Lecture Quiz 3

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Lecture Quiz 3
2014-04-03 00:04:58

cell to cell connections (plasmodesmata, gap junctions, tight junctions and des- mosomes), energy coupling, endergonic/exergonic reactions, free energy, catalysis and enzyme structure and regulation
Show Answers:

  1. What are the 3 types of molecular structures in the cytoskeleton?
    • Microtubules
    • Intermediate filaments
    • Microfilaments
  2. How do you distinguish between the types of molecular structures in the cytoskelton?
    • Type of protein
    • Size
    • Stability
    • Function
  3. Microtubules
    Thickest, resists compression, has an alpha and beta form, help moderate the movement of cilia and flagella
  4. Intermediate filaments
    Variable, middle sized structure, formed like a cable (winding around itself but not hollow), they support cell shape and hold organelles in place, are more permanent structures than microtubles or microfilaments
  5. Microfilaments
    The smallest structure, built from double twisted chains made of actin subunits, structural role is to bear tension and resist pulling forces in the cell
  6. What is an MTOC?
    Microtubule organizing center or centrosome
  7. The ECM (extracellular matrix) is made up of what?
    Glycoproteins such as collagen, proteoglycans, and fibronectin
  8. Integrins
    Receptor proteins in the plasma membrane on which ECM proteins bind to
  9. Functions of the ECM
    • Support
    • Adhesion
    • Movement
    • Regulation
  10. What are the different types of intercellular junctions?
    • Plasmodesmata
    • Tight Junctions
    • Desmosomes
    • Gap Junctions
  11. Plasmodesmata
    Cytoplasmic bridge in plant cells, used to allow water and small solutes to pass from cell to cell
  12. Tight Junction
    Membranes of neighboring cells are pressed together, preventing leakage
  13. Desmosomes
    Anchoring junctions, fasten cells together into strong sheets
  14. Gap Junctions
    Communicating junctions, provide cytoplasmic channels between adjacent animal cells
  15. Catabolic pathways
    Release energy by breaking down complex molecules into simpler compounds, degradative
  16. Anabolic pathways
    Consume energy to build complex molecules from simpler ones, synthesis
  17. Free energy
    Energy that can do work when temperature and pressure are uniform
  18. What does ΔG mean?
    Change in free energy
  19. What does ΔH mean?
    Change in total energy, enthalpy
  20. What does ΔS mean?
    Change in entropy (disorder)
  21. What does T mean?
    Change in temperature in Kelvin
  22. Equation for change in free energy
    ΔG=ΔH - TΔS
  23. Spontaneous processes
    Processes that occur without energy input
  24. What kind of processes are spontaneous?
    Ones with a negative ΔG
  25. Exergonic reaction
    Proceeds with a net release of free energy and is spontaneous, products have less energy than reactants, -ΔG
  26. Endergonic reaction
    Absorbs free energy, non-spontaneous, +ΔG
  27. What are the 3 main kinds of work that a cell does?
    • Chemical
    • Transport
    • Mechanical
  28. Energy coupling
    The use of an exergonic process to drive an endergonic one
  29. What is ATP made up of?
    Ribose (a sugar), adenine (a nitrogenous base), and 3 phosphate groups
  30. Phosphorylation
    How ATP drives endergonic reactions, transferring a phosphate group
  31. How is ATP regenerated?
    The addition of a phosphate group to adenosine diphosphate (ADP)
  32. Catalyst
    Chemical agent that speeds up a reaction without being consumed by the reaction
  33. Activation Energy (Ea)
    Free energy of activation, initial energy needed to start a chemical reaction
  34. Enzymes catalyze reactions by
    Lowering the Ea barrier
  35. The active site can lower an Ea barrier by
    • Orienting substrates correctly
    • Straining substrate bonds
    • Providing a favorable microenvironment
    • Covalently bonding to a substrate
  36. Enzymes activity can be affected by
    • General environmental factors such as temp and pH
    • Chemicals that specifically influence the enzyme
  37. Cofactors
    Nonprotein enzyme helpers, may be inorganic
  38. Coenzyme
    organic cofactor
  39. Competitive inhibitors
    Bind to the active site, competing with substrate
  40. Noncompetitive inhibitors
    Bind to other sites besides the active site
  41. Allosteric regulation
    May either inhibit or stimulate an enzyme's activity, occurs when a regulatory molecule binds to a protein at one site, and affects the protein's function at another site
  42. Feedback inhibition
    The end product of a metabolic pathway shuts down the pathway
  43. What do you need to know to determine nutritional mode of an organism?
    • Carbon source
    • Energy source
  44. What are the different types of nutritional modes?
    • Chemoautotrophs
    • Photoautotrophs
    • Chemoheterotrophs
    • Photoheterotrophs
  45. Chemoautotroph
    • Carbon source: inorganic molecule
    • Energy source: organic molecule
  46. Photoautotrophs
    • Carbon source: inorganic molecule
    • Energy source: light
  47. Chemoheterotrophs
    • Carbon source: organic molecule
    • Energy source: organic molecule
  48. Photoheterotrophs
    • Carbon source: organic molecule
    • Energy source: light
  49. First law of thermodynamics
    Energy can be transferred or transformed but not destroyed or created
  50. Second law of thermodynamics
    • –Every energy transfer or
    • transformation increases the entropy
    • (disorder) of the universe
  51. Fermentation
    Partial degradation of sugars that occurs without O2
  52. Aerobic respiration
    •consumes organic molecules and O2 and yields ATP
  53. Anaerobic respiration
    • •similar to aerobic respiration but
    • consumes compounds other than O2