Energy-and-respiration in humans and plants.pptx

Biology

1. Energy and Respiration A Level – 9700 Biology

2. Need for Energy Anabolic Reactions

3. ATP: universal energy currency ATP is a nucleotide ; it has : five-carbon sugar ( hence a pentose ): ribose a nitrogen-containing ring structure called a base: adenine . phosphate groups .

4. When the third phosphate group of ATP is removed by hydrolysis , a substantial amount of free energy is released . Obs : The exact amount depends on the conditions , but we shall use a value of 7.3 kcal per mole. ATP + H 2 O → ADP + Pi

5. ATP is synthesised by transfer of phosphate in substrate-linked reactions chemiosmosis in membranes of mitochondria and chloroplasts

6. A Chemistry reminder… REDOX   REACTION ...        e- passed from one molecule to another    OXIDATION  =    removal of electron &/or proton from food covalent bond    REDUCTION   =   gaining electron &/or proton; adds an electron to an acceptor molecule

7. Aerobic Respiration: C 6 H 12 O 6 + 6 O 2 → 6 CO 2 + 6 H 2 O Is it endo or exothermic? What could happen if this reaction happened as a single event, in cells?

8. The main “actors” of respiration

9. Glycolysis Glycolysis is the phosphorylation of glucose and the subsequent splitting of fructose 1,6-bisphosphate (6C) into two triose phosphate molecules (3C), which are then further oxidised to pyruvate (3C) , with the production of ATP and reduced NAD . If oxygen is available, it enters mitochondria.

10. Link Reaction

11. Krebs Cycle Obs. - Guanosine triphospate (GTP) – similar to ATP; it gives Pi to ADP Reduction of NAD + Reduction of FAD + CO 2 formation

12. Krebs Cycle: main highlights Oxaloacetate (4C) acts as an acceptor of the 2C fragment from acetyl coenzyme A to form citrate (6C), which is converted back to oxaloacetate in a series of small reactions. Reactions in the Krebs cycle involve decarboxylation and dehydrogenation and the reduction of the coenzymes NAD and FAD.

13. Production of ATP during respiration : Substrate level – phosphorylation using Pi from the molecules involved in the reactions Oxidative phosphorylation – electron transport chain Note: each reduced NAD forms 2.5 ATP; each reduced FAD forms 1.5

14. Electron Transport Chain (ETC) is a chain of reactions that converts redox energy available from oxidation of NADH and FADH 2 , into proton-motive force which is used to synthesize ATP through conformational changes in the ATP synthase complex through a process called  oxidative phosphorylation . NAD and FAD - hydrogen carriers; to the inner mitochondrial membrane.

15. Oxidative phosphorylation: main highlights hydrogen atoms split into protons and energetic electrons energetic electrons release energy as they pass through the electron transport chain (details of carriers are not expected) the released energy is used to transfer protons across the inner mitochondrial membrane protons return to the mitochondrial matrix by facilitated diffusion through ATP synthase, providing energy for ATP synthesis (details of ATP synthase are not expected) oxygen acts as the final electron acceptor to form water

16. Glycolysis – 2 ATP 2 NADH  4 ATP Acetil CoA – 2 NADH  6ATP Krebs Cycle – 2 ATP 6 NADH  18 ATP 2 FADH2  4 ATP TOTAL: 36 ATP 1 Reduced NAD – 2 ATP 1 Reduced FAD – 1.5 ATP

17. Mitochondrion Describe the relationship between the structure and function of mitochondria using diagrams and electron micrographs.

18. yeast mammals

19. Ethanol pathway conversion of  pyruvate  to  ethanol  in alcoholic fermentation, e.g. by yeast

20. Lactate pathway conversion of  pyruvate  to  lactate  (lactic acid), e.g. by mammalian muscle.

21. Rice is adapted to grow with its roots submerged in water

22. How rice is adapted to grow with its roots submerged in water development of aerenchyma in roots; ethanol fermentation in roots and faster growth of stems - these plants produce more ethanol dehydrogenase which breaks down ethanol (toxic substance).

23. Respiratory Substrates Respiratory Substrate Energy released (kJ g -1 ) Carbohydrate 16 Lipid 39 Protein 17 Why do different respiratory substrates release different amounts of energy?

24. Respiratory Quotient (RQ) RQ = volume ( or number of moles) of CO 2 given out volume ( or number of moles) of O 2 taken in Respiratory Substrate RQ Carbohydrate 1.0 Lipid 0.7 Protein 0.9

25. Respirometers

26. Calculate O 2 consuption Use soda lime to absorb CO 2 Then observe the volume of liquid displaced . Calculate the volume of liquid displaced ( length x ∏r 2 ) – this is the volume of consumed O 2 (x cm 3 min -1 )

27. Calculate CO 2 released Remove soda lime and set up the respirometer keep all the other variables constant If the volume of air does not change (y): Vol CO 2 = Vol O 2 RQ=1 If the volume of air increases (y): Vol CO 2 > Vol O 2 If the volume of air decreases (z): Vol CO 2 < Vol O 2 RQ = vol O 2 - z vol O 2 Then you just have to calculate the RQ RQ = vol O 2 + y vol O 2

28. Plan an experiment in order to measure the RQ of germinating seeds . Please include details about : Dependent variable Independent variables Standardised variables Material Method

29. Measuring the rate of respiration using redox indicators DCPIP Methylene blue blue colourless blue colourless

30. Past Paper Practice 1 – (a) All cells need ATP for energy-requiring processes in the body.

31. Past Paper Practice: Mark scheme 1 -

32. Self Evaluation Checklist I can… Needs more work Needs teacher’s guidance Got it! outline the need for energy in living organisms describe the features of ATP that make it suitable as the universal energy currency state how ATP is synthesized (substrate linked reactions and chemiosmosis) describe glycolysis, the link reaction, the Krebs cycle, oxidative phosphorylation outline the roles of NAD, FAD, coenzyme A describe the relationship between the structure and function of mitochondria outline respiration in anaerobic conditions in mammals (lactate fermentation) and in yeast cells (ethanol fermentation) explain why the energy yield from respiration in aerobic conditions is much greater than the energy yield from respiration in anaerobic conditions explain how rice is adapted to grow with its roots submerged in water explain the relative energy values of carbohydrates, lipids and proteins as respiratory substrates define the respiratory quotient (RQ) calculate RQ values of different respiratory substrates from equations for respiration describe and carry out investigations, using simple respirometers describe and carry out investigations using redox indicators