C 1.2 SL Cell Respiration PDF

C 1.2 Cell Respiration “What are the roles of hydrogen and oxygen in the release of energy in cells? “How is energy distributed and used inside cells?” Learning Objectives Include the full name of ATP (adenosine triphosphate) and that it is a...

C 1.2 Cell Respiration “What are the roles of hydrogen and oxygen in the release of energy in cells? “How is energy distributed and used inside cells?” Learning Objectives Include the full name of ATP (adenosine triphosphate) and that it is a ATP as the molecule that distributes C1.2.1 nucleotide. Students should appreciate the properties of ATP that make it energy within cells suitable for use as the energy currency within cells. Include active transport across membranes, synthesis of macromolecules Life processes within cells that ATP C1.2.2 (anabolism), movement of the whole cell or cell components such as supplies with energy chromosomes. Students should know that energy is released by hydrolysis of ATP (adenosine triphosphate) to ADP (adenosine diphosphate) and phosphate, Energy transfers during interconversions C1.2.3 but energy is required to synthesize ATP from ADP and phosphate. between ATP and ADP Students are not required to know the quantity of energy in kilojoules, but students should appreciate that it is sufficient for many tasks in the cell. Students should appreciate that glucose and fatty acids are the principal Cell respiration as a system for producing substrates for cell respiration but that a wide range of carbon/organic C1.2.4 ATP within the cell using energy released compounds can be used. Students should be able to distinguish between from carbon compounds the processes of cell respiration and gas exchange. Include which respiratory substrates can be used, whether oxygen is required, relative yields of ATP, types of waste product and where the Differences between anaerobic and reactions occur in a cell. Students should be able to write simple word C1.2.5 aerobic cell respiration in humans equations for both types of respiration, with glucose as the substrate. Students should appreciate that mitochondria are required for aerobic, but not anaerobic, respiration. Students should make measurements allowing for the determination of Variables affecting the rate of cell the rate of cell respiration. Students should also be able to calculate the C1.2.6 respiration rate of cellular respiration from raw data that they have generated experimentally or from secondary data. Cellular Respiration as a system to produce energy All organism require energy to live. This energy (in the form of ATP) is produced during cellular respiration by breaking down nutrients and food (organic compounds) using enzymes into CO2, H2O and ATP. Organic compounds are the initial source of energy. Organic compounds are molecules which contain carbon-carbon or carbon-hydrogen bonds such as glucose or fatty acids. Through a number of metabolic steps the molecules are oxidized and potential energy stored in the compounds is transferred to ATP.  Cellular Respiration as a system to produce energy The source of organic compounds broken down in cell respiration is the food that we eat. Carbohydrates (sugars or starch) and lipids (fatty acids), http://2012books.lardbucket.org/books/principles-of-general-chemistry-v1.0/section_22/4d63af61c4222e206af1bbb7ff53a6c5.jpg but also proteins are used for energy production in cell respiration. Glucose Fatty acids ATP is produced by attaching a phosphate group to ADP. This step requires energy – ultimately coming from food. The covalent bond created stores energy until it is released again for processes required by cells. ADP is therefore recycled again. Cellular Respiration as a system to produce energy http://www.exploringnature.org/graphics/biology/cellular_respiration2_72.jpg Cellular Respiration is not the same as Breathing! Breathing is the intake of oxygen into the lungs and release of carbon dioxide from the lungs to enable gas Cell respiration is the controlled release of exchange and to provide the body with energy from organic compounds to produce ATP. oxygen for cellular respiration. It takes place in the mitochondria of all cells. ATP as the molecule that distributes energy within cells Energy in cellular respiration is transferred in small quantities rather than one big release. If energy would be all given out in one go most of it would be lost as heat to the surrounding. Instead, energy is transferred to ATP in many small steps with only little heat loss. ATP as the molecule that distributes energy within cells The nucleotide ATP (Adenosine http://www.uic.edu/classes/bios/bios100/lectures/atp_energy.jpg triphosphate) produced during respiration, is the molecule which directly fuels many biological reactions. It is referred to as universal energy currency. What properties make ATP suitable as an energy source? It contains chemical energy locked up in its structure The energy can be released in small managable quantities by hydrolysing ATP into ADP – useful for many energy requiring processes in the cell It is a very reactive molecule, taking part in cell respiration and metabolism It is small and can be moved easily into cells by facilitated diffusion It cannot move simply through cell membranes, keeping it under control Energy transfers during interconversions between ATP and ADP During cellular respiration the energy from food is used to form ATP from ADP and Pi. Energy requirying processes in the body can then use ATP together with enzymes as energy source converting it back into ADP. Interconversion of ATP and ADP The reverse process, where water Hydrolysis of ATP splits it into ADP is released and energy required to by removing one phosphate group form ATP from ADP and Pi, is using water. Energy contained in referred to as condensation. the covalent bond is released. Energy transfers during interconversions between ATP and ADP In many metabolic reactions ATP reacts with other metabolites with the help of enzymes to form phosphorylated intermediates. This phosphorylation makes them more reactive for the process in which they need to take part in. Energy transfers during interconversions between ATP and ADP When muscles contract, they shorten in length as a result of actin and myosin protein filaments in muscle cells sliding in and out of each other. The sliding depends on the hydrolysis of ATP and the energy released is used for the “power stroke”. Cellular Respiration: Uses of ATP Chemical energy (ATP) produced by an organism through cellular respiration can be converted into a number of different forms of energy with only little being lost to heat: Chemical energy stored in ATP can be converted into electrical energy when transmitting a nerve impulse, into kinetic energy during muscle contractions, into light energy in bioluminiscence, into other forms of chemical energy in the synthesis of molecules or when transporting materials. Cellular Respiration: Uses of ATP Although there are many uses of ATP in a cell, the three main types of purposes can be summarized below: Synthesizing macromolecules Movements Active transport Cellular Respiration: Uses of ATP Although there are many uses of ATP in a cell, the three main types of purposes can be summarized below: Synthesizing macromolecules Movements Active transport Anaerobic and aerobic cell respiration in humans Anaerobic and aerobic cell respiration in humans Anaerobic respiration All forms of cellular respiration start wih glycolysis in the cytoplasm. If oxygen is available aerobic respiration commences. Without oxygen pyruvate will be converted into lactic acid (in humans) during anaerobic respiration. Aerobic respiration In aerobic respiration substrate are gradually reduced using oxygen as the final electron acceptor. A lot of energy (ATP) is produced. Anaerobic respiration After glycolysis, pyruvate is broken down in anaerobic cell respiration without using any oxygen. The yield of ATP is relatively small , but the ATP can be produced quickly. This is of importance in particular in following situations: When a short and rapid burst of ATP is needed When oxygen supplies run out in respiring cells In environments which are oxygen deficient (e.g. waterlogged soil)  Anaerobic respiration http://www.workoutstories.com/wp-content/uploads/2008/02/boxing-training-myths.jpg High intensity exercise such as sprinting, boxing or weight-lifting require anaerobic respiration. This is because…. There is not enough time to deliver O2 to the cells for aerobic respiration. The supply of energy needs to be fast and quickly available so that power can be maximized. Lactate and a small amount of ATP is produced in this process. This process is only sufficient to produce ATP for ca.2 minutes. Beyond this duration, hydrogen ions (H+) accumulate and prevent further anaerobic respiration Anaerobic respiration maximizes power contractions For exercises which demand ATP at a fast rate, little aerobic respiration is performed and a lot of glycolysis with subsequent anaerobic/lactic acid fermentation is carried out. ATP needs to be supplied at a fast rate to maximize the power contractions. Creatine phosphate system Anaerobic respiration Lactic acid accumulates in the muscle tissue. There is a limit to how much lactic acid the muscle cells can tolerate. The accumulation of lactic acid decreases the pH inhibits actin-myosin interactions and prevents muscle contractions to proceed. In aerobic respiration oxygen is required and a large amount of ATP is produced If oxygen is available, the intermediate product pyruvate is absorbed by mitochondria Inside the mitochondrion the pyruvate is gradually broken down (reduced) into carbon dioxide, water and 36-38 molecules of ATP. Aerobic cell respiration therefore has a much higher yield of ATP per gram of glucose than anaerobic cell respiration. In aerobic respiration oxygen is required and a large amount of ATP is produced 3 If oxygen is available, pyruvate is transported into the mitochondrion, where it gradually broken down into carbon dioxide, water and a large amount of ATP. water carbon dioxide 1 Glucose from food and oxygen is transported via the bloodstream to the cells, where it is absorbed into 2 In the cytoplasm glucose is 4 Carbon dioxide is a waste product the cytoplasm. turned into pyruvate during and diffuses into the bloodstream glycolysis. This produces a from where it is transported to the small amount of ATP. lungs where it is exhaled. Anaerobic versus Aerobic respiration Anaerobic respiration Aerobic respiration Use of oxygen (as electron acceptor) Substrates used Waste products Yield of ATP Location of reactions in the cell Word equation for reaction Purpose of reaction Anaerobic versus Aerobic respiration Measurement of cellular respiration A number of environmental factors affect respiration rate in organism, and for scientists it is often interesting to investigate the factors affecting respiration scientifically. Discuss in groups: 1. How could cellular respiration be measured? http://sites.sinauer.com/animalphys3e/boxex/AnPhys3e-BoxEx-07-04-A-0.jpg 2. What is a rate of respiration? 3. What could be investigated (which factors affecting cellular respiration could be investigated)? Measurement of respiration using a respirometer A respirometer is a simple device that is used to measure respiration rate. A respirometer usually involves… The use of a sealed glass container in which the organism is places. http://sites.sinauer.com/animalphys3e/boxex/AnPhys3e-BoxEx-07-04-A-0.jpg A substance which absorbs CO2 produced by cell respiration. A capillary tube containing fluid which allows the changes in pressure to be monitored. Measurement of respiration using a respirometer Respirometers can have many shapes and forms. The components and functions of a simple respirometer is shown below. Capillary tube: Thin glass tube filled with coloured Syringe: Use to reset the liquid to monitor the changes in gas volume inside position of the coloured oil the tubes to measure respiration rate. The volume of air inside the container will reduce Rubber bungs: seal tubes due the use of O2 during and close the system airtight aerobic cell respiration of to avoid changes in volume the organisms in it. Metal cage: a platform for the Temperature control organism away from the alkali The respirometer should be immersed in a water Alkali: Usually potassium bath to prevent hydroxide (KOH) – this temperate affecting the absorbs the CO2 released by pressureand hence the organism during cellular volume of air in the respiration. This allows to apparatus. see changes in pressure due to uptake of oxygen only. Measurement of respiration using a respirometer 1. Go to this link and open the simulation. Select your preferred type of seed and increase the number of seeds to 25. Make sure to always keep it at this temperature. 2. Select 5°C as the first temperature you will investigate. Click start and wait for the reaction to be complete. Record the increase in water level in ml (Look at the initial level of water in the tube!) 3. Repeat the procedure with 5 different https://amrita.olabs.edu.in/?sub=79&brch=17&sim=204&cnt=4 temperatures and record the results. Make sure to keep your controlled variables the same. What do you notice? Measurement of respiration using a respirometer 1. Describe what factors can be investigated when using a respirometer (independent variables): 2. Explain the need for a base (KOH) inside the respirometer. 3. What direction will the fluid in the capillary tube move if the organisms in the right-hand chamber are respiring and how can this be used to calculate a respiration rate? http://umbrellamarketingteam.com/wp-content/uploads/2015/03/Baby.jpg Measurement of respiration using a respirometer When designing an experiment like this, which factors need to stay controlled? What would you do in order to analyze these results? What are ethical implications of the use of invertebrates in respirometer experiments? http://umbrellamarketingteam.com/wp-content/uploads/2015/03/Baby.jpg Design a lab activity for students! http://www.bch.cuhk.edu.hk/vlab2/index.html#2/slide3