Midterm 4
Predict what would happen if an embryonic epidermal cell switched from expressing E-cadherin to N-cadherin. - The cell would die. - The cell would become a neural cell. - The cell would leave the epidermis and adhere to neural cells. - There would be no effect.
The cell would leave the epidermis and adhere to neural cells
Which structures are responsible for the shape of a cell during cell division? - cytoskeleton - microvilli - cell junctions - organelles
cytoskeleton
First-division nondisjunction will only yield gametes with an extra chromosome, whereas second-division nondisjunction will only yield gametes missing a chromosome. - true - false
false
Nondisjunction can only occur in the sex chromosomes and not the autosomes. - true - false
false
A phragmoplast functions to: - anchor microtubules to sister chromatids. - stimulate the growth of the microtubule spindle. - form a new cell wall. - break down the nuclear envelope.
form a new cell wall
A human cell with a total of 23 chromosomes is: - diploid. - aneuploid. - haploid. - polyploid.
haploid
Which cellular property do red blood cells have that allows them to pass through narrow blood vessels? - the ability to anchor to the extracellular matrix - strong cell junctions to maintain connections to other cells - All of these choices are correct a flexible cytoskeleton
a flexible cytoskeleton
What protein forms the contractile ring during cytokinesis in animal cells?: - DNA polymerase - dynein - kinesin - actin
actin
Asexual reproduction occurs in: - animal cells - plant cells - bacterial cells - unicellular eukaryotes - all of these choices are correct
all of these choices are correct
During what step in meiosis do homologous chromosomes separate? - anaphase II - metaphase II - prophase II - anaphase I
anaphase I
The assembly of what cytoskeletal structures are initiated by the M cyclin-CDK complex? - intermediate filaments - All of these choices are correct. - microfilament - microtubules
microtubules
Synapsis is best described as: - the pairing of homologous chromosomes in prophase I. - the alignment of non-sister chromatids at the metaphase plate. - the exchange of genetic information between sister chromatids. - the exchange of genetic information between non-sister chromatids.
the pairing of homologous chromosomes in prophase I
Why don't plant cells use a contractile ring to divide their daughter cells? - Plant cells don't have plasma membranes. - Plant cells don't have an actin cytoskeleton. - Plant cells don't form daughter cells. - A contractile ring can't "pinch" a cell wall.
A contractile ring can't "pinch" a cell wall
Cell cycle checkpoints: - All of these choices are correct - provide opportunities to check if the cell has carried out steps necessary for cell division. - can be blocked by the protein p53. - act as a brake on cell division if something is not right.
All of these choices are correct
What is the advantage of forcing materials to travel through cells instead of between cells? - Exposure to bacteria or viruses is limited. - The exposure in internal tissues to the outside environment is limited. - All of these choices are correct. - Cells can control which materials are transported.
All of these choices are correct
Which cellular conditions promote progression of the cell cycle? - the accumulation of cyclins - the activation of CDKs - binding of cyclins to CDKs - the expression and synthesis of cyclin proteins - All of these choices are correct.
All of these choices are correct
Which statement regarding cancer, according to Douglas Hanahan and Robert Weinberg, are true? - All of these choices are correct. - Cancer cells can sometimes metastasize and travel throughout the body. - Mutations in growth factor receptors are sometimes required for cancer cell division. - Cancer cells can resist cell-death signals. - Cancer cells typically secrete factors that promote blood vessel formation.
All of these choices are correct
Which statement is true regarding binary fission? - DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions. - In binary fission, cell division is typically asymmetrical, with one daughter cell appearing much smaller than the other. - Tubulin, rather than FtsZ, is responsible for cell division during binary fission. - Proteins only anchor the original circular genome to the plasma membrane; the copy produced by DNA replication is free-floating.
DNA replication of the circular bacterial chromosome during binary fission is a bidirectional process, starting at one point but progressing in opposite directions
Suppose you are observing some cells with a microscope, and you see a cell that appears to be dividing. You can see that as the cell starts to pinch in half, the DNA seems to be attached to the plasma membrane via a membrane protein. On further analysis, you find that this organism's DNA is circular - that is, it consists of a closed loop. What can you conclude about this organism and its mode of cell division? - It is a prokaryote that is dividing by binary fission. - It is a eukaryote that is dividing by mitosis. - It is a eukaryote that is dividing by binary fission. - It is a prokaryote that is dividing by mitosis.
It is a prokaryote that is dividing by binary fission.
A person has the genotype XXY. What syndrome does this person have and what sex is the person? - Klinefelter; female - Turner; female - Klinefelter; male - Turner; male - no syndrome; male
Klinefelter; male
Which of the answer choices is a characteristic of meiotic cell division?: - meiotic cell division ultimately results in the formation of two cells - the cells produced by meiosis are genetically identical -meiotic cell division results in halving the number of chromosomes - meiotic cell division requires two rounds of DNA replication
Meiotic cell division results in halving the number of chromosomes
Could melanin granules be moved by dynein and kinesin along an actin microfilament? - No, these motor proteins are specific to microtubules and cannot move along microfilaments. - Yes, motor proteins all use ATP to cause a conformation change. - Yes, melanin granules would be moved by these motor proteins along microfilaments.
No, these motor proteins are specific to microtubules and cannot move along microfilaments
Which of the statements about viruses is true? - None of the other answer options is correct. - Viruses are a type of prokaryotic cell. - Viruses are the root cause of most, if not all, cancers. - Human cancers have not been associated with viruses. - Viruses contain multiple genes, and each of these genes is an oncogene.
None of the other answer options is correct
A researcher is studying phases of the cell cycle in a population of cells during which there is an increase in the DNA content. This stage is most likely: - S phase. - cytokinesis. - mitosis. - G1 phase.
S phase
Which of the answer choices is true about gametes?: - They are genetically identical to other gametes formed during meiosis. - They are formed by mitotic cell division. - They are found in animals but not plants. - They have the same number of chromosomes as a somatic cell of the same individual. - They fuse to form a new organism during fertilization.
They fuse to form a new organism during fertilization
There are no discernible phenotypic effects for an individual with the genotype XXY: True of False
True
The process of cell division in a prokaryotic cell is called: - binary fission - mitosis - cytokinesis - binary fusion
binary fission
A protein that has regular up-and-down pattern of abundance during the cell cycle and that triggers progress of the cell cycle by activating kinases is called a: - protein kinase. - cyclin-CDK complex. - cyclin dependent kinase. - cyclin.
cyclin
Crossing over occurs during which step in meiosis? - metaphase I - anaphase I - prophase II - prophase I
prophase I
What type of gene is c-src (cellular-src)? - growth factor - oncogene - tumor suppressor - proto-oncogene
proto-oncogene
Reproduction by mitotic cell division: - does not require the replication of chromosomes. - involves the formation of gametes. - results in two daughter cells that are genetically identical. - reduces the number of chromosomes by half.
results in two daughter cells that are genetically identical
Joan Caron found that culturing liver cells with an extracellular matrix containing laminin altered gene expression and increased the cellular expression of mRNA for albumin. Which answer option is most likely to have caused the change in gene expression in cells cultured with laminin? - formation of hemidesmosomes with the basal lamina by liver cells - binding of laminin-bound cadherins on the liver cells - signaling through laminin-bound integrins on the liver cells
signaling through laminin-bound integrins on the liver cells
Second-division nondisjunction occurs when: - homologous pairs fail to separate during anaphase I. - homologous pairs fail to separate during anaphase II. - homologous pairs fail to separate during mitosis. - sister chromatids fail to separate during anaphase II. - sister chromatids fail to separate during anaphase I.
sister chromatids fail to separate during anaphase II
Metastatic cancer cells have a dynamic actin cytoskeleton associated with their plasma membrane. The presence of the membrane cytoskeleton most likely accounts for: - the high mutation rate in cancer cells. - All of these choices are correct. - the high cell division rate in cancer cells. - the ability of these cells to move and crawl to new locations in the body.
the ability of these cells to move and crawl to new locations in the body
Synapsis
the fusion of chromosome pairs at the start of meiosis.
Many scientists are working to generate organs in vitro. In some cases, cells are seeded onto a "scaffold" shaped like the desired target organ. Such scaffolds are likely composed of extracellular matrix proteins. - true - false
true
Proteins whose normal activities inhibit the cell cycle are: - sarcomas - oncogenes - tumor suppressors - proto-oncogenes
tumor supressors
