CELL QUESTION 1995:			L. PETERSON/AP BIOLOGY

   Energy transfer occurs in all cellular activities. For 3 of the following 5 processes     
   involving energy transfer, explain how each functions in the cell and give an example. 
   Explain how ATP is involved in each example you choose.
	Cellular movement
	Active transport
	Synthesis of molecules
	Chemiosmosis
	Fermentation

  
  
  1 pt     function of process
  1 pt     example                      1 pt additional for detail
  1 pt     ATP involvement
  4 pts =  MAX/process
  
  ATP   <====>   ADP  +  Pi  +  Energy  1 pt
  
  Cellular Movement
     Function  Locomotion, Mitosis, Cytoplasmic Streaming, 
          Muscle Contraction (sliding filaments)
     Examples   Cilia, Flagella, Pseudopodia, Exocytosis, Endocytosis,
          Microfilaments, Spindle Fibers
     Details   9 + 2 Microtubules, Dynein, Actin-Myosin (Myosin heads),
          Kinesins
     ATP Involvement   ATP used
          Motor molecules powered by ATP hydrolysis
          (Conformational change with ATP use)
  
  Active Transport
     Function   Concentration gradient   low to high / Protein carrier w/use of ATP
     Examples   Sodium/Potassium Pump, Other Transports Specified
     Details   Protein carrier related to example
     ATP Involvement   ATP used
          Conformational change with ATP use
  
  Synthesis of Molecules
     Function   Small to Large / Monomer to Polymer
     Examples  
          Intermediates to Monosaccharides to Polysaccharides
          Intermediates to Fatty Acids (Glycerol) to Lipids
          Intermediates to Amino Acids to Proteins
          Intermediates to Nucleotides to Nucleic Acids
          Intermediates to Vitamins
     Details   Charging tRNA
          Reactions catalyzed by enzymes
     ATP Involvment   ATP used
          ATP's energy stored in chemical bonds
  
  Chemiosmosis
     Function   Form electrochemical proton (H+) gradient
     Examples   Mitochondria, Chloroplasts, Bacterial Cell Membrane
     Details   Cristae, Thylakoids, Direction/  H+  vs e-
     ATP Involvement   ATP formed
          Proton pump/gradient with ATP synthase yields ATP
  
  Fermentation
     Start with glucose                 Start with pyruvate
     
     Function   breakdown of organic         recycling NADH
                        compounds
     Examples   Ethanol / Lactic Acid        Ethanol / Lactic Acid
     Details   Anaerobic                Anaerobic
          Less energy produced               Regenerate oxidized NAD
          Cytosolic process             Cytosolic process
          Yeast, Muscle                 Yeast, Muscle
     ATP Involvement 
          ATP used and formed           (No direct involvement)
          Substrate-level               Makes ATP production
          Phosphorylation               possible in glycolysis
  
  
  
  Overall Commentary on Question:
  
     This question was a cell biology energetics question that required both breadth and depth
  of knowledge to answer the question successfully. Full credit could only be obtained by
  responding to three of the process examples listed in the question. Also, if more than three
  processes were discussed, readers were directed to grade the first three unless specifi indications
  directed one to be omitted. Each process had a four point maximum score. One point was
  available for description of the function of the process, which might also be a definition or
  description of a mechanism. One point came from an example in context with the process. One
  point was available for showing how ATP was involved in the process. For each of these points, it
  was possible to get an additional point for detail (elaboration). In addition, it was possible to obtain
  a point frordescription of the ATP  <==>  ADP cycle.