Energy (chapter 6)

1. Energy(chapter 6)

2. Metabolism the chemical processes occurring within a living cell or organism that allow it to get and use energy. anabolic (building up or synthetic) catabolic (tearing down or degradative)

4. Anaerobic metabolism occurs without oxygen

5. Aerobic metabolism requires free oxygen (which functions as the final electron acceptor during the generation of ATP).

6. Metabolic pathways 1. Substrates enter the reaction 2. End products remain after the reaction 3. In some cases intermediates are formed

7. Enzymes • speed up reactions that would normally occur • are not used up in the reaction • work (usually) for both the forward and reverse reactions • are specific a property that is based on the shape of the enzyme and thus activity is sensitive to temperature, pH, and amount of the substrate (lock and key mechanism).

10. Energy - the ability to do work Types include: 1. Kinetic - energy that is associated with motion 2. Potential - energy that is stored as is available for use. Chemical potential energy is stored in the bond between atoms of a molecule or compound. 3. Thermal- heat energy

12. LAWS OF THERMODYNAMICS

13. The First Law of Thermodynamics states that energy can neither by created or destroyed but it can change from one form to another The Second Law of Thermodynamics states that during transformations, some or all of the energy is spontaneously converted from more ordered forms to less ordered forms (thus entropy or disorder increases).

14. Energy Transfer

15. Entropy

16. The ultimate source of energy for life on Earth is the Sun. Energy transfer is not complete (most is lost as heat remember entropy increases) from one tropic (feeding) level to another. Thus energy is a limiting resource

17. Energy flow

19. Most metabolic reactions are reversible and tend to run spontaneously toward chemical equilibrium.Photosynthesis and respiration are two important and necessary processes for energy conversion.

20. Oxidation-Reduction Reactions involve the transfer of one or more electrons from a donor molecule to an acceptor molecule. 1. The donor molecule is oxidized. 2. The acceptor molecule is reduced. 3. Photosynthesis and respiration consist of these types of reactions.

22. ATP (adenosine triphosphate) the universal energy currency of all cells energy is stored within the bonds of this energy intermediate (ADP + Pi ATP) The formation of ATP occurs by a process known as phosphorylation (oxidative or substrate-level)

25. Respiration and Fermentation (Chapter 7)

26. Aerobic Respiration • Occurs in the presence of Oxygen • Oxygen acts as the final electron acceptor • The cpe in glucose is transferred into cpe in ATP • The glucose is dismantled during the steps of aerobic respiration: glycolysis, prep for the Kreb’s cycle, Kreb’s cycle, and ETS • Carbon and oxygen are lost as CO2 • The hydrogens are used in the ETS for ATP formation

28. Prep for the Kreb’s cycle

29. Kreb’s cycle

30. Electron Transport System

31. Fermentation

32. Photosynthesis The ultimate source of biological energy - the Sun

33. Plants, some protists, and some prokaryotes capture sunlight energy with photosynthetic pigments Chlorophyll which is found in chloroplasts is the most common pigment. It appears green because it absorbs light of colors other than green and allows green light to be reflected and thus detected by other organisms. There are also accessory photosynthetic pigments that make plants appear yellow and orange. The primary photosynthetic organs of plants are leaves ( know thylakoids, stroma, granuum, and inner and outer membranes)

36. Chlorophyll

37. Leaf structure

38. Plant cell

39. Chloroplast

40. Thylakoid

41. Photosynthesis: 12H2O +6CO2 sunlight energy> 6O2 +C6H12O6 + 6H2O

42. Light dependent reactions Light absorption. Photochemical reactions involve the trapping of light. Light energy excites pigment molecules and causes an electron to be freed which begins moving through an ETS. There are two photosystems [Photosystem I (with chlorophyll a absorbing lightwaves of 700 most efficiently; P700) and Photosystem II (also with chlorophyll a but absorbing lightwaves of 680 most efficiently; P680)] that are involved in capturing the energy and the beginning of electron transfer.

43. Electron transfer. The electron that is excited in Photosystem I is sent along the ETS to NADP+ and as another electron is passed to NADP+, the latter is reduced to NADPH (a coenzyme and energy intermediate) which carries electrons. Now light energy absorbed by Photosystem II is transferred into an electron thus exciting it and causing it to be sent to P700 (of Photosystem I) which can now absorb more light energy because of the replaced electron (note that Photosystem II has electrons replaced from split water molecules which also results in the formation of O2).

44. Light Independent Reactions • Chemiosmotic synthesis of ATP. This is the final phase of energy capture and involves the movement of the hydrogen ions along a series of membrane proteins with the release of energy and finally the synthesis of ATP from ADP. • Carbon fixation • 1. Carbon fixation occurs when a gas (CO2) is incorporated into a solid (e.g., a carbohydrate) • 2. During energy capture the energy and the hydrogen needed for carbon fixation are required. • 3. Carbon fixation involving atmospheric CO2 occurs during the reactions of the Calvin-Benson Cycle