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Energy for Living Systems
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  1. Energy for Living Systems

  2. Energy • Ability to do work   • Types of energy   Potential Energy   Energy of position   For living organisms, potential energy is stored in chemical bonds   Kinetic Energy  Energy of motion   Breaking of chemical bonds in various life processes.   Activation Energy   Energy necessary to trigger a chemical reaction   Lighted match held to a piece of paper

  3. Energy All living things require energy.   • Necessary for carrying out all life processes - building, repairing, growing, and reproducing.   • Energy comes from food (glucose)   Energy is stored in glucose bonds - potential energy   No organism can make energy - comes from the sun.   Law of Conservation of Energy - Energy can be neither created nor destroyed, but can only be changed from one form to another.  

  4. Energy • Organisms divided into 2 groups according to the way they get their food.   Autotrophs – organisms that can combine inorganic molecules into organic molecules for use as food; make their own food   Heterotrophs - organisms that don't make their own food but depend directly on other organisms for food.  

  5. Energy Energy is not recycled, matter is recycled   • Energy available for use decreases with each transformation   • Some of the energy used to break bonds and some is lost as heat.   • New energy must be constantly supplied - must come from sunlight.   • Materials used in producing new molecules can be reused.  

  6. Energy Energy processes of living organisms   • Photosynthesis   Process in which carbon dioxide and water is used to form glucose.   Requires light energy from the sun.   Takes place in the presence of chlorophyll.   • Respiration   Process in which glucose molecule is broken down and chemical energy it contains is released.   Carbon dioxide and water released.   Performed by all cells - releases energy of food

  7. Adenosine Triphosphate • Usable energy from by one reaction may be stored by another molecule and used in a later reaction.   • Many times the storage molecule for the released energy is ATP.  

  8. Adenosine Triphosphate Composed of 3 parts   • Adenine - a nitrogen base   • Ribose - a 5-carbon sugar   • Three (3) phosphate groups   Adenine joins with ribose to form adenosine Phosphate groups attach in sequence to adenosine   • Adenosine monophosphate - AMP - 1 phosphate group   • Adenosine diphosphate - ADP - 2 phosphate groups   • Adenosine triphosphate - ATP - 3 phosphate groups

  9. Adenosine Triphosphate

  10. Adenosine Triphosphate • High energy bonds form between the phosphate groups - indicated by a wavy line (~)   Requires a great deal of energy to form bond. Energy is released when bond is broken.   ATP - A - P ~ P ~ P   ADP - A - P ~ P  

  11. Adenosine Triphosphate Normally reaction is cyclic - moves between ADP and ATP Controls the cell's production through cycle of energy storage and release.   ADP + P + energy ---> ATP - energy is stored   ATP ---> ADP + P + energy - energy is released   Normally cell does not use ADP as energy source; ADP not converted to AMP

  12. Photosynthesis Process by which green plants convert the sun's light energy into chemical energy stored as food in the form of glucose.   • Photo - means "light"   • Synthesis - means "to build a complex substance from simple substances"  

  13. Photosynthesis Raw materials - the reactants of the reaction • Carbon dioxide - CO2 • Water - H2O   • Light energy

  14. Photosynthesis Products • Glucose - C6H12O6 • Oxygen - O2 • Water - H2O

  15. Photosynthesis Chlorophyll is necessary Acts as a catalyst - causes the reaction to move forward. • Pigment in green plants that gives them their color   • Primary light absorbing pigment of green plants.  

  16. Photosynthesis Represented by the following reaction:   chlorophyll   6 CO2 + 12 H2O + light -----------> C6H12O6 + 6 O2 + 6 H2O  

  17. Photosynthesis Process is series of reactions that change reactants to the products - divided into 2 main reactions   • Light Reactions - require light energy   • Dark Reactions - Do not require light energy

  18. Light Sunlight is white light; mixture of different wavelengths of light   • Each wavelength of light has a characteristic color -   • Colors that make up white light can be separated by prism to produce the visible part of the spectrum - ROYGBIV – Red, Orange, Yellow, Green, Blue, Indigo, Violet   Shorter the wavelength of light, the more energy it has Blue – shorter wavelengths; more energy Red – longer wavelengths; less energy

  19. Light

  20. Light Objects appear to be a certain color because they transmit or reflect light of that color.   • Colors absorbed by an object are not seen   • Color of object is the wavelength of light that is reflected or transmitted by the object.   • Plants appear green because they reflect green light and absorb other colors of light.  

  21. Light Absorption by Green Plants

  22. Plant Pigments Primary pigment in plants that absorbs light energy is chlorophyll   • Green in color - reflects green wavelengths   • Absorbs mainly red and blue wavelengths of light   • Act as catalysts to speed the reaction of photosynthesis.   • Types   Chlorophyll a Chlorophyll b Chlorophyll c Chlorophyll d Bacteriochlorophyll  

  23. Plant Pigments Accessory Pigments - may be used to transfer some energy to chlorophyll • Types Carotenoids - yellow, brown and orange pigments of plants Carotene Xanthophyll Phycobilins - accessory pigments of red algae and blue-green bacteria • Not normally visible in tree leaves - masked by chlorophyll; appear when chlorophyll production ceases  

  24. Chloroplasts Organelle in plant cells where photosynthesis occurs.   • Contain the Chlorophyll pigment.   • Structure   Grana - tiny stacked structures in the chloroplasts   Contains the chlorophyll   Also contains the accessory pigments.   Site of light reactions   Stroma - protein-rich solution around the grana   Site of dark reaction  

  25. Chloroplasts

  26. Light Reactions • Chlorophyll traps the light energy   Causes chlorophyll molecules to become energized; electrons released from molecule   Two different photosystems active in photosynthesis   Photosystem I   Photosystem II   • Water molecules are split and oxygen is released.   • Energy is stored in ATP and NADPH2 (electron acceptor)   Both used in the Dark Reactions   Supply the energy for the Dark Reactions  

  27. Light Reactions

  28. Dark Reactions Light is not required; energy comes from ATP and NADPH2; Called the Calvin cycle • Carbon dioxide bonds to 5-carbon sugar called ribulose diphosphate, RuDP - forms unstable 6-carbon compound • 6-carbon compound immediately breaks down into two 3-carbon molecule of phosphoglyceric acid, PGA. • Each PGA reacts with hydrogen atoms in NADPH2 to produce 3-carbon molecule of phosphoglyceraldehyde, PGAL, water reformed • Two molecules of PGAL combine to produce glucose molecule. • Some PGAL used to reform RuDP.

  29. Dark Reactions

  30. Respiration Process in which cells take energy, stored in chemical bonds of food and incorporates it into chemical bonds of ATP • Occurs in the mitochondria   • Series of chemical reactions  

  31. Respiration Reactants • Glucose - C6H12O6 • Oxygen - O2

  32. Respiration Products • Carbon dioxide - CO2 • Water - H2O   • ATP - adenosine triphosphate  

  33. Respiration Overall equation of cellular respiration (aerobic) enzymes C6H12O6 + 6 O2 ----------> 6 CO2 + 6 H2O + 36 ATP

  34. Respiration Types • Anaerobic Respiration - doesn't require oxygen   • Aerobic Respiration - requires oxygen  

  35. Stages of Aerobic Respiration • Glycolysis - Anaerobic • Kreb’s (Citric Acid)Cycle - Aerobic • Electron Transport Chain - Aerobic

  36. Glycolysis • First stage of respiration; occurs outside the mitochondria • Does not require oxygen. • Glucose breaks down into two 3-carbon molecules of pyruvic acid • Requires 2 molecules of ATP to supply activation energy • Produces 4 molecules of ATP; net gain of 2 ATP's • Pyruvic acid can go in two directions - depends on of organism type and oxygen availability Aerobic respiration - oxygen required Anaerobic respiration - oxygen not needed

  37. Glycolysis

  38. Transition to Aerobic Respiration

  39. Aerobic Phases Divided into two major reactions   • Citric acid cycle (Krebs Cycle)   • Electron Transport Chain

  40. Citric Acid Cycle • Pyruvic acid loses a carbon dioxide forms 2-carbon molecule that enters cycle.   • Process takes place in the mitochondria   • Hydrogen atoms released during the cycle - will carry electrons to the next reactions • 2 molecules of ATP are produced  

  41. Citric Acid Cycle

  42. Electron Transport Chain • Involves a series of electron acceptors   • Accepts electrons and H ions from NADH &FADH  • 24 hydrogen atoms produce 24 electrons and 24 hydrogen ions form 12 pairs of hydrogen ions and 12 pairs of electrons   • Near end of chain 12 molecules of hydrogen bond with 6 oxygen molecules to produce 12 molecules of water.   • 32 molecules of ATP produced  

  43. Electron Transport Chain

  44. Summary of ATP ProductionIn Aerobic Respiration • Glycolysis 2 ATP   • Citric Acid Cycle 2 ATP   • Electron Transport 32 ATP • Total 36 ATP  

  45. Anaerobic Repiration • Occurs when cell obtains energy from breakdown of food molecules in the absence of oxygen   • Also known as Fermentation • First step similar to aerobic respiration - glucose converted to pyruvic acid - glycolysis   • Types of Fermentation   Alcoholic Fermentation   Lactic Acid Fermentation

  46. Alcoholic Fermentation • Pyruvic acid is converted to ethyl alcohol • Most of the energy is still stored in the alcohol. • Summary equation: enzymes C6H12O6 ----------> 2 C2H5OH + 2 CO2 + 2 ATP • Industries that depend on alcoholic fermentation   Baking - carbon dioxide; makes bread rise.   Brewing - ethyl alcohol in alcoholic beverages

  47. Alcoholic Fermentation

  48. Lactic Acid Fermentation • Occurs in muscle tissue especially during heavy exercise   • Blood can't bring oxygen fast enough; lactic acid builds up causing soreness (cramps); muscles go into oxygen debt.   • Summary equation:   enzymes   C6H12O6 -----------> 2 CH3CHOHCOOH + 2 ATP  

  49. Lactic Acid Fermentation