphosphate) captures and transfers free energy. ATP releases a large amount of energy when hydrolyzed. ATP can phosphorylate, or donate phosphate groups, to other molecules.

37. What Are Enzymes? Enzymes and ribozymes are highly specific. Reactants are called substrates. Substrate molecules bind to the active site of the enzyme. The three-dimensional shape of the enzyme determines the specificity. E + S →  ES → E + P

38. How and Where Did the Small Molecules of Life Originate? Francesco Redi first disproved spontaneous generation in 1668. About 4 billion years ago, chemical conditions, including the presence of water, became just right for life. Two of the theories on the origin of life: 1. Life came from outside Earth 2. Life arose on Earth through chemical evolution.

39. Adapted from Life: The Science of Biology, Tenth Edition, Sinauer Associates, Sunderland, MA, 2014 Inc. All rights reserved