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Introduction to Respiration

Introduction to Respiration. IGCSE Biology. What do we need energy for ?. You have 2 min as a group to act out different activities your body requires energy for !. How is digested food used by the body?. The body needs a constant supply of energy which comes from digested food.

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Introduction to Respiration

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  1. IntroductiontoRespiration IGCSE Biology

  2. What do weneedenergyfor? Youhave 2 min as a grouptoactoutdifferentactivitiesyourbodyrequiresenergyfor!

  3. How is digested food used by the body? The body needs a constant supply of energy which comes from digested food. Glucose, from digested carbohydrates, is an important substance that contains stored chemical energy. This is released when it reacts with oxygen in cells. The energy is used in many ways, such as for: • enabling muscles to contract • Transmitting nerve impulses • keeping warm in mammals and birds • Cell division • building new molecules, cells and tissues – e.g. proteins • ACTIVE transport to move substances across cell membranes

  4. + ( energy) What is respiration? Respirationis the process that the body uses to release energy from digested food (glucose). carbon dioxide + + glucose oxygen  water from the digestive system from the respiratory system waste product (exhaled) waste product (exhaled) This type of respiration is called aerobicrespiration because energy is released in the presence of oxygen. How do the glucose and oxygen needed for aerobic respiration get to the all the body’s cells?

  5. Equations for aerobic respiration All of these are fine!....

  6. Equation for Cellular Respiration C6H12O6 + 6O2 YIELDS 6CO2 + 6H20 + e- + 36-38ATP + heat

  7. There are two kinds of respiration Anaerobic respiration: release of a SMALL amount of energy by the breakdown of food substances in the absence of oxygen IN THE CYTOPLASM Aerobic respiration: release of a LARGE amount of energy by the breakdown of food substances in the PRESENCE of oxygen IN THE MITOCHONDRION

  8. Glycolysis: Always the initial stage of respiration • Location: cytoplasm • Substrate: glucose • Requires input of 2 ATP • Products: pyruvate, (NADH), 4 ATP Glycolysis is an anaerobic process: no oxygen required

  9. Aerobic respiration • Takes place in the mitochondria of eukaryotic cells • Produces LOTS of ATP : 90% of total ATP from respiration • Also produces carbon dioxide, water and heat • Oxygen is the final electron acceptor

  10. If no oxygen is available, glycolysis (anaerobic) is followed by fermentation (anaerobic)

  11. Fermentation 1. Alcoholic fermentation Pyruvate is converted into ethanol plus carbon dioxide and NAD+ • Lactate fermentation Pyruvate is converted into lactate and NAD+

  12. Alcoholic fermentation in yeast

  13. ‘Alcoholic’ fermentation in yeast • Pyruvate is produced from glycolysis • 3-carbon pyruvate is converted to 2-carbon ethanol and carbon dioxide • Generation of carbon dioxide helps bread products to rise • Yeast is used to produce ethanol

  14. Yeast is used for breadmaking AND for wine, beer and spirit production BREADMAKING • In bread dough, starch in bread has been broken down by amylase into maltose and glucose • Yeast respires both aerobically and anaerobically, producing CO2 which makes the bread rise ALCOHOL PRODUCTION • yeast is dissolved in warm maltose solution • The yeast respires anaerobically, making alcohol • The carbon dioxide makes beer/ wine fizzy

  15. In mammals, anaerobic fermentation produces LACTATE • Lactate is a 3-carbon molecule

  16. Comparing aerobic and anaerobic respiration

  17. What do younoticeaboutthesetwoequations?

  18. Plants respire too! glucose + oxygen Water + carbon dioxide (+ energy) Reactants Products • Aerobic respiration (uses oxygen) • Happens all the time • Overall plants produce more oxygen by photosynthesis than they use by respiration YouTube - Plant Physiology: Respiration (Britannica.com)

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