cell and developmental quiz questions

What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only? a. The cells produced would get smaller and smaller. b. Cells would get larger and larger. c. The mitotic spindle could not assemble. d. Cells would not be able to replicate their DNA.

a. The cells produced would get smaller and smaller.

in paracrine signaling, the signaling molecule... a. acts on cells in close proximity to the secreting cell b. acts on target cells far away from the secreting cell c. acts on the same cells that secrete the signaling cell d. is carried to the target cells by the blood

a. acts on cells in close proximity

In which phase of the cell cycle do cells check to determine whether the DNA is fully and correctly replicated? a. at the end of G2 b. at the transition between G1 and S c. during M d. when cells enter G0

a. at the end of G2

When cells respond to an extracellular signal, they most often convert the information carried by this molecule from one form to another. What is this process called? a. signal transduction b. signal integration c. signal amplification d. signal detection

a. signal transduction

how are signals generated by a sending cell transported over long distances to a receiving cell? a. via the blood stream b. via the extracellular matrix c. via metastasis d. via second messengers

a. via the blood stream

Which of the following is the correct series of events leading to the creation of a new cell? a. G1 - M - cytokinesis - S - G2 b. G1 - G2 - S - M - cytokinesis c. G1 - cytokinesis - S - M - G2 d. G1 - S - G2 - M - cytokinesis

d. G1 - S - G2 - M - cytokinesis

Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G2? a. The cell would be unable to enter M phase. b. The cell would pass through M phase more slowly than normal cells c. The cell would be unable to enter G2. d. The cell would enter M phase under conditions when normal cells would not.

d. The cell would enter M phase under conditions when normal cells would not.

The TGFβ superfamily of receptors are membrane-bound receptor tyrosine kinases. Dimerization of TGFβ receptors causes.... a. activation of the signaling pathway via glycosylation. b. repression of the signaling pathway via phosphorylation. c. activation of the signaling pathway via nitrosylation. d. activation of the signaling pathway via phosphorylation.

d. activation of the signaling pathway via phosphorylation.

Cell cycle events monitored by checkpoint pathways include a. spindle position. b. DNA damage. c. cell growth. d. all of the other answers are correct

d. all of the other answers are correct

cyclins.... a. propel the cell cycle forward by regulating the stage in which they are expressed, and set in motion the preparation events necessary for the next stage. b. are present only during the cell cycle stage that they trigger. c. bind and activate cyclin-dependent kinases. d. all of the other answers are correct

d. all of the other answers are correct

what kind of cell behavior could be elicited by receiving an extracellular signal? a. cell movement b. cell proliferation c. cell death d. all of the other answers are correct

d. all the other answers are correct

Programmed cell death occurs ________________. a. rarely and selectively only during animal development. b. only during embryonic development. c. only in unhealthy or abnormal cells. d. by means of an intracellular suicide program.

d. by means of an intracellular suicide program.

which is true of signal integration? a. It relies on positive and negative feedback amplifying and dampening a signal. b. It might involve a kinase in one signaling pathway inactivating a kinase in another pathway. c. It can only take place between receptors of the same class. d. It takes place when a single, activated target protein delivers a signal to many downstream effectors.

b. It might involve a kinase in one signaling pathway inactivating a kinase in another pathway.

Which of the following statements about the cell cycle is false? a. An unfavorable environment can cause cells to arrest in G1. b. Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells. c. A cell has more DNA during G2 than it did in G1. d. The cleavage divisions that occur in an early embryo have short G1 and G2 phases.

b. Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eukaryotic cells.

How can loss-of-function methods such as RNA interference or CRISPR, be used to assess the role of a protein in cell signaling? a. They can be used to produce intracellular second messenger molecules. b. They can be used to shut down genes encoding components of a signaling pathway. c. They can be used to isolate the proteins involved in a signaling pathway. d. They can be used to introduce into cells the genes encoding components of a signaling pathway.

b. They can be used to shut down genes encoding components of a signaling pathway.

Of the following mutations, which are likely to cause cell-cycle arrest? a. a mutation that destroyed the kinase activity of S-Cdk b. a mutation in a gene encoding a cell-surface mitogen receptor that makes the receptor active even in the absence of the mitogen c. a mutation that allowed G1-Cdk to be active independently of its phosphorylation status d. a mutation that inhibited the activity of Rb

b. a mutation in a gene encoding a cell-surface mitogen receptor that makes the receptor active even in the absence of the mitogen

The growth factor Superchick stimulates the proliferation of cultured chicken cells. The receptor that binds Superchick is a receptor tyrosine kinase (RTK), and many chicken tumor cell lines have mutations in the gene that encodes this receptor. Which of the following types of mutation would be expected to promote uncontrolled cell proliferation? a. a mutation that destroys the kinase activity of the receptor b. a mutation that inactivates the protein tyrosine phosphatase that normally removes the phosphates from tyrosines on the activated receptor c. a mutation that prevents the binding of the normal extracellular signal to the receptor d. a mutation that prevents dimerization of the receptor

b. a mutation that inactivates the protein tyrosine phosphatase that normally removes the phosphates from tyrosines on the activated receptor

Mitogens are _____. a. kinases that cause cells to grow in size. b. extracellular signals that stimulate cell division. c. transcription factors important for cyclin production. d. produced by mitotic cells to keep nearby neighboring cells from dividing.

b. extracellular signals that stimulate cell division.

foreign substances like nicotine, morphine, and menthol exert their initial effects by _______. a. killing cells immediately, exerting their physiological effects by causing cell death. b. interacting with cell-surface receptors, causing the receptors to transduce signal inappropriately in the absence of the normal stimulus. c. removing cell-surface receptors from the plasma membrane. d. diffusing through cell plasma membranes and binding to transcription factors to change gene expression.

b. interacting with cell-surface receptors, causing the receptors to transduce signal inappropriately in the absence of the normal stimulus.

Enzymes that add a phosphate group to a switch protein are called? a. phosphatases b. kinases c. GTPases d. G-proteins

b. kinases

What type of cell response would take the longest amount of time (on the scale of minutes to hours) to execute? a. one that involves the firing of an action potential along a neuron b. one that involves a change in gene expression c. one that uses a phosphorylation event to activate an enzyme d. one that involves the release of secretory vesicles

b. one that involves a change in gene expression

The creation of cells from pre-existing cells via a regulated cycle of events is known as... a. procreation b. proliferation c. procrastination d. proletariat

b. proliferation

Which molecule performs the primary signal transduction step in cell signaling? a. intracellular protein kinase b. receptor protein c. scaffold protein d. transcription regulator

b. receptor protein

Which of the following events does not usually occur during interphase? a. DNA is replicated b. the nuclear envelope breaks down c. the centrosomes are duplicated d. cells grow in size

b. the nuclear envelope breaks down

Progression through the cell cycle requires a cyclin to bind to a Cdk because _________. a. without cyclin binding, a cell-cycle checkpoint will be activated. b. cyclin binding inhibits Cdk activity until the appropriate time in the cell cycle. c. the cyclins are the molecules with the enzymatic activity in the complex. d. the binding of a cyclin to Cdk is required for Cdk enzymatic activity.

d. the binding of a cyclin to Cdk is required for Cdk enzymatic activity.

Which of the following is true? a. Because endocrine signals are broadcast throughout the body, all cells will respond to the hormonal signal. b. Paracrine signaling involves the secretion of signals into the bloodstream for distribution throughout the organism. c. The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling. d. The axons of neurons typically signal target cells using membrane-bound signaling molecules that act on receptors in the target cells.

c. The regulation of inflammatory responses at the site of an infection is an example of paracrine signaling.

Under what condition will a target cell always respond quickly to an extracellular signal? a. The response relies on second messengers. b. The signal molecules binds to an intracellular receptor. c. The response does not require changes in gene expression. d. The signal molecule is present in high concentrations.

c. The response does not require changes in gene expression.

Which of the following mechanisms is not directly involved in inactivating an activated RTK? a. dephosphorylation by protein tyrosine phosphatases b. removal of the RTK from the plasma membrane by endocytosis c. dephosphorylation by serine/threonine phosphatases d. digestion of the RTK in lysosomes

c. dephosphorylation by serine/threonine phosphatases

What kinds of molecules act as extracellular signals? a. lipids b. ions c. proteins d. all the answers are correct

c. proteins

What is true of the GTP-binding proteins that act as molecular switches inside cells? a. they are active only in their trimeric forms b. they turn themselves on by phosphorylation GDP to form GTP c. they are active when GTP is bound d. they are active when GDP is bound

c. they are active when GTP is bound

BrdU and EdU are frequently used as assays to measure the number of actively proliferating cells. Why does the incorporation of these synthetic nucleotides into cellular DNA reflect active cell proliferation? a. BrdU and EdU are analogs of thymidine, and are added to the new DNA strand at replication. b. BrdU and EdU are necessary for cells to divide. c. BrdU and EdU are fluorescent, so cells take up the reagents when the nuclear envelope breaks down. d. BrdU and EdU are analogs of ATP, which is necessary for cells to proliferate.

a. BrdU and EdU are analogs of thymidine, and are added to the new DNA strand at replication.

Which statement about cell signaling is correct? a. All cell types are able to respond to the same set of signal molecules. b. Each type of extracellular signal molecule induces the same response in all target cells. c. Each receptor is generally activated by only one type of signal molecule. d. Each receptor triggers one particular type of cell behavior, for example, activating gene expression.

c. Each receptor is generally activated by only one type of signal molecule.

which of the following statements is true? a. A cell-surface receptor capable of binding only one type of signal molecule can mediate only one kind of cell response. b. To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol. c. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior. d. Any foreign substance that binds to a receptor for a normal signal molecule will always induce the same response that is produced by that signal molecule on the same cell type.

c. Extracellular signal molecules that are hydrophilic must bind to a cell-surface receptor so as to signal a target cell to change its behavior.

Commitment of a cell to a new cell division (referred to as "START") occurs in a. G2 b. M c. G1 d. S

c. G1