________ form a small group of proteins that bind to GPCRs and compete for binding to those GPCRs with heterotrimeric G proteins.
Arrestins
_____ is formed from the amino acid L-______ in a reaction catalyzed by the enzyme _____.
Nitric oxide, arginine, nitric oxide synthase
The process that blocks active receptors from turning on additional G proteins is called ________.
desensitization
What molecule is responsible for activating Rsk-2?
MAPK
_________ are enzymes that phosphorylate specific tyrosine residues on protein substrates.
Protein-tyrosine kinases
Why do colds cause us to lose some of our appreciation for the taste of food?
The symptoms of colds prevent stimuli from reaching olfactory neurons efficiently, thus dulling the perception of taste.
What group of enzymes phosphorylates most of the carbons on inositol?
phosphoinositide kinases
Accessory proteins that maintain monomeric G proteins in an inactive state by inhibiting GDP-GTP exchange are called:
GDIs
The concentration of calcium ions in the ER lumen, the plant cell vacuole and the extracellular space are on average more than _______ times higher than in the cytosol.
10.000
What does the interaction between arrestin and clathrin promote?
the uptake of phosphorylated GPCRs into the cell by endocytosis
How can one identify oncogenes?
by introducing the DNA suspected of containing the oncogene into cultured cells and looking for altered growth properties
What happens if one cultures cells from a tumor lacking a functional RB gene after reintroducing a wild-type copy of the gene into those cells?
The cancer phenotype disappears.
__________ is new blood vessel formation.
Angiogenesis
What generally happens if cells that have been transformed into cancer cells in culture by carcinogenic chemicals or viruses are introduced into a host animal?
They generally cause tumors in the host animal.
What is the name for tiny regulatory RNAs that negatively regulate the expression of target mRNAs?
microRNAs
A well-known cell-survival pathway involves a kinase called _______ that is activated by the _______, leading to a larger chance that the cell will survive a stimulus that would normally lead to its destruction.
PKB, phosphoinositide PIP3
The fact that tumor cells depend, in many cases, on glycolysis may reflect ________.
the high metabolic requirements of cancer cells and an inadequate blood supply within the tumor
A lack of a functional TP53 gene __________.
causes a cell carrying damaged DNA to fail to be destroyed
and
will allow genetically unstable cells to continue to divide
Which of the following enzymes is known to be expressed at a high level in the cancer cells of patients suffering from acute myeloid leukemia and at low levels in the cancer cells of patients suffering from acute lymphoblastic leukemia?
catalase
Whether a cell lives or dies after a particular event depends to a large degree on ________ between ________ and _________ signals.
the balance, proapoptotic, antiapoptotic
Which of the following features would be a requirement for a receptor that exhibits ligand-mediated dimerization?
The ligand has two binding sites for receptors.
How were nitroglycerine's therapeutic benefits discovered?
the fact that dynamite factory workers with heart conditions had less angina on days that they worked
The _________ pathway of apoptosis is one in which external stimuli activate apoptosis via a signaling pathway.
extrinsic
What kind of enzyme is the RAS gene product, the Ras protein?
a GTPase
Which of the following processes is not regulated by eicosanoids?
neurotransmission
What can cause the stockpile of intracellular calcium ions to be depleted?
periods of repeated cellular responses
In which organism below has calmodulin not been found?
bacteria
In order to begin desensitization, the ________ domain of the activated G protein-coupled receptor is phosphorylated by a specific enzyme called a(n) ________.
cytoplasmic, G protein-coupled receptor kinase
While bound to phosphorylated GPCRs, to what else can arrestins bind?
clathrin molecules in clathrin-coated pits
From what molecule are the steroids derived?
cholesterol
Why do tumor viruses transform normal cells into cancer cells?
They carry genes whose products interfere with the cell's normal growth-regulating activities.
Which of the following is not a mechanism of action for a small-molecule targeted therapy?
Inhibition of estrogen synthesis
___________ of miRNAs ____________.
Expression; has been shown inhibit the expression of human oncogenes, abnormal expression; has been implicated as a causal factor in tumor cell invasiveness and metastasis and, expression; has been shown inhibit the expression of RAS and MYC
Which cells generally lack the ability to divide?
differentiated end products of a tissue
Which type of new screening test will be able to identify cancers based on the presence of specific genes associated with various types of cancer?
genomics
Chronic infection with what stomach-dwelling bacterium has been associated with certain gastric lymphomas?
Helicobacter pylori
Retinoblastoma is inherited as a ____________.
dominant genetic trait
How might blocking angiogenesis have a negative impact as a cancer treatment?
by creating a more O2-deficient environment for the tumor cells, and by driving tumor cells to seek out other sites in the body
For what disease has the human monoclonal antibody Arzerra been approved for treatment?
chronic lymphocytic leukemia
What generally happens if cells that have been transformed into cancer cells in culture by carcinogenic chemicals or viruses are introduced into a host animal?
They generally cause tumors in the host animal.
Which of the following enzymes is known to be expressed at a high level in the cancer cells of patients suffering from acute myeloid leukemia and at low levels in the cancer cells of patients suffering from acute lymphoblastic leukemia?
catalase
What is unusual about the inheritance of retinoblastoma, given that it appears to be inherited as a dominant trait?
Not all children who inherited the RB deletion developed retinoblastoma.
If any of the proteins involved in mismatch repair are damaged, the mutation rate and cancer risk will rise; this is called the ___________.
mutator phenotype
The cancer vaccine DCVax utilizes which type of cells from the patient?
dendritic cells
Which one of the following viruses does not appear to be linked to human cancers?
rhinovirus
Mutant forms of which of the following genes have been associated with melanomas and colorectal cancers, respectively?
BRAF and APC
What part of the cell cycle does the pRB protein help to regulate?
the G1 - S transition
Which of the genes below would be a viral gene?
par
With respect to cancer genetics and the cancer genome, what are passenger genes?
genes that are subject to mutation but have no effect on the phenotype of a cancer cell
What happens quite often to the number of normal receptors in the plasma membranes of malignant cells as compared to normal cells?
Malignant cells usually have a much larger number of plasma membrane receptors than normal cells.
What is responsible for deactivating glycogen synthase kinase-3?
its phosphorylation by PKB
Following a nerve impulse, what triggers the opening of plasma
membrane voltage-gated Ca2+
channels?
membrane depolarization
Which of the following are not natural ligands that bind to G-protein coupled receptors?
steroid hormones
Where is the guanine nucleotide-binding site of the G protein located?
on the Gα subunit
The subunits of the heterotrimeric G protein are called ___________ subunits.
α, β and γ
From what molecule are the steroids derived?
cholesterol
What happens to cells if the receptors are degraded once they are internalized?
The cells lose, at least temporarily, sensitivity for the ligand in question.
How are drug companies trying to combat the ability of the BCL-2 gene to lower the effectiveness of chemotherapy?
They are trying to develop drugs that make cancer cells more likely to undergo apoptosis.
Which molecule do Bexxar and Zevalin antibodies attack?
CD20
What types of genetic alterations might make humans more likely to develop a particular type of cancer?
those that a human obtains from his/her parents and those that occur during a human’s lifetime
You study two cell lines. In one, the MDM2 protein is overexpressed; in the other the p53 protein is absent. What difference would you expect in the behavior of these two cell lines?
In cells containing overexpressed MDM2, p53 levels will be low; in cells lacking the TP53 gene, p53 levels are also low; thus there is no difference in behavior.
Studies of identical twins suggest that ________. (Select the best answer).
the genes we inherit have a significant influence on our risks of
developing cancer,
and the greatest impact on cancer development
comes from genes altered during our lifetime
What evidence suggested that the elevated sensitivity of cancer cells to radiation therapy and chemotherapy was not due to their more rapid division?
Some cancer cells divide more slowly than their normal counterparts, yet they are still more sensitive to drugs and radiation than are normal cells.
Who made the first known correlation between environmental agents and cancer development?
Percivall Pott
Why can cancer cells proliferate in the absence of serum?
The cell cycle of cancer cells does not depend on signals transmitted from serum growth-factor receptors located at their surface.
What is the name of a calcium-binding protein that acts in conjunction with calcium to bring about the responses associated with cytoplasmic rises in calcium ion concentration?
calmodulin
To which amino acid is nitric oxide added, altering the activity, turnover and/or interactions of proteins like hemoglobin, Ras, ryanodine channels and caspases?
cysteine
The passage of signals back and forth between different pathways is referred to as _________.
crosstalk
Type I diabetes is caused by ________.
an inability to produce insulin
For many years, _______ was the only member of the GPCR superfamily to have its X-ray crystal structure determined.
rhodopsin
Once activated, what does caspase-9 itself activate?
downstream executioner caspases
What is the largest protein superfamily encoded by animal genomes?
G-protein coupled receptors
Viruses that carry their genetic information in the form of RNA are called ________.
retroviruses
Which type of new screening test will be able to identify cancers based on the relative levels of various proteins in the blood?
proteomics
What happens to a cell that is carrying damaged DNA if both of its TP53 alleles become inactivated?
It lacks the genetic integrity required for controlled growth and it fails to be destroyed
A single layer of cells that covers a culture dish is called a(n) _________.
monolayer
After his initial discoveries and for the rest of his life, Coley tried to develop a ______ extract that when injected under the skin would stimulate a patient's immune system to destroy their malignancy. His approach called ________ worked against some uncommon__________.
bacterial, Coley's toxin, soft-tissue sarcomas
What is a humanized monoclonal antibody, as used in passive immunotherapy?
A human antibody with an antigen recognition surface of mouse origin
The addition of nitric oxide to the sulfhydryl groups of certain cysteine residues in a number of proteins, including hemoglobin, Ras, ryanodine channels and caspases alters the activity, turnover or interactions of the proteins. This posttranslational modification is called _______
S-nitrosylation
What part of an insulin-receptor substrate binds to tyrosine phosphorylation sites on the activated insulin receptor?
a PTB protein
What enzyme below does diacylglycerol (DAG) recruit and activate?
protein kinase C
How is signaling by an activated Gα subunit terminated?
The bound GTP is hydrolyzed to GDP
Where are steroid receptors generally located and where do they bind the steroid hormone once it enters the cell?
They are located and bind steroids in the cytoplasm
In cells exposed to stressful stimuli, like X-rays or damaging chemicals, what response does the MAP kinase cascade coordinate?
withdrawal from the cell cycle
Which of the following supports the ligand-mediated model of receptor dimerization?
Some growth and differentiation factors like PDGF or CSF-1 are composed of two similar or identical disulfide-linked subunits, each of which has a binding site for a receptor
Evidence suggests that TNFR1 is present in the plasma membrane as __________.
a preassembled trimer
Which cells secrete epinephrine?
medulla cells in the adrenal gland
How is the distribution of free calcium ions in the living cell detected?
fluorescent probes that emit light in the presence of calcium ions
Why did the smooth muscle in cultured strips of aorta not respond to acetylcholine by relaxing, while the smooth muscle of aortic rings did?
The delicate endothelial layer in aortal strips had been rubbed away during dissection, while in aortal rings it remained intact.
Ora1 is a tetrameric _______ that has been identified as being involved in a particular type of inherited human immune deficiency that results from a lack of Ca2+ stores in ________.
Ca2+-ion channel, T lymphocytes
perception of sour taste depends upon ____.
protons in the food that enter cation channels in the taste receptor plasma membrane, leading to a membrane depolarization
About 25% of breast cancers are composed of cells that overexpress the HER2 gene. What property does the overexpression of this gene confer upon the tumor cells?
These cells are especially sensitive to growth factor stimulation
The BCL-2 oncogene is the oncogene most closely linked to _________; it encodes a membrane-bound ____________.
apoptosis, protein that normally acts to inhibit apoptosis
William Coley, a New York physician in the late 1800s, studied spontaneous remissions of terminal cancer cases. He read that one man, who had an inoperable neck tumor, had gone into remission after what event?
After a streptococcal infection beneath his skin
What virus seems to be related to the development of Burkitt's lymphoma in African patients, while it is associated only with minor infections, like mononucleosis, in the Western world?
Epstein-Barr virus
Another word for malignant transformation is ________.
tumorigenesis
What enzyme is responsible for maintaining the length of the DNA sequences on the ends of chromosomes (telomeres)?
telomerase
Patients suffering from familial adenomatous polyposis coli have typically been found to have _________, which is the site of the _________.
a small chromosome 5 deletion, APC oncogene
Judah Folkmann suggested that solid tumors __________.
might be destroyed by inhibiting their ability to form new blood vessels
The sis oncogene of the simian sarcoma virus was derived from what normal cellular gene?
the gene for platelet-derived growth factor (PDGF)
After the DNAs attached to the glass slide of a microarray are exposed to a probe, how are they usually visualized?
The cDNA probes are fluorescently labeled.
When telomerase appears in a cell, it is not because the coding sequences of the gene have been changed. Instead, the protein produced is essentially normal, but it is being produced at an abnormal time. A gene that is normally repressed has been activated for some reason. Such an alteration in cell behavior is referred to as a(n) _________ change.
epigenetic