RESPIRATION AND FERMENTATION: AEROBIC AND ANAEROBIC OXIDATION OF ORGANIC MOLECULES. Bio 107 Week 6

Transcription

1 RESPIRATION AND FERMENTATION: AEROBIC AND ANAEROBIC OXIDATION OF ORGANIC MOLECULES Bio 107 Week 6

2 Procedure 7.2 Label test tubes well, including group name 1) Add solutions listed to small test tubes 2) Fill remaining volume with yeast suspension 3) Slide larger test tube over the smaller tubes; hold smaller tube against the bottom of the larger tube and invert. There should be no air trapped at the top of the tube. Practice this first with just water. 4) Incubate tubes at 37 C for 30 minutes. 5) After 30 minutes, measure the height (in millimeters) of the bubble of accumulated CO 2. Record results in table 7.2

3 Tips and Tricks Shake yeast bottles before using Clean benches immediately when done (this stuff gets sticky) Rinse test tubes well and put upside-down in rack at table.

4 Cellular Respiration Cellular Respiration: oxidation of organic molecules into energy in the form of ATP ATP = Adenosine Triphosphate: organic molecule containing high-energy phosphate bonds

5 Cellular Respiration - Summary C 6 H 12 O 6 + 6O 2 6CO 2 + 6H e ATP Glucose is oxidized [removes electrons], O 2 is reduced (oxidation-reduction reaction or REDOX) Remember OIL RIG Oxidized Is Loss (of electrons) and Reduction Is Gain) Remember that adding/removing a hydrogen is a way of adding/removing an electron One glucose yields ATP Electrons (as H) moved by coenzymes NAD+ and NADH 2

6 Steps of Cellular Respiration Glycolysis Prep Reactions Krebs Cycle Electron Transport Chain

7 Respiration: Glycolysis Energy Investment Step Two ATP used to split glucose into two 3-carbon molecules Energy-Harvesting Step 1) 3-carbon molecules oxidized by NAD+, resulting in two NADHs 2) Phosphate group added to each. 3) Substrate-level ATP synthesis or substrate-level phosphorylation: enzyme passes high-energy phosphate to ADP, and ATP results (adenosine diphosphate triphosphate (+2 ATP, 3PG (3- phosphoglycerate)) 4) 3PG is oxidized by the removal of water (+2H 2 O, 2 PEP) 5) Substrate-level ATP synthesis again. (+2 more ATP, 2 pyruvate) NET GAIN: 2 ATP, (because we used two in energy investment) + 2 pyruvate.

8 Respiration: Glycolysis Glycolysis: Sugar-splitting or Energy investing step Occurs in cytoplasm Requires 2ATP Glucose split into 2 Pyruvate

9 Respiration: First Set of Reactions Glycolysis: Sugar-splitting or Energy investing step Occurs in cytoplasm Requires 2ATP Glucose split into 2 Pyruvate Final Products: 2 NET ATP (4 produced, but 2 were used) 2 NADH 2 Pyruvate

10 If Oxygen is Present Prep Reactions Pyruvate oxidation into acetyl-coa One NADH produced Citric Acid Cycle Occurs in matrix of mitochondria Acetyl-CoA oxidized into two CO 2 Produces 1 ATP per turn Store energy in electron carries such as NAD+ and FAD+ Electron Transport Chain Electrons from NADH and FADH 2 move through a series of proteins called the ETC Potential energy released during these redox reactions creates proton gradient across a membrane; flow of protons across the membrane generates ATP

11 If No Oxygen is Present NADH reduces Pyruvate Glucose C 6 H 12 O 6 2CO 2 + 2C 2 H 5 OH + ATP C 6 H 12 O 6 2CH 3 CHOHOCOOH + ATP Occurs in anaerobic organisms (anaerobes) Glycolysis Occurs temporarily in plants and animals Roots in anaerobic soils In muscles for rapid bursts of energy Animals, some microbes Pyruvate Plants, some microbes NADH NADH CO 2 NAD+ NAD+ Lactate Ethanol

12 Yeast our organism Unicellular sac fungi eukaryotes, kingdom Fungi, phylum Ascomycota Obtain food from organic matter In the wild found in soil, water, surface of animals and plants Many species/strains used to make bread, beer, whiskey and more! Also can cause disease (Candida, opportunistic)

13 What undergoes Fermentation? Anaerobes organisms that live without oxygen Some use nitrate, sulfate or other inorganic compounds as electron acceptors instead of oxygen Some use glycolysis reduce the pyruvate Other organisms can undergo fermentation when their cells are depleted of oxygen (such as during exercise)

14 Advantages/Disadvantages? Disadvantages: Less ATP produced (2 VS 36/38 in aerobic respiration) Produces toxins (lactic acid or ethanol) Advantages: Can produce ATP without oxygen survival! Byproducts used in many foods (economic value, not a biological advantage)

15 Lab Results Table 7.2 Fermentation By Yeast Tube Sugar Initial Gas Height Final Gas Height Net Change Ease of Fermentation (Rank) 1 Water/None 2 Glucose 3 Fructose 4 Sucrose Glucose Sucrose

16 Procedure 7.2 Label test tubes well, including group name 1) Add solutions listed to small test tubes 2) Fill remaining volume with yeast suspension 3) Slide larger test tube over the smaller tubes; hold smaller tube against the bottom of the larger tube and invert. There should be no air trapped at the top of the tube. Practice this first with just water. 4) Incubate tubes at 37 C for 30 minutes. 5) After 30 minutes, measure the height (in millimeters) of the bubble of accumulated CO 2. Record results in table 7.2

17 Tips and Tricks Shake yeast bottles before using Clean benches immediately when done (this stuff gets sticky) Rinse test tubes well and put upside-down in rack by the sink.