BIO 201 Exam 2

d

After you eat, insulin is secreted by pancreatic Beta cells into the bloodstream, where it diffuses throughout the body to bind to receptors on target cells, telling them to take up glucose. This mode of signaling is referred to as: a) Autocrine b) Paracrine c) Juxtacrine d) Endocrine

a, b, e, f, g, i

All living organisms, including both bacteria and Eukaryotes have: (Select all that apply; you may want to review Lecture 7 in addition to the current material for this one) a) double stranded DNA b) L-amino acids c) Nuclei d) Robust cytoskeleton, including actin and microtubules e) The ability to extract energy from the environment to do work f) Plasma membranes made of phospholipids g) Ribosomes h) Peptidoglycan i) D-monosaccharides

a

As we learned in class, protein phosphatases catalyze removal of phosphate groups from proteins. How would the activity of a protein phosphatase affect a cell's response to growth factors? a) Decrease proliferation b) Increase proliferation c) Increase glucose production d) Decrease glucose production

a

Bacteria are approximately _____ in diameter; eukaryotic cells are typically at least _____ times this size. a) 1µm; 10x b) 10 µm; 100x c) 100 µm; 10x d) 100µm; 100x

a

Based on their differences in cell structure, which of the following would you be more likely to see in bacteria than in Eukaryotes? a) More proteins with primary structure changes b) More time between stimulus and response when the response requires production of new proteins c) Faster transcription d) All of the above

b

Ca++ flowing down its concentration gradient through a Ca++ channel is an example of: a) Simple diffusion b) Facilitated diffusion c) Direct active transport d) Indirect active transport

a

Cell adhesion molecules are important components of: a) Tight junctions b) Plant cell walls c) Extracellular matrix d) Bacterial cell walls

c

Cells shrink when you place them in a solution with a high concentration of the amino acid glycine. This indicates that the cell membrane: a) IS permeable to BOTH glycine and water b) IS permeable to glycine but NOT to water c) Is NOT permeable to glycine but IS permeable to water d) Is permeable to NEITHER glycine NOR water

c

Chloride ion (Cl-) concentrations are approximately 10x higher outside of cells than inside. Imagine you discovered a novel protein that is required in liver cells for transporting Cl- out of the cell up its concentration gradient, and further found that this protein only functions if the Na+/K+ ATPase is active. Which of the following might you reasonably conclude about the Cl- transport protein? a) a Na+/Cl- sympoter b) a Cl- ATPase c) a K+/Cl- symporter d) a Cl- channel

c

Chloride ion (Cl-) concentrations must be maintained much higher outside of cells than inside of cells. How this gradient is maintained is complex, but a key transporter co-transports Cl- along with K+ ions. The name of this transport protein could be ____ and its mode of transport would be ____. a) Na+/K+ ATPase; direct active transport b) Na+/Cl- antiporter; indirect active transport c) K+/Cl- symporter; indirect active transport d) K+/Cl- antiporter; indirect active transport

c

Cholesterol generally makes up what percentage of the lipid mass of the plasma membrane? a) 5% b) 0% c) 25% d) 10%

c

Consider the reaction: A <=> B. Under standard conditions at equiliubrium, the concentrations of the compounds are [A] = 0.1 M, and [B] = 1.1 M. Keq' for this reaction is ____ and ∆G°' is _____. (You do not need a calculator for this.) a) <1; <0 b) >1; > 0 c) > 1; < 0 d) < 1; > 0

a

Depletion of ATP causes rigor (don't worry - I don't think this is cat is actually dead!). Why? a) ATP is required for myosin to release from actin b) ATP is required for actin polymerization c) ATP is required for dynein-mediated vesicle transport d) ATP is required for kinesin-mediated vesicle transport

d

Differential centrifugation separates particles based on _______ by applying different _______. a) Charge; Temperatures b) Density; Solutions c) Enzyme activity; pH d) Mass; Spin speeds

a

Endosymbiosis is most likely to succeed when it involves a/an ______ host and a/an _____ endosymbiont. a) Anaerobic host; photosynthetic endosymbiont b) Photosynthetic host; photosynthetic endosymbiont c) Photosynthetic host; anaerobic endosymbiont d) Aerobic host; anaerobic endosymbiont

d

Even though the blood glucose concentration may drop below the intracellular glucose concentration - for example, during a long fast - brain cells can still absorb glucose from the bloodstream. Under these circumstances, how does glucose get into the cells? a) Simple diffusion b) Facilitated diffusion c) Direct active transport d) Indirect active transport e) It doesn't

a

Factors that increase membrane fluidity have the effect of _______ membrane permeability: a) Increasing b) Decreasing c) There is no relationship

microtubules

Fill in the blank: The cytoskeleton "railroad tracks" used by motor proteins to transport vesicles and other organelles to and from the plasma membrane is called ___.

dynein

Fill in the blank: The motor protein responsible for transporting endosomes from the plasma membrane to the interior of the cell is named ___. (spelling matters!)

kinesin

Fill in the blank: The motor protein responsible for transporting vesicles to the plasma membrane is named ___. (spelling matters!)

myosin

Fill in the blank: The name of the motor protein that uses actin as its cytoskeletal partner is called ___. (one word; spelling matters!)

c

If you were attempting to identify natural product inhibitors of kinesin activity, which of the following would be a good assay for screening them? a) Muscle contraction b) Secretion of neurotransmitters c) Anterograde transport in cells d) Retrograde transport in cells

d

Inhibition of which of the following would prevent indirect active transport of glucose into cells? a) GluT1 b) Ca++ ATPase c) Ligand-gated ion channels d) Na+/K+ ATPase

d

Liver cells respond to epinephrine by breaking down glycogen. What is the second messenger in this patway? a) ATP b) Adenine c) Acetylcholine d) cyclic AMP

a

Loss of peptidoglycan, combined with increased cell size during evolution of eukaryotes led to a less stable cell. Which of the following evolutionary adaptations compensated for this decreased structural stability? a) Cytoskeleton b) Nuclei c) Mitochondria and chloroplasts d) Double-stranded DNA

a

Loss of peptidoglycan, combined with increased cell size during evolution of eukaryotes led to a less stable cell. Which of the following evolutionary adaptations compensated for this decreased structural stability? a) Cytoskeleton b) Nuclei c) Mitochondria and chroroplasts d) Double stranded DNA

b

Pancreatic acinar cells produce and secrete digestive enzymes into the duodenum. What would happen if pancreatic acinar cells were treated with a toxin that causes lysis (breakage) of smooth ER membranes? a) The enzymes would stop being synthesized b) Digestive enzymes would be immediately secreted into the duodenum c) Lysosomal enzymes would leak into the smooth ER, which would degrade the Ca++ d) No effect; the smooth ER does not need to be intact for cells to function normally

d

Pancreatic acinar cells were selected for the original original Pulse-Chase experiment of Dr. Palade and his colleagues because almost all of the proteins they produce are: a) Similar b) Enzymes c) Hormones d) Secreted

a

Pancreatic acinar cells were selected for the original original Pulse-Chase experiment of Dr. Palade and his colleagues because they wanted to better understand how _________ were transported through the cell. a) Secreted proteins b) Teeny tiny automobiles c) Peroxisomes d) Bacteria

c

Production of antibiotics is an arms race, given the speed with which bacteria can evolve antibiotic resistance. Antibiotics that ____ are most likely to be effective against bacteria without causing side effects to their human (or animal) patient. a) Prevent actin polymerization b) Prevent transcription c) Prevent synthesis of peptidoglycan d) Prevent translation

d

Protein makes up what percentage of the mass of the plasma membrane in a typical cell (e.g. red blood cells)? a) 5% b) 10% c) 25% d) 50%

a

Protons (H+) are moved up their concentration gradients into the lysosome in order to activate lysosomal enzymes. This is an example of: a) Active transport b) Simple diffusion c) Facilitated diffusion d) Ion channels

a

Shown below are the results of two fluorescence recovery after photobleaching (FRAP) experiments. Which of the following could explain the difference between the data represented by the dashed line as compared to that represented by the solid line? a) FRAP was performed on the same cell but at a lower temperature b) The membrane of the cell indicated by the dashed line is more fluid than the membrane of the cell represented by the solid line c) The membrane of the cell indicated by the dashed line has fewer saturated fatty acids in its phospholipids d) All of the above

c

Shown here is a graph illustrating data from the origial Pulse-Chase experiment analyzing protein secretion in pancreatic acinar cells. Trace A corresponds to radioactivity in which structure? a) Endosome b) Golgi complex c) Secretory vesicle d) Smooth ER e) Rough ER

d

The H+ ATPase (a.k.a. "proton pump") creates electrochemical gradients across the membranes of many protists. This is an example of: a) Indirect active transport b) Simple diffusion c) Facilitated diffusion d) Direct active transport.

d

The diameter of this organelle is approximate 1 µm. What is this organelle and its primary function? a) Nucleus; Transcription b) Secretory vesicle; storage and secretion of proteins c) Lysosome; Biological macromolecule breakdown d) Peroxisome; sequestration and breakdown of damaging peroxides

d

The hormone glucagon is secreted by the pancreas in response to low blood sugar. Liver cells respond to glucagon by breaking down glycogen to form glucose, which is then release into the bloodstream for the other tissues. Based on this information, what mechanism is most likely used to transport glucose out of the cell into the bloodstream? a) Simple diffusion b) Direct active transport c) Indirect active transport d) Facilitated diffusion

c

The lipid:protein ratio in a typical membrane (e.g. red blood cells) is approximately: a) 10:1 b) 2:1 c) 1:1 d) 1:2

c

The protein:lipid ratio in a typical membrane (e.g. red blood cells) is approximately: a) 1:10 b) 1:2 c) 1:1 d) 2:1

false

True or False: The concentration of Ca++ in the cytoplasm is higher than it is in the smooth ER.

false

True or False: The concentration of Ca++ inside the cell is higher than it is outside.

true

True or False: The concentration of Ca++ outside the cell is higher than it is inside.

true

True or False: The concentration of K+ inside the cell is higher than it is outside

false

True or False: The concentration of K+ outside the cell is higher than it is inside

false

True or False: The concentration of Na+ inside the cell is higher than it is outside

d

Unlike in animals, in which the Na+ gradient is used, it is the H+ gradient in some other species that fuels transport of other compounds up their concentration gradients. This type of transport is: a) Simple diffusion b) Direct active transport c) Facilitated diffusion d) Indirect active transport

d

What do microtubules and actin have in common? a) They both require GTP for polymerization b) They are both stable c) They are both found in the center of the cell d) They are both enzymes

a

What do plant, (most) protist, and fungus cells have that animals do not? a) Cell walls b) Smooth ER c) Peroxisomes d) Peptidoglycan

d

What is the second messenger in the receptor tyrosine kinase signaling pathway? a) The kinase b) The small GTPase ras c) The enzyme MAPK that gets transported into the nucleus to activate gene transcription d) None of the above

b

What is ∆G°' for the hydrolysis of ATP? a) +7.3 kcal/mol b) -7.3 kcal/mol c) 0 d) +1

a

Where in the cell would you expect to see a Ca++ ATPase? a) Smooth ER b) Nucleus c) Golgi complex d) Lysosome

a

Which of the following should be able to diffuse most easily through a cell's plasma membrane? a) O2 b) glucose c) H2O d) H+

b

Chloride ion (Cl-) concentrations are approximately 10x higher outside of cells than inside. Imagine you discovered a novel protein that is required in liver cells for transporting Cl- out of the cell up its concentration gradient, and further found that this protein only functions if the Na+/K+ ATPase is active. Which of the following might you reasonably conclude about the Cl- transport protein? a) a Cl- channel. b) a Na+/Cl- antiporter c) a Cl- ATPase d) a K+/Cl- antiporter

actin

Fill in the blank: The name of the cytoskeleton fiber that polymerizes to form pseudopods during amoeboid cell migration is called ___. (one word; spelling matters!)

tubulin

Fill in the blank: The name of the protein dimer that multimerizes to form the cytoskeleton "railroad tracks" in the cell is ___. (one word; spelling matters!)

b

For solutes that cannot diffuse through the membrane, water moves across the membrane from a region of ______ to a region of ______ solute concentration. a) High to low b) Low to high

a

Imagine you walk into lab after spring break, and your TA hands you a beaker containing a solution of A, B, and C in water represented by the equilibrium shown below. If the solution has reached equilibrium, and the beaker is at pH 7.0, 25°C, and 1 atm pressure, what other information do you need to obtain in order to calculate ∆G°' for this reaction? a) The concentrations of A, B, and C b) The mechanism of the reaction c) The density of the solution d) The molecular weights of A, B, and C e) All of the above

b

In the original Pulse-Chase experiment of Palade and colleagues, what can we conclude from the fact that radioactivity in the Golgi complex is initially very low, increases to its highest levels in 15 minutes, and then the radioactivity in Golgi decreases again to near zero by two hours? a) It takes about fifteen minutes to synthesize a protein b) Proteins are not made in the Golgi complex, but are transported in after they are synthesized and then eventually exit c) Proteins are made in the Golgi complex d) Proteins are secreted e) Proteins are degraded within two hours

c

In the original Pulse-Chase experiment of Palade and colleagues, what was does the radioactivity (% or # of grains on the y axis) represent? a) Amino acids b) Secretory vesicles c) Proteins d) RNA

e

Shown here is a graph illustrating data from the origial Pulse-Chase experiment analyzing protein secretion in pancreatic acinar cells. Trace B corresponds to radioactivity in which structure? a) Endosome b) Golgi complex c) Secretory vesicle d) Smooth ER e) Rough ER

b

Shown here is a graph illustrating data from the origial Pulse-Chase experiment analyzing protein secretion in pancreatic acinar cells. Trace C corresponds to radioactivity in which structure? a) Endosome b) Golgi complex c) Secretory vesicle d) Smooth ER e) Rough ER

c

Shown here is a transmission electron micrograph (TEM) of the interior of a cell. What structure is circled, and what happens in this structure? a) Smooth ER; Protein processing, e.g. glycosylation b) Smooth ER; Calcium storage c) Rough ER; Translation d) Nucleus; Translation e) Nucleus; Transcription

a

Shown here is a transmission electron micrograph (TEM). What is the most likely identity of this organelle, and what is its primary function (from lecture)? a) Smooth ER; Calcium storage b) Rough ER; Translation c) Peroxisome; sequestration of reactions that produce harmful compounds and degradation of those compounds d) Nucleus; Transcription

d

Taxol, derived from the Pacific Yew tree, was one of the first effective anti-cancer compounds discovered. It acts by inhibiting microtubule depolymerization. Which of the following is a likely cellular side effect of treatment with Taxol? a) Increased exocytosis b) Loss of pseudopod formation in white blood cells c) Decreased endocytosis d) Increased cell size

a

The Na+/K+ ATPase transports Na+ up its concentration gradient and K + ______ its concentration gradient. This is an example of ______ . a) Up; Direct active transport b) Down; indirect active transport c) Down; facilitated diffusion d) Up; Indirect active transport e) Down; facilitated diffusion

d

The ancestor to all Eukaryotes was likely an _________ that ingested a/an _________ , which led to evolution of mitochondria. a) Aerobic cyanobacterium; Anaerobic bacterium b) Aerobic bacterium; Cyanobacterium c) Aerobic bacterium; Anaerobic bacterium d) Anaerobic archaeum; Aerobic bacterium

b

What type of transport brings glucose into cells soon after eating a large meal? a) Simple diffusion b) Facilitated diffusion c) Direct active transport d) Indirect active transport

b

What would happen if you treated cells with a toxin that inhibits tubulin's enzymatic activity? a) It would prevent polymerization of microtubules b) It would prevent depolymerization of microtubules c) Both of the above d) Neither of the above

e

What would happen to the cytoskeleton if you replaced all of the normal GTP in cells with a chemical variant of GTP that acts like normal GTP but cannot be hydrolyzed (broken down) to GDP? a) It would prevent actin polymerization. b) It would prevent actin depolymerization c) It would prevent microtubule polymerization d) Nothing, the cytoskeleton would behave normally e) It would prevent microtubule depolymerization

d

What would likely happen to a cell treated with a compound that causes lysis (breakage) of ribosomal membranes? a) Proteins would leak out and fail to be secreted, but cytoplasmic proteins would be unaffected b) All protein synthesis would cease c) Proteins would not be glycosylated d) Ribosomes don't have membranes

d

When doing differential centrifugation, microsomes pellet to the bottom of the tube at faster spin speeds than lysosomes. This indicates that microsomes are ___________ than lysosomes. a) Larger b) Smaller c) Heavier d) Lighter

d

Which adaptation specific to becoming multicellular compensates for the destabilizing effect of increased size? (Think carefully about answer choices!) a) Extracellular matrix b) Tight junctions c) Cytoskeleton d) Both ECM and tight junctions e) All of the above

c

Which of the following IS CONSISTENT with or TRUE regarding the endosymbiotic theory for the origins of mitochondria and chloroplasts? a) Chloroplasts evolved before mitochondria b) An anaerobic cell engulfed photosynthetic bacterium c) An anaerobic cell engulfed an aerobic bacterium d) Plants are not aerobic

d

Which of the following SUPPORTS the endosymbiotic theory for the origins of mitochondria and chloroplasts? a) Mitochondria and chloroplasts are genetically similar to bacteria b) Mitochondria and chloroplasts have double membranes c) Mitochondria and chloroplasts divide independently of the cell d) All of the above

b

Which of the following can diffuse most easily through the cell membrane? a) Ions b) O2 c) Glucose d) water

d

Which of the following distinguishes plant cells from animal cells? a) They arose through endosymbiosis b) They have circular genomes c) They have mitochondria d) They have cell walls and chloroplasts

c

Which of the following do eukaryotes have that bacteria do not? a) Double stranded DNA b) RNA c) Nuclei d) all of the above

a

Which of the following does NOT specifically support of the endosymbiotic theory for the origins of mitochondria and chloroplasts? a) Mitochondria and chloroplasts are very common b) Mitochondria and chloroplasts have double membranes c) Mitochondria and chloroplasts have circular genomes d) Mitochondria and chloroplasts divide by fission independently of the cell

b

Which of the following does NOT specifically support of the theory that Eukaryotes evolved through endosymbiosis? (i.e. the Endosymbiotic Theory) a) Mitochondria and chloroplasts have two membranes b) Plants have both mitochondria and chloroplasts c) Mitochondria and chloroplasts are genetically related to bacteria d) Mitochondria and chloroplasts have circular genomes

c

Which of the following is NOT a tenet of the fluid mosaic model of cell membranes? a) Proteins and lipids are oriented asymmetrically in the membrane b) Membranes are amphipathic: regions of both lipids and proteins are in the membrane interior with hydrophilic regions on the outside c) Membranes consist of essentially solid patches of phospholipids arranged together in a mosaic like the tectonic plates d) Membranes are fluid, which allows proteins to move laterally in the membrane like "icebergs floating in a lipid sea"

c

Which of the following is a DISadvantage of paracrine signaling? a) It is slow b) It is bidirectional c) It affects only a small number of cells d) It is irreversible. e) All of the above

b

Which of the following is a disadvantage of being a multicellular organism specifically as opposed to unicellular? (read and think carefully!) a) Need for increased mobility to escape predators b) More difficult to absorb nutrients c) Loss of peptidoglycan reduces stability d) All of the above

c

Which of the following is a mechanism by which cells ensure a strong response to a small amount of ligand? a) Receptor-mediated endocytosis b) GTP hydrolysis by G-proteins c) Enzyme cascades d) 2nd messengers e) All of the above

d

Which of the following is an advantage of multicellularity? a) Larger size b) Greater mobility c) Functional specialization of cells/tissues d) All of the above

a

Which of the following is found in eukaryotes BUT NOT in bacteria? a) Membrane-bound organelles b) Cell walls c) Double-stranded DNA d) Ribosomes e) Phospholipids

b

Which of the following is least likely to diffuse through a cell's plasma membrane? a) O2 b) H+ c) H2O d) Glycerol

c

Which of the following is true of steroid hormones but not a signaling molecule such as a ligand for G-protein coupled receptors? a) An extracellular signal is transduced to an intracellular response b) Their cellular effects are strong due to signal amplification c) Their receptors regulate gene transcription d) They may have widespread effects because they may be secreted into the bloodstream

d

Which of the following is/are found in bacteria BUT NOT in eukaryotes? a) Cell walls b) Phospholipids c) DNA genomes d) None of the above: All are found in bacteria and some or all Eukaryotes

a

Which of the following is/are found in bacteria but not eukaryotes? a) Peptidoglycan b) Mitochondria c) Single-stranded DNA d) All of the above

b

Which of the following is/are found in eukaryotes but not bacteria? a) Ribosomes b) Mitochondria c) Phospholipids d) Both ribosomes and phospholipids

a, b, c, e

Which of the following is/are required in order for an endosome to be transported from the plasma membrane to the Golgi complex? (Select all that apply!) a) Microtubules b) ATP c) Dynein d) Actin e) GTP f) Kinesin g) Myosin

a, b, c, d

Which of the following is/are required in order for pancreatic acinar vesicles to be transported to the plasma membrane prior to secretion? (Select all that apply!) a) Kinesin b) ATP c) GTP d) Microtubules e) Actin f) Myosin g) Dynein

a

Which of the following never uses simple diffusion to pass through the cell membrane? a) Ions b) Small polar uncharged molecules c) Small hydrophobic molecules d) Large hydrophobic molecules

d

Which of the following observations constitutes evidence that mitochondria evolved before chloroplasts? a) Mitochondria are aerobic. Chloroplasts are photosynthetic b) Aerobic bacteria evolved before photosynthetic bacteria (cyanobacteria) c) Some protists have separately evolved their own plastids (chloroplast-like structures) through endosymbiosis of cyanobacteria, or even through endosymbiosis of photosynthetic protists d) All Eukaryotes have mitochondria; only a subset of Eukaryotes have chloroplasts

c

Which of the following statements is NOT CONSISTENT with Cell Theory? a) Bacteria and Eukaryotic cells divide using different mechanisms b) Archaea and Bacteria are structurally similar, but Archaea are genetically more similar to Eukaryotes c) Viruses are living organisms d) All of the above

d

Which of the following statements is TRUE? a) Polymerization is favored when tubulin is bound to GDP b) Microtubules do not undergo polymerization or depolymerization until the cell receives a signal c) Polymerization occurs predominantly at the minus (-) ends of microtubules d) Tubulin is an enzyme

d

Which of the following statements is TRUE? a) Some cytoskeletal elements are carbohydrates. b) Microtubules are static, but actin is dynamic. c) Actin is static, microtubules are dynamic. d) Tubulin and actin are both enzymes. e) All of the above

d

White blood cells migrate to a source of infection using amoeboid migration along the surfaces of endothelial cells. Imagine you have discovered a toxin that suppresses the immune system by specifically inhibiting pseudopod formation in white blood cells. Which of the following is your toxin's most likely mechanism of action? a) Inhibiting GTPase activity b) Inhibiting ATPase activity c) Causing Ca++ to leak out of the smooth ER d) Depleting the cell of ATP

a

Why did Palade and his colleagues use pancreatic acinar cells in their original Pulse-Chase experiment? a) Almost all of the proteins produced by pancreatic acinar cells are secreted b) Pancreatic acinar cells are responsible for secretion of insulin, which can be disrupsed in diabetes, which affects over 10% of the population and is the 7th leading cause of death in the U.S c) No reason - just lucky! d) Acinar cells are the most abundant cell type in the body and they are easy to culture

b

You are most likely to find Ca++ channels in the membranes of what organelle? a) Nucleus b) Smooth ER c) Golgi complex d) Secretory vesicle e) Lysosome