Cell Bio Exam Final pt 1

According to the Skin Cancer Foundation website, skin cancer is the most common form of cancer in the United States. More than 3.5 million skin cancers in over two million people are diagnosed annually. Each year there are more new cases of skin cancer than the combined incidence of cancers of the breast, prostate, lung and colon. One in five Americans will develop skin cancer in the course of a lifetime. Over the past 31 years, more people have had skin cancer than all other cancers combined. This is perhaps not surprising, given that skin contains a high proportion of the body's epithelial cells and is exposed to many types of mutagens. Based on this information and the information presented in class, which of the following is TRUE? a) Skin cancers are carcinomas. b) In the U.S., lymphomas and leukemias are more common than skin cancers. c) Skin cancer cells are undergoing apoptosis. d) Hyperplasia is suppressed in skin cancer. e) Skin cancer does not involve metastasis.

A

Actin filaments are found in all of the following EXCEPT the a) flagella of bacteria b) sarcomeres of skeletal muscle cells c) stress fibers of fibroblasts d) microvilli of the intestinal brush border e) contractile rings of dividing animal cells

A

All of the following statements about the type-B cyclin proteins are correct EXCEPT: a) Their presence is required for exit from mitosis b) They are present in cells during the G2 phase c) They are degrade via the ubiquitin pathway d) They activate the Cdc2 kinase e) They are newly synthesized during every cell cycle

A

Anaphase-promoting complex... a) ubiquitylates securin and mitotic cyclin, thereby triggering their destruction and progression through mitosis. b) associates with and activates CDK proteins. c) is an enzyme that degrades CDK proteins. d) associates with caspases and suppresses apoptosis after DNA damage. e) is inhibited by Avastin.

A

If a cell is injured, it can lyse and die in a relatively uncontrolled manner. This process is... a) called 'necrotic cell death'. b) called 'apoptosis'. c) triggered by caspase activation. d) dependent upon cyclin dependent kinases. e) both b and c.

A

Inflammation and cell proliferation involve activation of cyclooxygenase (COX) enzymes. COX enzymes that catalyze the formation of prostaglandins from fatty acids. Prostaglandins are signaling molecules. There are three COX enzymes: COX-1, COX-2, and COX-3. COX-2 activity is basically undetectable in normal tissues, but upregulated during inflammation and in many tumor cells. Nonsterioidal anti-inflammatory drugs (NSAIDs), like aspirin and ibuprofen, inhibit COX enzymes. Recently, a long-term study of aspirin's effects on cardiovascular health revealed that people taking low doses of aspirin for years also had lower incidence of colon cancer. Based on this, which of the following is likely TRUE? a) Prostaglandins promote angiogenesis. b) NSAIDs promote stem cell proliferation. c) COX-2 is a type of CDK. d) Tumor cells do not contain fatty acids. e) Aspirin suppresses apoptosis.

A

Ovaries produce a lot of estrogen. Male transsexuals who use estrogen to give themselves a female appearance have increased risk of breast cancer, but not prostate or skin cancer. What is the most likely explanation for this? a) Estrogen is a mitogen. b) Estrogen is a tumor suppressor. c) Estrogen facilitates DNA repair. d) Estrogen is an oncogene. e) Estrogen is an anti-angiogenesis factor.

A

Selective destruction of which location will greatly reduce the concentration of growth hormone receptors? a) the plasma membrane b) the cytosol c) the nucleus d) the nucleolus

A

The first step in tumor development is usually... a) accumulation of mutations that lead to cell proliferation b) angiogenesis c) metastasis d) progression e) triggered by release of VEGF

A

Type I diabetes is caused by loss of pancreatic beta cells that synthesize and secrete insulin. Usually this cell loss occurs because the patient's immune system attacks and kills the insulin-producing pancreatic beta cells, for reasons that are not yet clear. In 2007, 15 early-stage diabetics in Brazil (the procedure was not approved in the U.S.) were given drugs to increase blood stem cell production. These cells were then harvested and saved while the patients' bone marrow was then killed with chemotherapy. The harvested stem cells were then re-injected, and gave rise to a new immune system that did not attack the remaining pancreatic beta cells. 14 of the 15 patients did not then need insulin injections for several years. Based on this information, which of the following is most likely TRUE? a) The harvested stem cells were pluripotent b) The harvested stem cells differentiated into pancreatic beta cells c) Insulin suppresses cell differentiation d) The patients can now be considered clones e) Pancreatic beta cells are stem cells

A

Which of the following accounts for the extent of proliferation observed in the retrovirus-infected cells NOT treated with growth factors? a) The v-erbB product has a function similar to that of activated EGF receptor b) EGF binds to both the EGF receptor and the v-erbB product c) The v-erbB product activates both the LCGF and the EGF receptors d) The v-erbB product antagonizes the action of the EGF receptor e) The v-erbB product induces secretion of EGF and LCGF

A

Which of the following is most likely to be involved with initiation and/or progression of cancer? a) Loss of G-protein GTPase activity downstream of a growth factor receptor b) Activation of P53 c) Activity of Rb protein, which represses expression of proteins required for cell cycle progression d) Immunotherapy e) Activation of proteases capable of breaking down the basal lamina

A

Which of the following is probably the WORST idea for a cancer treatment? a) An inhibitor of caspases b) An inhibitor of VEGF c) A growth factor inhibitor d) A cyclin inhibitor e) An inhibitor of DNA replication enzymes

A

Which of the following things is TRUE about malignant tumors? a) Malignant tumor cells tend to contain mutations that activate oncogenes. b) Malignant tumor cells tend to have mutations that increase the activity of tumor suppressor proteins. c) Malignant tumors secrete factors that suppress angiogenesis. d) Malignant tumors tend to overexpress cadherins. e) Malignant tumors are all formed from epithelial cells.

A

Which of the following types of mutations is most likely to cause a genetically-linked cancer (e.g. a cancer found more often in related individuals)? a) Mutations in a tumor suppressor gene. b) Mutations that cause an increase in Rb protein. c) Mutations that increase VEGF signaling. d) Mutations that impair MAP kinase signaling pathways. e) Mutations that impair diacylglycerol production.

A

Bcl2 family proteins... a) associate with integrins and the extracellular matrix. b) are intracellular mitochondrial-associated proteins that regulate apoptosis. c) bind to and activate CDK proteins. d) are a type of viral protein that causes leukemia. e) are inhibited by Herceptin.

B

CDK proteins... a) tend to be suppressed in tumor cells. b) must associate with cyclin to be active. c) are caspase-dependent kinases. d) bind actin to form spindle fibers during mitosis. e) are a type of mitogen receptor.

B

Cultured fibroblasts were labeled with radioactive 32P-ortho-phosphate. Subsequent EGF treatment increased the radioactivity detected in a small subset of total cell proteins. Which of the following best explains this finding? a) EGF acts as a protein phosphatase b) EGF activates a protein kinase c) EGF activates an ATPase d) EGF is phosphorylated e) The activated receptor acts as a protein phosphatase

B

Retinoblastoma is a rare rapidly-developing type of retinal cancer that is associated with mutations in the Rb gene. Approximately half of all victims have inherited mutations in the Rb gene. These victims typically develop the disease in childhood. The other cases (termed 'sporadic retinoblastoma') are due to spontaneous mutations. The cure rate for retinoblastoma is among the highest of all cancers: 95-98%. Which of the following things is TRUE about Rb protein? a) Rb protein promotes apoptosis by triggering release of cytochrome C. b) Rb protein is inactivated when it is phosphorylated by active CDK. c) Rb protein is a type of growth factor receptor. d) Rb protein is a small GTPase. e) Rb protein forms a complex with other proteins to repair damaged DNA.

B

Sodium nitrite is added to processed meats (mainly bacon, hot dogs, etc). Nitrite is a preservative (it inhibits bacterial growth) and also enhances the meat's color and taste. Unfortunately, nitrites are converted to nitrosamines during digestion. Nitrosamines are highly carcinogenic, because most amine chemicals are mutagens (they cause mutations). Imagine that a parietal cell is exposed to nitrosamines, becomes mutated, and proliferates into a tumor that is 3 cm in diameter. Which of the following is likely TRUE? a) The stomach will become less acidic. b) The parietal cell probably has a mutation in the P53 gene. c) There will be less CCK2 protein in the stomach. d) The mutant parietal cells secrete less VEGF. e) All of the above.

B

TeloVac is a new vaccine that just recently (April 2011) entered clinical trials for pancreatic cancer in the United Kingdom. Pancreatic cancer has the worst survival rate of any cancer. Any treatment that could help would be extremely valuable. Telovac is a vaccine against telomerase, which many tumor cells tend to overexpress and display on their cell surface. It is hoped that the immune systems in patients vaccinated with TeloVac will attack tumor cells. Telomerase is an enzyme that replaces telomeres. Unless telomeres are replaced, a cell can undergo only a limited number of rounds of DNA replication. Which of the following might be an expected side effect of this vaccine? a) Increased angiogenesis leading to internal bleeding b) Loss of stem cells (causing, for example, gastrointestinal problems, hair loss, or loss of blood cells) c) Increased mutation rates, leading to more cancers d) Insensitivity to morphogens, such that tissues do not develop correctly e) Increased signaling in contact inhibition pathways, such that wounds do not heal

B

The cartoon above refers to the ethical debate concerning use of embryonic stem cells. Which of the following might be a biomedically useful substitute for embryonic stem cells? a) Cytokines b) Induced pluripotent stem cells c) Morphogens d) Bone marrow e) Cell differentiation

B

The diagram to the right shows the cellulose synthase complex. Which of the following is TRUE? a) Cellulose is a polymer of fructose. b) Cellulose is a component of the extracellular matrix. c) Cellulose synthase synthesizes collagen. d) Sucrose synthase is a mitochondrial protein. e) Cellulose is secreted via SNARE-dependent exocytosis.

B

The most common form of diabetes is Type II diabetes. The number of people with Type II diabetes in the U.S. has doubled over the past 15 years. Approximately 8% of the U.S. population now has type II diabetes. In type II diabetes, pancreatic beta cells produce insulin, but other cell types do not respond very well to this insulin. Most often, type II diabetes results from chronically high blood glucose. Type II diabetes is strongly associated with obesity. Which of the following drugs is most likely to help type II diabetics? a) Synthetic glucagon b) Metformin, which suppresses gluconeogenesis (glucose synthesis) in the liver c) BW-414X, a glucose transporter inhibitor d) Firplakinolide, a drug that increases transport of glucose transporters to lysosomes e) CK0106023, a kinesin inhibitor that suppresses movement of secretory vesicles

B

You are trying to develop a drug that will inhibit metastasis. Which of the following types of drugs is most likely to inhibit epithelial tumor metastasis? a) A drug that increases epithelial cell motility. b) A drug that increases epithelial cell adhesion. c) A drug that increases the ability of epithelial cells to secret proteases. d) A drug that promotes the secretion of VEGF. e) A drug that inhibits the ability of epithelial cells to be recognized by the immune system.

B

Cancer cells grown in culture are similar to normal cells grown in culture in that they a) divide an indefinite number of times b) do not display contact inhibition c) require oxygen and nutrients d) proliferate to the same cell density e) require similar levels of growth factors for proliferation

C

Cells which can develop into any type of tissue in an organism are called... a) multipotent stem cells b) pluripotent stem cells c) totipotent stem cells d) iPS cells e) hematopoietic stem cells

C

Hematopoietic stem cells differentiate into blood cells. If you were to compare the stem cells to the differentiated blood cells, which of the following would you most likely find to be TRUE? a) The hematopoietic stem cells have very few membrane receptors, relative to blood cells. b) The hematopoietic stem cells are slowly proliferating, relative to blood cells. c) The hematopoietic stem cells are expressing different genes compared to blood cells. d) The hematopoietic stem cells are terminally differentiated, compared to blood cells. e) The hematopoietic stem cells contain more DNA mutations, compared to blood cells.

C

Medullary thyroid carcinoma is a type of thyroid cancer that occurs in the parafollicular cells. Which of the following can be used as a tumor marker in order to identify medullary carcinoma? a) thyroid hormone b) cell membrane receptors c) abnormal rate of cell division d) epidermal growth factor

C

The level of active mitotic CDK rises and falls during the cell cycle. Which of the following best explains why the levels of active mitotic CDK rise? a) Cyclin is degraded by APC, removing MPF inhibition b) Active MPF that already exists in the cell stimulates APC, which phosphorylates cyclin c) New cyclin is produced, binds CDK, and then undergoes a series of phosphorylation and dephosphorylation reactions to generate active CDK d) Checkpoint proteins trigger a MAP kinase cascade which activates transcription factors such as jun, that promote transcription of CDK protein. e) Lots of things rise. For example, the sun rises every morning, bread rises during cooking, and vampires rise from their graves. CDK basically works the same way as these things. It's best not to question why.

C

Transdifferentiation: 1. The change of a cell or tissue from one differentiated state to another. 2. The differentiation of an already differentiated cell into another type of cell as, for example, a bone cell differentiating into a neuron. Which of the following is TRUE? a) Transdifferentiation requires embryonic stem cells. b) Totipotent stem cells transdifferentiate. c) Transdifferentiation requires changes in gene expression. d) Transdifferentiation likely occurs independent of morphogens. e) Mitochondrial ATPases regenerate irreversibly by processing stem cell lineages uncoupled from the extracellular matrix, thereby leading to synthesis, and most likely initiation, of carcinoma.

C

Which of the following cells is likely be proliferating most rapidly? a) A cell with lots of CDK but no cyclin. b) A cell wherein CDK is not phosphorylated. c) A cell in which phosphorylated CDK is associated with cyclin. d) A cell in which mitochondria are releasing cytochrome C into the cytoplasm. e) A cell in which APC activity is suppressed.

C

Which of the following statements about the EGF and LCGF treatments is LEAST likely? a) Some cell types have receptors for more than one growth factor b) Hepatoma cells have an LCGF receptor but not an EGF receptor c) EGF and LCGF trigger growth by binding with different affinities to the same receptor d) Growth factors show some specificity regarding target cell type e) Both normal and tumor cells can respond to growth factors

C

Which of the following types of mutations would most likely lead to cancer? a) A mutation that makes a chemokine receptor nonfunctional b) A mutation that makes the GTPase RAS inactive c) A mutation that reduces expression of p53 d) A mutation that leads to overexpression of caspases e) A mutation in increases expression of Rb protein

C

A crazy (but brilliant!) scientist wants to clone himself from stem cells and build an army of mad warriors, but is unable to obtain the human stem cells he needs for his plan. Luckily he remembers that plants also have stem cells, and decides to clone himself from plant stem cells. Do you think his plan will work? a) Sure, it might work. A stem cell is a stem cell, and by definition a stem cell can differentiate into any other type of cell. b) Yes, for the reason given in answer a, but ONLY if differentiation of the plant stem cell occurs in the presence of human cells that are needed to provide appropriate cell growth signals (for example, the proper signal that occurs when skin cells separate from the basal lamina). c) The plan will never work because plants do not really have stem cells. d) The plan will not work because plant stem cells can only differentiate into plant cells (in part because the genomes are different between humans and plants). e) The scientist will be able to clone himself fine from the plant cells, but he will not be able to produce more than one clone because the telomeres will get too short.

D

Cancer cells tend to be particularly good at... a) proliferation, apoptosis, basal lamina secretion, and angiogenesis b) proliferation, DNA repair, and basal lamina breakdown c) cell adhesion and inhibition of mitosis d) degrading extracellular matrix and avoiding immune system recognition e) initiating promosis

D

Caspases are... a) proteases activated by APC to degrade cyclin. b) proteins that suppress apoptosis. c) protein kinases. d) activated during apoptosis. e) Proteins that degrade the extracellular matrix to promote metastasis.

D

Cell proliferation during development is typically regulated by growth factor receptors. Which of the following is a type of growth factor receptor? a) The myostatin receptor b) The her2 receptor c) The EGF receptor d) All of the above e) None of the above

D

Cellular proteins destined for secretion are sorted and packaged in the a) lysosomes b) endosomes c) endoplasmic reticulum d) trans golgi network e) peroxisomes

D

The Wartburg effect suggests that... a) tumor cells cannot perform fermentation b) stem cells consume more oxygen than other types of cells c) tumor cells contain higher-than-normal numbers of mitochondria d) rapidly proliferating cells produce more lactic acid than cells in cell cycle arrest e) tumor cells do not require ATP

D

Where are stem cells found? a) Bone marrow b) epidermis (skin) c) Adult humans d) All of the above e) None of the above

D

Which is NOT characteristic of most malignant tumor cells? a) An ability to proliferate in the absence of growth factors. b) Inhibition of apoptosis. c) An ability to replicate beyond normal limits. d) Suppression of angiogenesis e) A decrease in cell adhesion and/or increase in motility

D

Which of the following does NOT normally occur in healthy developing tissue? a) Differentiation b) Angiogenesis c) Apoptosis d) All of the above normally occur in healthy developing tissue. e) None of the above normally occur in healthy developing tissue.

D

Which of the following is TRUE about angiogenesis? a) It leads to necrotic cell death. b) It leads to p53 activation and subsequent cell 'suicide'. c) It is inhibited by VEGF. d) It is typically increased in malignant tumors. e) It is caused by release of avastin from epithelial cells.

D

Which of the following is an example of cell differentiation? a) Apoptosis b) Binding of a chemokine to a receptor tyrosine kinase c) Phosphorylation of Rb protein d) Increased expression of matrix metalloproteases by tumor cells e) Sloughing (shedding) of keratinized skin cells

D

Which of the following statements about the cell cycle is TRUE? a) The activity of cyclin/CDK protein complexes determine whether a cell will progress through the cell cycle. b) Cells which are not activity progressing through the cell cycle are said to be 'arrested'. c) Relatively rapid and uncontrolled progression through the cell cycle leads to hyperplasia. d) All of the above are true. e) None of the above are true.

D

Which of the following statements is TRUE? a) Necrosis is the first stage of apoptosis. b) Cells typically lyse during apoptosis. c) Apoptosis is triggered by active CDK. d) Caspase activation leads to apoptosis. e) Caspases cause polyubiquitination of cyclin.

D

Which of the following would likely be the best anti-cancer drug? a) A drug that promoted CDK activity b) A drug that suppressed DNA repair c) A drug that inhibited cadherin function d) A drug that inhibited APC e) A drug that suppressed apoptosis

D

'Ischemia' is the medical term for loss of blood flow to tissues. Ischemia deprives affected tissues of nutrients and oxygen. The cells in these tissues eventually undergo necrotic cell death. Which of the following is TRUE in cells undergoing ischemic cell death? a) Pro-apoptotic proteins (e.g. Bax) accumulate in the mitochondrial cell membrane, and the mitochondria then release cytochrome c into the cytoplasm. b) Caspases degrade cytoskeletal and other proteins. c) Protein complexes called 'apoptosomes' form and activate caspases. d) All of the above e) None of the above

E

Elevation of intracellular inositol trisphosphate (IP3) results in a release of Ca2+ from which of the following organelles? a) peroxisome b) lysosome c) mitchondiron d) nucleus e) smooth endoplasmic reticulum

E

If you were to clone yourself, which of the following would be TRUE? a) The clone would be the same age as you. b) The clone would have your memories. c) The clone's genome would have the same epigenetic modifications. d) All of the above. e) None of the above.

E

Now imagine that the tumor (described in question #41) is removed, and the tumor cells are studied in detail. Which of the following things do you think is most likely to be TRUE? a) The tumor cells show decreased cyclin/CDK activity b) The tumor cells have mutations that inactivate the CDK1 gene promoter c) Microtubules in the tumors cells cannot form properly d) The tumor cells have become prokaryotic e) None of the above is likely to be true

E

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that is encoded by a proto-oncogene. Which of the following is therefore TRUE? a) Mutations that disrupt EGFR's ability to autophosphorylate will likely cause cancer. b) Mutations that disrupt EGFR's ability to dimerize will likely cause cancer. c) Mutations that delete the EGFR gene will likely cause cancer. d) All of the above. e) None of the above.

E

The level of active mitotic CDK rises and falls during the cell cycle. Which of the following best explains why the levels of active mitotic CDK fall? a) Transcription of cyclin stops after activation of P53. b) Polyubiquitination of APC triggers degradation of CDK. c) Active CDK stimulates a phosphatase that dephosphorylates CDK. d) APC degrades securin, which allows separin to degrade cohesions holding sister chromatids together, which allows anaphase to begin. e) Active CDK activates anaphase promoting complex, causing polyubiquitination of cyclin.

E

What is "vascular endothelial growth factor"? a) A protein encoded by a tumor suppressor gene b) A substance secreted by blood vessels that promotes tumor growth c) Another name for 'avastin.' d) All of the above. e) None of the above.

E

Which of the following is TRUE about stem cells? a) Stem cells are terminally differentiated. b) Stem cells do not express any genes. c) Stem cells have no epigenetic modifications. d) Stem cells are found only in embryos. e) Stem cells are capable of 'self-renewal' (replacing themselves).

E

Which of the following is probably NOT true? a) MMPs degrade collagenase b) MMP activity requires SNARE-mediated exocytosis c) Mutations that cause increased MMP enzymatic activity are common in tumor cells d) MMP proteins are produced by endothelial cells (the cells that make blood vessels) during angiogenesis e) MMP proteins bind to and regulate the activity of cyclin-dependent kinases

E

Why do some stem cells become epithelial cells? a) Transcription factors like jun are activated by MAP kinases b) Laminin triggers creation of islet-like structures c) Because of they are induced pluripotent stem cells d) Stem cells can't become epithelial cells e) Because some stem cells express genes that are expressed mainly in epithelial cells.

E