5. Energy Capacity to perform work Two examples: 1. Kinetic energy 2. Potential energy
6. Kinetic Energy Energy in the process of doing work. Energyof motion. Examples: 1. Heat 2. Light energy SUN
7. Potential Energy Energythat matter occupies because of it’s location, arrangement, or position. Energyof position. Examples: 1. Water behind a dam 2. Chemical energy (gas) GAS
8. Thermodynamics The study of energytransformationsthat occur in a collection of matter. Two Laws: 1. First Law of Thermodynamics 2. Second Law of Thermodynamics
9. First Law of Thermodynamics Energy cannot be created or destroyed, but only converted to other forms. This means that the amount of energy in the universe is constant.
10. The First Law is not much help... What prevents a melting ice cube from spontaneously refreezing? Why doesn’t water flow uphill? Will L-alanine convert into D-alanine? The energy of the system and its surrounds won’t change. If it does not occur, what is driving force?
11. The Second Law helps resolve problem Only those events that result in a net increase in disorder will occur spontaneously
12. Second Law of Thermodynamics All energy transformations are inefficient because every reaction results in an increase in entropy and the loss of usable energy as heat. Entropy: the amount of disorder in a system.
13. What Can Cells Do with Energy? Cells use energy for: Chemical work Mechanical work Electrochemical work
14. What Can Cells Do with Energy? In some cells, as much as half of a cell’s energy output is used to transfer molecules across the cell membrane, a process called ‘active transport.’ Cell movements require energy and thousands of energy-hungry chemical reactions go on in every living cell, every second, every day. The kind of energy cells use is chemical bond energy, the shared electrons that holds atoms together in molecules
16. Endergonic Reactions Chemical reaction that requires a net input of energy. Example: 1. Photosynthesis 6CO2 + 6H2O C6H12O6 + 6O2 Light Energy SUN photons (glucose)
17. Exergonic Reactions Energy ATP (glucose) Chemical reactions that releases energy. Example: 1. Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O +
18. Cellular Metabolism Cells use thousands of different chemical reactions this is what is referred to by the term metabolism
19.
20. Anabolism, which uses energy from ATP to synthesize large molecules, including macromoleculesExergonicand Endergonic reactions
21. Anabolic Pathway light energy SUN (glucose) Metabolic reactions,which consume energy(endergonic), to build complicated molecules from simpler compounds. Example: 1. Photosynthesis 6CO2 + 6H2O C6H12O6 + 6O2
22. Catabolic Pathway energy ATP (glucose) Metabolic reactionswhich release energy(exergonic) by breaking downcomplex molecules in simpler compounds. Example: 1. Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O +
24. Answer: ATP is the universal energy carrier Most cell processes use the same energy source, the rechargeable energy carrier, adenosine-tri-phosphate ATP.
25. adenine phosphate group P P P ribose ATP Components 1. adenine: nitrogenous base 2. ribose: five carbon sugar 3. phosphate group: chain of three
27. Answer: The phosphate groups are held to each other by very high energy chemical bonds. Under certain conditions, the end phosphate can break away and the energy released to the energy-hungry reactions that keep a cell alive.
28. Answer: When the end phosphate is released, what is left is ADP, adenosine diphosphate. This change from tri to diis taking place constantly as ATPs circulate through cells. The recharging of ADP to ATP requires a huge energy investment, and that energy comes from the food we eat.
29. Adenosine triphosphate (ATP) P P P Hydrolysis (add water) + P P P Adenosine diphosphate (ADP) Hydrolysis of ATP ATP + H2OADP + P(exergonic)
30. Dehydration of ADP Adenosine triphosphate (ATP) P P P Dehydration synthesis (remove water) + P P P Adenosine diphosphate (ADP) ADP + P ATP + H2O (endergonic)
31. Cells Get Most of Their Energy by Oxidizing Carbohydrates, Lipids & Proteins
32. Carbohydrates as energy sources The storage sugar, glycogen is broken down to glucose when needed Almost all cells "burn"glucose (6 carbon sugar) to get energy Glucose is metabolized by glycolysis to pyruvate The pyruvate can be further metabolized to acetylCoA, which enters the Krebs cycle
33. Lipids as energy sources Storage fats, triglycerides, are broken down into fatty acids & glycerol Fatty acids are split into 2 carbon pieces, acetylCoA, which feed into the Krebs cycle
34. Proteins as energy sources Proteins are degraded to amino acids After the amino group is removed different amino acids feed into both glycolysis and the Krebs cycle The nitrogen from the amino group is eliminated as urea
35. Energy Releasing Reactions ATP Forms Energy Requiring Reactions Cellular Work
36. To maintain your body at rest you need about 2000 Calories/day This is called the basal metabolic rate (BMR) You could get this much energy from 500 grams of sugar (2000 gm/4 cal/gm = 500 gm) or from 222 gm of fat (2000 gm/9 Cal/gm = 222 gm) In the American diet about 65% of our energy comes from sugar and 35% from fat
37. ATP: Main Energy Carrier ATP couples energy inputs and outputs ATP/ADP cycle regenerates ATP ATP energy output energy input ADP + Pi
38. How energy is extracted from food molecules and used to synthesize ATP is one of the great discoveries of modern biochemistry.
