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Energy and Enzymes

  1. All of the chemical reactions that occur within an organism that are necessary for the maintenance of life
    Metabolism
  2. Catabolic reactions
    Breakdown complex molecules and release energy
  3. Anabolic reactions
    Use energy to build complex molecules
  4. The capacity to do work
    Energy
  5. Energy of motion
    Kinetic Energy
  6. Kinetic energy associated with random movement of molecules
    Heat
  7. Energy stored in position
    Potential energy
  8. Potential energy available for release in a chemical reaction (i.e. the breakdown of food)
    Chemical Energy
  9. The study of the energy transformations that occur in a collection of matter
    Thermodynamics
  10. 1st Law of Thermodynamics
    • Energy can be transferred/transformed but not destroyed
    • Principle of conservation of energy
  11. 2nd Law of Thermodynamics
    • Every energy transformation or transfer increases the entropy of the universe
    • Entropy= measure of disorder/randomness
  12. Does the increasing complexity seen in biological systems contradict the 2nd law?
    We take energy from the environment, but we also release it back.
  13. How do living organisms create macromolecules, cells, and tissues?
    They create order locally, but energy transformations generate waste heat that increases the entropy of the universe
  14. Portion of a system's energy that can perform work
    Free energy
  15. What state is the reaction if delta G (free energy) is negative?
    • The reaction is spontaneous (energetically favorable)
    • Loss of free energy, final state is more stable
    • Exergonic Reaction (Energy is Exiting)
  16. What kind of a reaction is a catabolic reaction
    Exergonic
  17. What state is the reaction if delta G (free energy is positive?
    • The reaction requires energy input
    • Endergonic reaction (Energy is ENtering)
  18. What kind of a reaction is an anabolic reaction?
    Endergonic
  19. -State of maximum stability
    -Lowest possible G value
    • Equilibrium
    • Any change will require energy therefore systems are never spontaneously move away from equilibrium (can do no work)
  20. Are most chemical reactions in cells at equilibrium?
    No
  21. How is work done in a cell?
    • Energy Coupling
    • Use of exergonic rxns to drive endergonic rxns
    • The exergonic gives off energy
  22. Redox Reactions
    • Transfer of electrons releases energy stored in organic molecules
    • Oxidation-reduction reaction
  23. Oxidation
    Loss of electrons (LEO)
  24. Reduction
    • Gain electrons (GER)
    • Adding electrons REDUCES the amount of positive charge of an atom
  25. Adenosine triphosphate (ATP)
    Bonds between phosphate groups can be broken by hydrolysis
  26. How is ATP broken up
    • It is an exergonic reaction 
    • ATP+H2O -> ADP + Pi
    • deltaG= -7.3 kcal/mol
    • The products have less potential energy than reactants
  27. Regeneration of ATP
    • The reverse reaction must be endergonic
    • ADP + Pi -> ATP + H2O
    • DeltaG= 7.3 kcal/mol
  28. What provides necessary energy for cellular respiration and light energy
    Exergonic reactions
  29. Enzymes
    • Proteins (mostly) which act as catalysts and speed up reactions
    • Not consumed by the reactions
    • Act by lowering the activation energy (Ea)
  30. Substrate
    Reactant acted on by the enzyme
  31. Is the reaction catalyzed by a particular enzyme very specific
    Yes
  32. Active site
    • Region that actually binds the substrate
    • Only specific substrate can fit in active
  33. Induced Fit
    • Binding of substrate causes the enzyme to slighly change shape
    • Brings chemical groups of active site into optimal position to catalyze reactions
  34. What do starting molecules have to be in order for a reaction to occur
    They have to be contorted into an unstable form for reactions to occur
  35. Activation energy
    The energy that reactants absorb from their surroundings to reach a state where bonds can change
  36. How do enzymes catalyze reactions
    By lowering activation energy so it takes less to go through the reaction
  37. How do enzymes lower activation energy?
    • Act as a docking station to bring reactants together in proper orientation
    • Stretch reactants toward transition-state form, stressing and bending chemical bonds
    • By providing a microenvironment more favorable to a particular reaction
    • Participate directly in the chemical rxn
  38. Steps on how substrates are converted using enzymes
    • Substrates enter active site
    • They are held by weak interactions
    • Active site can lower activation energy and speed up a reaction
    • They are converted to products and then the products are released
    • Active site is available for two new substrate molecules
  39. What helps enzymes within the cell
    • Cofactors: inorganic ions (i.e. Fe, Zn, Mg)
    • Coenzymes: organic molecules (i.e. Nad, B vitamins, CoQ, folic acid)
    • Prosthetic groups: molecules tightly bound to the enzyme (i.e retinal, metal ions, vitamins)
  40. What factors affect enzyme activity
    • Temperature
    • pH
  41. What happens when you increase the temperature with enzymes?
    • It is more likely that molecules will collide with each other
    • The optimal temperature depends on the enzyme, if you get too hot then the proteins will denature (lose it's shape)
  42. What is the optimal pH for enzymes found in humans?
    • Depends on where the enzyme is located
    • Stomach enzymes need to be slightly acidic
  43. Enzyme regulation
    • Enzyme function is tightly regulated
    • Regulatory binding is usually reversible
  44. How might an amino acid change at a site distant from the active site of the enzyme substrate specificity?
    By changing the shape of the protein
  45. Competitive Inhibition
    • molecule resembles substrate and binds to active site
    • It is competing for the active site
  46. Allosteric regulation
    • Regulatory molecule binds away from active site and causes change in shape
    • Can either activate or inhibit activity
    • It can turn on and off
  47. What to toxins and poisons often act as in regards to enzymes?
    Enzyme inhibitors
  48. Feedback inhibition
    • End product of a pathway can bind to an enzyme that acts earlier in the pathway and inhibit it
    • Prevents cell from wasting energy to make excess product
  49. Phosphorylation and dephosphorylation can function as an on-off switch
    Protein kinasws are enzymes that catalyze phosphorylation of target proteins at specific sites, whereas protein phosphatases catayze removal of phosphate(s) from phosphorylated proteins
  50. Adenosine monophosphate (AMP) activates the enzyme phosphfructokinase (PFK) by binding @ a site distinct from substrate binding site. This is an example of?
    Allosteric activation
  51. Which of the following metabolic processes can occur without a net influx of energy from some other process?
    ADP + Pi -> ATP + H2
    C6H12O6 -> 6 CO2+ 6 H2O
    Amino acids -> protein
    Glucose + fructose -> sucrose
    C6H12O6 -> 6 CO2+ 6 H2O
Author
Zaqxz
ID
334739
Card Set
Energy and Enzymes
Description
akd
Updated

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