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Respiration – Miss Atkinson 2013 Respiration is the release of energy from food. The food involved in respiration is usually glucose. Internal respiration is controlled by enzymes which allow energy to be released in small amounts. The energy is trapped in molecules called ATP Types of Respiration Aerobic Respiration – the release of energy from food in the presence of oxygen Anaerobic Respiration The release of energy from food without requiring the presence of oxygen Aerobic Respiration Most living things get energy from aerobic respiration and are called AEROBES The energy stored in bonds in glucose is released and used to make ATP When ATP breaks down it supplies energy for all the reactions in a cell such as movement of muscles, growth of new cells etc. Adenosine Triphosphate (ATP) High energy compound with 2 “high energy” bonds ATP is the Energy currency of the cell providing a short-term energy store Generated during respiration and light stage of photosynthesis Phosphate added to ADP requires energy The addition of a phosphate is called phosphorylation food energy (respiration) light energy (photosynthesis) ATP is converted to ADP with the release of energy and a phosphate group: ATP ADP + P + energy out. e.g. Dark phase of photosynthesis Energy is used when ATP is formed: ADP + P + energy in ATP e.g. Respiration Equation for Aerobic Respiration C6H12O6 + 6O2 Glucose + Oxygen 6CO2 + 6H2O + Energy Carbon dioxide + water + energy Aerobic respiration is relatively efficient, 40% of the energy in glucose is used to make ATP. Any energy not used to produce ATP is lost as heat Aerobic Respiration occurs in 2 stages: Stage 1 Glycolysis Stage 2 Stage 1 - Glycolysis Takes place in the cytosol (the cytoplasm without the organelles) as enzymes are found here. Does not require oxygen It only releases small amounts of energy Is the same for both aerobic and anaerobic respiration A 6 carbon carbohydrate (Glucose) is converted to two 3-molecules with the release of a small amount of energy. Most of the energy in the glucose molecule remains stored in each 3- carbon molecule Glycolysis 6 carbon glucose is converted to 2 x 3C molecules called pyruvate 2 ATPs are produced from the energy released Some of the energy is also used to generate NADH. Each NADH enters an electron transport chain (E.T.C.). Stage 2 This stage requires and uses oxygen It releases a large amount of energy It occurs in the mitochondria as the necessary enzymes are found here The 3- carbon molecules are broken down to Carbon Dioxide and Water If O2 is available... Pyruvate enters the mitochondrion and loses a CO2 Pyruvate also loses 2 electrons to NAD to form NADH Pyruvate is converted to acetyl CoA The CoA is recycled as acetyl enters the Krebs Cycle The Electron Transport system: HL The electron transport system happens in the inner membrane of the mitochondria. The electron transport system is composed of a series of proteins that transfer NADH from protein to protein. With each transfer to a new protein some of the energy in the NADH is released to form ATP At the end of the electron transport system electrons are used to combine hydrogen with oxygen to form water. Anaerobic Respiration Anaerobic respiration can occur in the presence of oxygen but it does not need to use it In anaerobic respiration Glycolysis occurs this means glucose is broken into two 3-carbon molecules A small amount of energy is released this way There are different forms of anaerobic respiration where the 3 –carbon molecules are converted to different substances but no extra energy is released Anaerobic respiration is said to be less efficient than aerobic respiration as less energy is released Fermentation Anaerobic Respiration is also known as Fermentation Two types of fermentation: 1. Lactic Acid Fermentation 2. Alcohol Fermentation 1. Lactic Acid Fermentation This occurs in some anaerobic bacteria and fungi and in animal muscles when there is not enough oxygen In this fermentation Lactic acid is produced: Glucose 2Lactic Acid + small amount of energy Uses: 2. Alcohol Fermentation Takes place in Bacteria and some fungi such as yeast and in plants when they are deprived of oxygen Involves the partial breakdown of glucose: Glucose The ethanol itself is high energy Uses: 2Ethanol + 2Carbon dioxide + small amount energy Efficiency of Aerobic Respiration versus Anaerobic Respiration For each molecule of glucose respired: PROCESS: Stage 1 Stage 2 Glycolysis ATP PRODUCTION 2 Krebs cycle 2 ETC 34 Aerobic respiration total: 38 ATPs 2 Stage 1 Glycolysis Fermentation Lactic Acid Fermentation Alcohol Fermentation 2 2 Anaerobic respiration total: 4 ATPs Inefficiency of Fermentation Fermentation is very inefficient- only 2 ATPs are generated for each glucose molecule respired Lactic acid is produced in animal muscle if the supply of oxygen is insufficient (i.e. during strenuous exercise). An oxygen debt is paid back during rest. O2 is needed to break down the lactic acid replenish what was taken from the now oxygen-starved red blood cells. Ethanol is an alcohol and is produced by plants and fungi. Carbon dioxide is also produced during the process. Brewing and baking: 2 industries which rely on ethanol fermentation by yeast. Industrial Fermentation BIOTECHNOLOGY refers to the use of living things (such as microorganisms and enzymes) to carry our useful reactions In industrial fermentation the microorganisms are placed in a container with a suitable substrate on which they can react The vessel in which biological reactions can take place is called a BIOREACTOR A fermentation bioreactor: When the microorganisms are mixed with the substrate foam may be formed so a foam breaker is used Oxygen is pumped in through a sparger Quality and amount of product depend on the quality of the microorganism and substrate, the design of the bioreactor, a correct rate of mixing, a correct temperature and pH and elimination of contaminating microorganisms Microorganisms used in bioprocessing: Bacteria can be used to make yoghurts, antibiotics + enzymes Yeasts can be used to make Beer and wine, carbon dioxide for baking and single cell protein Fungi can produce antibiotics and citric acid Learning Check Bioprocessing with Immobilised cells To ensure the microorganisms used in a bioreactor are not lost at the end of every reaction they are often immobilised or fixed The microorganisms can be immobilised by bonding them to each other bonding them to an insoluble support or suspending them in a gel or membrane Uses of Immobilised Cells/Micro-organisms: In the treatment of sewage bacteria and fungi may be attached to sand and gravel and then decompose the waste In the production of alcohol yeast cells are immobilised with sodium alginate Advantages of Immobilised Cells: Immobilisation is gentle it does not damage cells Immobilised cells can be easily recovered Immobilised cells reduce the need for filtration at the end of bioprocessing Immobilised cells can be reused reducing costs Uses of Immobilised Cells: Immobilised cells are becoming more popular than immobilised enzymes as it saves time isolating and purifying enzymes which is an expensive process