Exam #4 Review (Ch. 12-15)

Exam #4 Review (Ch. 12-15) Study Notes

Fill in the Blank: Cell Cycle and Mitosis

1. G1 phase: A non-dividing state when a cell has not passed the “restriction point”.

2. Anaphase: Sister chromatids separate and chromosomes move apart.

3. Prophase: Mitotic spindle begins to form.

4. Telophase / Cytokinesis: Cell plate forms or cleavage furrow pinches cells apart.

5. S phase: Chromosomes replicate.

6. Metaphase: Chromosomes line up at the equatorial plane.

7. Telophase: Nuclear membranes form around separated chromosomes.

8. Prophase: Chromosomes become visible.

9. Metaphase: Kinetochore-microtubule interactions move chromosomes to midline.

10. G1 phase: Restriction point occurs in this phase.

11. S phase: Amount of DNA in a cell is doubled.

12. Interphase (G1, S, G2): Longest stage of the cell cycle; composed of three substages.

13. Metaphase: Microtubules interact with kinetochore proteins at the centromere region.

14. Anaphase: Nonkinetochore microtubules lengthen which starts to elongate the cell.

Multiple Choice: Key Concepts

1. Question: A plant cell has 12 chromosomes at the end of mitosis. How many chromosomes would it have in the G2 phase of its next cell cycle?
   Answer: d. 24 (The cell doubles its DNA content during the S phase).

2. Question: How many chromatids would this same plant cell have in the G2 phase of its cell cycle?
   Answer: e. 48 (24 chromosomes d7 2 = 48 chromatids).

3. Question: The longest part of the cell cycle is
   Answer: d. interphase (G1 + S + G2).

4. Question: Humans have 46 chromosomes. That number of chromosomes will be found in
   Answer: 3. the somatic cells.

5. Question: Which of the following would not be exhibited by cancer cells?
   Answer: b. density-dependent inhibition (cancer cells often ignore signals that inhibit division).

6. Question: A cell that passes the restriction point in G1 will most likely
   Answer: 1. undergo chromosome duplication.

7. Question: The restoration of the diploid chromosome number after halving in meiosis is due to
   Answer: c. fertilization.

8. Question: The somatic cells derived from a single-celled zygote divide by which process?
   Answer: C. mitosis.

9. Question: What is a karyotype?
   Answer: 4. a pictorial display of an individual’s chromosomes.

10. Question: What are autosomes?
    Answer: d. the first 22 pairs of chromosomes (in humans).

11. Question: A tetrad complex would be found during
    Answer: a. prophase I of meiosis.

12. Question: During the first meiotic division (meiosis I):
    Answer: 5. all of the above occur.

13. Question: The DNA content of a cell is measured in the G2 phase. After meiosis I, the DNA content of one of the two cells produced would be
    Answer: 2. one-half that of the G2 cell.

14. Question: Meiosis II is similar to mitosis because
    Answer: 1. sister chromatids separate.

15. Question: Which of the following is not true of homologous chromosomes?
    Answer: 1. They synapse during the S phase of meiosis (this happens during prophase I).

16. Question: One difference between a cancer cell and a normal cell is that
    Answer: 4. cancer cells continue to divide even when they are tightly packed together.

17. Question: Eukaryotic chromosomes are composed of which of the following macromolecules?
    Answer: c. DNA and proteins.

18. Question: A human cell containing 22 autosomes and a Y chromosome is
    Answer: a. a sperm.

19. Question: Which of the following does NOT occur in mitosis?
    Answer: 5. synthesis of DNA (DNA synthesis occurs in the S phase).

20. Question: Sister chromatids separate in
    Answer: 5. both b (anaphase II of meiosis) and c (anaphase of mitosis).

Visual Identifications

21. Question: Identify the cell in prophase of mitosis using lettered circles.

22. Question: Identify the cell in prophase II of meiosis using lettered circles.

23. Question: Identify the cell after mitosis and cytokinesis is complete using lettered circles.

24. Question: Identify the cell after meiosis II and cytokinesis is complete using lettered circles.

Comparison of Reproduction

25. Question: Asexual reproduction and sexual reproduction are different in that
    Answer: e. all of the above (transmission of genes, genetic identity, parental involvement).

26. Question: At which phase of the cell cycle do centrioles begin to move apart and chromatin condenses into chromosomes?
    Answer: c. prophase.

True/False: Mitosis and Meiosis

28. Statement: Cytokinesis is the division of the cytoplasm. True

29. Statement: The S-Phase is when the DNA is copied. True

30. Statement: G1, S, and G2 make up interphase. True

31. Statement: Bacteria cells use binary fission. True

32. Statement: Sister chromatids are identical. True

33. Statement: Chromatids separate during metaphase. False (they separate during anaphase).

34. Statement: Human cells have 46 pairs of chromosomes. False (they have 23 pairs, totaling 46).

35. Statement: The name of the microtubule-organizing center found in animal cells is called centrosomes. True

36. Statement: Gametes are diploid. False (gametes are haploid).

37. Statement: Crossing over can occur in meiosis I but not in meiosis II. True

38. Statement: A zygote represents an egg cell right before fertilization. False (a zygote is the fertilized egg).

39. Statement: Meiosis starts with 1 cell and produces 4 cells. True

40. Statement: Mitosis starts with 1 cell and produces 2 genetically distinct cells. False (produces genetically identical cells).

41. Statement: The region where sister chromatids are most closely held together is called centromere. True

42. Statement: Sister chromatids are held together by cohesins. True

43. Statement: The mitotic spindle plays a role in separating sister chromatids. True

44. Statement: Metaphase is characterized by alignment of chromosomes on the equator of the cell. True

Additional Questions

45. What are two components of an active MPF?: Cyclin and cyclin-dependent kinase (CDK).

46. What process explains this: As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells, and they signal each other to stop dividing.
    Answer: a. Density-dependent inhibition.

47. Which of the following is characteristic of transformed (cancer) cells?
    Answer: d. all of the above (loss of control, anchorage, and density-dependent inhibition).

48. What is a genome?: The complete set of genes or genetic material present in a cell or organism.

49. What is a syndrome?: c. a group of traits typically found in conjunction with a particular chromosomal aberration or gene mutation.

50. In pea plants, the tall phenotype is dominant to the dwarf phenotype. If a heterozygous pea plant is crossed with a homozygous tall pea plant, what is the probability that the offspring will be dwarf in size?
    Answer: d. 0 (since tall is dominant).

51. Define Monohybrid cross: A cross involving organisms that are heterozygous for one character.

52. Males are ________ for the X chromosome.
    Answer: A. Hemizygous (having one allele for the X chromosome).

53. Amniocentesis and CVS are used for what?: To detect genetic abnormalities in a fetus.

54. Gregor Mendel’s significant conclusion from pea plants: Traits are inherited independently and do not blend.

55. Sex-linked recessive traits example: Red-green color blindness in humans.

56. Example of epistasis: The interaction between the genes affecting coat color in Labrador retrievers.

57. Dihybrid cross: A cross between two organisms that are heterozygous for two characters.

58. Gender differentiation occurs how?: Through the presence of X and Y chromosomes influencing developmental pathways.

59. Homozygous genotype (pure) example: AA or aa (individuals with identical alleles for a trait).

60. Example of incomplete dominance: Red and white flowers producing pink offspring.

61. How many unique gametes from AaBBCCDdEe?: 16 unique gametes (calculated via the formula: number of unique alleles = 2^n where n = number of heterozygous pairs).

62. An aneuploidy that has the most severe impact on health: Trisomy 21 (Down syndrome).

63. Genotype BbHh: all possible gametes from this?: BH, Bh, bH, bh.

64. Recombinant chromosomes?: Chromosomes that have undergone recombination during meiosis, resulting in new genetic combinations.

65. Heterozygous genotype (hybrid) example: Bb (individuals with different alleles for a trait).

66. Who will inherit X-linked allele from father who carries it?: All daughters will inherit the X-linked allele.

67. _______ is the only viable monosomy known to occur in newborns: Monosomy X (Turner syndrome).

68. Examples of polygenic inheritance: Traits such as skin color, height, and eye color, where multiple genes contribute to the phenotype.

69. Why closely linked genes are inherited together?: Because they are located close to each other on the same chromosome.

70. The F1 offspring of Mendel's classic pea cross always looked like one of the two parental varieties because: c. one phenotype was completely dominant over another.

Down Syndrome Correlation

71. The frequency of Down syndrome in the human population is most closely correlated with which of the following?: a. Age of the mother.

72. Independent assortment of chromosomes is a result of: Random alignment during metaphase I of meiosis.

73. Explain Barr bodies and their purpose: Barr bodies are inactivated X chromosomes in females, ensuring dosage compensation of X-linked genes, allowing equal expression regardless of the number of X chromosomes present.

Visual Identification - Cell Stages

• Use the terms interphase, prophase, metaphase, anaphase, and telophase/cytokinesis in the context of both plant and animal cell images to label each stage accurately.