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ER → Golgi → vesicles that fuse with plasma membrane
What is the most likely pathway taken by a newly synthesized protein that will be secreted by a cell?
Asbestos is a material that was once used extensively in construction. One risk from working in a building that contains asbestos is the development of asbestosis caused by the inhalation of asbestos fibers. Cells will phagocytize asbestos, but are not able to degrade it. As a result, asbestos fibers accumulate in _____.
The smallest cell structure that would most likely be visible with a standard (not super- resolution) research-grade light microscope is a _____.
light microscopy allows one to view dynamic processes in living cells
The advantage of light microscopy over electron microscopy is that _____.
Electron beams have much shorter wavelengths than visible light.
What is the reason that a modern transmission electron microscope (TEM) can resolve biological images to the subnanometer level, as opposed to tens of nanometers achievable for the best super-resolution light microscope?
standard light microscopy
What technique would be most appropriate to use to observe the movements of condensed chromosomes during cell division?
The toy microscope magnifies a good deal, but has low resolution and therefore poor quality images.
A newspaper ad for a local toy store indicates that an inexpensive toy microscope available for a small child is able to magnify specimens nearly as much as the more costly microscope available in your college lab. What is the primary reason for the price difference?
an endoplasmic reticulum
All of the following are part of a prokaryotic cell EXCEPT _____.
surface to volume ratios
Cell size is limited by _____.
Eukaryotic cells have more intracellular organelles than prokaryotes.
Which of the following is a major difference between prokaryotic cells and eukaryotic cells?
Round the clay up into a sphere.
You have a cube of modeling clay in your hands. Which of the following changes to the shape of this cube of clay will decrease its surface area relative to its volume?
Bacteria and Archaea
Prokaryotes are classified as belonging to two different domains. What are the domains?
Which structure is common to plant and animal cells?
In a bacterium, we will find DNA in _____.
Which organelle or structure is absent in plant cells?
It regulates the movement of proteins and RNAs into and out of the nucleus.
What is the function of the nuclear pore complex found in eukaryotes?
Which of the following macromolecules leaves the nucleus of a eukaryotic cell through pores in the nuclear membrane?
Proteins secreted by prokaryotes are synthesized on ribosomes bound to the cytoplasmic surface of the plasma membrane.
Proteins secreted by prokaryotes are synthesized on ribosomes bound to the cytoplasmic surface of the plasma membrane.
Large numbers of ribosomes are present in cells that specialize in producing which of the following molecules?
a change in the shape of the nucleus
The nuclear lamina is an array of filaments on the inner side of the nuclear membrane. If a method were found that could cause the lamina to fall into disarray, what would you most likely expect to be the immediate consequence?
primarily producing proteins in the cytosol
A cell with a predominance of free ribosomes is most likely _____.
Which organelle often takes up much of the volume of a plant cell?
Which structure is NOT part of the endomembrane system?
All of the listed responses correctly describe polarity characteristics of the Golgi function. Answer: D
The Golgi apparatus has a polarity, or sidedness, to its structure and function. Which of the following statements correctly describes this polarity?
function of the Golgi apparatus in sorting and directing membrane components
The difference in lipid and protein composition between the membranes of the endomembrane system is largely determined by the _____.
Tay-Sachs disease is a human genetic abnormality that results in cells accumulating and becoming clogged with very large, complex, undigested lipids. Which cellular organelle must be involved in this condition?
The liver is involved in detoxification of many poisons and drugs. Which of the following structures is primarily involved in this process and, therefore, abundant in liver cells?
are part of the endomembrane system
Which of the following is NOT true? Both chloroplasts and mitochondria _____.
Which organelle is the primary site of ATP synthesis in eukaryotic cells?
Thylakoids, DNA, and ribosomes are all components found in _____.
in the nucleus, mitochondria, and chloroplasts
In a plant cell, DNA may be found _____.
transfer the hydrogen to oxygen molecules to generate hydrogen peroxide
In a liver cell detoxifying alcohol and some other poisons, the enzymes of the peroxisome remove hydrogen from these molecules and _____.
endosymbiosis of an aerobic bacterium in a larger host cell—the endosymbiont evolved into mitochondria
The evolution of eukaryotic cells most likely involved _____.
Where are proteins produced other than on ribosomes free in the cytosol or ribosomes attached to the ER?
nearly any eukaryotic organism
Suppose a cell has the following molecules and structures: enzymes, DNA, ribosomes, plasma membrane, and mitochondria. It could be a cell from _____.
Cyanide binds with at least one molecule involved in producing ATP. If a cell is exposed to cyanide, most of the cyanide will be found within the _____.
Suppose a young boy is always tired and fatigued, suffering from a metabolic disease. Which of the following organelles is most likely involved in this disease?
components of the cytoskeleton
Motor proteins provide for molecular motion in cells by interacting with what types of cellular structures?
flagella and motile cilia
Which of the following contain the 9 + 2 arrangement of microtubules, consisting of nine doublets of microtubules surrounding a pair of single microtubules?
separate chromosomes during cell division
Vinblastine, a drug that inhibits microtubule polymerization, is used to treat some forms of cancer. Cancer cells given vinblastine would be unable to _____.
a motor protein called dynein
Cilia and flagella bend because of _____.
Spherocytosis is a human blood disorder associated with a defective cytoskeletal protein in the red blood cells (RBCs). What do you suspect is the consequence of such a defect?
move vesicles within a cell
Cytochalasin D is a drug that prevents actin polymerization. A cell treated with cytochalasin D will still be able to _____.
Cells require which of the following to form cilia or flagella?
Movement of cilia and flagella is the result of motor proteins causing microtubules to move relative to each other
Which of the following statements about the cytoskeleton is true?
They are constructed of polymers that are synthesized in the cytoplasm and then transported out of the cell.
The cell walls of bacteria, fungi, and plant cells and the extracellular matrix of animal cells are all external to the plasma membrane. Which of the following is a characteristic common to all of these extracellular structures?
Golgi apparatus and extracellular matrix
A mutation that disrupts the ability of an animal cell to add polysaccharide modifications to proteins would most likely cause defects in its _____.
The extracellular matrix is thought to participate in the regulation of animal cell behavior by communicating information from the outside to the inside of the cell via which of the following?
Plasmodesmata in plant cells are most similar in function to which of the following structures in animal cells?
Ions can travel directly from the cytoplasm of one animal cell to the cytoplasm of an adjacent cell through _____.
allows adjacent cells to adhere to one another
In plant cells, the middle lamella _____.
in the epithelium of an animal's stomach
Where would you expect to find tight junctions?
The molecules responsible for cell-cell adhesion (cell junctions) differed between the two species of sponge.
H. V. Wilson worked with sponges to gain some insight into exactly what was responsible for holding adjacent cells together. He exposed two species of differently pigmented sponges to a chemical that disrupted the cell-cell interaction (cell junctions), and the cells of the sponges dissociated. Wilson then mixed the cells of the two species and removed the chemical that caused the cells to dissociate. Wilson found that the sponges reassembled into two separate species. The cells from one species did not interact or form associations with the cells of the other species. How do you explain the results of Wilson's experiments?
The lysosomes lack sufficient amounts of enzymes necessary for the metabolism of lipids.
Gaucher disease is the most common of lipid storage diseases in humans. It is caused by a deficiency of an enzyme necessary for lipid metabolism. This leads to a collection of fatty material in organs of the body including the spleen, liver, kidneys, lungs, brain, and bone marrow.
Using your knowledge of the structure of eukaryotic cells, identify the statement below that best explains how internal membranes and the organelles of cells would be involved in Gaucher disease.
Cell 2 since it has the highest surface area-to-volume ratio which facilitates the exchange of materials between a cell and its environment.
Both the volume and the surface area for three different cells were measured. These values are listed in the following table:
Volume Surface Area
Cell 1 9.3 μm3 26.5 μm2
Cell 2 12.2 μm 337.1 μm2
Cell 3 17.6 μm 340.6 μm2
Using data from the table above, select the best explanation for why that cell will be able to eliminate waste most efficiently?
amphipathic, with at least one hydrophobic region
For a protein to be an integral membrane protein, it would have to be _____.
Permeability to glucose will increase
You have a planar bilayer with equal amounts of saturated and unsaturated phospholipids. After testing the permeability of this membrane to glucose, you increase the proportion of unsaturated phospholipids in the bilayer. What will happen to the membrane's permeability to glucose?
can move laterally along the plane of the membrane
According to the fluid mosaic model of cell membranes, phospholipids _____.
increasing the percentage of unsaturated phospholipids in the membrane
The membranes of winter wheat are able to remain fluid when it is extremely cold by _____.
are less fluid than the surrounding membrane
Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. At higher temperatures, these regions _____.
consist of protein molecules embedded in a fluid bilayer of phospholipids
Singer and Nicolson's fluid mosaic model of the membrane proposed that membranes_____.
An animal cell lacking oligosaccharides on the external surface of its plasma membrane would likely be impaired in which function?
Which of these are NOT embedded in the hydrophobic portion of the lipid bilayer at all?
There are only weak hydrophobic interactions in the interior of the membrane.
Why are lipids and proteins free to move laterally in membranes?
Which component is a peripheral protein?
Which component is cholesterol?
Which component is a protein fiber of the extracellular matrix?
Which component is a microfilament (actin filament) of the cytoskeleton?
Which component is a glycolipid?
The two sides of a cell membrane face different environments and carry out different functions.
Cell membranes are asymmetrical. Which of the following statements is the most likely explanation for the membrane's asymmetrical nature?
Certain proteins are unique to each membrane.
In what way do the membranes of a eukaryotic cell vary?
The double bonds form kinks in the fatty acid tails, preventing adjacent lipids from packing tightly.
Which of the following is a reasonable explanation for why unsaturated fatty acids help keep a membrane more fluid at lower temperatures?
What kinds of molecules pass through a cell membrane most easily?
Only certain molecules can cross a cell membrane.
Which of the following most accurately describes selective permeability?
It exhibits a specificity for a particular type of molecule.
Which of the following is a characteristic feature of a carrier protein in a plasma membrane?
Which of the following would likely move through the lipid bilayer of a plasma membrane most rapidly?
Which of the following allows water to move much faster across cell membranes?
similarity of the drug molecule to other molecules transported by the target cells
You are working on a team that is designing a new drug. For this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that determines whether the molecule selectively enters the target cells?
is a passive process in which molecules move from a region of higher concentration to a region of lower concentration
There is random movement of substances into and out of the cell.
When a cell is in equilibrium with its environment, which of the following occurs for substances that can diffuse through the cell?
In osmosis, water moves across a membrane from areas of lower solute concentration to areas of higher solute concentration.
Which of the following is true of osmosis?
Refer t o the figure. Initially, in terms of tonicity, the solution in side A with respect to the solution in side B is _____.
Refer to the figure. After the system reaches equilibrium, what changes are observed?
The patient's red blood cells will swell and possibly burst because the blood has become hypotonic compared to the cells.
A patient was involved a serious accident and lost a large quantity of blood. In an attempt to replenish body fluids, distilled water—equal to the volume of blood lost—is added to the blood directly via one of his veins. What will be the most probable result of this transfusion?
side A is hypotonic to side B
Refer to the figure. At the beginning of the experiment,
a decrease in the concentration of NaCl and a decrease in the water level
Refer to the figure. If you examine side A after three days, you should find _____.
Which line in the graph represents the bag that contained a solution isotonic to the 0.6 M solution at the beginning of the experiment?
Which line in the graph represents the bag with the highest initial concentration of sucrose?
Which line or lines in the graph represent(s) bags that contain a solution that is hypertonic at 50 minutes?
is hypotonic and the salt solution is hypertonic to the cells of the celery stalks
Celery stalks that are immersed in fresh water for several hours become stiff. Similar stalks left in a 0.15 M salt solution become limp. From this we can deduce that the fresh water_____.
an isotonic solution, and the plant cell is in a hypotonic solution
Which of the following statements correctly describes the normal tonicity conditions for typical plant and animal cells? The animal cell is in _____.
a salmon moving from a river into an ocean
In which of the following would there be the greatest need for osmoregulation?
When a plant cell, such as one from a rose stem, is submerged in a very hypotonic solution, what is likely to occur?
The sodium-potassium pump is called an electrogenic pump because it _____.
movement of Na+ ions from a lower concentration in a mammalian cell to a higher concentration in the extracellular fluid
Which of the following membrane activities requires energy from ATP?
The voltage across a membrane is called the _____.
Ions diffuse across membranes through specific ion channels down _____.
Which of the following would increase the electrochemical gradient across a membrane?
The phosphate transport system in bacteria imports phosphate into the cell even when the concentration of phosphate outside the cell is much lower than the cytoplasmic phosphate concentration. Phosphate import depends on a pH gradient across the membrane—more acidic outside the cell than inside the cell. Phosphate transport is an example of _____.
In some cells, there are many ion electrochemical gradients across the plasma membrane even though there are usually only one or two proton pumps present in the membrane. The gradients of the other ions are most likely accounted for by _____.
A substance that blocks sodium ions from binding to the cotransport protein will also block the transport of glucose.
Which of the following is most likely true of a protein that cotransports glucose and sodium ions into the intestinal cells of an animal?
Proton gradients across a membrane were used by cells that were the common ancestor of all three domains of life.
Proton pumps are used in various ways by members of every domain of organisms: Bacteria, Archaea, and Eukarya. What does this most probably mean?
hydrating drinks with high concentrations of salts and glucose
Several epidemic microbial diseases of earlier centuries incurred high death rates because they resulted in severe dehydration due to vomiting and diarrhea. Today they are usually not fatal because we have developed which of the following?
the concentration gradient; ATP
The force driving simple diffusion is _____, while the energy source for active transport is _____.
An organism with a cell wall would most likely be unable to take in materials through _____.
White blood cells engulf bacteria using _____.
defective LDL receptors on the cell membranes
Familial hypercholesterolemia is characterized by _____.
pinocytosis is nonselective in the molecules it brings into the cell, whereas receptor-mediated endocytosis offers more selectivity.
The difference between pinocytosis and receptor-mediated endocytosis is that _____.
on the inside surface of the vesicle
In receptor-mediated endocytosis, receptor molecules initially project to the outside of the cell. Where do they end up after endocytosis?
A bacterium engulfed by a white blood cell through phagocytosis will be digested by enzymes contained in _____.
by ribosomes in the rough ER and arrive at the plasma membrane in the membrane of secretory vesicles
In an HIV-infected cell producing HIV virus particles, the viral glycoprotein is expressed on the plasma membrane. How do the viral glycoproteins get to the plasma membrane? They are synthesized _____.
The red fluorescent dye-labeled lipids will appear in the infected cell's interior.
What would be observed by live-cell fluorescence microscopy immediately after HIV entry if HIV is endocytosed first, and then later fuses with the endocytotic vesicle membrane?
Osmosis of water molecules from unknown solution A likely caused the increase in mass observed.
Three lab groups carried out an experiment to identify the correct molarities for five solutions. Each unknown contained one of the following sucrose concentrations: 0.0 M, 0.2 M, 0.4 M, 0.6 M, 0.8 M, and 1.0 M. Each data entry represents the average of 3 sample replications
of 1 cm3 sweet potato cubes expressed as percent change in mass after an overnight (24 hr) soak in the unknown solutions. From the data given, which statement most accurately describes what is occurring in response to a particular unknown solution.
Metabolism consists of all the energy transformation reactions in an organism.
Which of the following is true of metabolism in its entirety in all organisms?
a molecule of glucose
Which of the following is an example of potential rather than kinetic energy?
Temperature is usually uniform throughout a cell
Most cells cannot harness heat to perform work because _____.
Which of the following involves a decrease in entropy?
catabolism (catabolic pathways)
Which term most precisely describes the cellular process of breaking down large molecules into smaller ones?
consume energy to build up polymers from monomers
Anabolic pathways _____.
Which of the following is a statement of the first law of thermodynamics?
The organism ultimately must obtain all of the necessary energy for life from its environment.
For living organisms, which of the following is an important consequence of the first law of thermodynamics?
Every chemical reaction must increase the total entropy of the universe.
Which of the following statements is a logical consequence of the second law of thermodynamics?
Cells require a constant input of energy to maintain their high level of organization.
Which of the following statements is representative of the second law of thermodynamics?
Which of the following types of reactions would decrease the entropy within a cell?
has occurred in accordance with the laws of thermodynamics
Biological evolution of life on Earth, from simple prokaryote-like cells to large, multicellular eukaryotic organisms, _____.
ΔG is the change in free energy.
The mathematical expression for the change in free energy of a system is ΔG =ΔH - TΔS. Which of the following is (are) correct?
A system at chemical equilibrium _____.
The reaction proceeds with a net release of free energy.
Which of the following is true for all exergonic reactions?
A chemical reaction that has a positive ΔG is best described as _____.
a chemical reaction in which both the reactants and products are not being produced or used in any active metabolic pathway at that time in the cell
Chemical equilibrium is relatively rare in living cells. An example of a reaction at chemical equilibrium in a cell would be _____.
Choose the pair of terms that correctly completes this sentence: Catabolism is to anabolism as _____ is to _____.
Hydrolysis increases entropy and is exergonic.
In solution, why do hydrolysis reactions occur more readily than condensation reactions?
It provides energy coupling between exergonic and endergonic reactions.
Why is ATP an important molecule in metabolism?
Reactant and product concentrations in the test tube are different from those in the cell.
When 10,000 molecules of ATP are hydrolyzed to ADP and i in a test tube, about half as
much heat is liberated as when a cell hydrolyzes the same amount of ATP. Which of the following is the best explanation for this observation?
Which of the following is most similar in structure to ATP?
supply energy, primarily in the form of ATP, for the cell's work
Catabolic pathways _____.
When chemical, transport, or mechanical work is done by an organism, what happens to the heat generated?
It may be used to form a phosphorylated intermediate.
When ATP releases some energy, it also releases inorganic phosphate. What happens to the inorganic phosphate in the cell?
ATPase activity must be pumping calcium from the cytosol to the SR against the concentration gradient.
If a resting muscle cell's cytosol has a free calcium ion
concentration of 10-7 while the concentration in the SR is 10-2, then how is the ATPase acting?
ATP is a molecule that acts as an intermediary to store energy for cellular work.
Which of the following is the most correct interpretation of the figure?
Cells use the cycle to recycle ADP and phosphate.
How do cells use the ATP cycle shown in the figure?
Enzymes increase the rate of chemical reaction by lowering activation energy barriers.
Which of the following is true of enzymes?
The catalyzed reaction will have the same ∆G.
Which of the following is true when comparing an uncatalyzed reaction to the same reaction with a catalyst?
The lock-and-key analogy for enzymes applies to the specificity of enzymes _____.
Either the enzyme has two distinct active sites or the reactants involved in the two reactions are very similar in size and shape.
You have discovered an enzyme that can catalyze two different chemical reactions. Which of the following is most likely to be correct?
Reactants capable of interacting to form products in a chemical reaction must first overcome a thermodynamic barrier known as the reaction's _____.
During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a ∆G of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G for the new reaction?
The active site of an enzyme is the region that _____.
the binding of the substrate changes the shape of the enzyme's active site
According to the induced fit hypothesis of enzyme catalysis, _____.
Increasing the substrate concentration in an enzymatic reaction could overcome which of the following?
a cofactor necessary for enzyme activity
Zinc, an essential trace element for most organisms, is present in the active site of the enzyme carboxypeptidase. The zinc most likely functions as _____.
A noncompetitive inhibitor decreases the rate of an enzyme reaction by _____.
You collect data on the effect of pH on the function of the enzyme catalase in human cells. Which of the following graphs would you expect?
How might a change of one amino acid at a site, distant from the active site of an enzyme, alter an enzyme's substrate specificity?
For the enzyme- catalyzed reaction shown in the figure, if the initial reactant concentration is 1.0 micromolar, which of these treatments will cause the greatest increase in the rate of the reaction?
In the figure, why does the reaction rate plateau at higher reactant concentrations?
A) Feedback inhibition by product occurs at high reactant concentrations.
B) Most enzyme molecules are occupied by substrate at high reactant concentrations.
C) The reaction nears equilibrium at high reactant concentrations.
D) The activation energy for the reaction increases with reactant concentration.
E) The rate of the reverse reaction increases with reactant concentration.
Which curves on the graphs may represent the temperature and pH profiles of an enzyme taken from a bacterium that lives in a mildly alkaline hot springs at temperatures of 70°C or higher?
Which temperature and pH profile curves on the graphs were most likely generated from analysis of an enzyme from a human stomach where conditions are strongly acid?
exergonic, ∆G < 0
Which of the following terms best describes the forward reaction in the figure?
Which of the following in the figure would be the same in either an enzyme-catalyzed or a noncatalyzed reaction?
Which of the following represents the activation energy required for the enzyme-catalyzed reaction in the figure?
Succinate is the substrate, and fumarate is the product.
Based on this information, which of the following is correct?
What is malonic acid's role with respect to succinate dehydrogenase? Malonic acid _____.
HIV is the virus that causes AIDS. In the mid-1990s, researchers discovered an enzyme in HIV called protease. Once the enzyme's structure was known, researchers began looking for drugs that would fit into the active site and block it. If this strategy for stopping HIV infections were successful, it would be an example of what phenomenon?
A series of enzymes catalyze the reaction X → Y → Z → A. Product A binds to the enzyme that converts X to Y at a position remote from its active site. This binding decreases the activity of the enzyme.
53) What is substance X?
With respect to the enzyme that converts X to Y, substance A functions as _____.
The mechanism in which the end product of a metabolic pathway inhibits an earlier step in the pathway is most precisely described as _____.
It is probably an enzyme that works through allosteric regulation.
You have isolated a previously unstudied protein, identified its complete structure in detail, and determined that it catalyzes the breakdown of a large substrate. You notice it has two binding sites. One of these is large, apparently the bonding site for the large substrate; the other is small, possibly a binding site for a regulatory molecule. What do these findings tell you about the mechanism of this protein?
Allosteric enzyme regulation is usually associated with _____.
a molecule binding at one unit of a tetramer, allowing faster binding at each of the other three
Which of the following is an example of cooperativity?
localization of enzymes into specific organelles or membranes
Besides turning enzymes on or off, what other means does a cell use to control enzymatic activity?
They can more readily encounter and phosphorylate other membrane proteins.
Protein kinases are enzymes that transfer the terminal phosphate from ATP to an amino acid residue on the target protein. Many are located on the plasma membrane as integral membrane proteins or peripheral membrane proteins. What purpose may be served by their plasma membrane localization?
The organism must ultimately obtain all the necessary energy for life from its environment.
Biological systems use free energy based on empirical data that all organisms require a constant energy input. The first law of thermodynamics states that energy can be neither created nor destroyed. For living organisms, which of the following statements is an important consequence of this first law?
Succinate is the substrate, and fumarate is the product in the reaction.
In a biological reaction, succinate dehydrogenase catalyzes the conversion of succinate to fumarate. The reaction is inhibited by malonic acid, a substance that resembles succinate but cannot be acted upon by succinate dehydrogenase. Increasing the amount of succinate molecules to those of malonic acid reduces the inhibitory effect if malonic acid. Select the correct identification of the molecules described in the reaction.
Substrate-level phosphorylation occurs _____.
loses electrons and loses potential energy
The molecule that functions as the reducing agent (electron donor) in a redox or oxidation- reduction reaction _____.
When electrons move closer to a more electronegative atom, what happens? The more electronegative atom is _____.
C6H12O6 is oxidized and O2 is reduced.
Which of the listed statements describes the results of the following reaction? C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy
When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes _____.
NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.
Which of the following statements about NAD+ is true?
Carbohydrates and fats are considered high-energy foods because they _____.
A cell has enough available ATP to meet its needs for about 30 seconds. What is likely to happen when an athlete exhausts his or her ATP supply?
Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?
Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
The free energy for the oxidation of glucose to CO2 and water is -686 kcal/mol and the free
energy for the reduction of NAD+ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?
2 NADH, 2 pyruvate, and 2 ATP
Starting with one molecule of glucose, the energy-containing products of glycolysis are _____.
two molecules of ATP are used and four molecules of ATP are produced.
In glycolysis, for each molecule of glucose oxidized to pyruvate _____.
an agent that closely mimics the structure of glucose but is not metabolized
Which kind of metabolic poison would most directly interfere with glycolysis?
Most of the CO2 from the catabolism of glucose is released during _____.
Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with
some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is in the form of _____.
Which electron carrier(s) function in the citric acid cycle?
The rates of ATP production and carbon dioxide production would both increase.
If you were to add one of the eight citric acid cycle intermediates to the culture medium of yeast growing in the laboratory, what do you think would happen to the rates of ATP and carbon dioxide production?
oxidation of pyruvate to acetyl CoA and the citric acid cycle
Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?
If glucose is the sole energy source, what fraction of the carbon dioxide exhaled by animals is generated by the reactions of the citric acid cycle?
For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of
CO2 are released in the citric acid cycle (see the accompanying figure)?
Oxaloacetate will accumulate and citric acid will decrease.
If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?
3 ATP, 6 CO2, 9 NADH, and 3 FADH2
Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle (see the accompanying figure)?
acetyl CoA, NADH, and CO2
In the presence of oxygen, the three-carbon compound pyruvate can be catabolized in the citric acid cycle. First, however, the pyruvate (1) loses a carbon, which is given off as a molecule of CO2, (2) is oxidized to form a two-carbon compound called acetate, and (3) is bonded to coenzyme A. The three listed steps result in the formation of _____.
Which one of the following is formed by the removal of a carbon (as CO2) from a molecule
the extraction of energy from high-energy electrons remaining from glycolysis and the citric acid cycle
Which of the following events takes place in the electron transport chain?
is a series of redox reactions
The electron transport chain _____.
how ATP is synthesized by a proton motive force
The chemiosmotic hypothesis is an important concept in our understanding of cellular metabolism in general because it explains _____.
glucose → NADH → electron transport chain → oxygen
During aerobic respiration, electrons travel downhill in which sequence?
mitochondrial inner membrane
Where are the proteins of the electron transport chain located?
During aerobic respiration, which of the following directly donates electrons to the electron transport chain at the lowest energy level?
act as an acceptor for electrons and hydrogen, forming water
The primary role of oxygen in cellular respiration is to _____.
During aerobic respiration, H2O is formed. Where does the oxygen atom for the formation of the water come from?
energy released from movement of protons through ATP synthase, down their electrochemical gradient
In chemiosmosis, what is the most direct source of energy that is used to convert ADP + to ATP?
mitochondrial intermembrane space
Energy released by the electron transport chain is used to pump H+ into which location in eukaryotic cells?
creation of a proton-motive force
When hydrogen ions are pumped from the mitochondrial matrix across the inner membrane and into the intermembrane space, the result is the _____.
Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?
an endergonic reaction coupled to an exergonic reaction
The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of _____.
If a cell is able to synthesize 30 ATP molecules for each molecule of glucose completely oxidized to carbon dioxide and water, approximately how many ATP molecules can the cell synthesize for each molecule of pyruvate oxidized to carbon dioxide and water?
It increases the surface for oxidative phosphorylation.
In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?
It was released as CO2 and H2O.
You have a friend who lost 7 kg (about 15 pounds) of fat on a regimen of strict diet and exercise. How did the fat leave his body?
all of the electron transport proteins and ATP synthase
After the disruption, when electron transfer and ATP synthesis still occur, what must be present?
become acidic inside the vesicles when NADH is added
These inside-out membrane vesicles will _____.
all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors
Chemiosmotic ATP synthesis (oxidative phosphorylation) occurs in _____.
Which of the following normally occurs regardless of whether or not oxygen (O2) is present?
glycolysis and fermentation
Which of the following occurs in the cytosol of a eukaryotic cell?
ATP, CO2, and ethanol (ethyl alcohol)
In the absence of oxygen, yeast cells can obtain energy by fermentation, resulting in the production of _____.
oxidize NADH to NAD+
One function of both alcohol fermentation and lactic acid fermentation is to _____.
is a facultative anaerobe
An organism is discovered that thrives in both the presence and absence of oxygen in the air. Curiously, the consumption of sugar increases as oxygen is removed from the organism's environment, even though the organism does not gain much weight. This organism _____.
It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.
Why is glycolysis considered to be one of the first metabolic pathways to have evolved?
Yeast cells that have defective mitochondria incapable of respiration will be able to grow by catabolizing which of the following carbon sources for energy?
What is the oxidizing agent in the following reaction?
Pyruvate + NADH + H+ → Lactate + NAD+
High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of _____.
Glycolysis is active when cellular energy levels are _____; the regulatory enzyme, phosphofructokinase, is _____ by ATP.
Canine phosphofructokinase (PFK) deficiency afflicts Springer spaniels, affecting an estimated 10% of the breed. Given its critical role in glycolysis, one implication of the genetic defect resulting in PFK deficiency in dogs is _____.
His mitochondria lack the transport protein that moves pyruvate across the outer mitochondrial membrane.
A young dog has never had much energy. He is brought to a veterinarian for help and she decides to conduct several diagnostic tests. She discovers that the dog's mitochondria can use only fatty acids and amino acids for respiration, and his cells produce more lactate than normal. Of the following, which is the best explanation of the dog's condition?
Even though plants cells photosynthesize, they still use their mitochondria for oxidation of pyruvate. This will occur in _____.
In respiration, beta oxidation involves the _____.
Fatty acids usually have an even number of carbons in their structures. They are catabolized by a process called beta-oxidation. The end products of the metabolic pathway are acetyl groups of acetyl CoA molecules. These acetyl groups _____.
During anaerobic respiration, lactate levels increase when muscles cells need more energy, however muscles cells eventually fatigue, thus athletes should modify their activities to increase aerobic respiration.
New biosensors, applied like a temporary tattoo to the skin, can alert serious athletes that they are about to "hit the wall" and find it difficult to continue exercising. These biosensors monitor lactate, a form of lactic acid, released in sweat during strenuous exercise.
Which of the statements below is the best explanation of why athletes would need to monitor lactate levels?
The process of photosynthesis probably originated _____.
In autotrophic bacteria, where is chlorophyll located?
Plants photosynthesize _____.
Early investigators thought the oxygen produced by photosynthetic plants came from carbon dioxide. In fact, it comes from _____.
If photosynthesizing green algae are provided with CO2 containing heavy oxygen (18O), later
analysis will show that all of the following molecules produced by the algae contain 18O EXCEPT _____.
Every ecosystem must have _____.
When oxygen is released as a result of photosynthesis, it is a direct by-product of _____.
Autotrophs, but not heterotrophs, can nourish themselves beginning with CO2 and other
nutrients that are inorganic.
Which of the following statements is a correct distinction between autotrophs and heterotrophs?
Other pigments absorb light in addition to chlorophyll a.
The figure shows the absorption spectrum for chlorophyll a and the action spectrum for photosynthesis. Why are they different?
What wavelength of light in the figure is most effective in driving photosynthesis?
Bacteria congregated in these areas because these areas had the most oxygen being released.
Theodor W. Engelmann illuminated a filament of algae with light that passed through a prism, thus exposing different segments of algae to different wavelengths of light. He added aerobic bacteria and then noted in which areas the bacteria congregated. He noted that the largest groups were found in the areas illuminated by the red and blue light.
What did Engelmann conclude about the congregation of bacteria in the red and blue areas?
An outcome of Engelmann's experiment was to help determine the relationship between _____.
A spaceship is designed to support animal life for a multiyear voyage to the outer planets of the solar system. Plants will be grown to provide oxygen and to recycle carbon dioxide. Since the spaceship will be too far from the sun for photosynthesis, an artificial light source will be needed.
What wavelengths of light should be used to maximize plant growth with a minimum of energy expenditure?
Suppose a plant has a unique photosynthetic pigment and the leaves of this plant appear to be reddish yellow. What wavelengths of visible light are absorbed by this pigment?
Halobacterium has a photosynthetic membrane that appears purple. Its photosynthetic action spectrum is the inverse of the action spectrum for green plants. (That is, the Halobacterium action spectrum has a peak where the green plant action spectrum has a trough.) What wavelengths of light do the Halobacterium photosynthetic pigments absorb?
This arrangement enables the plant to absorb light energy of a variety of wavelengths.
Why are there several structurally different pigments in the reaction centers of photosystems?
Paper chromatography would separate the pigments from a particular plant into several bands.
If pigments from a particular species of plant are extracted and subjected to paper chromatography, which of the following is most likely?
carotenoids and other pigments are still present in the leaves
In autumn, the leaves of deciduous trees change colors. This is because chlorophyll is degraded and _____.
What event accompanies energy absorption by chlorophyll (or other pigment molecules of the antenna complex)?
As electrons are passed through the system of electron carriers associated with photosystem II, they lose energy. What happens to this energy?
The final electron acceptor associated with photosystem I is _____.
The electrons of photosystem II are excited and transferred to electron carriers. From which molecule or structure do the photosystem II replacement electrons come?
absorb and transfer light energy to the reaction-center chlorophyll
In the thylakoid membranes, the pigment molecules in a light-harvesting complex _____.
receiving electrons from the thylakoid membrane electron transport chain
Which of the following are directly associated with photosystem I?
test for liberation of O2 in the light
Some photosynthetic organisms contain chloroplasts that lack photosystem II, yet are able to survive. The best way to detect the lack of photosystem II in these organisms would be to _____.
What are the products of linear electron flow?
As a research scientist, you measure the amount of ATP and NADPH consumed by the Calvin cycle in 1 hour. You find that 30,000 molecules of ATP were consumed, but only 20,000 molecules of NADPH were consumed. Where did the extra ATP molecules come from?
Assume a thylakoid is somehow punctured so that the interior of the thylakoid is no longer separated from the stroma. This damage will most directly affect the _____.
thylakoid membrane and inner mitochondrial membrane
In a plant cell, where are the ATP synthase complexes located?
stroma to the thylakoid space
In mitochondria, chemiosmosis moves protons from the matrix into the intermembrane space, whereas in chloroplasts, chemiosmosis moves protons from the _____.
Photosynthesis stores energy in complex organic molecules; respiration releases energy from complex organic molecules
Which of the following statements best describes the relationship between photosynthesis and respiration?
In photosynthetic cells, synthesis of ATP by the chemiosmotic mechanism occurs during _____.
Carbon dioxide is split to form oxygen gas and carbon compounds _____.
What is the relationship between the wavelength of light and the quantity of energy per photon?
It obtains electrons from the oxygen atom in a water molecule, so it must have a stronger attraction for electrons than oxygen has.
P680+ is said to be the strongest biological oxidizing agent. Given its function, why is this necessary?
They protect against oxidative damage from excessive light energy.
Carotenoids are often found in foods that are considered to have antioxidant properties in human nutrition. What related function do they have in plants?
In a plant, the reactions that produce molecular oxygen (O2) take place in _____.
The accumulation of free oxygen in Earth's atmosphere began with the origin of _____.
oxidative phosphorylation in cellular respiration
In its mechanism, photophosphorylation is most similar to _____.
Which process is most directly driven by light energy?
A gardener is concerned that her greenhouse is getting too hot from too much light and seeks to shade her plants with colored translucent plastic sheets, the color of which allows passage of only that wavelength. What color should she use to reduce overall light energy but still maximize plant growth?
A flask containing photosynthetic green algae and a control flask containing water with no algae are both placed under a bank of lights, which are set to cycle between 12 hours of light and 12 hours of dark. The dissolved oxygen concentrations in both flasks are monitored. Predict what the relative dissolved oxygen concentrations will be in the flask with algae compared to the control flask. The dissolved oxygen in the flask with algae will _____.
Which of the following are products of the light reactions of photosynthesis that are utilized in the Calvin cycle?
Where does the Calvin cycle take place?
What is the primary function of the Calvin cycle?
In the process of carbon fixation, RuBP attaches a CO2 to produce a six-carbon molecule,
which is then split to produce two molecules of 3-phosphoglycerate. After phosphorylation and reduction produces glyceraldehyde 3-phosphate (G3P), what more needs to happen to complete the Calvin cycle?
Refer to the figure. If the carbon atom of each of the incoming CO2 molecules is labeled
with a radioactive isotope of carbon, which organic molecules will be radioactively labeled after one cycle?
The CO2 acceptor concentration would increase when the CO2 is cut off, but decrease when
the light is cut off.
Refer to the figure. To identify the molecule that accepts CO2, Calvin and Benson manipulated the carbon-fixation cycle by either cutting off CO2 or cutting off light from cultures
of photosynthetic algae. They then measured the concentrations of various metabolites immediately following the manipulation. How would these experiments help identify the CO2
H2O → NADPH → Calvin cycle
Which of the following sequences correctly represents the flow of electrons during photosynthesis?
Which of the following does NOT occur during the Calvin cycle?
What compound provides the reducing power for Calvin cycle reactions?
C3 plants would have faster growth; C4 plants would be minimally affected.
What would be the expected effect on plants if the atmospheric CO2 concentration was
They use PEP carboxylase to initially fix CO2.
Why are C4 plants able to photosynthesize with no apparent photorespiration?
fix CO2 into organic acids during the night
CAM plants keep stomata closed in the daytime, thus reducing loss of water. They can do this because they _____.
Both minimize photorespiration but expend more ATP during carbon fixation.
The alternative pathways of photosynthesis using the C4 or CAM systems are said to be compromises. Why?
There would be more light-induced damage to the cells.
If plant gene alterations cause plants to be deficient in photorespiration, what would most probably occur?
can continue to fix CO2 even at lower CO2 concentrations and higher oxygen concentrations
Compared to C3 plants, C4 plants _____.
It represents a C4 photosynthetic system.
Which of the following statements is true concerning the accompanying figure?
cell II only
Referring to the accompanying figure, oxygen would inhibit the CO2 fixation reactions in _____.
generates carbon dioxide and consumes ATP and oxygen
binds to receptors on the membranes of other types of yeast cells
In yeast signal transduction, a yeast cell releases a mating factor which _____.
is cell-cell communication in eukaryotes
Which of the following statements about quorum sensing is FALSE? Quorum sensing _____.
aggregation of bacteria that can cause cavities
In the formation of biofilms, such as those forming on unbrushed teeth, cell signaling serves which function?
Which of the following is a type of local signaling in which a cell secretes a signal molecule that affects neighboring cells?
have receptors that recognize and bind the hormone molecule
Hormones are chemical substances produced in one organ that are released into the bloodstream and affect the function of a target organ. For the target organ to respond to a particular hormone, it must _____.
Plant hormones most often travel in air as a gas.
In which of the following ways do plant hormones differ from hormones in animals?
When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?
Which of the following types of signaling is represented in the figure?
In the figure, the dots in the space between the two structures represent which of the following?
Glycogen breakdown was observed only when epinephrine was administered to intact cells.
Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?
A G-protein receptor with GTP bound to it _____.
binding with a receptor protein that enters the nucleus and activates specific genes
Testosterone functions inside a cell by _____.
Scientists have found that extracellular matrix components may induce specific gene expression in embryonic tissues such as the liver and testes. For this to happen there must be direct communication between the extracellular matrix and the developing cells. Which kind of transmembrane protein would most likely be involved in this kind of induction?
receptor tyrosine kinases
One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding phosphate groups, and then activating relay proteins. Which type does this?
a decrease in transcriptional activity of certain genes
A drug designed to inhibit the response of cells to testosterone would most likely result in _____.
at the cytosol surface
Where would you expect to find the carboxyl end?
at the loop between H5 and H6
The coupled G protein most likely interacts with this receptor _____.
ligand-gated ion channel
Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?
intracellular receptors are present only in target cells
Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect only target cells because _____.
It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane.
If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?
The receptor may be inside the nucleus of a target cell.
Which of the following is true of steroid receptors?
if the patient's cancer cells have excessive levels of HER2
Particular receptor tyrosine kinases (RTKs) that promote excessive cell division are found at high levels on various cancer cells. A protein, Herceptin, has been found to bind to an RTK known as HER2. HER2 is sometimes excessive in cancer cells. This information can now be utilized in breast cancer treatment if which of the following is true?
receptor tyrosine kinase activity
Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins?
Which of the following is characteristic of a steroid hormone action?
steroid hormones are lipid soluble, so they can readily diffuse through the lipid bilayer of the cell membrane
The receptors for steroid hormones are located inside the cell instead of on the membrane surface like most other signal receptors. This is not a problem for steroids because _____.
Not all intercellular signals require transduction. Which one of the following signals would be processed without transduction?
The physical form of the signal changes from one form to another.
What does it mean to say that a signal is transduced?
activation of G protein-coupled receptors
Protein phosphorylation is commonly involved with all of the following EXCEPT _____.
results in a conformational change to each protein
In general, a signal transmitted via phosphorylation of a series of proteins _____.
insufficient ATP levels in the cytosol
Which of the following is the best explanation for the inability of a specific animal cell to
reduce the Ca2+ concentration in its cytosol compared with the extracellular fluid?
modifies a G protein involved in regulating salt and water secretion
The toxin of Vibrio cholerae causes profuse diarrhea because it _____.
protein kinase activity
Which of the following would most likely be an immediate result of a growth factor binding to its receptor?
Adenylyl cyclase has the opposite effect of which of the following?
Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of _____.
An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?
Protein kinase A activation is one possible result of signal molecules binding to G protein- coupled receptors.
Which of the following statements is true of signal molecules?
GTPase activity and hydrolysis of GTP to GDP
Which of the following is a correct association?
activates or inactivates other proteins by adding a phosphate group to them
Protein kinase is an enzyme that _____.
the hydrolysis of cGMP to GMP
Viagra causes dilation of blood vessels and increased blood flow to the penis, facilitating erection. Viagra acts by inhibiting _____.
serine and threonine
Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?
inactivate protein kinases and turn off the signal transduction
In signal transduction, phosphatases _____.
to block G protein activity in liver cells
If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound _____.
that increases phosphodiesterase activity
If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound _____.
Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. The second messenger in this pathway is _____.
elevates cytosolic concentrations of cyclic AMP
Sutherland discovered that the signaling molecule epinephrine _____.
Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs.
Which of the following is true during a typical cAMP-type signal transduction event?
3, 1, 5, 2, 4
Put the steps of the process of signal transduction in the order they occur:
1. A conformational change in the signal-receptor complex activates an enzyme. 2. Protein kinases are activated.
3. A signal molecule binds to a receptor.
4. Target proteins are phosphorylated.
5. Second messenger molecules are released.
control gene expression
Transcription factors _____.
Estrogen binds to specific receptors inside many kinds of cells, each with different responses.
At puberty, an adolescent female body changes in both structure and function of several organ systems, primarily under the influence of changing concentrations of estrogens and other steroid hormones. How can one hormone, such as estrogen, mediate so many effects?
large molecules to which several relay proteins attach to facilitate cascade effects
Scaffolding proteins are _____.
amplify the original signal many times
Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because they _____.
hydrolyzes GTP to GDP, thus shutting down the pathway
GTPase activity is important in the regulation of signal transduction because it _____.
The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development.
Why has C. elegans proven to be a useful model for understanding apoptosis?
The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell's parts are packaged in vesicles that are digested by specialized cells.
Which of the following describes the events of apoptosis?
a form of cancer in which there is insufficient apoptosis
If an adult person has a faulty version of the human analog to ced-4 of the nematode, which of the following is most likely to result?
Lysosomal enzymes exiting the dying cell would damage surrounding cells.
Why is apoptosis potentially threatening to the healthy "neighbors" of a dying cell?
It prevents the caspase activity of ced-3 and ced-4.
In the nematode C. elegans, ced-9 prevents apoptosis in a normal cell in which of the following ways?
Growth factor ligands do not bind as efficiently to receptors.
In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following, if found in cells or organisms as they age, would provide evidence that this is related to cell signaling?
lysis of the cell
Apoptosis involves all but which of the following?
During apoptosis, cellular agents chop up the DNA and fragment the organelles and other cytoplasmic components of a cell.
Cells that are infected, damaged, or have reached the end of their functional life span often undergo "programmed cell death." This controlled cell suicide is called apoptosis. Select the appropriate description of this event on a cell's life cycle.
Signal transduction molecules identified in distantly related organisms are similar.
Which of the following poses the best evidence that cell-signaling pathways evolved early in the history of life?
Messenger RNA (m-RNA) levels would increase in order to be translated into the protein required by the cell.
Which of the following statements would explain what would occur as a result of the signal pathway represented by the diagram?
In eukaryotic cells, chromosomes are composed of _____.
genetically identical 2n somatic cells
What is the final result of mitosis in a human?
Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells?
If there are 20 duplicated chromosomes in a cell, how many centromeres are there?
in the S phase of the cell cycle
Scientists isolate cells in various phases of the cell cycle. They find a group of cells that have 1.5 times more DNA than G1 phase cells. The cells of this group are _____.
normal growth and cell function
The first gap in the cell cycle (G1) corresponds to _____.
The microtubule-organizing center found in animal cells is an identifiable structure present during all phases of the cell cycle. Specifically, it is known as the _____.
the attachment of microtubules to kinetochores
In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit _____.
separation of sister chromatids
The mitotic spindle is a microtubular structure that is involved in _____.
aligning of chromosomes on the equator
Metaphase is characterized by _____.
creating tension by pulling toward opposite poles
Kinetochore microtubules assist in the process of splitting centromeres by _____.
The cell underwent repeated mitosis, but cytokinesis did not occur.
Some cells have several nuclei per cell. How could such multinucleated cells be explained?
Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow.
How is plant cell cytokinesis different from animal cell cytokinesis?
the cleavage furrow of eukaryotic animal cells
FtsZ is a bacterial cytoskeletal protein that forms a contractile ring involved in bacterial cytokinesis. Its function is analogous to _____.
At which phase are centrioles beginning to move apart in animal cells?
If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis?
the structure of the mitotic spindle
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly, this stops mitosis. Specifically, Taxol must affect _____.
Which of the following are primarily responsible for cytokinesis in plant cells but not in animal cells?
shortening of microtubules
Movement of the chromosomes during anaphase would be most affected by a drug that prevents _____.
Measurements of the amount of DNA per nucleus were taken on a large number of cells from a growing fungus. The measured DNA levels ranged from 3 to 6 picograms per nucleus. In which stage of the cell cycle did the nucleus contain 6 picograms of DNA?
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G2?
Cohesin is cleaved enzymatically.
The beginning of anaphase is indicated by which of the following?
During which phase of mitosis do the chromatids become chromosomes?
a groove in the plasma membrane between daughter nuclei
A cleavage furrow is _____.
What is the correct chromosomal condition at prometaphase of mitosis
What is the correct chromosomal condition for one daughter nucleus at telophase of mitosis?
formation of telophase nuclei
If the cell whose nuclear material is shown in the accompanying figure continues toward completion of mitosis, which of the following events would occur next?
I or V
In the figure above, G1 is represented by which numbered part(s) of the cycle?
In the figure above, which number represents DNA synthesis?
In the figure above, at which of the numbered regions would you expect to find cells at metaphase?
gamma contains more DNA than beta
Of the following, the best conclusion concerning the difference between the S phases for beta and gamma is that _____.
They maintain a nuclear envelope during division.
These protists are intermediate in what sense?
They show some but not all of the evolutionary steps toward complete mitosis.
What is the most probable hypothesis about these intermediate forms of cell division?
What is the length of the S phase of the cell cycle?
Which of the following questions might be answered by using the method described?
The research team used their experiments to study the incorporation of labeled nucleotides into a culture of lymphocytes and found that the lymphocytes incorporated the labeled nucleotide at a significantly higher level after a pathogen was introduced into the culture. They concluded that _____.
a plant cell in the process of cytokinesis
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely _____.
replication of the DNA
Which of the following does NOT occur during mitosis?
cleavage furrow formation and cytokinesis
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the cell cycle would be most disrupted by cytochalasin B?
ATP as an energy source
Motor proteins require which of the following to function in the movement of chromosomes toward the poles of the mitotic spindle?
The best conclusion concerning delta is that the cells _____.
have entered into G0
Neurons and some other specialized cells divide infrequently because they _____.
cyclin and a cyclin-dependent kinase
MPF is a dimer consisting of _____.
an enzyme that attaches phosphate groups to other proteins
Cyclin-dependent kinase (Cdk) is _____.
What happens if MPF (mitosis-promoting factor) is introduced into immature frog oocytes that are arrested in G2?
The cyclin component of MPF is degraded.
Once a cell completes mitosis, molecular division triggers must be turned off. What happens to MPF during mitosis?
The M-phase checkpoint ensures that all chromosomes are attached to the mitotic spindle. If this does not happen, cells would most likely be arrested in _____.
Which of the following is released by platelets in the vicinity of an injury?
Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex?
Which of the following is a protein maintained at steady levels throughout the cell cycle that requires cyclin to become catalytically active?
Which of the following triggers the cell's passage past the G2 checkpoint into mitosis?
The cyclin component of MPF is destroyed toward the end of which phase?
In the figure above, MPF reaches its highest concentration during this stage.
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells and they stop dividing.
Density-dependent inhibition is explained by which of the following?
lack of appropriate cell death
Besides the ability of some cancer cells to overproliferate, what else could logically result in a tumor?
response of the cell cycle controls to signals from the plasma membrane
Anchorage dependence of animal cells in vitro or in vivo depends on which of the following?
For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable?
Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. What might explain the association between malignant tumors and chromosomal abnormalities?
They are involved in the disassembly of the nuclear envelope.
Exposure of zebrafish nuclei to meiotic cytosol resulted in phosphorylation of NEP55 and L68 proteins by cyclin-dependent kinase 2. NEP55 is a protein of the inner nuclear membrane, and L68 is a protein of the nuclear lamina. What is the most likely role of phosphorylation of these proteins in the process of mitosis?
As cells become more numerous, the amount of required growth factors and nutrients per cell becomes insufficient to allow for cell growth.
Density-dependent inhibition is a phenomenon in which crowded cells stop dividing at some optimal density and location. This phenomenon involves binding of a cell-surface protein to its counterpart on an adjoining cell's surface. A growth inhibiting signal is sent to both cells, preventing them from dividing. Certain external physical factors can affect this inhibition mechanism. Select the statement that makes a correct prediction about natural phenomena that could occur during the cell cycle to prevent cell growth.
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