Chapter 6: Metabolism: Fueling Cell Growth

1. Chapter 6:Metabolism:Fueling CellGrowth

2. Don’t worry too much about the details of Glycolysis, Cellular Respiration, or Photosynthesis onward. • These topics are covered on pp. 144-151 and pp. 156-163. • Note, however, that we will cover Glycolysis and Cellular Respiration in class at least from the perspectives of the importance of NAD+ regeneration. Chapter 6 Notes

3. Important Point: If you are having trouble understanding lecture material: Try reading your text before attending lectures. And take the time to read it well!

4. Products of Microbial Metabolism

5. Beer, wine, and other alcoholic beverages. • Bread (all of above are mostly products of the yeast Saccharomyces cerevisiae). • Products of lactic-acid bacteria (LAB) including sour milks, various cheeses, half-sour pickles, sauerkraut, etc. (e.g., of Lactococcus spp. & Lactobacillus spp.). • Organic solvents including acetone (product of Clostridium acetobutylicum), butanol (ditto), and, of course, ethanol (product of S. cerevisiae). • Acetic acid (vinegar). • Biochemical identification of bacterial species. • Unique (e.g., not found in animals) targets for antimicrobial action. • Disease (e.g., dental caries). Important Consequencesof Microbial Metabolism

6. Metabolism =Catabolism + Anabolism sum = metabolism Pay particular attention to those words in bold in this figure.

7. More generally, sun or reduced inorganic chemicals (ocean vents). Bioenergetics (see Fig. 6.3) More generally, photoautotrophs (or just autotrophs). E.g., glucose More generally, chemoheterotrophs. Note that bacteria don’t have mitochondria: aerobic bacteria “are” mitochondria!

8. Metabolic pathway = highly evolved intracellular sequence of chemical reactions. • Each step of a metabolic pathway usually is enzymatically catalyzed (and enzymes are proteins). • Substrates are molecules that enter into enzymatically catalyzed reactions. • Products are what substrates are enzymatically converted into. • Enzymes typically are very precise in terms of what substrates they will accept (often no more than one specific chemical) and they will convert a substrate into (often no more than one specific chemical). • Precursor molecules are found at the start of metabolic pathways. • Intermediate molecules are found within metabolic pathways. • End products are the molecules ultimately produced by a given metabolic pathway. Metabolism Terms & Concepts

9. Chemical Energetics How cells “burn” glucose.

10. Enzyme names generally are indicated by an “-ase” ending, e.g., dehydrogenase (lysozyme is exception). • Enzymes have active sites (a.k.a., catalytic sites). • Cofactors are non-protein components of enzymes; they can be organic or inorganic. • Coenzymes are organic cofactors; they generally are carriers of other molecules or ions. • NAD+ for example is a coenzyme. Enzyme Terms & Concepts

11. Ezyme with Cofactor

12. Environment Impact on Enzyme Activity

13. Enyzmatic Inhibition

14. Variation on Metabolic Pathways

15. Variation on Metabolic Pathways Glycolysis is a catabolic pathway. Krebs citric acid cycle is a cyclic catabolic pathway. E.g., ATP, CO2, and NADH.

16. ATP – Energy Currency of Cells

17. ATP, ADP, and Metabolism

18. Oxidation-Reduction (Redox)

19. Oxidation-Reduction (Redox)

20. Oxidation-Reduction (Redox) Note that 2 hydrogen ions are removed along with the 2 electrons (only one H+ ends up attached to NAD+, hence the charge change). Note NAD+ (not “NAD”).

21. Overview of Metabolism

22. Glucose NAD+ NADH ATP ATP Pyruvate Glycolysis (see Fig. 6.14) An Enzyme and Coenzyme Mediated Catabolic Pathway

23. Glycolysis (see Fig. 6.14) An Enzyme and Coenzyme Mediated Catabolic Pathway

24. Glucose NAD+ NADH ATP ATP Pyruvate Glycolysis (see Fig. 6.14) An Enzyme and Coenzyme Mediated Catabolic Pathway     

25. Regeneration of NAD+ Fermenation Pathways

26. Glycolysis Pyruvate (2e-) Regeneration of NAD+ E.g., see Fig. 6.17-6.19 (6.16-6.18) Cellular Respiration

27. Glycolysis Pyruvate (2e-) Regeneration of NAD+        above is why aerobes need O2

28. Glycolysis Lactic Acid Fermentation (see Fig. 6.20)

29. Bread Glycolysis Beer Ethanol Fermentation (see Fig. 6.20) No, These are Not Lemons!

30. Simple Fermentation Pathways

31. This is why we Fart!  Mixed-Acid Fermentation

32. Other Fermentation Pathways

33. Other Fermentation Pathways Beer, wine, bread. Flatulence! Swiss cheese. LAB & our own muscles.

34. Anaerobic Respiration …employs an inorganic molecule other than O2 as a terminal electron acceptor.

35. Amylases = enzmes that hydrolyze starches to their constituent glucoser subunits. • Disaccharidases = enzymes that hydrolyze dissacharides to constituent monosaccharides. • -galactisidase is the most famous of disaccharidases; it breaks down the sugar lactose (into galactose and glucose). • Lipases = enzymes that hydrolyze fats (into glycerol or and fatty acids). • Proteases = enzymes that break down proteins. • Deaminases = enzymes that remove amino groups from individual amino acids. • The resulting products can be used as alternatives to glucose as carbon and energy sources. • Chemolithotrophs (a.k.a., chemoautotrophs) utilize substances other than organic compounds as energy sources and get their organic carbon from CO2. Hydrolytic Enzymes

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