Metabolism involves the chemical processes that take place in organisms. There are catabolic pathways that break down molecules and release energy, and anabolic pathways that use energy to build molecules. Energy exists in different forms like kinetic and potential energy, and transformations are governed by thermodynamics laws. Cellular respiration uses energy from food molecules and involves glycolysis, breakdown of pyruvic acid, the citric acid cycle, and the electron transport chain, requiring oxygen. Without oxygen, anaerobic respiration like lactic acid fermentation allows glycolysis to continue to produce ATP.

1. An Introduction To Metabolism

2. MetabolismThe totality of an organism’s chemical processes.Concerned with managing the material and energy resources of the cell.

4. Catabolic PathwaysPathways that break down complex molecules into smaller ones, releasing energy.Example: Respiration

5. Anabolic PathwaysPathways that consume energy, building complex molecules from smaller ones.Example: Photosynthesis

6. Energy Ability to do work.The ability to rearrange a collection of matter.Forms of energy:KineticPotentialActivation

7. Kinetic EnergyEnergy of action or motion.

8. Potential EnergyStored energy or the capacity to do work.

9. Activation EnergyEnergy needed to convert potential energy into kinetic energy.Activation EnergyPotential Energy

10. Energy TransformationGoverned by the Laws of Thermodynamics.

11. 1st Law of ThermodynamicsEnergy can be transferred and transformed, but it cannot be created or destroyed.Also known as the law of Conservation of Energy.

12. 2nd Law of ThermodynamicsEach energy transfer or transformation increases the entropy of the universe.

13. EntropyMeasure of disorder.

14. Free EnergyThe portion of a system's energy that can perform work.

15. Chemical Reactions Are the source of energy for living systems.

16. Cell - Types of WorkMechanical - muscle contractionsTransport - pumping across membranesChemical - making polymers

17. ATPAdenosine TriphosphateMade of: - Adenine (nitrogenous base) - Ribose (pentose sugar) - 3 phosphate groups

19. AdeninePhosphatesRibose

20. Key to ATPIs in the three phosphate groups.Negative charges repel each other and makes the phosphates unstable.

21. ATPWorks by energizing other molecules by transferring phosphate groups.

22. ATP vs FoodATP: Renewable energy resource.Unstable bondsFood:Long term energy storage Stable bonds

23. ATP Cycle

24. ATP in CellsA cell's ATP content is recycled every minute.Humans use close to their body weight in ATP daily.No ATP production equals quick death.

25. EnzymesBiological catalysts made of protein.Cause the rate of a chemical reaction to increase.

26. Chemical ReactionAB + CD AC + BDAB and CD are “reactants”AC and BD are “products”

27. EnzymesLower the activation energy for a chemical reaction to take place.

28. Enzyme TermsSubstrate - the material and enzyme works on.Enzyme names: Ex. Sucrase - ase name of an enzyme 1st part tells what the substrate is. (Sucrose)

29. Enzyme NameSome older known enzymes don't fit this naming pattern.Examples: pepsin, trypsin

30. Active SiteThe area of an enzyme that binds to the substrate.Structure is designed to fit the molecular shape of the substrate.Therefore, each enzyme is substrate specific.

32. Enzymes Usually specific to one substrate. Each chemical reaction in a cell requires its own enzyme.

33. Factors that Affect EnzymesEnvironmentCofactorsCoenzymesInhibitorsAllosteric Sites

34. EnvironmentFactors that change protein structure will affect an enzyme.Examples:pH shiftstemperaturesalt concentrations

35. Enzyme InhibitorsCompetitive - mimic the substrate and bind to the active site.Noncompetitive - bind to some other part of the enzyme.

37. Control of MetabolismIs necessary if life is to function.Controlled by switching enzyme activity "off" or "on” or separating the enzymes in time or space.

38. Process of Cellular Respiration

39. Process of Cellular RespirationThe process by which food molecules are broken down to release energy is respiration.Respiration that occurs in the presence of oxygen is called aerobic respiration.Respiration that occurs without oxygen is called anaerobic respiration.The energy payoff is much greater when molecules are broken down aerobically.

43. Glycolysis1st step of respirationGlycolysis is the breakdown of glucose (6-carbon molecule to pyruvic acid (3-carbon molecule).Glycolysis occurs in the cytoplasm and is anaerobic.Glycolosis produces hydrogen ions and electrons, which combine with carrier ions called NAD+ (nicotanamidedinucleotide) to form NADH.End product is 2 ATP’s

46. Breakdown of Pyruvic AcidThe 2nd step that takes place in respiration is the breakdown of pyruvic acid, and aerobic process.Pyruvic acid (3-carbon molecule) is changed to acetic acid (2-carbon molecule). The carbon that comes off makes CO2. Acetic acid combines with a substance called coenzyme A (CoA), forming acetyl-CoA.This process takes place in the mitochondria.

49. Citric Acid CycleThe 3rd step of aerobic respiration is the citric acid cycle.Acetyl-CoA combines with a 4-carbon molecule to form a 6-carbon molecule, citric acid. Citric acid is broken down 1st to a 5-carbon molecule and then to a 4-carbon molecule, releasing CO2 at each step.This cycle of chemical reactions produces more ATP and releases additional electrons.

52. Electron Transport ChainThe 4th part of aerobic respiration is the electron transport chain (ETC).The ETC is a series of molecules along which electrons are transferred, releasing energy.Carrier molecules bring the electrons released during glycolysis and the citric acid cycle to the ETC.

53. ETC (con’t)The molecules of the ETC are located on the inner membranes of the mitochondria.This is an aerobic process, because oxygen combines with two hydrogen ions to produce with water.

58. What happens if no oxygen is present?If the final electron acceptor, oxygen, is used up, the chain becomes jammed. The reactions of the ETC can’t take place without oxygen.

59. Anaerobic Respiration

60. Anaerobic Respiration If oxygen isn’t present, there’s no electron acceptor to accept the electrons at the end of the ETC.If this occurs, then NADH accumulates.Once all the NAD+ has been converted to NADH, the Krebs cycle and glycolysis both stop (both need NAD+ to accept electrons).

61. Once this happens, no new ATP is produced, and the cell soon dies. Cells have derived a method to escape dying – ANAEROBIC RESPIRATION.The main objective of anaerobic respiration is to replenish NAD+ so that glycolysis can proceed once again. It occurs in the cytoplasm right along with glycolysis.

62. There are two forms of anaerobic respiration:Alcoholic fermentationLactic acid fermentation

63. Alcoholic FermentationAlcoholic fermentation occurs in plants, fungi (yeast), and bacteria.There are 2 steps to alcoholic fermentation:The conversion of pyruvic acid to acetaldehyde1 CO2 and 1 acetaldehyde is producedThe conversion of acetaldehyde to ethanolNADH is used to drive the reaction, releasing NAD+

65. The goal of this reaction is not to produce ethanol, but it is to free the NAD+, which allows glycolysis to continue.The reward is 2 ATP from glycolysis for each 2 converted pyruvate. This is better than the alternative, which is 0 ATP.

66. Lactic Acid FermentationLactic acid can occur in some bacteria and plants, but it is mostly found in animals, including humans.Anytime your muscle cells require energy at a faster rate than it can be supplied by aerobic respiration, they begin to carry out lactic acid fermentation.

67. There is only one step in lactic acid fermentation:Now, NAD+ can be used for glycolysis.When O2 becomes available again, lactic acid can be broken down and its store of energy can be retrieved.Because O2 is required to do this, lactic acid fermentation creates what is often called an oxygen debt.

69. Lactic Acid FermentationUses only Glycolysis.An incomplete oxidation - energy is still left in the products (lactic acid). Does NOT require O2Produces ATP when O2 is not available.

71. Lactic Acid FermentationDone by human muscle cells under oxygen debt.Lactic Acid is a toxin and causes soreness and stiffness in muscles.

72. Fermentation - SummaryWay of using up NADH so Glycolysis can still run.Provides ATP to a cell even when O2 is absent.

74. Aerobic vs AnaerobicAerobic - Rs with O2Anaerobic - Rs without O2Aerobic - All three Rs steps.Anaerobic - Glycolysis only.