Cell Bio HW #9

Which class of cancer-critical gene must be inactivated to promote the development of cancer? Choose one: A. oncogene B. tumor suppressor gene C. proto-oncogene

B. tumor suppressor gene

What is the best description of connective tissue? Choose one: A. All of its cells are sparsely distributed in the extracellular matrix. B. All of its cells associate via cadherins in their plasma membrane. C. All of its cells are electrically connected via gap junctions. D. All of its cells rest on a basal lamina.

A. All of its cells are sparsely distributed in the extracellular matrix.

Which statement is true about stem cells? Choose one: A. They can divide for the lifetime of the organism. B. They are usually present in large numbers, especially in tissues that undergo rapid renewal. C. They are terminally differentiated. D. They always divide asymmetrically, giving rise to two different daughter cells.

A. They can divide for the lifetime of the organism.

What gives the plant cell wall its tensile strength? Choose one: A. cellulose B. starch C. myosin D. actin filaments

A. cellulose

In animal connective tissues, tensile strength is chiefly provided by which one of the following? Choose one: A. collagen fibrils and fibers B. cellulose microfibrils C. actin filaments D. the cells themselves E. polysaccharides

A. collagen fibrils and fibers

A fibroblast can attach indirectly to collagen via which type of extracellular matrix protein? Choose one: A. fibronectin B. elastins C. cadherins D. glycosaminoglycans

A. fibronectin

Which cancer-causing gene can be activated by a single mutation in only one allele? Choose one: A. proto-oncogene B. tumor suppressor gene C. DNA repair gene

A. proto-oncogene

Which of the following can give rise to cancer-promoting mutations? Choose one or more: A.DNA replication errors B.exposure to excess sunlight C.exposure to ionizing radiation D.inhalation of tobacco smoke

A.DNA replication errors B.exposure to excess sunlight C.exposure to ionizing radiation D.inhalation of tobacco smoke

Knowledge of the driver mutations underlying cancer has led to targeted therapeutics, such as the protein kinase inhibitor imatinib (trade name Gleevec) in cases of chronic myeloid leukemia. Cancer cells often become resistant to a given drug, so researchers continue searching for new drugs that target proteins that contribute to the cancerous phenotype. One recent promising approach uses drugs that lead to ubiquitination and proteasomal degradation of the target protein. Which of the following mutated proteins are good candidates for this approach? Choose one or more: A.oncogenes B.proteins with loss-of-function mutations C.proteins with gain-of-function mutations D.tumor suppressor genes

A.oncogenes C.proteins with gain-of-function mutations

Many of the genes mutated in individual tumors are involved with which of the following regulatory pathways? Choose one or more: A.pathways governing the initiation of cell division B.pathways controlling the catabolism of lactose C.pathways regulating the cell's response to DNA damage or stress

A.pathways governing the initiation of cell division C.pathways regulating the cell's response to DNA damage or stress

Which of the following is not true of integrin? Choose one: A. Certain intracellular chemical signals can activate integrins from inside the cell, causing them to reach out and grab hold of extracellular structures. B. Integrin molecules serve as stable, permanent anchors that anchor a cell to the extracellular matrix. C. Integrins undergo extensive conformational changes on binding to molecules on either side of the plasma membrane. D. When integrin binds to the extracellular matrix, it stretches into an extended, activated state to attach to molecules on the inside of the cell.

B. Integrin molecules serve as stable, permanent anchors that anchor a cell to the extracellular matrix.

Some cancer cells are missing a key protein needed to repair double-strand DNA breaks. They survive by relying on alternative DNA repair mechanisms. To treat these cancers, researchers have developed drugs that do which of the following? Choose one: A. prevent mitotic division B. inhibit alternative DNA repair mechanisms C. inhibit genetic instability D. promote alternative DNA repair mechanisms in normal cells

B. inhibit alternative DNA repair mechanisms

In most cases, how many mutations are required for a normal cell to turn into a cancer cell? Choose one: A. generally only one B. more than three C. Cancers are not caused by mutations.

B. more than three

Fibroblasts play a role in doing which of the following? Choose one: A. triggering apoptosis B. orienting collagen C. orienting cellulose microfibrils D. destructing collagen E. synthesizing bone

B. orienting collagen

Which of the following is most consistent with the data contained within these karyotypes? Choose one: A. The karyotype on the left is most likely from an advanced tumor due to its significant evidence of genetic instability. B. The karyotype on the right is most likely from an advanced tumor due to its significant evidence of genetic instability. C. The karyotype on the right is most likely from a young tumor because it is still demonstrating genetic stability. D. The karyotype on the left is not likely that of human and the karyotype on the right is from a normal human male.

B. The karyotype on the right is most likely from an advanced tumor due to its significant evidence of genetic instability.

Which is true of cadherin proteins? Choose one: A. They create an electrical and metabolic coupling between epithelial cells. B. They link epithelial cells together by binding to similar cadherins in adjacent epithelial cells. C. They allow ions and small molecules to pass from one plant cell to another. D. They anchor epithelial cells to the basal lamina.

B. They link epithelial cells together by binding to similar cadherins in adjacent epithelial cells.

Which of the following are the plant equivalent of a gap junction? Choose one: A. adherens junctions B. plasmodesmata C. desmosomes D. tight junctions

B. plasmodesmata

Cells export collagen to the extracellular matrix as which of the following? Choose one: A. collagen fibrils, made of collagen molecules B. procollagen, a precursor with additional peptide extensions at each end C. a single-stranded collagen polypeptide chain D. a triple-stranded collagen molecule E. collagen fibers, made of collagen fibrils

B. procollagen, a precursor with additional peptide extensions at each end

In the extracellular matrix of animal tissues, which of the following molecules allows the matrix to resist compression? Choose one: A. collagen B. proteoglycans C. integrin D. fibroblasts E. fibronectin

B. proteoglycans

The surface of the villi in the small intestine is covered by a single layer of epithelial cells called enterocytes. Enterocytes absorb nutrients from the intestinal lumen as they move up the side of the villus. The enterocytes are shed from the end of the villus through apoptosis after 3 to 4 days. Consequently, new cells must be continuously supplied from the crypt and move up the villus. When a stem cell in the crypt divides, what are its immediate daughter cells? Choose one: A. another stem cell and a goblet cell B. another stem cell and a transit amplifying cell C. a transit amplifying cell and an enterocyte D. a transit amplifying cell and a goblet cell E. another stem cell and an enterocyte

B. another stem cell and a transit amplifying cell

Which of the following animal tissues is characterized by a plentiful extracellular matrix? Choose one: A. nervous B. connective C. epithelial D. muscular

B. connective

Stem cells hold great promise both for studying cell fate determination and organ development and for clinical use, such as blood stem cell transplants to treat patients whose own immune systems have been severely impaired. Clinicians also hope that stem cells can be coaxed into specific cell types to treat diseases in which that cell type is damaged, such as replacing neurons in Parkinson's disease. In 2008, researchers assessed the ability of neurons derived from reprogrammed fibroblasts to ameliorate the symptoms of Parkinson's disease in a rat model. Based on your knowledge of stem cells and cell differentiation, what intermediate step was necessary to convert fibroblasts into neurons? Choose one: A. converting fibroblasts into embryonic stem cells via introduction of transcription factors B. converting fibroblasts into induced pluripotent stem cells C. converting fibroblasts into organoids in culture D. converting fibroblasts into embryonic stem cells via introduction of tumor suppressor genes

B. converting fibroblasts into induced pluripotent stem cells

Which type of mutation would not be involved in the inactivation of a tumor suppressor gene? Choose one: A. chromosomal deletion of a region containing the tumor suppressor gene B. duplication of the gene C. silencing of the gene's activity by epigenetic changes D. loss of a whole chromosome containing the tumor suppressor gene E. loss-of-function mutation in tumor suppressor gene

B. duplication of the gene

Which of the following animal cell types, under appropriate conditions, can be kept proliferating indefinitely in culture and yet retain unrestricted developmental potential? Choose one: A. germ cells B. embryonic stem cells C. somatic cells D. proliferating precursor cells

B. embryonic stem cells

Supportive tissues, such as bone or wood, derive their strength from which of the following?Choose one: A. turgor pressure B. extracellular matrix C. cytoskeletal filaments D. mitochondria E. cell walls

B. extracellular matrix

Which epithelial cell junctions serve to seal neighboring cells together so that water-soluble molecules cannot easily leak between them? Choose one: A. desmosomes B. tight junctions C. adherens junctions D. plasmodesmata E. gap junctions

B. tight junctions

Some types of cancer run in families: individuals in such predisposed families are prone to develop these cancers early in adult life. Mutations in which type of cancer-critical gene would most likely be responsible for "hereditary" cancers that are not immediately present in the phenotype of offspring but develop as age increases? Choose one: A. Mutations in cancer-critical genes cannot be inherited because cancer is not a hereditary condition. B. tumor suppressor genes C. either proto-oncogenes or tumor suppressor genes D. proto-oncogenes

B. tumor suppressor genes

The drug Avastin binds and inhibits VEGF. How does this drug help treat cancer? Choose one or more: A.New capillaries form and aid in delivery of chemotherapy to the tumor. B.Angiogenesis is inhibited, blocking formation of new capillaries to the tumor. C.The drug directly kills cancer cells. D.The cancer cells are starved of oxygen.

B.Angiogenesis is inhibited, blocking formation of new capillaries to the tumor. D.The cancer cells are starved of oxygen.

Cancer cells often lack normal DNA damage response and cell-cycle control mechanisms. Why does this make them more susceptible to DNA-damaging chemotherapies? Choose one: A. Cancer cells will arrest in the cycle and will not grow further. B. Cancer cells have the ability to repair the DNA properly and thus will not accumulate mutations as quickly. C. Cancer cells might ignore the normal mechanisms that halt the cell cycle in response to damage, and subsequent division with damage leads to death. D. Cancer cells with activating mutations in Ras will amplify the damage through the Ras signaling pathway.

C. Cancer cells might ignore the normal mechanisms that halt the cell cycle in response to damage, and subsequent division with damage leads to death.

How is β-catenin involved in cancer? Choose one: A. It is a tumor suppressor because overactivation of both copies of Brca1 or Brca2 allows cancer cells to ignore cell-cycle checkpoints. B. It is a proto-oncogene because mutations in β-catenin make the protein more active in its association with DNA polymerase during S phase. C. It is a proto-oncogene because mutations in β-catenin make the protein resistant to degradation, promoting cell proliferation. D. It is a tumor suppressor because the inactivation of both copies of it allows cancer cells to continue to survive and divide, even in the presence of damaged DNA.

C. It is a proto-oncogene because mutations in β-catenin make the protein resistant to degradation, promoting cell proliferation.

Which of the following is not true of the basal lamina? Choose one: A. The basal lamina contains a specialized type of collagen type IV. B. The basal lamina is a thin, tough sheet of extracellular matrix. C. The basal lamina lines the cytosolic side of the epithelial cell's basal plasma membrane. D. The basal lamina supports epithelial cells by interacting with integrins in the basal plasma membrane.

C. The basal lamina lines the cytosolic side of the epithelial cell's basal plasma membrane.

Which feature of glycosaminoglycans (GAGs) allows the extracellular matrix in cartilage to resist compression? Choose one: A. The negative charges on GAGs attract calcium phosphate, which forms a hard, resilient mesh that resists compression. B. GAGs form stiff rods in the extracellular matrix and thereby resist compression. C. The negative charges on GAGs attract sodium ions, which draw water into the extracellular matrix to form a water-filled gel. D. GAGs are typically attached to proteins to form proteoglycans, and both the protein and GAG chains resist compression.

C. The negative charges on GAGs attract sodium ions, which draw water into the extracellular matrix to form a water-filled gel.

What does the small drug molecule called imatinib (trade name Gleevec) do to help treat cancer cells? Choose one: A. encourages the activity of a hyperactive mutant kinase B. encourages the activity of a hyperactive tumor suppressor C. blocks the activity of a hyperactive mutant kinase D. blocks the activity of a hyperactive tumor suppressor

C. blocks the activity of a hyperactive mutant kinase

Which of the following is absent from the structure of a hemidesmosome? Choose one: A. keratin filaments B. laminins C. cadherins D. integrins E. linker proteins

C. cadherins

An oncogene is different from a tumor suppressor gene in that Choose one: A. oncogene mutations more rarely lead to cancer. B. mutation of the gene can contribute to cancer. C. oncogenes have mutations causing increased activity of the protein. D. oncogenes have mutations causing decreased activity of the protein.

C. oncogenes have mutations causing increased activity of the protein.

The simplest method for identifying proteins that bind tightly to one another is co-immunoprecipitation. What protein was discovered to co-immunoprecipitate with Adenomatous Polyposis Coli (APC) protein? Choose one: A. Brca2 B. p53 C. β-catenin D. Brca1

C. β-catenin

Which of the following is inconsistent with the function of gap junctions? Choose one: A. They allow inorganic ions to move directly between attached cells. B. They can open or close as needed. C. They allow the cytoplasm of two adjacent cells to be continuous with each other. D. They allow ATP-driven pumps to move substances between attached cells. E. They allow an electrical and a metabolic coupling between attached cells.

D. They allow ATP-driven pumps to move substances between attached cells.

Colon cancer can occur when cells in the crypt become mutated and do not migrate properly out of the crypt. Which of the following drugs could potentially block the development of colon cancer? Choose one: A. a drug that leads to degradation of APC B. a drug that increases survival of transit amplifying cells C. a drug that decreases differentiation of transit amplifying cells D. a drug that leads to degradation of β-catenin

D. a drug that leads to degradation of β-catenin

Which type of epithelial cell junction plays a major role in an epithelial sheet's ability to develop tension and change its shape? Choose one: A. tight junction B. desmosome C. gap junction D. adherens junction

D. adherens junction

Fibroblasts are the major cellular component in which tissues?Choose one: A. nervous B. epithelial C. muscle D. connective

D. connective

Which of the following junctions binds a cell to another cell and is linked to keratin intermediate filaments? Choose one: A. tight junction B. adherens junction C. hemidesmosome D. desmosome

D. desmosome

What attaches epithelial cells to the basal lamina? Choose one: A. desmosomes B. adherens junctions C. cadherins D. hemidesmosomes E. tight junctions

D. hemidesmosomes

Which type of protein in a fibroblast's plasma membrane attaches to the extracellular matrix on the outside of the cell and (through adapter molecules) to actin inside the cell? Choose one: A. collagen B. fibronectin C. cadherin D. integrin E. proteoglycan

D. integrin

In desmosomes, cadherin molecules are anchored inside an epithelial cell to which type of cytoskeletal filament? Choose one: A. actin filaments B. fibronectins C. microtubules D. intermediate filaments

D. intermediate filaments

Abnormally stretchy skin is part of a genetic syndrome that could result from which of the following? Choose one: A. overactivity of proteinase that cleaves procollagen B. hypersecretion of procollagen C. synthesis of excess cellulose D. loss of proteinase that cleaves procollagen E. increased production of collagen

D. loss of proteinase that cleaves procollagen

Epithelial cells line body cavities and, in organs like the intestine, separate the extracellular environment (intestinal lumen) from the body. The barrier function of epithelial tissues is important for maintaining homeostasis and preventing infections from gut-associated microbiota and viruses. Some bacteria and viruses compromise this barrier function, aiding their pathogenesis. Which of the following structures, most critical to the barrier function of epithelial tissue, is targeted by these infectious agents? Choose one: A. desmosomes B. gap junctions C. hemidesmosomes D. tight junctions

D. tight junctions

What is the difference between a malignant and benign tumor? Choose one: A. A benign tumor grows from a single cell, whereas a malignant tumor arises from multiple cells, making it more difficult to eradicate. B. A malignant tumor proliferates in defiance of normal constraints, while a benign tumor does not. C. A benign tumor can be treated, while a malignant tumor cannot. D. A malignant tumor grows into a large destructive mass, whereas a benign tumor remains very small. E. A malignant tumor invades and colonizes other tissues, while a benign tumor does not.

E. A malignant tumor invades and colonizes other tissues, while a benign tumor does not.

Which is true of induced pluripotent stem (iPS) cells? Choose one: A. They can be produced by incubating adult fibroblasts with Ca2+. B. They can be produced artificially using a single transcription regulator. C. They are produced by nuclear transplantation. D. They can be used to produce whole organs for transplantation. E. They behave like embryonic stem cells.

E. They behave like embryonic stem cells.

Which type of mutation would not typically convert a proto-oncogene into an oncogene? Choose one: A. chromosomal rearrangement that leads to overproduction of the normal proto-oncogene protein B. chromosomal rearrangement that leads to the production of a hyperactive protein C. mutation in the coding sequence that leads to the production of a hyperactive protein D. gene amplification E. chromosomal deletion of the region containing the proto-oncogene

E. chromosomal deletion of the region containing the proto-oncogene

Which of these human cells undergoes the most rapid turnover? Choose one: A. bone-forming cells B. skin epidermal cells C. nerve cells D. red blood cells E. intestinal epithelial cells

E. intestinal epithelial cells

Which of the following is responsible for the most cancer cases? Choose one: A. red meat consumption B. ultraviolet light C. human papillomavirus (HPV) D. polychlorinated biphenyls (PCBs) E. tobacco smoke

E. tobacco smoke

Determine whether the following statement is true or false: A stem cell can only produce a single type of differentiated cell. This statement is

False

Determine whether the following statement is true or false: Using just three or four genes, scientists can transform adult cells into cells that behave like embryonic stem cells. This statement is

True

Determine whether the following statement is true or false: Most cases of cervical cancer are caused by a viral infection. This statement is

True

Determine whether the following statement is true or false: Proto-oncogenes can play an important role in controlling the division of normal cells. This statement is

True

Determine whether the following statement is true or false: The rate of cell turnover varies in different tissue types. This statement is

True