CELL BIO UNIT 3 QUESTIONS

A GAP…

An extracellular signal that is in the vicinity of the cell that secretes it and thereby activates signaling in the surrounding cells is classified as...

Endocytosis of receptors followed by degradation in lysosomes in response to a signal is a mode of...

Which of these domains bind to proline rich sequences?

Which of these is not a type of receptor?

Which of these responses to a signal are likely to occur in seconds?

Which of these is false?

______ cells in select tissues release hormones that are distributed to the rest of the body

Among which of these signaling molecules move farthest away from cells that release them?

Which of these are secreted extra cellular signaling molecules that work only in the neighborhood they are released in?

Electrical impulses sent along a neuronal axon reaches the synapse and triggers secretion of a chemical called...

Charged phosphoinositides are recognized and bound by

Scaffold proteins affect amplification and speed of signal by

Sec homology domains (SH2) bind to which of these residues on activated receptors?

Activation of which of these proteins leads to the activation of a monomeric GTPase by releasing GDP and binding GTP?

Which of these enzymes Phosphorylate a protein by transferring the terminal phosphate from ATP onto a serine, threonine, or tyrosine molecule?

A signaling molecule can generate a strong signaling response that persists even after the signaling molecule is removed and this can be due to

Amplification of response to a signal can be generated when receptor activation leads to generation of a large number of intracellular signaling molecules called...

α subunit of G-protein is bound to _____________, that is replaced with __________________ upon activation of GPCR.

cAMP is synthesized from ATP by............

Response to a signal reaches a maximum level before it shuts itself off followed by another pulse of maximal response even in the presence of the signaling molecule leading to an oscillatory response due to............

PKA is activated by binding of cAMP to the .........

Which type of mutation in the regulatory subunits of PKA would lead to a permanently inactive state?

NO produced in endothelial cells diffuses across the membranes into smooth muscle cells to stimulate synthesis of cGMP by binding to.....

NOS catalyzed deamination of which of these amino acids produces NO?

Cholera toxin activates the alpha subunit of Gs by ADP ribosylation, which.........

Increase in cAMP levels by extracellular signals can be balanced by breakdown of cAMP by enzyme.........

Activation of phospholipase C by G protein leads to .......

Exposure of target cells to prolonged signals can lead to desensitization of GPCR by...................

IP3 produced by phospholipase C activation binds to IP3 receptors and leads to .......

During nervous-system development in Drosophila, the membrane-bound protein Delta acts as an inhibitory signal to prevent neighboring cells from developing into neuronal cells. Delta is involved in ______________ signaling.

If signaling molecules act on the same cells that release them, it is an example of _____ signaling

Monomeric GTPases are in an "ON state" upon binding to

Which of these occur more rapidly in response to a signal

In the following graphs, the cellular response, as measured in real time by the concentration of a certain active effector protein, is plotted over time for five cell types (A to E) that are treated with three different concentrations of a signal molecule. During the time period indicated by the horizontal gray bar, the signal molecule is present in the culture media at a concentration of 1 nM (dotted curve), 5 nM (gray curve), or 25 nM (solid curve). Answer the following question(s) based on these graphs; Which of the cell types A to E shows the fastest signal adaptation?

In the following graphs, the cellular response, as measured in real time by the concentration of a certain active effector protein, is plotted over time for five cell types (A to E) that are treated with three different concentrations of a signal molecule. During the time period indicated by the horizontal gray bar, the signal molecule is present in the culture media at a concentration of 1 nM (dotted curve), 5 nM (gray curve), or 25 nM (solid curve). Answer the following question(s) based on these graphs; Which cell type shows a response with highest persistence?

Which of these best describe the GPCRs?

The length of time a G protein will signal is determined by ____

Which of these statements about nuclear receptors are true?

Mutations that disrupt the tyrosine 1009 and 1021 residues in PDGF receptor.............................

PI 3 kinase....

Which of these do NOT describe notch?

Mutations that disrupt the protease activity of gamma-secretase will...................

Mutations in the SH2 domains of the Grb2 adaptor that inhibit recognition of RTKs will lead to.....................

Activation of the EGF receptor includes which of these mechanisms?

In reference to AKT-dependent regulation of Bad, select the statement that is false?

AKT and ERK activate mTORC1 activity by directly phosphorylating and inhibiting which of these GAPs?

Upon activation of Ras, the final kinase activated in the MAP Kinase module is...........

What of these statements about mTORC1 or mTORC2 are true?

The GEF that activates Rag GTPase is..............

Mutations that inhibit TSC activity leads to the disease- Tuberous Sclerosis that has benign tumors and giant cells and this is due..............

Enhancement of Gator1 GAP activity will lead to.................

In the absence of a Wnt signal.............

Degradation of Beta-Catenin by the proteasome is stimulated by..................

Which of these events are likely to occur if Beta-Catenin is unable to bind to LEF1/TCF in the presence of Wnt signal?

A receptor tyrosine kinase-A (RTK-A) is activated by binding to a growth factor (GF). Which type of mutation is likely to inhibit the dimerization of RTK.

The two monomers in a TRK dimer phosphorylate each other and the process is called

Which of the following mechanisms is not directly involved in inactivation an activated RTK

Activation of notch is irreversible

All GPCRs act by increasing cAMP?

What domain of son of sevenless (Sos) recruits it to the plasma membrane so that it gets in close proximity to Grb2?

Mutations altering the GPCR binding interface in arrestin are likely to..................

For Notch to be recognized by Delta, it has to be transported to the..............

PI3 Kinase primarily phosphorylates...............

Which of these enzymes is bound to the cytosolic side of the plasma membrane and converts PI(4,5)P2 to IP3 and diacylglycerol?

Why doesn't the beta subunit of the trimeric G-protein need a lipid anchor like the alpha and gamma subunits?

Select the mechanism of activation of AKT by PI-3K ?

G-proteins are bound to GPCRs......................

Mutations in Ras are found in a majority of cancers. Which of these mutations will lead to permanent activation of Ras-signaling?

Which of these kinases is activated by binding to diacylglycerol that is released by breakdown of PI(4,5)P2?

Which of these factors belong to a family of local mediators that were originally identified as the gene important for wing development in Drosophila?

Which mechanism is NOT likely to sharpen the cellular response to a signal?

DNA replication is initiated by____________.

M-Cdk complex is activated by_______.

CKIs such as p27 ____________.

Cdk activity is stimulated by phosphorylation of the T-loop by ________.

EdU incorporation marks cells in..........

M-cyclin _______________.

Which of these techniques can be used to separate cells rapidly based on their fluorescence signal corresponding to their DNA content?

Cdk activity fluctuates during the cell cycle, partly because ________________.

Which of these statements about Cdc25 phosphatase is true?

One half of a duplicated chromosome at the end of S phase is called

A key control system crucial for triggering cytokinesis is.............

If cell cycles were repeated with only the S phase and M phases, what is likely to occur?

Which of these fluorescently-tagged proteins can be used to monitor G2 phase in live cells?

Which of these factors inactivates Cdks by adding phosphates on specific sites on Cdks?

Activation of Greatwall kinase...........

Mutations in Ensa that prevents its binding to PP2A-B55 will...........

Which of these mechanisms serve as positive feedback to activate M-Cdks?

CAK-dependent phosphorylation of M-Cdk is sufficient to fully activate M-Cdk activity even in the presence of Cdk phosphorylation by Wee1?

Which of the following events does not usually occur during interphase?

Progression through the cell cycle requires a cyclin to bind to a Cdk because________.

Substrate specificity is highly dependent on which of these submits of PP2A phosphatase?

Cdt1 is activated by ____________.

During metaphase..................

Condensins ________________.

Cdc20-APC and Cdh1-APC complexes are similar because........................

ORC is phosphorylated in which phase?

DNA helicase deposition on DNA at the replication origins occurs mainly in which phase of cell cycle?

At the beginning of S phase in a cycling cell, which of these events are likely to occur?

In the metaphase to anaphase transition, activation of which of these factors is important?

Which of these complexes keep M-cyclin levels low in G1 phase of cell cycle?

S-cdk ensures that replication happens only once per cell cycle- how?

If a cell in G1 phase and another cell in G0 phase are induced to pass the restriction point by the addition of a signaling molecule, but the signal is then immediately removed, what is likely to occur?

Disassembly of nuclear envelope marks which phase of mitosis?

Which statement is false?
A. CDC25 activity is further stimulated by M Cdk phosphorylation, which creates a positive feedback for M Cdk activity
B. Wee1 activity is inhibited by M Cdk phosphorylation, which creates a positive feedback for M Cdk activity
C. Activation of M CDK activates PP2A-B55

Which complex of APC/C is active in early G1

Activation of APC/C is important for..

Activation of which of these factors inhibit MCM2 loading onto DNA?

At the end of DNA replication, the sister chromatids are held together by the...

The concentration of M cyclin _________

Which of these statements about APC is false?

Which of these proteins play a direct role in anaphase B?

Which of these motor proteins are minus-end directed motors that cross link interpolar microtubules and pull the poles together?

Duplication of centrosomes occurs in ________.

Polar ejection force that pulls chromosomes to the spindle equator is mediated by ______.

The polar ejection force does which of the following?

Which of the following statements is TRUE?

Some cell types in animals do not have centrosomes and therefore they do not have....

The plus ends of these microtubules are attached to large protein structures at the centromeres and they are called..............

Proper bi-orientation of the sister-chromatid pair on the spindle generates a tension that is sensed by_____.

Degradation of securin is important for ________.

The length of a kinetochore microtubule does not change much during metaphase because there is no addition or removal of tubulin subunits

Which statement about centrosomes is TRUE?

Contractile ring is made of ________.

Disassembly of the nuclear envelope ________________.

Which statement about kinetochores is true?

Which event indicated below happens before the nuclear envelope is re-assembled in M phase?

Which statement about drugs targeting microtubules is FALSE?

Consider the centrosome duplication cycle and in relation to replication, is centrosome duplication:

For MT organization in mitosis chromosomes are not as important as centrosome

Centriole tether is broken at what phase?

Separase is kept inactive due to:

Actin and myosin filaments are also main components of mitotic spindle

What are mitogens?

DNA damage induced checkpoint response in G1 ________________.

UV exposure can cause DNA damage. Which of the following would you NOT expect to occur as a result of genomic damage?

Which event contributes to helping the cells progress from G1 to S phase?

Which of these is an immediate early gene whose expression is triggered by Ras activation to promote cell cycle entry?

ATM and ATR kinases phosphorylate Ser-15 residue in p53 which________.

G1/S Cdk also phosphorylates and inactivates APC/C towards end of G1 phase, which directly helps in accumulation of ..................

Retinoblastoma is caused by excessive proliferation of some cells in retina that is induced by ..................

The Chk1-mediated checkpoint response to DNA damage can arrest cells in G2/M phase by inhibiting which of these factors?

Which of these is the purpose of activating cell cycle checkpoint responses to DNA damage?

p53 expression is often lost in early stages of cancer development, and in the absence of p53, which of these factors serve to initiate key cell cycle checkpoint-response to DNA damage? (see lecture-8 ppt.)

A regulator critical for enhancing cell growth through stimulation of protein synthesis rates is ...........

Metastasis is...

The rate at which mutations occur in the cells within a tumor is most likely.....

Epigenetic silencing includes

Tumor cells contain mutations that are not derived from germ cells and they are called..................

Somatic mutations are not as prevalent in cancers compared to inherited mutations.

Which statement about cell cycle mutations is TRUE?

Incidence of cancers rises steeply with age because....................

Which of these statements about tumor-stroma relationship is FALSE?

Contact inhibition is a feature where...................

Extensive chromosomal rearrangement and DNA damage in the chromosome of micronuclei is called.......

Which statement about cancer stem cells is FALSE?

Which statement is TRUE with regards to Warburg effect in cancers?

Tumor cells bypass replicative cell senescence by.................

Replicative senescence involves______.

About half of all cancers are thought to arise by infection with viruses, bacteria, or parasites.

An enzyme that normally suppresses PI3K acttivity is inactivated. This is expected to lead to_____.

Complete loss of function of Rb by just one somatic event is seen in _____________.

What is Src?

Which of the following proteins is NOT encoded by a proto-oncogene?

Which of these mutations lead to cancer?

Which of the following stressors can lead to p53 stabilization and activation?

The similarity between Apc in colon cancers and Rb in retinoblastomas is that both ________.

Mutation in which of the following genes is most prevalent in a rare hereditary form of colorectal cancer ?

Mutations in p53 and Rb contribute to many cancers. What type of mutations are these?

Cancer-inducing mutations in these genes are commonly seen in the form of nonsense (truncating) mutations that abort protein synthesis. What are these genes likely to be?

Genetically knocking out both copies of the p53 gene in rats ...

Which of these mutations occur as a result of genomic instability but are not primary regulators of tumor development?

Which of the following is an epigenetic change that coud inactivate a tumor suppressor?

Which statement about Cancers is FALSE?

Which of the following sequential barriers to metastasis is the easiest to overcome for cancer cells in general?

Which group would you expect to have loss-of-function mutations in the DNA mismatch repair system genes MSH2 and MLH1 as their primary driver mutations?

Cancer-inducing mutations in these genes include gene duplications and these genes are likely to be...............

Bioluminescence imaging can track cancer cells in mice by capturing the activity of which of the following proteins?

Which of the following is NOT a consequence of high AKT activity?

Abl kinase is made hyperactive in CML by which of the following mechanisms?

Secondary mutations in the kinase domain of Bcr-Abl that prevent the binding of Imatinib......

Which statement is false?

The progression from early adenoma to intermediate adenoma in most cases of colorectal cancers is caused by...........

Most DNA tumor viruses inhibit these protein products ____.

Which of these statements about Human Papilloma Virus is FALSE?

In Ames test, the potential mutagen is metabolically activated by mixing it with____.

Imatinib has been used to treat patients with CML with much success by targeting____

Development of drugs to target cancers can be aided by understanding the molecular mechanisms that underlie the respective cancers. Which of the following is NOT true regarding such drugs.

For Ames test, special bacteria that lack the ability to grow in the absence of histidine were cultured in media that lacked histidine. However, even after treatment with chemical X, the bacteria were unable to grow in media lacking histidine. The results of the Ames test suggest which of the following:

Cancer epithelial cells lose their polarity and adhesiveness and become more invasive. This process is called............

Which statement about cancer gene alterations is FALSE?

A malignant tumor is more dangerous than a benign tumor because

A single mutation is enough to convert a normal cell to a cancer cell

A great deal of lactate is produced in tumor cells even in the presence of oxygen

The surrounding network of connective tissue that supports the tumor is called

Inhibition of Rb activity by mutation in just one allele is sufficient to cause retinoblastoma

Some genes are important for normal growth but they can have gain of function mutations that make them cancer drivers. These genes before they gain such mutations are called

Which of the following leads to hyper activation of PI3K signaling?

The loss of p53 protein makes some cancer cells less sensitive to irradiation and to some anti cancer drugs, which would otherwise destroy tumors by inducing cell death or by inducing cell cycle arrest

Immediate results of the Ames test will identify:
A. Cancer river mutations
B. Tumor suppresor genes
C. Oncogenes
D. Mutagenic nature of chemicals