bio exam 3 answers

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bio exam 3 answers
2014-04-25 00:26:28
cell bio
bio 214
answers to exam 3
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  1. When cells respond to an extracellular signal, they most often convert the information from one form to another. This process is called:
    signal transduction
  2. Many of the extracellular signal molecules that regulate inflammation are released locally at the site of infection. What form of cell-to-cell signaling is being used?
  3. When the hormone insulin is released into the bloodstream, what form of cell-to-cell signaling is being used?
  4. Which type of receptors do steroid hormones employ?
    Nuclear receptors
  5. GTP binding proteins, which act as molecular switches inside cells,
    are active when GTP is bound
  6. GPCRs are often referred to as seven-pass transmembrane receptors because they have:
    a polypeptide chain that crosses the lipid bilayer seven times
  7. Which of the following is not a small intracellular signaling molecule(second messenger)?
    Phopholipase C
  8. When activated by a GPCR, adenylyl cyclase:
    converts ATP to cAMP
  9. How does IP3 function in the inositol phospholipid pathway?
    it binds to and opens Ca2+ channels that are embedded in the ER membrane, releasing Ca2+ into the cytosol
  10. Mutant Ras poteins, which are found in many cancer cells, can't hydrolyze their bound GTP to GDP, and therefore:
    can't turn themselves off
  11. When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?
    signal molecule
  12. Testosterone functions inside a cell by
    binding with a receptor protein that enters the nucleus and activates specific genes
  13. One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups to itself, and then activating relay proteins. Which type does this?
    receptor tyrosine kinases
  14. In general, signal transmission through phosphorylation of a series of proteins:
    brings a conformational change to each protein
  15. In cell signaling, "cross-talk" refers to what?
    Relay molecules activated by 2 different receptors affect the same pathway
  16. Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?
    ligand-gated ion channel
  17. An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?
    phospholipase C
  18. Which type of signaling has the shortest signaling distance?
  19. Sugars derived from food are broken down by:
    glycolysis, the citric acid cycle, and oxidative phosphorylation
  20. The end products of glycolysis are:
    pyruvate, ATP, and NADH
  21. Which of the following is NOT required for glycolysis to occur?
  22. Under anaerobic conditions, which metabolic pathway regenerates the supply of NAD+ for glycolysis?
  23. What does it mean for a bond to be "high energy," such as between phosphate groups in ATP?
    The hydrolysis of such a bond is particularly energetically favorable
  24. One function of both alcohol fermentation and lactic acid fermentation is to:
    oxidize NADH to NAD+
  25. Although the citric acid cycle itself does not use O2, it requires a functioning electron transport chain (which uses O2) in order to regenerate which molecule for further use in the citric acid cycle?
  26. In eukaryotic cells, what is the final electron acceptor in the electron transport chain?
  27. The complete oxidation of glucose to H2O and CO2 produces about how many molecules of ATP per molecule of glucose?
  28. What is the main chemical energy currency in cells?
  29. Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?
    oxidative phosphorylation (chemiosmosis)
  30. Which of the following is NOT true of mitochondria?
    They are replaced by chloroplasts in plants
  31. In a eukaryotic cell, where are most of the proteins for the electron transport chain located?
    In the mitochondrial inner membrane
  32. The electron transport chain pumps protons:
    from the matrix to the intermembrane space to the matrix
  33. When protons move down their electrochemical gradient into the mitochondrial matrix, they:
    produce ATP
  34. Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?
  35. Where is oxygen created in the photosynthetic process?
    photosystem II
  36. What main products generated from the light-dependent reactions in plant cells are used to help make sugar
    ATP and NADPH
  37. In the electron transport chain in chloroplasts, which molecule serves as the final electron acceptor?
  38. When a chlorophyll molecule captures light energy, what form does the energy take?
    Excited electrons
  39. In photosynthesis, what drives generation of ATP by ATP synthase?
    A proton gradient across the thylakoid membrane
  40. When an electron is removed from the reaction center of photosystem II, how is the missing electron then replenished?
    With an electron removed from water
  41. What provides the fuel to convert CO2 into sugars in chloroplasts
    ATP and NADPH generated in the photosynthetic light reactions
  42. What is the correct order of processes in generating the maximum amount of ATP from glucose?
    Glycolysis, pyruvate oxidation, citric acid cycle, oxidative phosphorylation
  43. Where do glycolysis and the citric acid cycle take place?
    cytosol and mitochondrial matrix, respectively
  44. In cellular respiration, the energy for most ATP synthesis is supplied by
    a proton gradient across a membrane and chemisosmosis
  45. Oxidation and reduction result in
    the loss of electrons and gain of electrons, respectively
  46. What is the purpose of beta oxidation in respiration?
    breakdown of fatty acids
  47. Which metabolic pathway is common to both cellular respiration and fermentation?
  48. Which of the following intermediary metabolites enters the citric acid cycle and is formed, in part, by the removal of a carbon (CO2) from one molecule of pyruvate during pyruvate oxidation?
    acetyl CoA
  49. during aerobic respiration, electrons travel downhill in which sequence?
    food->NADH->electron transport chain-> NADH
  50. Which of the following processes use CO2 to build up a 3 carbon molecule that is the precursor to making sugars?
    Calvin cycle