Fermentation

1. Fermentation

2. Main Ideas • Review of Cellular Respiration • What is Fermentation? • Metabolic Classification of Microbes

3. I. Review of Cellular Respiration • Why do cells undergo cellular respiration? TO MAKE CHEMICAL ENERGY – IN THE FORM OF…… ATP

4. I. Review of Cellular Respiration • Equation for cellular respiration: C6H1206 + 6 O2 6 CO2 + 6 H20 CARBON DIOXIDE WATER GLUCOSE OXYGEN

5. I. Review of Cellular Respiration • Three main stages 1. Glycolysis 2. Kreb’s Cycle 3. Electron Transport System

6. I. Review of Cellular Respiration • Glycolysis 1. Splits glucose (6 C) into 2 pyruvate (3 C) 2. Occurs in the cytoplasm of a cell 3. Produces a net of 2 ATP 4. Will occur with or without oxygen 5. Converts NAD+ into NADH (a carrier of electrons)

7. I. Review of Cellular Respiration • Kreb’s Cycle 1. Occurs in the mitochondrion of eukaryotic cells 2. Produces a net of 2 ATP 3. Releases CO2 as a byproduct 4. Converts NAD+ into NADH (a carrier of electrons)

8. I. Review of Cellular Respiration • Electron Transport Chain 1. Occurs in the mitochondrion of eukaryotic cells 2. Gets electrons from NADH 3. Electrons are ‘pulled’ by oxygen 3. Produces up to 34 ATP

10. AEROBIC CELLULAR RESPIRATION KREB’S CYCLE GLYCOLYSIS ELECTRON TRANSPORT SYSTEM

11. Main Ideas • Review of Cellular Respiration • What is Fermentation? • Metabolic Classification of Microbes

12. II. What is Fermentation? Without oxygen! A. Fermentation: An anaerobic process by which ATP is produced by glycolysis only

13. II. What is Fermentation? • Different kinds 1. Lactic acid fermentation a. In microbes that make cheese and yogurt b. In your muscle cells when O2 is unavailable c. Pyruvate makes lactic acid instead of entering Kreb’s Cycle

14. II. What is Fermentation? • Different kinds (cont.) 2. Alcoholic fermentation a. In yeast that make wine, beer, and root beer b. Pyruvate makes ethyl alcohol instead of entering Kreb’s Cycle

15. II. What is Fermentation? C. Why does it occur (from the microbe’s perspective)? 1. The NAD+ in glycolysis needs to be recycled! 2. If no NAD+, then no glycolysis and no ATP (=R.I.P.) NAD+

16. AN AEROBIC CELLULAR RESPIRATION =FERMENTATION KREB’S CYCLE GLYCOLYSIS ELECTRON TRANSPORT SYSTEM

17. II. What is Fermentation? D. Requirements for fermentation: 1. A microorganism → the yeast, a type of fungus 2. A source of glucose → the sugar we added 3. An environment with very low O2 → we capped and sealed the bottles

18. Main Ideas • Review of Cellular Respiration • What is Fermentation? • Metabolic Classification of Microbes

19. III. Metabolic Classification of Microbes A. Obligate anaerobes 1. Cannot live in the presence of O2 – oxygen is poisonous! 2. Examples: bacteria in marshes, at the bottom of lakes, in the stomachs of cows

20. III. Metabolic Classification of Microbes B. Obligate aerobes 1. Require oxygen to survive 2. Examples: bacterial pathogens such as those that cause tuberculosis

21. III. Metabolic Classification of Microbes C. Facultative anaerobes 1. Can survive whether or not oxygen is in the environment 2. If O2 present, they will complete all 3 stages of cellular respiration 3. If no O2, they will undergo fermentation

22. III. Metabolic Classification of Microbes So which category do the yeast (Saccaromyces cerevisiae) in our Root Beer Fermentation fit into? HINT: Look at the name of the lab. HINT 2: What sound does root beer make when you open a can of it?

23. III. Metabolic Classification of Microbes They ferment… but they also give off CO2. Since CO2 is a part of the Kreb’s cycle, they must be… FACULTATIVE ANAEROBES! For the first few days, they will be undergoing aerobic cellular respiration, and carbonating the brew in the process. After the O2 is all used up, they will revert to fermentation to give the root beer a unique flavor.