BIOL 151 Exam 1 Notes

Exam Structure

• The exam consists of multiple true/false questions and multiple choice questions.

• For true/false questions, record responses as "A" for True and "B" for False.

• Answers are numbered, and a total of 66 answers should be recorded on the answer sheet.

Problem Set Details

Problem 1-8: Statements About Living Cells

1. All living things are made of cells (including single-cell life forms).

   • Answer: A (True)

2. Somatic (body) cells are made from cell division.

   • Answer: A (True)

3. Stem cells are created from the assembly of molecules in the environment and not from cell division.

   • Answer: B (False)

4. Cells can receive signals through receptors but cannot send signals to other cells.

   • Answer: B (False)

5. Mitosis is a process that divides cells into two and assures that both cells have identical copies of the genetic material.

   • Answer: A (True)

6. Self-renewal stem cell divisions allow stem cells to make copies of themselves and create new stem cells.

   • Answer: A (True)

7. Transit amplifying cells display receptors for signaling pathways that cause them to differentiate into mature cell types.

   • Answer: A (True)

8. The only stem cells left in the adult body are located in the skin.

   • Answer: B (False)

Problem 9-15: Cellular Processes Timing

• Determine the phase in which the processes occur:

  • A = Occurs during interphase

  • B = Occurs during mitosis but before the metaphase to anaphase transition.

  • C = Occurs right at the metaphase to anaphase transition.

  • D = Occurs after the metaphase to anaphase transition.

1. The replication of homologs to form sister chromatids.

   • Answer: C

2. The breakdown of Cohesin.

   • Answer: C

3. Cytokinesis - the name for the full separation of dividing cells into two cells.

   • Answer: B

4. Signaling from unattached kinetochores.

   • Answer: B

5. The replication of centrioles and their movement to opposite poles in the cell.

   • Answer: A (Centrioles are the structures that spindle fibers extend from.)

6. The spindle fibers pull the sister chromatids to opposite sides of the cell.

   • Answer: C

7. The attachment of Ubiquitin to Securin.

   • Answer: C

Problem 16-19: Normal Healthy Cells in Anaphase Conditions

16. Some kinetochores have not yet attached to spindle fibers.

    • Answer: A (True)

17. MAD is binding to CDC20.

    • Answer: A (True)

18. Expression of the Securin gene has stopped.

    • Answer: B (False)

19. Cohesin has been destroyed, but new Cohesin is being made and binding sister chromatids together through protein turnover.

    • Answer: A (True)

Problem 20-30: Effects on Mitosis

20. Gain of function mutations cause kinetochores to release the "unattached" signal even when attached to kinetochores.

    • Answer: A (premature anaphase)

21. Loss of function in MAD prevents it from changing shape when the "unattached" signal is not present.

    • Answer: B (stuck in metaphase)

22. Gain of function mutation in MAD that produces twice as much MAD protein as normal.

    • Answer: C (completes mitosis normally)

23. Gain of function mutation in CDC20 that produces twice as much CDC20 protein as normal.

    • Answer: A

24. Gain of function mutation in APC that produces twice as much APC protein as normal.

    • Answer: B

25. Gain of function mutation in Separase that produces twice as much Separase protein as normal.

    • Answer: C

26. Gain of function mutation in Securin that produces twice as much Securin as normal.

    • Answer: B (stuck in metaphase)

27. Loss of function mutation in Separase that prevents it from binding to Securin.

    • Answer: (Insufficient context provided)

28. Gain of function mutation in Separase that causes it to break down APC even if bound to Securin.

    • Answer: A

29. Loss of function mutation in tubulin that prevents spindle fibers from growing/shrinking.

    • Answer: B

30. Reduction in the rate of protein turnover of APC that causes APC proteins to last longer in the cell.

    • Answer: C

Problem 31-35: Kinase Cascade Signaling Pathway

31. When no signal is present there is not ATP in the cell, causing no proteins to be phosphorylated.

    • Answer: B (False)

32. Activation of the kinase activity of TFa causes it to enter the nucleus.

    • Answer: A (True)

33. Activation of the kinase activity of TK2 causes TFa to enter the nucleus.

    • Answer: A (True)

34. An active phosphatase that targets TK2 could prevent TFa from entering the nucleus.

    • Answer: A (True)

35. Activation of the kinase function of the receptor causes TK1 to be phosphorylated and activated.

    • Answer: A (True)

Problem 36-40: Effects on Kinase Cascade Pathway

36. If TK1 activated TK2 and a new kinase, TK3, that targeted TFa.

    • Answer: A (functional but non-oscillating pathway)

37. If TFa activated a gene encoding a phosphatase that targets TK1.

    • Answer: B (pathway that would go on and off)

38. If TFa activated a gene that encodes a kinase that targets TK2.

    • Answer: C (permanent pathway for signaling)

39. If TKa activated a gene that caused receptor mediated endocytosis in degradation mode.

    • Answer: D (non-functional pathway)

40. If TK2 targeted TFa and activated a phosphatase that also targeted Ta.

    • Answer: D (non-functional pathway)

Problem 41-44: Oscillating Pathway Involving TFa

41. Ubiquitin-dependent proteolysis of TFa is underway at timepoints 2 and 3, but not at timepoint 1.

    • Answer: A (True)

42. TFa is unphosphorylated at timepoint 3; expression of the gene encoding the phosphatase has stopped.

    • Answer: A (True)

43. The pathway would oscillate more quickly if the phosphatase targeted TK1 rather than TK2.

    • Answer: B (False)

44. TK1 is not undergoing protein turnover.

    • Answer: A (True)

Problem 45-49: Properties of Ras in EGF Pathway

45. When Ras is bound to GTP, it can activate a kinase.

    • Answer: A (True)

46. When Ras is bound to GDP, it can get phosphorylated and activated by a kinase.

    • Answer: A (True)

47. Ras activates other proteins by making physical contact with them.

    • Answer: A (True)

48. NF1, the Ras GAP, is the enzyme that cuts the third phosphate off of GTP to make GDP.

    • Answer: A (True)

49. SOS, the Ras GEF, is a kinase that phosphorylates GDP to make GTP and activate Ras.

    • Answer: B (False)

Problem 50-56: Effects on EGF Pathway

50. A mutation in Raf that deleted the RBD (Ras-binding domain) of Raf protein.

    • Answer: A (it would block the pathway)

51. A mutation in Raf that causes it to target and phosphorylate MEK when Ras is binding to GDP.

    • Answer: B (over-activate the pathway)

52. A mutation in HER2 causing over-expression and production of many extra HER2 receptors.

    • Answer: B (over-activate the pathway)

53. A mutation in Cbl binding site of EGF receptor preventing Cbl from ubiquitinating the cytoplasmic domain of the receptor.

    • Answer: B (over-activate the pathway)

54. A mutation in the kinase domain of the receptor causing it to activate when no signal is present.

    • Answer: B (over-activate the pathway)

55. A mutation in Ras that blocks Ras GTPase function.

    • Answer: B (over-activate the pathway)

56. Increased expression of the gene encoding the phosphatase PTP1B that targets the cytoplasmic domain of the EGF receptor.

    • Answer: A (it would block the pathway)

Problem 57-61: Facts about Cancer

57. As you age, your chance of developing cancer increases.

    • Answer: A (True)

58. Cancer results from the accumulation of mutations in cells.

    • Answer: A (True)

59. As cancer spreads, signals from the original tumor cause healthy cells to mutate and become cancer cells.

    • Answer: A (True)

60. Cancerous cells can break away from the original tumor and move to other places in the body to form new tumors.

    • Answer: A (True)

61. Cancer detection and treatment is improving.

    • Answer: A (True)

62. Cancer rates are increasing among younger people for reasons that are not yet clear.

    • Answer: A (True)

These notes serve as a detailed guide for BIOL 151 Exam 1, encompassing key concepts, true/false responses, the impact of biological mutations on cellular processes, and significant facts about cancer. They offer exhaustive coverage necessary for a comprehensive understanding of the exam content.