BIOL 3090 Cell Bio (FINAL EXAM)

Though cyclopamine is known to cause birth defects as a cancer therapeutic, recently it has been nonetheless used to treat basal cell carcinoma of the skin. Why is it preferred? (A) Because it binds to and inhibits Smoothened, resulting in the down regulation of Hedgehog signaling 4 (B) Because it kills all cells (C) Because it stops mitosis (D) Because activates apoptosis

(A) Because it binds to and inhibits Smoothened, resulting in the down regulation of Hedgehog signaling 4

(See figure for quest 1 on HW Quiz 3) You have used a reporter gene system to investigate the contribution to gene expression of three cis-regulatory DNA sequences (A to C) from a key developmental gene. Reporter gene expression from constructs containing all three or only a subset of the regulatory sequences is summarized in the diagram below. According to these findings, indicate whether each of the following conclusions is or is not acceptable. (A) acceptable (B) not acceptable

(A) Region A is necessary for activation of gene expression. (B) Region B is likely to normally bind an activator and turn the gene on. (B)Region C is sufficient for activation of gene expression. (B) Region C is necessary for activation of gene expression

Synaptic signaling between adjacent neurons is like hormone signaling in which of the following ways? (A) It sends its signal molecules through the blood. (B) It sends its signal molecules quite a distance. (C) It requires calcium ions. (D) It requires binding of a signaling (E) It persists over a long period

(D) It requires binding of a signaling

What is the main function of lipid droplets in the cell?

1. lipid storage 2. the building blocks of membrane synthesis.

In your laboratory, you are studying a receptor protein found in the plasma membrane of neurons that has been genetically linked to familial epilepsy. In affected families, the gene for the receptor contains distinctive variants that are predicted to alter the threedimensional structure of the receptor (misfolding) in the region where it binds its neurotransmitter ligand. After performing antibody staining for the receptor protein in affected and normal cells, you observed that affected cells have less proteins in the plasma membrane when compared to normal cells. What would be a possible explanation for the low abundancy of proteins found in the affected cells? (hint: plasma membrane proteins are translated in the rough endoplasmic reticulum).

An explanation for low abundance of proteins in the affected cells would be that gene that affects the receptor which alters the structure of the receptor creates a misfolding. This in turn means that when the proteins travel to the rough ER, they become misfolded which means they are disfunctional. They creates less proteins in the plasma membrane bc the proteins that are folded are being folded incorrectly so they cannot do the correct function because proteins are folded based on their function.

Which of the following cell junctions uses cadherin cell adhesion molecules to anchor the actin cytoskeleton? A. Tight junction B. Adherens junction C. Desmosome D. Hemidesmosome E. Gap junction

B. Adherens junction

Particularly abundant in cells of heart muscle and the epidermis, ________ are structurally similar to adherens junctions and contain a number of homologous components. However, they are linked to intermediate filaments instead of the actin cytoskeleton. A. Gap junctions B. Cadherins C. Desmosomes D. Catenins E. Tight junctions

C. Desmosomes

What is true of overproduction of cadherins such as E-cadherin? A. It is often found in cancers originating from epithelia. B. It is induced by the transcription regulatory protein Twist. C. It induces epithelial-mesenchymal transition. D. It leads to stronger cell-cell adhesion.

D. It leads to stronger cell-cell adhesion.

Which of the following is NOT an anchoring junction? A. Actin-linked cell-matrix junction B. Adherens junction C. Desmosome D. Hemidesmosome E. Gap junction

E. Gap junction

A common step in the isolation of proteins from a sample of animal tissue is to treat the tissue with SDS and beta mercapthoethanol. 1. Why is such treatment necessary?

It denatures the tertiary structure of a protein to produce a linear protein molecule

The ability to detect viral infections has become essential during the SARS-CoV-2 (COVID-19) pandemic but is also widely used in the management of other viral diseases such as the flu or HIV. A patient can give a sample of infectious material to their doctor without knowing how different viral infections can be detected. 2. Describe two methods that would allow these molecules to be detected and recognized.

Mass spectrometry could also identify viral proteins but is cost, labor, and time-prohibitive. Nucleic acids could be detected by hybridization with a probe such as with in situ hybridization, but this technique requires imaging individual cells, and if only a small sample is viewed, the infected cells may not be detected. Nucleic acids could also be detected by PCR (or qRT-PCR), or DNA sequencing. DNA sequencing would be cost, labor, and time-prohibitive. RNA-seq or microarray could also be used, but since these tests typically detect many genes, using them for a specific viral nucleic acid detection may not be the most efficient choice.

The ability to detect viral infections has become essential during the SARS-CoV-2 (COVID-19) pandemic but is also widely used in the management of other viral diseases such as the flu or HIV. A patient can give a sample of infectious material to their doctor without knowing how different viral infections can be detected. Cite one type of biological macromolecules that these tests would be looking for?

Proteins, nucleic acids, and lipids are the biological macromolecules that are used to in disease testing.

A common step in the isolation of proteins from a sample of animal tissue is to treat the tissue with SDS and beta mercapthoethanol. 2. What do these components accomplish?

Reduce disulfide bonds in order to separate protein subunits for use in electrophoresis

"The Chemical Basis of Morphogenesis" is an article that the English mathematician Alan Turing wrote in 1952. It describes how patterns in nature, can arise naturally from a homogeneous, uniform state. Write one example of a pattern that can be explained by this theory.

The Turing Pattern: describes how patterns in nature, such as stripes and spots, CAN arise naturally and autonomously from a homogenous, uniform state. (EX: Patterns of stripes, spots, and spirals like those of the giant puffer fish may arise naturally)

The nucleus of the cell is surrounded by a nuclear envelope perforated by 3000-4000 nuclear pore complexes (NPCs). NPCs transport approximately 1000 macromolecules per second and can support simultaneous bidirectional transport. What information does a protein need to pass through the NPCs?

The information a protein would need to pass through NPCs is either to be small enough to pass right through passively. If the proteins are too large, the cell has to use active transport and active transport proteins to help move things through the membrane. Therefore, for proteins trying to pass through NPCs, they would need nuclear transport receptors to aid the process if they are too large.

All the cells in a multicellular organism contain the same DNA despite the massive differences in those cells' appearance and function. Briefly explain how this is possible.

This is because all of the cells in our bodies start from a single fertilized egg. With few exceptions, all cells in a person's body have the same DNA and genes because they all started from the sam fertilized egg and sperm.

TRUE/FALSE To generate cell-cell adhesion, the cadherin domain at the N-terminal tip of one cadherin molecule binds the cadherin domain at the N-terminal tip of a cadherin molecule on another cell.

True

The ability to detect viral infections has become essential during the SARS-CoV-2 (COVID-19) pandemic but is also widely used in the management of other viral diseases such as the flu or HIV. A patient can give a sample of infectious material to their doctor without knowing how different viral infections can be detected. 1. What types of biological macromolecules would these tests be looking for?

Viral particles contain proteins, nucleic acids, and lipids. Protein and nucleic acid detection techniques are the most common methods of testing for current or recent viral infection. Proteins could include antibodies against the virus (antibody testing looks for active or recent infection) or viral proteins (antigen testing for the virus itself looks for active infection in most cases). SDS-PAGE followed by Western blot could identify the desired proteins

Which of the following cell junctions uses cadherin cell adhesion molecules to anchor the actin cytoskeleton? a. Adherens junction b. Desmosome c. Gap junction d. Tight junction e. Hemidesmosome

a. Adherens junction

In which one of the following organisms is systemic RNAi possible through feeding the animal with the RNA? a. Caenorhabditis elegans b. Mus musculus c. Drosophila melanogaster d. Homo sapiens

a. Caenorhabditis elegans

What is the most common cancer in humans? a. Carcinoma b. Lymphoma c. Leukemia d. Sarcoma e. Myeloma

a. Carcinoma

Which of the following is NOT a carcinogenic agent? a. Inherited genetic defect b. X-rays c. Tobacco d. UV-light e. Viruses

a. Inherited genetic defect

What is true of overproduction of cadherins such as E-cadherin? a. It leads to stronger cell-cell adhesion b. It induces epithelial-mesenchymal transition. c. It is induced by the transcription regulatory protein Twist. d. It is often found in cancers originating from epithelia.

a. It leads to stronger cell-cell adhesion

Proteins are synthesised on ribosomes in the cell cytoplasm, and must be targeted to the appropriate compartment of the cell by special targeting sequences. What is likely to be the fate of a protein that contains no such targeting sequence? a. It remains in the cytoplasm b. It will be degraded immediately c. It will be replicated d. It will become an antibody

a. It remains in the cytoplasm

Regarding cancer cells and their use of glucose, which statement is true? a.Cancer cells use glucose to support the production of raw materials that enable cellular proliferation. b.Cancer cells use glucose mainly in the oxidative phosphorylation pathway. c.Cancer cells use glucose so that they can oxidize it into CO2. d.Cancer cells use glucose to induce aerobic respiration. e.Cancer cells use glucose mainly in the mitochondria.

a.Cancer cells use glucose to support the production of raw materials that enable cellular proliferation.

How are antibody-producing hybridoma cell lines immortalized to provide an unlimited source of monoclonal antibodies? a. By irradiation b. By cell fusion c. By transformation with a retrovirus d. By ectopic expression of telomerase e. By overproduction of introduced oncogenes

b. By cell fusion

Which of the following is NOT true about nanopore sequencing? a. It can detect modified nucleotides. b. It requires deoxyribonucleotides that have a fluorescent tag. c. It utilizes an electric current to pull DNA though a protein pore. d. It can be performed in a handheld device. e. It can be used for extremely long strands of DNA.

b. It requires deoxyribonucleotides that have a fluorescent tag.

(See figure for quest 4 on HW Quiz 3) A piece of DNA has been sequenced by automated dideoxy sequencing, in which each dideoxyribonucleoside triphosphate was labeled with a fluorescent tag of a different color. The data corresponding to a small segment with the sequence 5′-TGCCACA-3′ is shown in the following diagram. Knowing that ddGTP has been labeled with green fluorescence, what color do you think was the fluorescent tag used to label ddTTP in the sequencing experiment? a. green b. red c. yellow d. blue

b. red (The labeled ddTTP (red) is incorporated twice, opposite to the A nucleotides in the sequence. Hint: you must make the reverse strand to identify the color.)

Compared to cells of a normal tissue, which of the following occurs less frequently in cells within a solid tumor? a.Stress b.Apoptosis c.Cell division d.Miotic recombination e.Necrosis

b.Apoptosis

What is a nonpreventable cause of cancer? a.UV radiation b.Hereditary predisposition c.Diet d.Cigarette smoke e.Viruses

b.Hereditary predisposition

What is true for the α subunit of a heterotrimeric G protein? a. A GPCR acts as a GAP, whereas an RGS can act as a GEF. b. Both a GPCR and an RGS can act as a GEF. c. A G-protein-coupled receptor (GPCR) acts as a guanine nucleotide exchange factor (GEF), whereas a regulator of G protein signaling (RGS) can act as a GTPase-activating protein (GAP). d. Both a GPCR and an RGS can act as a GAP.

c. A G-protein-coupled receptor (GPCR) acts as a guanine nucleotide exchange factor (GEF), whereas a regulator of G protein signaling (RGS) can act as a GTPase-activating protein (GAP).

(See figure on quest 9 on HW Quiz 3) A portion of RNA-seq data obtained from two tissue samples is plotted in the following schematic diagram. Which region corresponds to an alternative exon? a. Region A b. Region B c. Region D d. Region E e. Region C

c. Region D

Which of the following is NOT correct regarding both Cas9 and EcoRI? a. They both create double-strand breaks in DNA b. They are both greatly useful in manipulating DNA and studying gene expression and function c. They both recognize their target sequences with the help of guide RNAs d. They are both endonucleases. e. They are both part of bacterial defense mechanisms against foreign DNA

c. They both recognize their target sequences with the help of guide RNAs

Which of the following can lead to p53 stabilization and activation? a.p53 mutation b.Normoxia c.E6 and E7 viral proteins d.DNA damage e.Chromosomal stability

c.E6 and E7 viral proteins

Which characteristic is among the hallmarks of cancer cells? a.Unaltered cell metabolism b.Manipulation of the tissue environment, inducing an immune response c.Evasion of cell-death signals d.Altered homeostasis that results in cells dividing at a faster rate, inducing apoptosis e.Maintenance of the limits to cell proliferation

c.Evasion of cell-death signals

In general, which of the following sequential barriers to metastasis is the easiest to overcome for cancer cells? a.Vessel entry through acquisition of local invasiveness b.Persistence of growth in the remote site c.Exit from the blood into a remote tissue or organ d.Initial growth of cells in the foreign tissue e.Survival of cells in the foreign tissue

c.Exit from the blood into a remote tissue or organ

How does the expression of Delta on the surface of a cell activate the expression of certain genes in the nucleus of its neighboring cell? a. Delta binding activates Notch, which activates a transcriptional activator through the JAK-STAT pathway. b. Delta binding leads to the proteolytic cleavage of Notch and inhibition of its activity as a transcriptional repressor, leading to the activation of target genes. c. Delta binding leads to the stabilization of a cytoskeleton-associated transcriptional activator. d. Delta binding releases the intracellular tail of Notch, which enters the nucleus and converts a transcriptional repressor into a transcriptional activator. e. Delta binding leads to Notch-mediated recruitment of protein complexes to the plasma membrane, resulting in the degradation of a transcriptional repressor.

d. Delta binding releases the intracellular tail of Notch, which enters the nucleus and converts a transcriptional repressor into a transcriptional activator.

Consider the role of the actin cytoskeleton in two cells attached to each other via adherens junctions. Which of the following statements is true? a. Contractile forces can strengthen the adherens junction by proteolytically cleaving associated catenin proteins. b. Myosin activity in one cell leads to a reduction in vinculin recruitment in the other cell c. The forces generated in the two cells do not depend on myosin activity. d. The forces generated in one cell are normally balanced by similar forces in the neighboring cell.

d. The forces generated in one cell are normally balanced by similar forces in the neighboring cell.

Which of the following descriptions applies to genomic DNA libraries rather than cDNA libraries? a. Their production requires use of reverse transcriptase. b. Different sequences are represented in them based on their transcription level. c. They are enriched in protein-coding genes d. They contain intronic sequences

d. They contain intronic sequences

Particularly abundant in cells of heart muscle and the epidermis, ________ are structurally similar to adherens junctions and contain a number of homologous components. However, they are linked to intermediate filaments instead of the actin cytoskeleton. a. Cadherins b. Desmosomes c. Tight junctions d. Gap junctions e. Catenins

d. desmosomes

What is the most common cancer in humans? a.Myeloma b.Lymphoma c.Leukemia d.Carcinoma e.Sarcoma

d.Carcinoma

The effect of the deletion of one copy of the gene encoding p53 is different from the effects caused by other p53 mutations. For example, some loss-of-function mutations in the DNA-binding domain of p53 cripple its function as a transcription regulator. Such a mutation in only one copy of the p53 gene can be enough to confer a p53 loss-of-function phenotype, even when the other copy of the gene on the homologous chromosome is wild type. Why is this the case? a.p53 can induce apoptosis. b.p53 is a tumor suppressor. c.p53 is a proto-oncogene. d.p53 forms a tetramer. e.These mutations are recessive.

d.p53 forms a tetramer.

Which of the following is NOT an anchoring junction? a. Adherens junction b. Actin-linked cell-matrix junction c. Desmosome d. Hemidesmosome e. Gap junction

e. Gap junction

Which technique generates a complete list of all major mRNAs expressed in every cell type in an organism? a. RT-PCR b. Illumina sequencing c. Ribosome profiling d. Nanopore sequencing e. Single-cell RNA sequencing

e. Single-cell RNA sequencing

What information can be gained from in situ hybridization but not a reporter gene experiment? a. Whether or not a specific sequence is being transcribed b. The life-span of a specific gene product c. If a protein is properly folded or not d. The sequence of the DNA being transcribed e. The location of non-coding RNAs in a cell

e. The location of non-coding RNAs in a cell

TRUE/FALSE In intestinal epithelial cells, the different plasma membrane domains are separated from each other by special barriers. These barriers are a result of a special structures called tight junctions in the cell surface that excludes proteins of the other domains.

true