front 1 *1. In bacterial cell division, the cell divides into two nearly equal halves. This process is referred to as: A. binary fission | back 1 * A. binary fission |
front 2 2. How does the organization of the bacterial genome differ from the
organization of the eukaryotic genome? | back 2 B. Most bacterial chromosomes are circular and the eukaryotic chromosomes contained in the nucleus are not. |
front 3 3. The division of a bacterial cell occurs as the: | back 3 D. new membrane and cell wall materials begin to grow and form a septum. |
front 4 *5. The accommodation of the very long DNA strands that are part of a
chromosome into the limited space of the nucleus is achieved by
coiling the DNA around beads of histones into repeating subunits.
These DNA-wrapped histones are called: | back 4 *B. Nucleosomes |
front 5 6. The point of constriction on chromosomes that contains certain
repeated DNA sequences that bind specific proteins is called: | back 5 B. The centromere |
front 6 7. Eukaryotic chromosomes are composed of a complex of 60% protein
and 40% DNA. This complex is referred to as: | back 6 B. Chromatin |
front 7 8. The number of chromosomes characteristic of diploid eukaryotic
cells, in general: | back 7 D. varies considerably from 2 to over 1000 in different species. |
front 8 9. A person whose cells all contain a chromosome number of 2n+1 most
likely has what type of condition? | back 8 B. Trisomy |
front 9 10. In later chapters, you will learn more about the regulation of
gene expression. One way to regulate gene expression is to make
changes to the histone proteins to alter how tightly the DNA is coiled
and wrapped. The more tightly coiled and wrapped a particular region
of DNA is, the less likely it is that the genes in that region will be
expressed. Bearing this in mind, how tightly do you think regions of
heterochromatin are compacted? | back 9 A. Very tightly |
front 10 11. You are assembling a model of a chromosome, but begin having some trouble when you get to the step of forming chromatin loops. If you are unable to resolve this problem, what step of chromosome structure would you be unable to achieve? A. Histone/DNA complex | back 10 D. Rosettes |
front 11 13. The two copies of each type of chromosome found in normal somatic
(body) cells in an organism, throughout the cell cycle, are
called: | back 11 B. Homologous chromosomes |
front 12 15. These structures are held together by cohesin: | back 12 B. Sister chromatids |
front 13 16. A cell biologist produces a karyotype of mouse somatic cells
arrested in mitosis. She sees 40 chromosomes, which is completely
normal for mice. Based on this information, what is the haploid number
of chromosomes for mice? | back 13 B. 20 |
front 14 *17. If there are 32 sister chromatids in a normal somatic cell, what
is the haploid number for that cell? | back 14 *A. 8 |
front 15 *18. If there are 32 sister chromatids in a normal somatic cell, how
many chromosomes are there? | back 15 *B. 16 |
front 16 19. A somatic cell from a garden pea normally contains 14
chromosomes. How many sister chromatids would that cell contain during
G1 of the cell cycle? | back 16 A. 0 |
front 17 20. A somatic cell from a corn plant normally contains 20
chromosomes. How many sister chromatids would that cell contain during
G2 of the cell cycle? | back 17 D. 40 |
front 18 21. What is the sequence of events in a typical eukaryotic cell
cycle? | back 18 B. G1 to S to G2 to mitosis to cytokinesis |
front 19 22. The portion of the cell cycle when the cell is growing and does
not contain a replicated genome is referred to as: | back 19 A. G1 |
front 20 23. The stage of the cell cycle during which the cytoplasm divides to
form two cells is called: | back 20 E. Cytokinesis |
front 21 *24. This stage of the cell cycle is characterized by growth and it
contains a checkpoint to verify that all of the DNA has been
replicated prior to mitosis. | back 21 *C. G2 |
front 22 25. A duplicate copy of all of the hereditary information contained
in the nucleus of eukaryotic cells is made during what stage of the
cell cycle? | back 22 B. S |
front 23 26. The physical distribution of cytoplasmic material into the two
daughter cells in plant cells is referred to as: | back 23 B. Cytokinesis |
front 24 27. If a cell has 32 chromosomes prior to S and undergoes mitosis
followed by cytokinesis, each new daughter cell will have how many
chromosomes? | back 24 B. 32 |
front 25 28. Embryonic cell cycles allow the rapid division of cells in the
early embryo. These mitotic cell cycles are much shorter in length
than the mitotic cell cycles of cells in a mature organism. In the
embryonic cell cycles, mitosis takes approximately the same amount of
time as it does in the cell cycles of mature cells. What do you think
is a result of the embryonic cycle? | back 25 A. Resulting daughter cells are smaller than the mother cell in the embryonic cell cycles. |
front 26 29. What is the portion of the cell cycle during which the
chromosomes are invisible under the light microscope because they are
not yet condensed? | back 26 A. Interphase |
front 27 30. Interphase is made up of what stages of the cell cycle? | back 27 A. G1 + G2 + S |
front 28 31. During what stages of the cell cycle are sister chromatids bound
together by cohesin? | back 28 D. S, G2, prophase, metaphase |
front 29 *32. Following S phase, a human cell would have how many pairs of
sister chromatids and individual DNA molecules? | back 29 *D. 46 pairs of sister chromatids and 92 individual DNA molecules |
front 30 33. If a chromosome contains a mutation such that it cannot bind to
the kinetochore complex, what would be the consequence? | back 30 C. That chromosome would not be able to bind to the mitotic spindle. |
front 31 34. Consider the cell cycle of a human cell. During G2, what is the
state of the homologous chromosomes? | back 31 B. The homologous chromosomes have all been copied through DNA replication and are beginning to condense. |
front 32 35. This is the stage of mitosis characterized by the alignment of
the chromosomes in a ring along the inner circumference of the
cell: | back 32 D. Metaphase |
front 33 36. The stage of mitosis characterized by the physical separation of
sister chromatids is called: | back 33 A. Anaphase |
front 34 *37. This stage of mitosis is characterized by the disassembly of
spindle apparatus, the reestablishment of the nuclear membrane, and
the decondensation of the chromosomes: | back 34 *B. Telophase |
front 35 38. During this stage of mitosis, the nuclear envelope begins to
break down and the spindle begins to form. | back 35 C. Prophase |
front 36 39. In prophase, ribosomal RNA synthesis stops when the chromosomes
condense, and as a result: | back 36 C. the nucleolus disappears. |
front 37 40. During this stage of mitosis, the chromosomes become attached to
the spindle at their kinetochores. | back 37 B. Prometaphase |
front 38 41. What happens during Anaphase B? | back 38 B. The spindle poles move apart. |
front 39 42. You are conducting a genetic screen using Caenorhabditis elegans
embryos to isolate mutations affecting anaphase (A). Therefore, you
need to look for embryos in which | back 39 A. the centromeres do not move toward the poles. |
front 40 43. What stage of mitosis is essentially the reverse of
prophase? | back 40 D. Telophase |
front 41 44. The drug Taxol, or Paclitaxel, is used to treat patients with a
variety of cancers, including breast, lung and ovarian cancers. The
drug works by stabilizing microtubules, and preventing their
disassembly. The goal of the drug is to prevent dividing cells from
being able to complete mitosis. As a result, cancerous cells can no
longer divide. In a cell treated with Taxol, at what stage of mitosis
will the cells arrest? | back 41 A. Prior to metaphase |
front 42 45. Why is it so important that all of the chromosomes align on the
metaphase plate during metaphase? | back 42 B. If they cannot, it suggests that they aren't properly attached to the spindle microtubules, and thus won't separate properly during anaphase. |
front 43 46. If a cell was capable of bypassing metaphase and going directly
from prometaphase to anaphase, what is the most likely consequence of
this? | back 43 C. The resulting daughter cells would have different numbers of chromosomes. |
front 44 47. Animal cells typically achieve cytokinesis by: | back 44 C. forming a cleavage furrow that pinches the cell into two. |
front 45 *48. Plant cells typically achieve cytokinesis by: | back 45 *B. forming a cell plate across the middle of the cell. |
front 46 49. If a drug that inhibited transport from the trans face of the
Golgi was applied to plant cells, which stage of the cell cycle would
be directly affected? | back 46 E. Cytokinesis |
front 47 50. The progress of the eukaryotic cell cycle is regulated primarily
by what proteins? | back 47 A. Cyclins |
front 48 51. At what checkpoint(s) does the cell arrest in response to DNA
damage? | back 48 D. G1/S and G2/M |
front 49 52. You are examining the effect of maturation-promoting factor (MPF)
in sea urchin cells, which have a diploid number of 36. If you fuse a
dividing sea urchin cell with a G1 arrested oocyte, what would be the
outcome? | back 49 A. The G1 cell would enter mitosis, but would likely arrest at the spindle checkpoint because the chromosomes have not been properly replicated. |
front 50 53. What time point represents G2? A. 1 | back 50 C. 3 |
front 51 54. You are studying cell cycle progression in yeast cells. If you
could prevent cdc2 from associating with the mitotic cyclin, the cells
would: | back 51 B. arrest in G2. |
front 52 55. You are studying cell cycle progression in an early frog embryo.
If you were to inject a protein synthesis inhibitor into a cell during
S phase, where do you predict that the cells would arrest? | back 52 B. G2 |
front 53 56. In G2, there are typically high levels of the mitotic cyclin. Why
is cdc2 not active during G2 if the mitotic cyclin is present? | back 53 A. Cdc2 is also regulated by phosphorylation. |
front 54 57. What is separase? | back 54 C. A protein that destroys cohesin through its protease activity. |
front 55 58. What is one of the roles of the APC/C during anaphase? | back 55 A. To directly target the mitotic cyclins for destruction. |
front 56 59. What would you expect to happen if the anaphase-promoting
complex/cyclosome (APC/C) failed to ubiquitinate securin? | back 56 B. The cohesin complex will persist, preventing the cell from entering anaphase. |
front 57 60. If you were to think of the cell as a car, and mitosis as a
process that drives that car to go, what would be a good analogy for a
cell that has a mutation in both copies of a tumor-suppressor
gene? | back 57 D. The brake pedal of a car does not work at all. |
front 58 4. If a cell contained a mutation in the gene that encodes FtsZ, what
process would be affected? | back 58 A. Septation |
front 59 61. You are leading a team of researchers at a pharmaceutical
company. Your goal is to design drugs that help fight cancer.
Specifically, you want to focus on drugs that bind to and inactivate
certain proteins, thereby halting cell cycle progression. One of your
team members suggests targeting the retinoblastoma (Rb) protein and
inhibiting this protein. Will this approach be successful? Why or why
not? | back 59 A. This approach will not be successful. Rb is tumor-suppressor protein, and functions to inhibit the action of a number of cell cycle regulatory proteins. A drug designed to inactivate the Rb protein would essentially create the same situation as in as a cell that lacks both copies of the Rb gene. Lack of Rb activity would release the inhibition of cell cycle regulatory proteins, thereby promoting cell cycle progression, rather than halting it. |
front 60 62. This protein or protein complex functions in the cell to stop
cell division if the cell has experienced extensive DNA
damage: | back 60 B. p53 |
front 61 11. What oxidizing agent is used to temporarily store high energy
electrons harvested from glucose molecules in a series of gradual
steps in the cytoplasm? | back 61 C. NAD+ |
front 62 14. What molecule can oxidize NADH? | back 62 A. Acetaldehyde |
front 63 ** 23. Homologous chromosomes pair along their length during
prophase I of meiosis. While two homologues are paired, genetic
exchange may occur between them in a process called ________.
| back 63 ** crossing over |
front 64 ** 27. All animal cells are diploid except | back 64 ** gametes |
front 65 ** 31. At the end of meiosis II, each of the four resulting cells
contains | back 65 ** c. one full set of chromosomes, each with 1 molecules of DNA |
front 66 ** All of the following increase genetic variation EXCEPT | back 66 mitosis |
front 67 ** You are studying meiosis in an organism where 2n=24. How many
chromosomes will each nucleus have after meiosis II is complete?
| back 67 12 |
front 68 Edouard van Beneden proposed that an egg and a sperm each containing
half the complement of chromosomes found in somatic cells, fuse to
produce in single cell called | back 68 zygote |
front 69 ______ is a process of nuclear division which reduces the number of
chromosomes per cell from sets to 1 set | back 69 meiosis |
front 70 ____ cells contain one set of chromosomes | back 70 haploid |
front 71 In life cycles that alternate between haploid and diploid stages,
fertilization doubles the number of chromosomes per cell while_____
reduces it in half | back 71 meiosis |
front 72 Homologous chromosomes pair along their length during prophase I of
meiosis. While two homologous are paired, genetic exchange may occur
between them in a process called | back 72 crossing over |
front 73 Compare to asexual reproduction, the main advantage of sexual
reproduction is that it | back 73 b. increases the genetic diversity of the offspring. |
front 74 Why does sexual reproduction require both meiosis and syngamy (fusion
of gametes to form a new cell) | back 74 b. the process of meiosis results in the production of gametes in which the number of chromosomes is reduced by half. During syngamy, two gametes fuse to form a new cell, and the number of chromosomes is restored to the full amount. Therefore, by coupling meiosis and syngamy, the organism ensures that the proper number of chromosomes will be maintained. |
front 75 Which cells never divide by meiosis | back 75 a. haploid germ line cells will eventually go through meiosis so it will divide |
front 76 If a germ-line cell from an owl contains 8 picograms of DNA during G1 of interphase, how many pictograms pf DNA would be present in each cell during prophase I of meiosis | back 76 16 |
front 77 If a somatic cell from a cat contains 40 picograms of DNA during G2 of interphase, how many pictograms pf DNA would be present in each cell during metaphase II of meiosis | back 77 20 |
front 78 If a germ-line cell from a salamander contains 10 picograms of DNA during G1 of interphase, how many pictograms pf DNA would be present in each gamete produced by this species | back 78 5 |
front 79 How many tetrads are present in a single elephant cell (2n=56) during metaphase I of meiosis | back 79 28 |
front 80 A geneticist examines a somatic cell from a fly during metaphase of
mitosis and determines that 16 chromatids are present. If a germ-line
cell from this species divides by meiosis then at the end of meiosis I
each cell will contain | back 80 d. 4 chromosomes with 8 DNA molecules |
front 81 Nondisjunction is the failure of homologous chromosomes to separate
during meiosis I, or the failure of sister chromatids to separate
during meiosis II or mitosis. As a result, both homologous chromosomes
or both sister chromatids migrate to the same pole of the cell. This
produces daughter cells with a imbalance of chromosomes. A cell
biologist examines the final products of meiosis in an earthworm
(2n=36) and finds 2 cells with 20 chromosomes and 2 cells with 16
chromosomes . Most likely this was because | back 81 c. 2 pairs of homologous chromosomes failed to separate during meiosis I |
front 82 Nondisjunction is the failure of homologous chromosomes to separate
during meiosis I, or the failure of sister chromatids to separate
during meiosis II or mitosis. As a result, both homologous chromosomes
or both sister chromatids migrate to the same pole of the cell. This
produces daughter cells with a imbalance of chromosomes. If 18 pairs
of sister chromatids segregate normally during meiosis II in cats
(n=19) but we have nondisjunction of 1 pair, then at the end of
meiosis II we will have | back 82 c. 2 cells with 19 chromosomes, 1 with 20 and 1 with 18 |
front 83 A cell biologist examines a diploid cell form a particular species of during metaphase of mitosis and determines that 8 centromeres are present. Based on this finding, how many centromeres should be present in a single cell form this species during anaphase II of meiosis | back 83 8 |
front 84 A cell biologist examines a diploid cell form a particular species of during prometaphase of mitosis and determines that 10 centromeres are present. Based on this finding, how many chromatids should be present in a single cell form this species during anaphase II of meiosis | back 84 20 |
front 85 Meiosis results in a reassortment of maternal chromosomes (inherited
form the mother) and paternal chromosomes (inherited form the father).
if n=4 for a given species and ignoring the effects of crossing over
what is the probability that a gamete will receive only paternal
chromosomes | back 85 1/16 |
front 86 A cell in G2 before meiosis begins, compared with one of the four
cells produced at the end of meiosis II has | back 86 b. four times as much DNA and twice as many chromosomes |
front 87 In meiosis, sister kinetochores are attached to the same pole of the
cell during meiosis I and sister chromatid cohesion is released during
anaphase II. What would be the likely result if sister kinetochores
were attached to different poles of the cell during meiosis I and
sister chromatid cohesion was released during anaphase I | back 87 a. sister chromatids would migrate to the opposite poles during anaphase I |