Background knowledge

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Andrew Colin Manning
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1 Background knowledge This is the required background knowledge: State three uses of energy in living things Give an example of an energy conversion in a living organism State that fats and oils contain more energy per gram than carbohydrates State that oxygen is required for aerobic respiration State the word equation for aerobic respiration State that CO 2 is a product of aerobic respiration State that heat may be produced by respiration Describe anaerobic respiration and compare it with aerobic respiration Explain the working of a simple respirometer.

2 Learning outcomes energy release To understand the importance of ATP as a means of transferring chemical energy To state the structure of ATP To describe the production of ATP To describe the role of ATP in cell processes To explain the terms oxidation and reduction

3 Effect of ATP on muscle fibres This experiment shows that the energy for muscle contraction comes from ATP

4 Structure of ATP Adenosine triphosphate (ATP) Adenosine Three phosphate groups Diagram of ATP

5 ATP a high energy molecule continually being hydrolysed and resynthesised.

6 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.

7 Transfer of chemical energy by ATP

8 Role of ATP ATP is the energy source for: Muscle contraction Cell division Building up (synthesis) of proteins Transmission of nerve impulses Active transport

9 Think!! Explain why ATP is known as the universal energy currency.

10 Metabolism Metabolism All reactions that take place within the organism Anabolism Build up of larger, more complex molecules from smaller, simpler ones Catabolism Breakdown of complex molecules into smaller, simpler ones Releases energy

11 Redox Reactions Oxidation Loss of electrons Loss of hydrogen atoms Reduction Gain of electrons Gain hydrogen atoms OIL RIG If one substrate becomes oxidised another becomes reduced.

12 Oxidation and Reduction Oxidation Hydrogen removed Energy released te reduced Substrate ox Reduction Hydrogen added Energy gained

13 Testing your progress Energy is defined as the ability to do. The energy of motion is known as energy, whereas energy is stored energy. Living organisms need energy for many reasons reactions in which simple molecules are built up into complex ones The movement of material by against a concentration gradient.

14 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.

15 ERQ 10 marks Discuss the role of ATP in living matter

16 Chemistry of Respiration Chapter 4 Higher Biology Unit 1: Cells

17 Respiration The complete oxidation of glucose during aerobic respiration takes place in three stages: Glycolysis Krebs Cycle Cytochrome system

18 Hydrogen acceptor and carrier Hydrogen release from respiratory substrate is temporarily bound to a coenzyme which acts as a hydrogen acceptor NAD = coenzyme NADH 2 = reduced coenzyme

19 Glycolysis Oxidation of Glucose (6 carbon) to two molecules of 3-carbon pyruvic acid. Occurs in cytoplasm Net gain of 2 ATP molecules. Hydrogen is released and combines with NAD to form NADH 2 oxygen is not required.

20 Glycolysis Glucose (6C) 2 x Pyruvic acid (3C)

21 Investigating dehydrogenase enzymes in yeast As glucose is oxidised, hydrogen is released The release of hydrogen is called dehydrogenation, this controlled by dehydrogenase enzymes. Resazurin dye changes from blue to colourless as it is reduced.

22 Investigating the activity of enzymes in aerobic respiration Set up the three test tubes as shown below. 10ml glucose 10ml yeast 5 ml dye

23 Investigating the activity of enzymes in aerobic respiration Shake tubes vigorously for 20 seconds, and place in a water bath set at 37 o C. Leave for a few minutes and observe what happens Draw a diagram of your results Can you explain your results.

26 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.

27 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.

28 Aerobic Respiration Kreb s cycle Occurs in the matrix of mitochondria Cytochrome system Across the inner mitochondrial membrane

29 Structure of Mitochondria Mitochondria have a double plasma membrane surrounding a fluid filled matrix The inner mitochondrial membrane is folded into cristae which provide a large surface area for the attachment of stalked particles.

30 Fate of pyruvic acid Molecules of pyruvic acid enter the cells mitochondria. Mitochondria are sausage shaped organelles surrounded by a double plasma membrane. The inner membrane is folded into cristae, provide a large surface area for the stalked particles on which ATP is produced.

31 Fate of pyruvic acid Pyruvic acid diffuses into the matrix of the mitochondria pyruvic acid is converted into 2C acetyl coenzyme A (Acetyl CoA), Hydrogen is released and combines with NAD Carbon dioxide is released Enzymes that control the release of CO 2 are called decarboxylases.

32 Kreb s Cycle Acetyl CoA (2C) combines with a 4 carbon compound to form citric acid (6C). Citric acid is coverted back into the 4 carbon compound by decarboxylation (removal of CO 2 ) and dehydrogenation. Enzymes involved in these steps are dehydrogenases and decarboxylases. Hydrogen combines with NAD to form NADH 2.

33 Cytochrome System NADH 2 (reduced coenzyme) transfers hydrogen to a chain of hydrogen carriers known as Cytochrome system. Each carrier molecule is alternately reduced and oxidised. The hydrogen from each NADH 2 releases energy to form 3 ATP molecules from ADP and Pi. This process is known as oxidative phosphorylation. Oxygen is the final hydrogen acceptor to form water (controlled by cytochrome oxidase)

34 Respiratory Substrates Fats and proteins can also be used as respiratory substrates

35 Respiratory substrates Glycogen or starch Protein Amino Acids Glucose Pyruvate Acetylcoenzyme A Lipid fatty Acids Krebs cycle

36 Anaerobic Respiration Partial breakdown of glucose If oxygen absent only glycolysis can occur Glucose is broken down to two molecules of pyruvic acid, with a net yield of 2 ATP molecules.

37 Anaerobic respiration in plants (and yeast) Glucose (6C) pyruvic acid (3C) ethanol (2C) + CO 2

38 Anaerobic respiration in animals Glucose pyruvic acid lactic acid During lactic acid formation an oxygen debt is build up

39 Respirometer

40 Respirometer Sodium hydroxide absorbs all CO 2 from the air in the apparatus from the beginning. As the germinating seeds use oxygen and the pressure reduces in tube A so the manometer level nearest to the seeds rises. Any CO 2 excreted is absorbed by the sodium hydroxide solution.

41 Respirometer The syringe is used to return the manometer fluid levels to normal. The volume of oxygen used is calculated by measuring the volume of gas needed from the syringe to return the levels to the original values If water replaces the sodium hydroxide then amount of carbon dioxide given off can be measured

42 Simple Respirometers

43 Na-K pump 3 Na + leave the cell 2 K + enter the cell Potential difference is created across the neurone membrane for nerve impulses.

44 Key

45 1

46 3

47 Summary of the sodium potassium pump!

Higher Biology. Unit 2: Metabolism and Survival Topic 2: Respiration. Page 1 of 25

Higher Biology. Unit 2: Metabolism and Survival Topic 2: Respiration. Page 1 of 25 Higher Biology Unit 2: Metabolism and Survival Topic 2: Respiration Page 1 of 25 Sub Topic: Respiration I can state that: All living cells carry out respiration. ATP is the energy currency of the cell