Chapter 5: What are the major types of organic molecules?

1. Chapter 5: What are the major types of organic molecules? • polymers • four major classes of biologically important organic molecules: • carbohydrates • lipids • proteins (and related compounds) • nucleic acids (and related compounds)

2. Discuss hydrolysis and condensation, and the connection between them.

3. many biological molecules are polymers • polymers: long chains w/ repeating subunits (monomers) • example: proteins - amino acids • example: nucleic acids – nucleotides • macromolecules: very large polymers (100s of subunits)

4. Polymers • hydrolysis (“break with water”)

5. Polymers • condensation(dehydration synthesis)

7. Discuss hydrolysis and condensation, and the connection between them.

8. Chapter 5: What are the major types of organic molecules? • four major classes of biologically important organic molecules: • carbohydrates • lipids • proteins (and related compounds) • nucleic acids (and related compounds)

9. For each organic molecule class, address what they are (structure) and what they are used for (function).

10. Carbohydrates: what are they, and what are they used for? • What terms are associated with them (including the monomers and the polymer bond name)? • Give some examples of molecules in this group.

11. Carbohydrates • carbohydrates: carbon, hydrogen, and oxygen • ratio typically (CH2O)n • sugars, starches, and cellulose

12. Carbohydrates • main molecules of life for energy storage; consumed for energy production • some used as building materials • monosaccharides, disaccharides, and polysaccharides

13. Carbohydrates • monosaccharides single monomer • 3, 4, 5, 6, or 7 carbons • trioses, tetroses, pentoses, hexoses, and heptoses • pentose examples: • ribose and deoxyribose • hexose examples: • glucose, fructose, and galactose

14. Carbohydrates • structural formulas for glucose, fructose, and galactose • isomers of each other • glucose and galactose are structural isomers of fructose • glucose and galactose are diastereomers

15. Carbohydrates • pentose and hexose sugars form ring structures in solution • carbons given position numbers

16. Carbohydrates • ring structures in solution • often creates diastereomers • example: a-glucose and b-glucose

17. Carbohydrates • disaccharides: two monosaccharide units • joined by a glycosidic linkage or bond • condensation • oxygen atom is bound to a carbon from each momomer • linkage typically carbon 1 to carbon 4

18. Carbohydrates • maltose, sucrose, lactose: common disaccharides • maltose (malt sugar): two glucose subunits • sucrose (table sugar): glucose + fructose • lactose(milk sugar): glucose + galactose +

19. Carbohydrates • polysaccharides • number of subunits varies, typically thousands • can be branched or unbranched • some are easily broken down and are good for energy storage (examples: starch, glycogen) • some are harder to break down and are good as structural components (example: cellulose)

20. Carbohydrates • starch: main energy storage carbohydrate of plants • polymer made from α-glucose units, mostly α1-4 linkages • amylose = unbranched starch • amylopectin= branched starch (branches usually 1-6 linkages) • amyloplasts, a type of plastid for starch storage

21. Carbohydrates • glycogen: main energy storage carbohydrate of animals • very highly branched • more water-soluble • is NOT stored in an organelle • mostly found in liver and muscle cells

22. Carbohydrates • cellulose: major structural component plant cell walls • b-glucose units • similar to starch, but note that the b1-4 linkage makes a huge difference

23. Carbohydrates • unlike starch, most organisms cannot digest cellulose • cellulose is a major constituent of cotton, wood, and paper • cellulose contains ~50% of the carbon in found in plants

24. Carbohydrates • fibrous cellulose is the “fiber” in your diet • some fungi, bacteria, and protozoa make enzymes that can break down cellulose • animals that live on materials rich in cellulose, e.g. cattle, sheep and termites, contain microorganisms in their gut that are able to break down cellulose for use by the animal

25. Carbohydrates • carbohydrates can be modified from the basic (CH2O)n formula • many modified carbohydrates have important biological roles • example: chitin – structural component in fungal cell walls and arthropod exoskeltons • example: galactosamine in cartilage • example: glycoproteins and glycolipids cellular membranes

26. Carbohydrates: what are they, and what are they used for? • What terms are associated with them (including the monomers and the polymer bond name)? • Give some examples of molecules in this group.

27. Lipids: what are they, and what are they used for? • What terms are associated with them (including majors classes and bond names)? • Give some examples of molecules in this group.

28. Lipids • lipids defined by solubility, not structure • oily or fatty compounds • lipids are principally hydrophobic • mainly carbon and hydrogen • some do have polar and nonpolar regions • some oxygen and/or phosphorus, mainly in polar regions

29. Lipids • roles of lipids include serving as: • membrane structural components • signaling molecules • energy storage molecules

30. Lipids • major classes of lipids that you need to know are: triacylglycerols (fats) phospholipids terpenes and terpenoids

31. Lipids • triacylglycerols: glycerol + 3 fatty acids • glycerol: 3C sugar alcohol w/ 3 (-OH) groups • fatty acid: long, unbranched hydrocarbon chain w/ (-COOH) at end

32. Lipids • saturated fatty acids: no carbon-carbon double bonds (usually solid at room temp)

33. Lipids • unsaturated fatty acids: one or more double bonds (usually liquid at room temp) • monounsaturated – one double bond • polyunsaturated – more than one double bond

34. Lipids • about 30 different fatty acids are commonly found in triacylglycerols; most have an even number of carbons

35. Lipids • condensation results in an ester linkage between a fatty acid and the glycerol

36. Lipids • names based on number of attached fatty acids: • one = monoacylglycerol • two = diacylglycerol • three = triacylglycerol

37. Carboxyl Glycerol Fatty acid (a) Ester linkage Palmitic acid Oleic acid Linoleic acid (b) A triacyglycerol (c) Palmitic (d) Oleic (e) Linoleic

38. Lipids • triacylglycerols (also called triglycerides) are the most abundant lipids, and are important sources of energy

39. Lipids • phospholipids consist of: • a diacylglycerol molecule • a phosphate group esterified to the third -OH group of glycerol • an organic molecule (such as choline) esterified to the phosphate

40. Lipids • phospholipids are amphipathic • polar end (the phosphate and organic molecule) • nonpolar end (the two fatty acids) • this is often drawn with a polar “head” and two nonpolar “tails”

41. Lipids • the nonpolar (or hydrophobic) portion of phospholipids tends to stay away from water • the polar (or hydrophilic) portion of the molecule tends to interact with water • this, along with shape, causes phospholipids to form bilayers when mixed with water • because of this character phospholipids are important constituents of biological membranes

42. Lipids terpenes are long-chained lipids built from 5-carbon isoprene units • many pigments, such as chlorophyll, carotenoids, and retinal, are terpenes or modified terpenes (often called terpenoids)

43. Lipids • other terpenes/terpenoids include natural rubber and “essential oils” such as plant fragrances and many spices

44. Lipids • steroids are terpene derivatives that contain four rings of carbon atoms • side chains extend from the rings; length and structure of the side chains varies • one type of steroid, cholesterol, is an important component of cell membranes • other examples: many hormones such as testosterone, estrogens

45. Lipids: what are they, and what are they used for? • What terms are associated with them (including majors classes and bond names)? • Give some examples of molecules in this group.

46. Polypeptides: what are they, and what are they used for? • What terms are associated with them (including the monomers and the polymer bond name)? • Give some examples of molecules in this group.

47. Proteins (polypeptides) • macromolecules formed from amino acid monomers • proteins have great structural diversity and perform many roles • roles include enzyme catalysis, defense, transport, structure/support, motion, regulation • protein structure determines protein function

49. proteins are polymers made of amino acid monomers linked together by peptide bonds • amino acids consist of a central or alpha carbon bound to: • a hydrogen atom • an amino group (-NH2) • a carboxyl group (-COOH) • and a variable side chain (R group)

50. proteins are polymers made of amino acid monomers linked together by peptide bonds • the R group determines the identity and much of the chemical properties of the amino acid • there are 20 amino acids that commonly occur in proteins • pay attention to what makes an R group polar, nonpolar, or ionic (charged) and thus their hydrophobic or hydrophilic nature