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Aerobic and Anaerobic Respiration. Intermediate 2 Biology Unit 1: Living Cells. Learning Objectives. Name the type of energy stored in food. Describe the energy change when food is burned. State the units used in measuring energy content of food. Define the term respiration.
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Aerobic and Anaerobic Respiration Intermediate 2 Biology Unit 1: Living Cells
Learning Objectives • Name the type of energy stored in food. • Describe the energy change when food is burned. • State the units used in measuring energy content of food. • Define the term respiration. • Name the food molecule that is the main source of energy in cells.
Energy Facts • Energy facts • Cannot be created or destroyed • Can be converted from one form to another • Takes a variety of forms • Measured in kilojoules
Energy • Food is a store of chemical energy. • When food is burned, chemical energy is converted into heat and light energy.
Energy in Living Organisms • “Work” • Synthesis of complex substances • Active transport e.g. sodium-potassium pump • Movement • Bioluminescence • Maintenance of body temperature • Production of electricity • Maintenance, repair and division
Respiration • The chemical process by which energy is released from cells is called respiration. • The main source of energy for respiration in cells is glucose. • This process is controlled by a series of enzymes.
Progress questions • Fireflies can produce light in a process called bioluminescence. Outline the energy transformations that occur in fireflies as they use energy from their food to produce luminescence. • Comment on the statement below. • Respiration produces energy to form ATP.
Learning Objectives • Give the full name of ATP and draw a simplified diagram of its structure. • Name the molecule from which ATP is formed in cells and draw a simplified version of its structure. • Explain where the energy for the formation of ATP in cells comes from. • Explain what the energy from the breakdown of ATP is used for.
Structure of ATP • Adenosine triphosphate (ATP) • Adenosine • Three phosphate groups • Diagram of ATP
ATP • a high energy molecule • continually being hydrolysed and resynthesised.
Formation and breakdown of ATP • The combining of ADP + Pi to make ATP is an energy requiring process. • The breakdown of ATP to ADP + Pi is an energy releasing process. • The energy required for the formation of ATP from ADP + Pi comes from the respiration of glucose.
Role of ATP • ATP is the energy source for: • Muscle contraction • Cell division • Building up (synthesis) of proteins • Transmission of nerve impulses • If ATP is added to muscle tissue, it causes the muscle fibres to contract. The overall effect is that the muscle tissue shortens in length.
Think!! • Explain why ATP is known as the universal energy currency.
Learning Objectives • Describe aerobic respiration (using the words glucose, pyruvic acid, glycolysis, carbon dioxide and water).
Chemistry of Respiration • Respiration is the process by which chemical energy is released during the breakdown of glucose • It occurs in every living cell • Involves the regeneration of ATP
Takes in energy A A Pi Pi Pi Pi Pi Pi Gives out energy High energy bond Regeneration of ATP Adenosine DiPhosphate (ADP) Adenosine TriPhosphate (ATP) + Inorganic Phosphate (Pi)
Glycolysis • Splitting of glucose into two molecules of pyruvic acid • Results in the production of 2ATP molecules
C C C C C 2 Pyruvic Acid C 1 Glucose C C C C C C Glycolysis 2 ADP + 2Pi 2 ATP
Aerobic breakdown of pyruvic acid • Pyruvic acid is broken down in a series of enzyme controlled steps. • Each pathway leads to formation of • Water • Carbon dioxide • 18 molecules of ATP • As this takes place twice for each molecule of glucose the total gain of ATP is 36
Investigating the activity of enzymes in aerobic respiration
Investigating the activity of enzymes in aerobic respiration • During respiration, glucose is broken down, hydrogen is released at various stages • This removal of hydrogen is controlled by an enzyme
Yeast contains stored food which can be used as a respiratory substrate • Resazurin dye changes colour when it gains hydrogen) bluepinkcolourless (no hydrogen) (lots of hydrogen)
Investigating the activity of enzymes in aerobic respiration Set up the three test tubes as shown below. 10ml glucose 10ml yeast 5 ml dye
Investigating the activity of enzymes in aerobic respiration Shake tubes vigorously for 20 seconds, and place in a water bath set at 37oC. Leave for a few minutes Draw a diagram of your results Can you explain your results.
Investigating the activity of dehydrogenase enzyme in yeast Tube A Colour change from blue via pink to colourless. Hydrogen has been rapidly released and has reduced the dye. For this to happen – enzymes present in yeast cells must have acted on the glucose, the respiratory substrate, and oxidised it.
Investigating the activity of dehydrogenase enzyme in yeast Tube B Change from blue – pink – colourless Reaction is slower since no glucose was added. enzymes could only act on any small amount of respiratory substrate already present in the yeast cells. Tube C Boiling has killed the yeast and denatured the enzymes.
Respirometer • A respirometer measures the rate of respiration • Sodium hydroxide is a chemical that absorbs carbon dioxide • Oxygen taken in by the animal causes a decrease in volume in the enclosed gas, the coloured liquid rises up the tube.
Learning Objectives • Describe anaerobic respiration as the breakdown of glucose to pyruvic acid by glycolysis. • State that anaerobic respiration in animals is reversible and results in the production of lactic acid. • Describe the effect of lactic acid on muscle cells and subsequent repayment of the oxygen debt. • State that anaerobic respiration in plants is irreversible and results in the production of ethanol and carbon dioxide
Anaerobic Respiration • Partial breakdown of glucose in the absence of oxygen • Glycolysis occurs as normal • 2ATP are produced • Pyruvic acid then gets converted into • Lactic acid in animals • Carbon dioxide and ethanol in plants and yeast (this is irreversible)
Anaerobic Respiration in animals • In muscles cells, lactic acid is formed during anaerobic respiration • A build up of lactic acid reduces the efficiency of muscles leading to muscle fatigue • Oxygen debt • is the oxygen that needs to be repaid during a rest period • Lactic acid is converted to pyruvic acid and respired aerobically
Anaerobic Respiration in plants and yeast • When oxygen is absent plants and yeast respire anaerobically • Carbon dioxide is lost from each molecule of pyruvic acid • Ethanol is formed • This is irreversible
Learning Objectives • Describe an experiment, including a labelled diagram of the apparatus, to investigate anaerobic respiration in yeast and say what happens.
