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Description
Flashcards by Becky Saunders, updated more than 1 year ago
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Created by Becky Saunders
over 7 years ago
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| Question | Answer |
| What is Anaerobic Respiration? | - the process by which complex organic compounds are broken down into simple inorganic compounds without the use of oxygen or the electron transport chain - the organic compounds are not fully broken down, thus fermentation produces less ATP than aerobically respiring. |
| How many ATP are produced in Anaerobic Respiration compared to Aerobic? | 2 ATP - Anaerobic 32 ATP - Aerobic |
| When do Eukaryotes respire anaerobically? | - When there is no oxygen available - or not enough oxygen is being supplied fast enough to respiring tissues |
| What is an obligate anaerobe? | an organism that can't survive in the presence of oxygen - mostly prokaryotes such as clostridium bacteria (food poisoning) & some fungi |
| What is a facultative anaerobe? | an organism that synthesises ATP by aerobic respiration when oxygen is present. But can switch to anaerobic respiration in the absence of oxygen, e.g. Yeast |
| What is an obligate aerobe? | An organism that can only synthesise ATP in the presence of Oxygen. However, some cells can be called facultative anaerobes, as in emergencies they supplement ATP supplies using anaerobic respiration |
| Why is ATP yield lower in Anaerobic Respiration? | - Only glycolysis can occur - The electron transport chain stops as there is no oxygen to act as the final electron acceptor - Thus, NAD can't be re-oxidised, preventing the Krebs Cycle & Link reaction |
| In what type of organism does Lactate Fermentation occur? | In mammals |
| What happens during Lactate Fermentation? | 1. Pyruvate accepts hydrogen from reduced NAD. 2. This converts pyruvate to lactate & re-oxidises NAD (to be reused in glycolysis) 3. Cells can't tolerate high levels of lactic acid as it lowers pH, so it is removed from cells into bloodstream. 4. Lactate is converted back to glucose in the liver by glyconeogenis, which requires oxygen, thus anaerobic respiration results in an oxygen debt where you have to breath deeply & quickly to repay it. |
| What type of organisms undergo Alcoholic Fermentation? | Yeast Cells |
| What happens during Alcoholic Fermentation? | 1. Pyruvate is converted into ethanal by the removal of Carbon Dioxide, catalysed by the enzyme pyruvate decarboxylase 2. Ethanal accepts a hydrogen from reduced NAD to form ethanol & NAD, catalysed by ethanol dehydrogenase 3. NAD can then be used in glycolysis |
| Up to which point can yeast respire anaerobically? | Until ethanol builds up to 15%, anywhere above that would kill the yeast due to the toxicity of the ethanol |
| What are the differences between Lactate & Alcoholic Fermentation? | In Alcoholic fermentation 2 enzymes are involved, pyruvate decarboxylase & ethanol dehydrogenase, whereas in Lactate fermentation lactate dehydrogenase is the enzyme used. Also in AF ethanol acts as the hydrogen acceptor, whereas in LF pyruvate is. CO2 is produced in AF but not in LF. the end products of AF are CO2 & ethanol, whereas in LF it is lactate. |
| What are the similarities between Lactate & Alcoholic Fermentation? | - Both take place in the cytoplasm - Both produce 2 ATP - Both start with glycolysis |
| Why can't Lactate Fermentation occur indefinitely in mammals? | 1. the lower quantity of ATP synthesised is not enough to supply the vital biological processes of the metabolism. 2. The lactic acid that builds up causes a drop in pH which denatures proteins, e.g. respiratory enzymes & muscle filaments; therefore is toxic to mammals. |
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