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Chapter 4

Chapter 4. Cellular Processes. Cellular Energy. Cells Use Energy. Maintain homeostasis To perform all cellular processes To make energy-storing molecules When they stop using energy, they are dead. Energy Relationships.

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Chapter 4

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  1. Chapter 4 Cellular Processes

  2. Cellular Energy

  3. Cells Use Energy • Maintain homeostasis • To perform all cellular processes • To make energy-storing molecules When they stop using energy, they are dead

  4. Energy Relationships • Energy is a one time commodity – every time it is used some escapes and becomes unusable • More energy is needed to build an energy-storing molecule than is stored in the molecule.

  5. How do organisms obtain their food? • Autotrophs • “auto” = self • “troph” = nourishment • Heterotrophs • “hetero” = others

  6. Autotrophs • Make their own food • They capture light energy and convert it into sugar • Ex: plants, algae, and some bacteria.

  7. Heterotrophs • Depend on other organisms for their energy source • Ex: humans, animals, fungi, and most bacteria.

  8. ATP – Adenosine Triphosphate • Most energy sources (fats, carbohydrates) are large and must be broken down into smaller units (sugar – glucose) • ATP stores energy in a usable form for all living organisms • The bonds between the three phosphate groups are unstable high-energy covalent bonds

  9. ATP

  10. Energy Production • When the bonds are broken, a large amount of energy is released (an exothermic reaction) and is available for use in any cellular function that requiresenergy (an endothermic reaction). • ATP  ADP + P + Energy

  11. Adenosine 1 2 3 Phosphates ATPadenosinetriphosphate

  12. ATP Production • ADP and P can be reused to form ATP with the proper enzymes and adequate supply of energy • ADP + P + Energy  ATP

  13. Adenosine Energy 1 2 Phosphates ADPadenosinediphosphate

  14. ATP-ADP Cycle

  15. 4A – 2 PHOTOSYNTHESIS The process of taking light energy and converting it into stored chemical energy

  16. The sunis the source of energy for living things!

  17. Photosynthesis Reaction • Reaction converting light energy into stored chemical energy 6 CO2 + 6 H2O + light energyC6H12O6 + 6 O2 (Carbon (water) (glucose)(oxygen) dioxide)

  18. Green plants and algae perform this energy transformation in large enough quantities to provide stored chemical energy for most living organisms

  19. Photosynthesis is important because… 1) It converts solar energy into usable chemical energy 2) It produces oxygen

  20. Light Absorption • Different wavelengths of visible light are seen by the human eye as different colors. • The color we see is actually the color reflected.

  21. Chlorophyll a • Primary catalyst of photosynthesis • Green pigment in the grana of chloroplasts • Becomes activated by lightenergy

  22. Chlorophyll a • Chlorophyll a is a blue green pigment – it reflects the blues and greens and absorbs the reds and violets

  23. Chlorophyll b • Is a yellow green pigment – that absorbs some of the same pigments as chlorophyll a as well as some of the blues not absorbed by chlorophyll a and reflects some of the yellow greens that chlorophyll a absorbs

  24. Absorption Spectrum

  25. The Process of Photosynthesis The Light-Dependent Phase • Requires sunlight and water • Occurs in the grana of the chloroplast • Produces: Oxygen , ATP and NADPH(electron carrier that stores energy for later use)

  26. Photosynthesis: The Process Light-Independent Phase • Light is NOT required • Occurs in the stroma of the chloroplast • Also called:“Dark phase,” “synthetic phase,” “Calvin cycle,” “carbon fixation cycle” • Is dependent upon the products of the light phase (ATP and NADPH) and CO2from the atmosphere

  27. Conditions for Photosynthesis • Proper wavelengths of light • Sufficient absorption of carbon dioxide • Proper temperatures • Proper amount of water

  28. Chemosynthesis: Other autotrophs • A few bacteria use inorganic chemicals (i.e. ammonia or sulfur) to obtain energy • Ex. Symbiotic bacteria in tubeworms in hydrothermal vents convert chemical energy in sulfur into usable energy

  29. Cellular Respiration

  30. Cellular Respiration The breakdown of a food substance into usable cellular energy in the form of ATP

  31. Summary Kinetic energy(sun) stored chemical energy(C6H12O6) =photosynthesis

  32. ready-to-use chemical energy() Summary stored chemical energy(C6H12O6) =cellular respiration

  33. Cellular Respiration • Aerobic • Requires oxygen, is the opposite of photosynthesis, combines oxygen with sugar to release energy, carbon dioxide and water • Anaerobic • Does not require oxygen

  34. Aerobic Cellular Respiration

  35. Aerobic Cellular Respiration C6H12O6+ O2 H2O + CO2+ energy (ATP)

  36. The Process of Cellular Respiration • Glycolysis • Citric Acid Cycle (Krebs Cycle) • Hydrogen and Electron Transport System

  37. Glycolysis • All types of cellular respiration begin with glycolysis. • Does not require oxygen • Occurs in the cytoplasm

  38. Glycolysis • Breakdown of glucose into pyruvic acid, H+, and electrons • 2 net ATP

  39. Aerobic Cellular Respiration The products from glycolysis are sent to the mitochondria.

  40. Aerobic Cellular Respiration 1. Citric Acid Cycle (Krebs Cycle) = Pyruvic acid is broken down into citric acid. • Pyruvic acid  Acetyl CoA • Acetyl CoA  Citric acid

  41. Aerobic Cellular Respiration 2. Hydrogen and Electron Transport System • Occurs in the cristae of the mitochondria

  42. Aerobic Cellular Respiration • 2. Hydrogen and Electron Transport System • At the end of the chain, H combines with oxygen to form water. • Oxygen is the rate-limiting factor.

  43. Energy Facts • Aerobic Cellular Respiration results in the net gain of 36 ATP molecules.

  44. Glycolysis Citric Acid Cycle H+ & e- transport system Location Cytoplasm Mitochondria(matrix) Mitochondria (cristae) Reactants Glucose Pyruvic acid H+; e- Products ATP; water Pyruvic acid; H+; e- CO2; H+; e- ATP 2 net 2 net 32

  45. Anaerobic Respiration • Breakdown of food (glucose) without oxygen • “Cellular fermentation”

  46. 2 Types of Fermentation 1) Alcoholic fermentation – pyruvic acid + NADH  alcohol + CO2 + NAD+ Ex: yeast 2) Lactic Acid fermentation – pyruvic acid + NADH  lactic acid + NAD+ Ex: produced in your muscles during rapid exercise when the body cannot supply enough oxygen to the tissue

  47. Energy Facts • Cellular fermentation supplies no ATP energy beyond glycolysis.

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