Card Set Information

2012-09-26 04:20:06

Show Answers:

  1. Define metabolism, name and define its two components
    • The sum of the chemical reactions in an organism or cell
    • Catabolism: degradative, exergonic
    • Anabolism: biosynthetic, endergonic
  2. Define enzyme and explain how enzymes can speed up a reaction (include discussion of specificity and efficiency)
    • Increase raterxn by decreasing energy of activation
    • Highly specific, and extremely efficient (108-1010 times faster)
  3. Name and explain the components of an enzyme
    • Apoenzyme: inactive protein portion
    • Cofactor: activor, nonprotein portion, inorganic
    • Coenzyme: organic cofactor
    • Holoenzyme: active
  4. Name some coenzymes important in cellular metabolism
    • Cafactors (inorganic): Zn, Fe, Mg, Ca
    • Coenzymes (organic): NAD+, NADP+, FAD, Coenzyme A
  5. Explain the mechanism of enzymatic activity
    • Substrate binds to enzyme, forming enzyme-substrate complex
    • Products leave enzyme
    • Enzyme remains, unaltered
  6. List and explain several factors that influence enzymatic activity
    • Temperature
    • pH
    • Substrate concentration
    • Inhibitors
  7. Explain how inhibitors - competitive and noncompetitive - affect enzymatic activity, and give an example of each
    • Competitive: has similar size/shape as substrate, competes for active site (sulfanilamide, PABA)
    • Noncompetitive: interact with allosteric site causing conformational change
  8. Explain feedback inhibition and give an example
    End product of pathway (with multiple intermediates) is also a noncompetitive inhibitor for the initial reaction in the pathway
  9. Name and explain the 3 mechanisms of phosphorylation used to generate ATP
    • Substrate-level phosphorylation: phosphorylated substrate donates inorganic P to ADP
    • Oxidative phosphorylation: Involves ETC.  Transfer of electrons results in energy release used to generate ATP by chemiosmosis
    • Photophosphorylation: Occurs only in photosynthetic cells, starts process of photosynthesis (light-dependent reactions)
  10. Explain the 3 stages of glucose catabolism - glycolysis, Krebs cycle, and electron transport chain - what goes in? What comes out?
    • Glycolysis: Oxidation of glucose.  Glucose in, Pyruvic Acid out.  Net Energy products 2 ATP and 2 NADH
    • Intermediate step: Pyruvic acid is oxidized and Acetyl Coa is formed
    • Krebs cycle: Series of redox reactions.  Oxidation of Acetyl Coa.  Production of NADH and FADH2.  For 2 Acetyl CoA (1 glucose) 6 NADH, 2 FADH2, 2 ATP
    • Electron transport chain: Series of electron carriers.  ATP synthase harnesses H+ coming down gradient to create ATP
  11. Give alternatives to glycolysis
    • Pentose phosphate pathway: Uses pentoses, operates with glycolysis (B. subtilis, E. coli, E. faecalis)
    • Entner-Doudoroff pathway: Produces NADPH and ATP, doesn't involve glycolysis (Pseudomonas, Rhizobium, Agrobacterium)
  12. Contrast aerobic vs. anaerobic respiration vs. fermentation
    • aerobic respiration: ATP generated by oxidative phosphorylation.  Final electron acceptor is O2.  Yields most ATP.
    • anaerobic respiration: ATP generated by oxidative phosphorylation.  Final electron acceptor is NOT O2. Yields less energy.
    • Fermentation: Respiration without the use of O2. Doesn't use Krebs cycle or ETC.  Uses an organic molecule as final electron acceptor. Smallest amount of ATP produced
  13. Explain the mechanism and importance of the electron transport chain and chemiosmosis
    • A series of electron carriers transfer electrons and used the energy released to produce ATP through chemiosmosis.
    • 3 classes of carrier molecules (Flavoproteins, Ubiquinones, Cytochromes)
    • Protons pumped across membrane and ATP synthase harnesses H+ following gradient to create ATP
  14. Define fermentation, list and explain the two types.
    • Releases energy from oxidation of organic molecules
    • Purpose is to regenerate NAD+
    • Does nnot require O2
    • Does not use the Krebs cycle or ETC
    • Uses an organic molecule as the final electron acceptor
    • Produces small amount of ATP
    • Lactic acid fermentation: produces homolactic fermentation (lactic acid is only product) or heterolactic fermentation (lactic acid + other)
    • Alcohol fermentation: produces ethanol + CO2.
  15. Explain lipid catabolism
    • Lipase breaks lipids into glycerol and fatty acids
    • Glycerol is used in Glycolysis as intermediate (glyceraldehyde 3-phosphate)
    • Fatty acids undergo Beta-oxidation and is converted to Acetyl CoA
  16. Explain protein catabolism (including amino acid catabolism)
    • Proteins broken down by proteases and peptidases and converted to amino acids
    • Amin acids become organic acids and are used as intermediates in the Krebs cycle
  17. List and discuss the categories of organisms based on energy source, carbon source, and carbon AND energy source
    • Energy source: phototrophs (use sunlight), chemotrophs (use organic or inorganic compounds)
    • Carbon source: autotrophs (use CO2 to make food), hetertroph (use organic compounds)
    • Photoautotroph: light/CO2
    • Photoheterotroph: light/Organic compounds
    • Chemoautotroph: chemical/CO2
    • Chemoheterotroph: chemical/Organic compounds
  18. Explain how ATP is used in the cell
    • Active transport
    • Flagellar motion
    • Biosynthesis of cellular components (polysaccharides, lipids, amino acids and proteins, purines and pyrimidines)