Lecture 5

1. Lecture 5 Biology 2500 Chapter 2: Secondary Metabolites

2. Learning Objectives Define Essential amino acids (and list all 9 of them) Phytoalexin Contrast Primary vs. secondary metabolites List: Examples of the 3 classes of secondary metabolites

3. The 9 Essential Amino Acids Our cells need 20 amino acids We make 11 Other 9 we must get from diet Therefore, they are �essential� Meat, eggs, dairy have all 20

4. Malnutrition Can occur when people don�t get all 9 In developing countries, often only 1 staple grain is available Corn or wheat or rice These are lacking in some amino acids Example: in Southern U.S., corn was staple Often the only food Severe medical condition occurred

5. Balanced Vegetarian Diets Some cultures have developed balanced diet through trial and error Beans and corn together have complete nutrition! All 9 essential a.a.�s are covered Traditional diet of Mexico Corn tortillas Beans

6. Primary Metabolites Found within all plants Necessary for the life of the plant Ex: Simple sugars Amino acids Proteins Nucleic acids

7. Secondary Metabolites Not necessarily in all plants Not necessarily in all tissues Functions: Can serve as chemical signals Protection against herbivores, pathogens, competitors Three classes (alkaloids, terpenoids, phenolics)

8. Alkaloids Medicinally the most important Generally, taste bitter (have alkaline, or basic chemical properties)

9. Examples of Alkaloids Morphine 1st to be isolated Analgesic, derived from opium poppies Cocaine From the coca plant An anesthetic, Incas use to alleviate hunger, pain Caffeine Stimulant in coffee, tea, cocoa Lethal to insects, fungi, nearby seedlings

10. More Examples of Alkaloids Nicotine Highly toxic, derived from tobacco Acts as a phytoalexin, produced when herbivores attack leaves Atropine Well-known pupil dialator Cleopatra used it Medieval Europeans known to derive from deadly nightshade plants (F: Solanaceae�why interesting?) Cardiac stimulant

11. Terpenoids Largest class of secondary metabolites All are built of isoprenes (C5H8) Isoprene is exuded by plants in large quantities Bluish haze over forests

12. Mints Have large amounts of monoterpenoids, sequiterpenoids Highly volatile Contribute to fragrance

13. Taxol A diterpenoid, has anti-cancer properties Chemotherapy: like radiation disrupts cell division, but more cleverly Freezes the spindle fibers, so they cannot pull the chromosomes Particularly effective against some breast and ovarian cancers Like radiation, there can be some side-effects

14. Taxol Websites Bristol-Meyers Squibb website Oregon State University website

15. 7th Inning Stretch

16. Chemotherapy and Conservation Taxol was discovered in Pacific yew bark Loggers cannot use it After clear-cutting, they plant only trees they consider �useful��not Pacific yew Saving wild places may help to save people too!

17. Rubber The largest terpenoid Contains 400 to 100,000 isoprene units Latex comes from a tropical tree Milky, sticky, �drowns� any attacking insects Harvested by indigenous peoples using knives, cups A renewable resource!

18. Cardiac Glycosides A class of terpenoids which can cause heart attacks We can use them to regulate heartbeat! Monarch butterfly uses these! Eat milkweed (rich in these terpenoids) Birds that eat a monarch eventually vomit

19. Phenolics ALL of these have a 6 carbon ring with hydroxyl group Include flavonoids, tannins, lignins

20. Flavonoids Water-soluble pigments, found in red wine, grape juice Intensely studied for cholesterol-reduction

21. Tannins Have a bad taste! Defends against herbivores Bind and modify protein structure Reduce proteins available to herbivores Used in leather tanning process Ex: Acorns must be soaked, dried before native Americans would grind into flour Apparently, not poisonous to mice, deer, squirrels

22. Lignins Add strength to cell wall Waterproof

23. Aspirin Greeks and native Americans used bark of willows (Genus: Salix) as analgesic