Unit 1-molecular cell bio
Some researchers have hypothesized that type II diabetes mellitus is caused by a mitochondrial defect. Which of the following would be the best way for them to study mitochondrial differences in fresh tissue samples from diabetic and non-diabetic mice?
Mitochondria from both tissues could be isolated from other cellular components by fractionating tissue homogenate using differential centrifugation followed by density gradient centrifugation.
The _____ is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell. -plasma membrane -nucleoid region -ribosome -pili -cell wall
plasma membrane
glycosilation
process by which proteins get modified by the addition of one or more carbohydrate chains
What is the function of a bacterium's capsule? -adhesion -protein synthesis -protection -DNA storage -propulsion
protection
ribosome:
protein synthesis
In general, enzymes are what kinds of molecules? lipids -nucleic acids -carbohydrates -minerals -proteins
proteins
Hydrogen bonding is most important in stabilizing the ________ structure of many proteins. -quaternary -primary, secondary, tertiary, and quaternary -tertiary -secondary -primary
secondary
The _____ is composed of DNA and protein.
Chromatin, which is composed of DNA and protein.
quantum tunneling
a phenomenon in which the wave properties of matter allow a particle to exist in a region where it would otherwise be forbidden according to classical mechanics
The 2'-oxygen on the ribose found in RNA makes RNA much more susceptible to breakdown.
It is important that mRNA be easily broken down, to ensure that the correct levels of protein are maintained in the cell.
Why is the Lineweaver - Burk plot important in enzyme kinetics? -It is a single-reciprocal plot. -It makes it easier to determine Vmax and Km. -It is nonlinear. -It illustrates enzyme specificity. -It reveals the presence of prosthetic groups in enzymes.
It makes it easier to determine Vmax and Km.
For the inverted vesicles, indicate whether each of the following should be present inside the vesicle, outside the vesicle, or not present at all in order to demonstrate ATP hydrolysis: Na+, K+, and ATP.
Na+ outside the vesicle -K+ inside the vesicle -ATP outside the vesicle
Adjacent plant cells frequently exchange cytoplasmic components through membrane-lined channels called plasmodesmata. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
intercellular communication (adjacent plant cells)
The active site for many enzymes -involves amino acids that are brought into close proximity by extensive protein folding and may require a prosthetic group such as a metal ion. -contains amino acids that are contiguous to one another along the primary sequence of the protein. -usually depends on only one amino acid. -may require a prosthetic group such as a metal ion. -involves amino acids that are brought into close proximity by extensive protein folding.
involves amino acids that are brought into close proximity by extensive protein folding and may require a prosthetic group such as a metal ion.
A peptide bond is -is a covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen of a second amino acid. -is a covalent bond between the functional R groups of adjacent amino acids. -is a noncovalent bond that dictates the tertiary structure of a protein. -is a covalent bond between adjacent glucose molecules in a peptide. -is a covalent bond between the NH group of one polypeptide and the CO group of an adjacent polypeptide that holds together multimeric proteins.
is a covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen of a second amino acid.
Caenorhabditis elegans
nematode worm
Viruses differ from cells because viruses do NOT, under any circumstances, have __________. -membranes -RNA -organelles -DNA
organelles
Of the following molecules, which would you predict diffuses most readily across membranes? -hydrogen ions -water -oxygen -serine -glucose
oxygen (small + non-polar)
chloroplast:
photosynthesis
Biochemical Strand of Cell Biology
centrifugation/ultracentrifugation, chromatography/electrophoresis
basal bodies
centrioles forming the bases of cilia and flagella
ribose
sugar in RNA
extracellular matrix:
support and regulation of cell properties
Golgi complex:
synthesis of complex polysaccharides
rough endoplasmic reticulum:
synthesis of secretory proteins
Disulfide bonds are often found to stabilize which of the following levels of protein structure? -tertiary -primary, secondary, and tertiary -primary -secondary -None of these structures involve disulfide bonds.
tertiary
RNA and DNA differ -in that RNA contains ribose and DNA contains deoxyribose. -in that RNA contains nucleosides and DNA contains nucleotides. -in that RNA contains uracil and DNA contains thymine. -in that RNA contains ribose and uracil, and DNA contains deoxyribose and thymine. -All of these are correct.
in that RNA contains ribose and uracil, and DNA contains deoxyribose and thymine.
80s
the size of eukaryotic ribosomes.
Which of the following would best be used to determine the lipid content of an isolated membrane fraction? -thin-layer chromatography -SDS-PAGE -freeze-fracture analysis -Western blot analysis -ferritin-linked antibodies
thin-layer chromatography
Deoxyribose
A five-carbon sugar that is a component of DNA nucleotides
A semipermeable membrane is placed between the following solutions. Which solution will decrease in volume? Solution A: 1.4% (m/v) starch Solution B: 7.62% (m/v) starch
Solution A: 1.4% (m/v) starch -The water molecules actually move in both directions, but they move to a greater extent toward Solution B because it has a higher solute concentration than Solution A. The net movement of water molecules causes Solution A to decrease in volume and Solution B to increase in volume.
The methanobacteria, halobacteria, and sulfobacteria are included in which domain? -blue-green algae -protista -archaea -bacteria -eukarya
archaea
The secondary structure of a protein results from _____.
hydrogen bonds -Electronegative oxygen and nitrogen atoms leave hydrogen atoms with partial positive charges.
Which of the following is NOT a function or a characteristic of biological membranes? -Membranes regulate the movement of substances into and out of the cell. -Membranes provide a means of cell-to-cell communication. -Membranes contain receptors for the detection of external signals. -Lipid polymers are major constituents of membrane structure.
-Lipid polymers are major constituents of membrane structure.
Which of the following is an example of membrane leaflet asymmetry? -nonenzymatic flip-flop of phospholipids -two membranes with differing amounts of cholesterol -the position of carbohydrates attached to an N-linked glycoprotein -a polarized cell with different proteins on different faces
-the position of carbohydrates attached to an N-linked glycoprotein
Gorter and Grendel's classic conclusion that the plasma membrane of the human erythrocyte consists of a lipid bilayer was based on the following observations: (i) the lipids that they extracted with acetone from 4.74×109 erythrocytes formed a monolayer 0.89 m2 in area when spread out on a water surface; (ii) the surface area of one erythrocyte was about 100 μm2, according to their measurements. Show from these data how they came to the conclusion that the erythrocyte membrane is a bilayer. -According to the given data, each cell has a monolayer area of 0.89×1012/4.74×109=188μm2. This is almost twice the surface area of an erythrocyte as Gorter and Grendel estimated it, leading to the conclusion that the surface of each cell was covered with two layers of lipid. -According to the given data, the number of erythrocytes should be 0.89×1012⋅100×10−4=8.9×109. This is almost twice the number of erythrocytes as Gorter and Grendel estimated it, leading to the conclusion that the surface of each cell was covered with three layers of lipid. -According to the given data, the surface area of all erythrocytes is 4.74×109/100×108m2=0.47m2. This is almost a half of the surface area formed by a monolayer as Gorter and Grendel estimated it, leading to the conclusion that the surface of each cell was covered with two layers of lipid.
-According to the given data, each cell has a monolayer area of 0.89×1012/4.74×109=188μm2. This is almost twice the surface area of an erythrocyte as Gorter and Grendel estimated it, leading to the conclusion that the surface of each cell was covered with two layers of lipid.
FRAP has revealed that some proteins move in cell membranes much slower than they move in reconstituted liposomes. Which of the following could account for limited mobility of proteins in cell plasma membranes? -association with other proteins in a large complex. -association with lipid rafts. -anchorage to the cell cytoskeleton. -anchorage to the extracellular matrix. -All could limit protein mobility.
-All could limit protein mobility.
Which of the following types of transport occur across the erythrocyte membrane? -glucose uniport -aquaporin water transport -O2 and CO2 passive diffusion -Cl - bicarbonate ion antiport -All of the above are correct.
-All of the above are correct.
Which of the following experimental data would suggest the presence of a transmembrane protein? -The protein isolates with the membrane fraction of the cell rather than the cytoplasmic fraction of the cell. -The protein has windows of the primary sequence with positive hydropathy values separated by windows of the primary sequence with negative hydropathy values. -The primary sequence contains stretches of polar and nonpolar amino acids, suggesting an amphipathic design. -All of the other answer choices suggest the presence of a multipass transmembrane protein.
-All of the other answer choices suggest the presence of a multipass transmembrane protein.
Covalent modification -affects the activity of an enzyme by adding or removing a chemical group. -can activate an enzyme. -can involve the addition of phosphate groups. -produces modifications that can sometimes be reversed. -All of these are correct.
-All of these are correct. (covalent mod)
We now know that the surface area of a human erythrocyte is about 145 um. Explain how Gorter and Grendel could have come to the right conclusion when one of their measurements was only about two-thirds of the correct value. -As it turned out, lipids spread on a water surface cannot form a perfect monolayer. In fact, one third of all lipids formed a bilayer and the surface area of all erythrocytes was underestimated. -As it turned out, the light microscope used by Gorter and Grendel had a low resolution. In fact, they counted only about two-thirds of the total number of erythrocytes. -As it turned out, the lipid extraction technique that Gorter and Grendel used was not quantitative. In fact, they extracted only about two-thirds of the total lipid from the erythrocytes.
-As it turned out, the lipid extraction technique that Gorter and Grendel used was not quantitative. In fact, they extracted only about two-thirds of the total lipid from the erythrocytes.
Why do you suppose that viral illnesses are more difficult to treat than bacterial illnesses? -Because viral enzymes are more pathogenic to the host cells than bacterial. -Because viruses have fewer components and thus fewer targets than bacteria. -Because viruses can affect all types of cells. -Because viruses do not have their own metabolism and are fed by the host cell.
-Because viruses have fewer components and thus fewer targets than bacteria.
Which of the following glucose transporters has properties that facilitate glucose transport out of human liver cells to maintain blood sugar level homeostasis? -GLUT5 -GLUT4 -GLUT2 -GLUT1 -GLUT3
-GLUT2
Knowing that it is possible to prepare inside-out vesicles from erythrocyte plasma membranes, can you think of a way to label a transmembrane protein with on one side of the membrane and with on the other side? -Treat membrane proteins of intact cells with both techniques before and after preparing inside-out vesicles. The side of the membrane that has more lactose residues will be labeled with LP/125I, the side in which galalctose predominates will be labeled with GO/3H−BH4. -Label membrane proteins of intact cells with LP/125I technique that will modify both sides of the membrane, then prepare inside-out vesicles and use 3H that will displace 125I on one side only. -Label membrane proteins of intact cells with one of the techniques described, then prepare inside-out vesicles and use the second labeling technique.
-Label membrane proteins of intact cells with one of the techniques described, then prepare inside-out vesicles and use the second labeling technique.
What was the limit of resolution Leeuwenhoek's microscope?
.83 micrometers
Which of the following experimental data are consistent with the conclusions of Unwin and Henderson's experiments on transmembrane protein structure? -Membranes undergo phase transitions that are determined by the molecular components of the membrane. -Many transmembrane proteins are characterized by one or more transmembrane alpha helices. -Membrane phospholipids have more lateral and rotational freedom of movement than flip-flop movement between membrane leaflets. -Biological membranes are relatively fluid structures.
-Many transmembrane proteins are characterized by one or more transmembrane alpha helices.
Ouabain is a specific inhibitor of the active transport of sodium ions out of the cell and is therefore a valuable tool in studies of membrane transport mechanisms. Which of the following processes in your own body would you expect to be sensitive to inhibition by ouabain? Explain your answer in each case. Active uptake of lactose by the bacteria in your intestine -Yes; active uptake of sugars in bacteria is driven by a sodium ion cotransport. -No; active uptake of sugars and amino acids in bacteria is driven by a proton gradient. -No; active uptake of sugars and amino acids in bacteria is driven by a potassium ion cotransport.
-No; active uptake of sugars and amino acids in bacteria is driven by a proton gradient.
Ouabain is a specific inhibitor of the active transport of sodium ions out of the cell and is therefore a valuable tool in studies of membrane transport mechanisms. Which of the following processes in your own body would you expect to be sensitive to inhibition by ouabain? Explain your answer in each case. Facilitated diffusion of glucose into a muscle cell -Yes; sodium ion cotransport is required for facilitated diffusion of glucose. -No; sodium ion cotransport is required for simple diffusion of glucose, but not for facilitated diffusion of glucose. -No; sodium ion cotransport is required for active transport of glucose, but not for facilitated diffusion of glucose.
-No; sodium ion cotransport is required for active transport of glucose, but not for facilitated diffusion of glucose.
If this mixture of phospholipids is resolved on a thin-layer chromatography (TLC) plate, what will be the order of the phospholipids on the plate at the end of the experiment, from closest to the solvent front to closest to the origin? Assume that the length of the phospholipid tails is the primary determining factor in the experiment. Four phospholipids are present in a mixture, with each phospholipid having a different length for its hydrocarbon tails: Phosphatidylcholine (PC): composed of C18 lipid tails Phosphatidylethanolamine (PE): composed of C16 lipid tails Phosphatidylinositol (PI): composed of C12 lipid tails Phosphatidylserine (PS): composed of C20 lipid tails If this mixture of phospholipids is resolved on a thin-layer chromatography (TLC) plate, what will be the order of the phospholipids on the plate at the end of the experiment, from closest to the solvent front to closest to the origin? Assume that the length of the phospholipid tails is the primary determining factor in the experiment. -PE, PC, PI, and finally PS -PC, PS, PI, and finally PE -PI, PE, PC, and finally PS -PS, PI, PC, and finally PE
-PI, PE, PC, and finally PS
The structure of the plasma membrane makes it selectively permeable, enabling it to regulate the transport of substances into and out of the cell.
-Small, nonpolar molecules are hydrophobic, so they can easily cross the phospholipid bilayer of the plasma membrane. -Polar molecules and ions are hydrophilic, so they cannot very easily cross the hydrophobic portion of the plasma membrane (formed by the phospholipid tails). Water is an unusual molecule because, despite the fact that it is polar, it is small enough to pass directly through the hydrophobic interior of the lipid bilayer, albeit slowly. -Polar molecules and ions generally cross the plasma membrane with the help of transport proteins. For example, water crosses the bilayer rapidly via transport proteins called aquaporins.
What conclusion would you draw if some of the proteins that become labeled by the method of part B were among those that had been labeled when intact cells were incubated with in the presence of and the membrane proteins, then extracted and analyzed on polyacrylamide gels? -Some proteins extend all the way through the membrane and actually protrude sufficiently on both sides of the membrane to allow them to be labeled on either side. -Even though some proteins protrude only on one side of the membrane, after labeling they change their conformation that allows them to penetrate to the other side of the membrane and to be labeled. -Even if these proteins are settle only from one side of the membrane, because of their large charge they can attract labels from the other side.
-Some proteins extend all the way through the membrane and actually protrude sufficiently on both sides of the membrane to allow them to be labeled on either side.
Suggest an advantage that such vesicles might have compared to intact red blood cells for studying the pump. -Such vesicles are free of exogenous energy sources and metabolize most substrates. -Such vesicles are free of endogenous energy sources and do not metabolize most substrates. -Such vesicles are free of exogenous energy sources and do not metabolize most substrates. -Such vesicles are free of endogenous energy sources and metabolize most substrates.
-Such vesicles are free of endogenous energy sources and do not metabolize most substrates.
What would be the expected result if a competitive, nonhydrolyzable analog of ATP were applied to the cytoplasmic side of a plasma membrane that contained a large concentration of the Na+/K+ pump? -The cell interior would experience higher than normal Na+ concentrations and lower than normal K+ concentrations. -The cell would accumulate Na+, but there would be no effect on K+. -Both Na+ and K+ would accumulate outside of the cell. -The cell would accumulate K+, but there would be no effect on Na+.
-The cell interior would experience higher than normal Na+ concentrations and lower than normal K+ concentrations.
A scientist is investigating the properties of two different biological membranes that have different amounts of cholesterol in them. Which of the following would accurately describe the membrane that has more cholesterol compared to the membrane with less cholesterol in it? -The two membranes will have the same degree of fluidity at all temperatures. -The membrane with more cholesterol will have decreased fluidity at low temperatures and lower fluidity at high temperatures compared to the membrane with less cholesterol. -The membrane with more cholesterol will have increased fluidity at low temperatures and lower fluidity at high temperatures compared to the membrane with less cholesterol. -The membrane with more cholesterol will have increased fluidity at all temperatures compared to the membrane with less cholesterol.
-The membrane with more cholesterol will have increased fluidity at low temperatures and lower fluidity at high temperatures compared to the membrane with less cholesterol.
Imagine a new type of cell was discovered on Mars in an organism growing in benzene, a nonpolar liquid. The cell had a lipid bilayer made of phospholipids, but its structure was very different from that of our cell membranes. What might be characteristic features of the phospholipid head groups? -The phospholipid head groups would likely bind to each other with hydrogen bonding that would pack well and not be bulky. -The phospholipid head groups would likely have equal numbers of hydroxyl and amino groups that would pack well and not be bulky. -The phospholipid head groups would likely bind to each other with covalent bonds that would pack well and not be bulky. -The phospholipid head groups would likely have equal numbers of positively and negatively charged groups that would pack well and not be bulky.
-The phospholipid head groups would likely have equal numbers of positively and negatively charged groups that would pack well and not be bulky.
What are some ways in which viruses resemble cells? Select the four correct statements. -They contain nucleic acids and proteins. -They are large enough to be seen with the naked eye. -They have only DNA or RNA. -They are too small to be seen with the naked eye. -They have multi-enzyme complex. -They are composed primarily of carbon, hydrogen, and oxygen. -They have their own ribosomes. -They have their own membranes. -They are able to reproduce.
-They contain nucleic acids and proteins. -They are too small to be seen with the naked eye. -They are composed primarily of carbon, hydrogen, and oxygen. -They are able to reproduce.
What are some ways in which viruses differ from cells? Select the six correct statements. They have, at most, less organells. They cannot replicate on their own. They are much larger than most cells. They have, at most, one or a few enzymes. They are much smaller than most cells. They have plasmids. They do not make their own membranes. They have, at most, more proteins. They do not have cytoplasm or ribosomes. They do not have both DNA and RNA.
-They have at most one or few enzymes. -They are more smaller than most cells. -They do not have both DNA and RNA -they do not make their own membrane -They cannot replicate on their own. -They donot have cytoplasm or ribosomes.
Some enzymes can transfer a hydrogen atom without lowering the activation energy barrier. How is this possible? -This is possible by means of a mechanism known as quantum tunneling. -This is possible by means of a mechanism known as electron transfer. -This is possible by means of a mechanism known as allosteric regulation.
-This is possible by means of a mechanism known as quantum tunneling.
Imagine a new type of cell was discovered on Mars in an organism growing in benzene, a nonpolar liquid. The cell had a lipid bilayer made of phospholipids, but its structure was very different from that of our cell membranes. Describe what might be a possible structure for this new type of membrane. -This membrane would have the nonpolar groups on the two surfaces facing the nonpolar solvent, and it would have a hydrophilic interior. -This membrane would have the polar groups on the two surfaces facing the nonpolar solvent, and it would have a hydrophobic interior. -This membrane would have the nonpolar groups on the two surfaces facing the nonpolar solvent, and it would have a hydrophobic interior. -This membrane would have the polar groups on the two surfaces facing the nonpolar solvent, and it would have a hydrophilic interior.
-This membrane would have the nonpolar groups on the two surfaces facing the nonpolar solvent, and it would have a hydrophilic interior.
Ouabain is a specific inhibitor of the active transport of sodium ions out of the cell and is therefore a valuable tool in studies of membrane transport mechanisms. Which of the following processes in your own body would you expect to be sensitive to inhibition by ouabain? Explain your answer in each case. Active transport of dietary phenylalanine across the intestinal mucosa -Yes; cotransport of sodium ions drives the inward movement of amino acids and can only occur if sodium ions are actively pumped back out again. -No; the movement of amino acids depends on a calcium ion cotransport. -No; the movement of amino acids depends on a potassium ion cotransport.
-Yes; cotransport of sodium ions drives the inward movement of amino acids and can only occur if sodium ions are actively pumped back out again.
Ouabain is a specific inhibitor of the active transport of sodium ions out of the cell and is therefore a valuable tool in studies of membrane transport mechanisms. Which of the following processes in your own body would you expect to be sensitive to inhibition by ouabain? Explain your answer in each case. Uptake of potassium ions by red blood cells -Yes; uptake of potassium ions can occur only via a pump that couples the inward pumping of potassium ions to the outward pumping of sodium ions. -No; uptake of potassium ions can occur only via a pump that couples the inward pumping of potassium ions to the outward pumping of protons. -No; uptake of potassium ions can occur only via a pump that couples the inward pumping of potassium ions to the outward pumping of calcium ions.
-Yes; uptake of potassium ions can occur only via a pump that couples the inward pumping of potassium ions to the outward pumping of sodium ions.
What results would you expect if such inside-out vesicles were subjected to the GO/3H−BH4 procedure? -You would expect no labeling, because all glycoproteins are associated with the outer layer and would therefore be on the interior of an inside-out vesicle. -You would expect to see labeling of all the proteins, because almost all glycoproteins are accessible from one side of the membrane or the other. -You would expect only oxidation of galactose groups with GO, because 3H−BH4 is too polar and wouldn't be able to penetrate through hydrophobic membrane.
-You would expect no labeling, because all glycoproteins are associated with the outer layer and would therefore be on the interior of an inside-out vesicle.
What results would you expect if such inside-out vesicles were subjected to the LP/125i procedure? -You would expect no labeling, because all membrane proteins are associated with the outer layer and would therefore be on the interior of an inside-out vesicle. -You would expect only oxidation of lactose groups with LP, because 125I is too polar and wouldn't be able to penetrate through hydrophobic membrane. -You would expect to see labeling of all the proteins, because almost all membrane proteins are accessible from one side of the membrane or the other.
-You would expect to see labeling of all the proteins, because almost all membrane proteins are accessible from one side of the membrane or the other.
A colleague gives you two tubes containing membrane fractions from an animal cell lysate. One tube contains the plasma membrane fraction, and the other tube contains the mitochondrial inner membrane fraction, but the tubes are not labeled. When you analyze the macromolecule composition of the samples, you are confident that the second tube contains the mitochondrial fraction, because the sample has -a higher protein to lipid ratio. -a lower protein to lipid ratio. -more GPI-anchored proteins. -more carbohydrate in glycoproteins. -a higher ratio of cholesterol to phospholipids.
-a higher protein to lipid ratio.
Most cells have a negative plasma membrane potential (Vm) because they have -an excess of water molecules inside the cell. -an excess of positively charged solute molecules inside the cell. -an excess of negatively charged solute molecules inside the cell. -equal concentrations of ions on both sides of the membrane. -an excess of negatively charged solute molecules outside the cell.
-an excess of negatively charged solute molecules inside the cell.
An allosteric inhibitor -is converted to an activator by the enzyme. -is identical to the active site. -binds and activates the high-affinity state of the enzymes. -increases the rate of substrate binding. -binds at the regulatory site.
-binds at the regulatory site.
A competitive inhibitor -irreversibly binds and inactivates the enzyme. -binds to and inactivates the substrate. -binds at a site other than the active site. -does not inhibit enzyme activity but does lower substrate concentration. -cannot be processed by the enzyme.
-cannot be processed by the enzyme.
Which of the following molecules can cross the lipid bilayer of a membrane directly, without a transport protein or other mechanism? Select all that apply. -carbon dioxide -ions -sucrose -proteins -oxygen -water -lipids
-carbon dioxide -oxygen -water -lipids
Which of the following lipids is found concentrated in lipid rafts in animal cell plasma membranes? -phosphatidylcholine -cholesterol -phophatidylethanolamine -phosphatidylinositol -phosphatidylserine
-cholesterol
The type of inhibitor that binds to the enzyme active site is a(n) ________ inhibitor. -competitive -uncompetitive -mixed-type -coenzyme -noncompetitive
-competitive
List five such bonds or interactions. -Select the five correct answers. -hydrophobic bond -peptide bond -metallic bond -glycosidic bond -hydrogen bond -ionic bond -disulfide bond -phosphodiester bond -coordination bond
-hydrophobic bond -peptide bond -hydrogen bond -ionic bond -disulfide bond
Consider a nerve cell with an internal concentration of 50 , a membrane potential of 60 and an external concentration of 100 . Each of the following is true for import into the cell except -import is down a concentration gradient. -import is down an electrochemical concentration gradient. -import requires energy input. -import ΔG is positive. -All are true.
-import is down an electrochemical concentration gradient.
Phosphorylation of glucose following its transport into a cell -maintains a higher level of glucose outside the cell. -converts glucose into a form that can more easily be exported from the cell. -increases glucose transport into the cell by increasing its concentration gradient across the plasma membrane. -decreases glucose transport into the cell by decreasing its concentration gradient across the plasma membrane. -targets the glucose for transport back out of the cell.
-increases glucose transport into the cell by increasing its concentration gradient across the plasma membrane.
On their outer surface tissue, cells of multicellular organisms carry specific glycoproteins that are responsible for cell-cell adhesion. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
-intercellular communication
Gentiobiose
-linked by Beta 1-6 glycosidic bonds
All of the acid phosphatase in a mammalian cell is found within the lysosomes. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
-localization of function (lysosomes)
purine
-more complex structure than pyrimidines -Adenine (A) and Guanine (G)=2 cyclic rings
Each of the following is an example of facilitated diffusion except -oxygen transport. -aquaporin transport. -chloride-bicarbonate exchange. -ion channel transport. -glucose transport by GLUT1.
-oxygen transport.
The most prominent lipids in animal cell membranes are -phytosterol. -cerebrosides. -glycolipids. -cholesterol. -phospholipids.
-phospholipids.
Enzymes that catalyze the phosphorylation of other enzymes are __________. -phosphoprotein phosphatases -protein kinases -oxidoreductases -ligases
-protein kinases
A multipass transmembrane protein with eight transmembrane alpha-helical segments will have __________. -the amino- and carboxyl-termini will be randomly distributed across the membrane -the amino- and carboxyl-termini will be buried within the hydrophobic core of the membrane -the amino- and carboxyl-termini on different sides of the membrane -the amino- and carboxyl-termini on the same side of the membrane
-the amino- and carboxyl-termini on the same side of the membrane
Which of the following accurately describes the driving force and directionality of the nonactive transport of all molecules across the membrane? -the movement toward equilibrium -pH drives molecule movement according to the charge of the molecule. -Osmosis of water drives molecule movement toward the hypertonic side. -The membrane potential drives transport in a direction related to the charge of the molecule.
-the movement toward equilibrium
Which of the following statements correctly describe(s) the driving forces for diffusion of Na+ and K+ ions through their respective channels? Select all that apply. 1. The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane. 2. The diffusion of Na+ ions into the cell is impeded by the electrical gradient across the plasma membrane. 3. The diffusion of K+ ions out of the cell is impeded by the K+ concentration gradient across the plasma membrane. 4. The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane. 5. The electrochemical gradient is larger for Na+ than for K+.
1. The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane. 4. The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane. 5. The electrochemical gradient is larger for Na+ than for K+.
steps for active transport for the sodium-potassium pump 1-6.
1. Three Na+ ions from the cytosol bind to the pump. 2. the binding of Na+ stimulates the phosphorylation of the pump protein by ATP. 3. Phosphorylation causes a conformational change in the pump that moves the three Na+ ions against their concentration gradient and releases them outside the cell. 4. The release of the Na+ ions permits two K+ ions from outside the cell to bind to the pump, and the phosphate group is released. 5. Release of the phosphate group causes another conformational change in the pump. 6. The conformational change in the pump moves the two K+ ions against their concentration gradient and releases them into the cytosol.
Imagine a new type of cell was discovered on Mars in an organism growing in benzene, a nonpolar liquid. The cell had a lipid bilayer made of phospholipids, but its structure was very different from that of our cell membranes. How might you isolate and visualize these unusual membranes? 1) It may require hydrophobic solvents to solubilize these membranes and release embedded proteins prior to visualization by conventional means. 2) It may require hydrophilic solvents to solubilize these membranes and release embedded proteins prior to visualization by conventional means. 3) It may require amphipathic solvents to solubilize these membranes and release embedded proteins prior to visualization by conventional means.
2) It may require hydrophilic solvents to solubilize these membranes and release embedded proteins prior to visualization by conventional means.
What are the approximate dimensions of the smallest structure that a contemporary cell biologist should be able to observe with a modern light microscope?
200-350 nanometers=.2-.35 micrometers
The presence of deoxyribose as the sugar in DNA makes the molecule more stable and less susceptible to ____________.
hydrolysis
Knowing the ion concentrations on both sides of the plasma membrane makes it possible to calculate the membrane potential (), because at equilibrium 1. ΔG is 1. 2. the Vm is always -60 mV. 3. ΔG is 0. 4. the Faraday constant is 0. 5. It is not possible to calculate Vm without also knowing the uncharged solute distribution across the membrane.
3. ΔG is 0.
Write the complementary sequence for the following DNA sequence, in order from 3' to 5': 5′−CGATATTGAGCTAAGCTT−3′
3′− GCTATAACTCGATTCGAA −5'
Prokaryotes have ________ ribosomes with ________ and ________ subunits, whereas eukaryotes have ________ ribosomes with ________ and ________ subunits. 100S, 60S, 50S; 90S, 60S, 40S 70S, 50S, 30S; 80S, 60S, 40S 80S, 50S, 30S; 100S, 60S, 40S 70S, 40S, 30S; 80S, 50S, 30S 80S, 60S, 40S; 70S, 50S, 30S
70S, 50S, 30S; 80S, 60S, 40S
what was the limit of resolution for hookes microscope?
8.3 micrometers
Which of the following is true of a nanometer? -The nanometer is the most common measurement used in measuring whole cells. -A nanometer is equivalent to 10 Angstroms (Å). -A nanometer is one millionth of a meter. -A nanometer is about the size of a common bacterial cell.
A nanometer is equivalent to 10 Angstroms (Å).
prosthetic group
A non-protein, but organic, molecule (such as vitamin) that is covalently bound to an enzyme as part of the active site.
Pair up the nucleotide bases with their complementary partners.
A-T G-C In a DNA sequence, the purine adenine always pairs with the pyrimidine thymine, and the purine guanine always pairs with the pyrimidine cytosine.
Based on the principle of complementary base pairing, you would expect the percentage of __________ to be equal to the percentage of __________. -Based on the principle of complementary base pairing, you would expect the percentage of __________ to be equal to the percentage of __________. -T; C -A; C -T; G -A; T
A; T
You have an enzymatic reaction proceeding at the optimum pH and optimum temperature. You add a competitive inhibitor to the reaction and notice that the reaction slows down. -Add more inhibitor to speed up the reaction. -Add more substrate; it will outcompete the inhibitor and increase the reaction rate. -Increase the temperature. -Increase the pH.
Add more substrate; it will outcompete the inhibitor and increase the reaction rate.
Which of the following statements does NOT correctly validate the three strands that compose modern cell biology? -Cellular DNA contains information about the structure and function of cellular proteins. -Mutations in the cellular DNA can compromise cellular and macromolecular structure and function. -Cellular structure arises from the combined structures of the macromolecules that compose cells. -All of the other available answer choices validate the relationships between the three strands that compose modern cell biology.
All of the other available answer choices validate the relationships between the three strands that compose modern cell biology.
Which of the following accurately details the relationship between wavelength of illumination, lens quality, magnification, and the limit of resolution for light microscopy? -Magnification and limit of resolution are independent of wavelength of illumination and lens quality for light microscopy. -As shorter wavelength illumination and better quality lenses are used, magnification will increase and the limit of resolution will decrease. -As shorter wavelength illumination and better quality lenses are used, magnification will decrease and the limit of resolution will decrease. -As shorter wavelength illumination and better quality lenses are used, magnification will increase and the limit of resolution will increase.
As shorter wavelength illumination and better quality lenses are used, magnification will increase and the limit of resolution will decrease.
What are the three general types of amino acids?
hydrophobic, polar (noncharged), polar (charged)
Which of the following is mismatched? -Drosophila melanogaster - embryogenesis -Caenorhabditis elegans - photosynthesis -Escherichia coli - genetics -Arabidopsis thaliana - plant gene function -Mus musculus - immunology
Caenorhabditis elegans - photosynthesis
Which of the following can only be viewed by electron microscopy? Which of the following can only be viewed by electron microscopy? -prokaryotes -frog eggs -mitochondria -nuclei -DNA
DNA
Suggest one advantage that DNA sequencing has over nucleic acid hybridization. -DNA sequencing makes it possible to determine the tertiary and quaternary structure of a DNA strand. -DNA sequencing makes it possible to identify species present in a sample of water, sewage, dirt, debris filtered from the air, or swab samples of organisms. -DNA sequencing makes it possible to determine the order of individual nucleotides along a DNA strand. -DNA sequencing can assess whether there is enough sequence complementarity to allow two strands to adhere to one another under specified conditions.
DNA sequencing makes it possible to determine the order of individual nucleotides along a DNA strand.
Suggest one advantage that the electron microscopy has over the light microscopy. -Electron microscopy is capable of much greater limit of resolution and hence much less resolving power. -Electron microscopy uses complex mathematical algorithms to increase the contrast and resolution of digital images. -Electron microscopy uses video cameras to collect digital images for computer storage. -Electron microscopy is capable of much greater resolution and hence much higher useful magnification.
Electron microscopy is capable of much greater resolution and hence much higher useful magnification.
Suggest one advantage that electrophoresis has over chromatography. -Electrophoresis separates molecules based on differences in chemical properties, thereby making it possible to separate molecules that undergo similar chemical reactions. -Electrophoresis separates molecules based on charge differences, thereby making it possible to separate molecules that are similar in size, shape, and density. -Electrophoresis separates molecules based on mass differences, thereby making it possible to separate molecules that are similar in molar mass. -Electrophoresis separates molecules based on differences in solubility, thereby making it possible to separate molecules that are similar in mass and size.
Electrophoresis separates molecules based on charge differences, thereby making it possible to separate molecules that are similar in size, shape, and density.
Rank the following base pairs according to their stability. G-C A-T A-U
G-C due to them having 3 H bonds between them
What structures could Hooke and Leeuwenhoek see with their microscopes?
Hooke and van Leeuwenhoek: liver cell van Leeuwenhoek, but not Hooke: bacterium, chloroplast, mitochondrion Neither of the biologists: ribosome, DNA helix, microfilament
Phospholipids make up the main fabric of the plasma membrane.
In the plasma membrane, the phospholipids are found in a bilayer. The hydrophilic heads are exposed to the aqueous environments of the cytoplasm and extracellular fluid, and the hydrophobic tails are sandwiched within, sheltered from these aqueous environments. Other elements of the plasma membrane conform to the hydrophilic and hydrophobic regions established by the phospholipids. For example, membrane proteins have hydrophilic and hydrophobic regions that are found among the hydrophilic and hydrophobic portions of the plasma membrane, respectively. Cholesterol is a hydrophobic molecule and is found among the hydrophobic tails, which you can see in the figure below.
An alternative solution is to lower the activation energy. What does it mean in molecular terms to say that a catalyst lowers the activation energy of a reaction? -Interaction of molecules is complicated. -Energy of products is increased. -Energy of products is decreased. -Interaction of molecules is facilitated.
Interaction of molecules is facilitated.
The effects of temperature and lipid composition on membrane fluidity are often studied by using artificial membranes containing only one or a few kinds of lipids and no proteins. Assume that you and your lab partner have made the following artificial membranes: Membrane 1: Made entirely from phosphatidylcholine with saturated 16-carbon fatty acids. Membrane 2: Same as membrane 1, except that each of the 16-carbon fatty acids has a single cis double bond. Membrane 3: Same as membrane 1, except that each of the saturated fatty acids has only 14 carbon atoms. After determining the transition temperatures of samples representing each of the membranes, you discover that your lab partner failed to record which membranes the samples correspond to. The three values you determined are -36∘C, 23∘C, and 41∘C. Assign each of these transition temperatures to the correct artificial membrane, and explain your reasoning.
Membrane 1 has uniformly long and saturated Membrane 1 has uniformly long and saturated fatty acids, so it has the highest transition temperature (41*C) . Double bonds disrupt Double bonds disrupt phospholipid packing in the membrane, so membrane 2 has the lowest transition temperature (-36*C). The shorter fatty acid tails of membrane 3 will lowerThe shorter fatty acid tails of membrane 3 will lower the transition temperature noticeably but not drastically, so this membrane will have the intermediate transition temperature (23*C).
Imagine a new type of cell was discovered on Mars in an organism growing in benzene, a nonpolar liquid. The cell had a lipid bilayer made of phospholipids, but its structure was very different from that of our cell membranes. What properties would you expect to find in membrane proteins embedded in this membrane? (Hydrophobic or Hydrophillic) Membrane proteins embedded in themembrane would likely have _____________ regions spanning the membrane with ____________ groups protruding from both sides. Protein transporters would be required for _____________ compounds that could not otherwise pass through the _______________ membrane interior.
Membrane proteins embedded in the membrane would likely have hydrophilic regions spanning the membrane with hydrophobic groups protruding from both sides. Protein transporters would be required for hydrophobic compounds that could not otherwise pass through the hydrophilic membrane interior.
Tertiary structure is NOT directly dependent on _____.
Peptide bonds link together the amino acids of a protein's primary structure.
Which of the following is NOT a characteristic of ribosomes that sets them apart from cellular organelles? -Ribosomes are much smaller than even the smallest organelles. -Ribosomes are not membrane-bound structures. -Ribosomes contain a mixture of biological macromolecules. -Ribosomes can be reconstituted and made functional from their component parts in vitro, whereas cellular organelles have not been successfully reconstituted in vitro.
Ribosomes contain a mixture of biological macromolecules.
Which of the following is true of purines? -Purines have a double-ringed structure. -Cytosine is a purine. -Adenine's bonding to thymine is stronger than is guanine's to cytosine. -Purines bind readily to deoxyribose but not to ribose. -Both adenine and thymine are purines.
Purines have a double-ringed structure.
Believed to be true until the discovery of RNA viruses.
Retrovirus-infected cells contain virally encoded reverse transcriptase, which uses an RNA template to synthesize DNA. Thus, their name contains the root retro.
Suggest one advantage that scanning electron microscopy has over transmission electron microscopy. -Scanning electron microscopy makes it possible to only visualize cells and tissues as if in three dimensions. -Scanning electron microscopy makes it possible to only visualize cells and tissues as if in two dimensions. -Scanning electron microscopy makes it possible to visualize sub-cellular structures and macromolecules as if in two dimensions. -Scanning electron microscopy makes it possible to visualize subcellular structures and macromolecules as if in three dimensions.
Scanning electron microscopy makes it possible to visualize subcellular structures and macromolecules as if in three dimensions.
Suggest one advantage that bioinformatics has over sequencing of a genome. -Sequencing of a genome uses computer analysis to aid in understanding and interpreting those data in terms of gene numbers and expression, whereas bioinformatics simply provides a large amount of data about the DNA present in the genome. -Sequencing of a genome simply provides a large amount of data about the DNA present in the genome, whereas bioinformatics techniques such as image and signal processing allow extraction of useful results from small amounts of raw data. -Sequencing of a genome simply provides a large amount of data about the DNA present in the genome, whereas bioinformatics uses computer analysis to aid in understanding and interpreting those data in terms of gene numbers and expression. -Sequencing of a genome simply provides a large amount of data about the DNA present on a chromome, whereas bioinformatics provides a large amount of data about the DNA present in the entire genome.
Sequencing of a genome simply provides a large amount of data about the DNA present in the genome, whereas bioinformatics uses computer analysis to aid in understanding and interpreting those data in terms of gene numbers and expression.
Cellulose, chitin, and the polysaccharide that makes up the cell walls of many bacteria are the structural polysaccharides, whereas starch and glycogen are the main storage polysaccharides. What must be true about these two classes of polysaccharides? -The beta-glycosidic bonds of storage polysaccharides are less stable than the alpha-glycosidic bonds of structural polysaccharides. -The alpha-glycosidic bonds of storage polysaccharides are more stable than the beta-glycosidic bonds of structural polysaccharides. -The alpha-glycosidic bonds of storage polysaccharides are less stable than the beta-glycosidic bonds of structural polysaccharides. -The beta-glycosidic bonds of storage polysaccharides are more stable than the alpha-glycosidic bonds of structural polysaccharides. -In addition, chemical stability correlates with permanence or nonreactivity. Which of the two types of polysaccharides would be expected to remain the same for longer?
The alpha-glycosidic bonds of storage polysaccharides are less stable than the beta-glycosidic bonds of structural polysaccharides.
A cell biologist isolates a protein-RNA complex that exhibits catalytic activity. Treatment of this complex with RNase completely abolishes catalytic activity. However, treatment of the complex with proteases results in only a 15% decrease in catalytic activity. Which of the following is the most likely explanation for these data? -The catalytic activity of the complex is completely dependent on the protein component and only enhanced by the RNA component of the complex. -The catalytic activity of the complex is enhanced by the protein component and enhanced by the RNA component of the complex. -The catalytic activity of the complex is enhanced by the protein component and completely dependent on the RNA component of the complex. -The catalytic activity of the complex is independent of the protein component and only enhanced by the RNA component of the complex.
The catalytic activity of the complex is enhanced by the protein component and completely dependent on the RNA component of the complex.
What name is given to the rigid structure, found outside the plasma membrane, that surrounds and supports the bacterial cell? 1. capsule 2. pili 3. cell wall 4. flagella 5. nucleoid region 3. cell wall
The cell wall-it is a rigid supporting structure.
What is the most likely mechanism of cell death if a culture of cells is exposed to a toxin that compromises the form and function of the nucleolus? -The cells would likely die due to the stopping of intracellular transport. -The cells will likely die due to a decline in protein synthesis. -The cells will likely die due to depletion of cellular ATP. -The cells would likely die due to all exocytosis stopping.
The cells will likely die due to a decline in protein synthesis.
Which of the following accurately summarizes how the discovery of aquaporins has changed the definition of osmosis across the plasma membranes of cells? -The discovery of aquaporins suggests that water osmotically crosses biological membranes by facilitated diffusion only. -The discovery of aquaporins suggests that water osmotically crosses biological membranes by active transport. -The discovery of aquaporins suggests that water osmotically crosses biological membranes by both simple diffusion and facilitated diffusion. -The discovery of aquaporins suggests that water osmotically crosses biological membranes by endocytosis.
The discovery of aquaporins suggests that water osmotically crosses biological membranes by both simple diffusion and facilitated diffusion.
You have added an irreversible inhibitor to a sample of enzyme and substrate. At this point, the reaction has stopped completely. -Removing the irreversible inhibitor should get the reaction working again. -The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity. -Adding more substrate will increase the rate of reaction. -Adding more inhibitor should get the reaction up to speed again.
The enzyme is inactive at this point. New enzyme must be added to regain enzyme activity.
Phospholipids have a hydrophilic head and hydrophobic tails.
The hydrophilic head includes a glycerol molecule attached to a single phosphate group, which is then attached to another small molecule. The phosphate group and its attachments are either polar or charged. Water molecules are polar and therefore are attracted to these charged regions of the phospholipid head. The hydrophobic tails are two fatty acids attached to the glycerol molecule of the head. Water molecules are not attracted to the tails because C-H bonds are relatively nonpolar and therefore do not result in charged regions in the tails.
Define limit of resolution.
The limit of resolution of a microscope is a measure of how close together two points can be and still be distinguished from one another when viewed through the microscope.
Which of the following is a true statement regarding lysosomes? -The lysosome functions in export packaging. -The lysosome may mature from a late endosome -The lysosome may function in glycosylation. -The contents of the lysosome originate in the smooth ER -None of these are correct.
The lysosome may mature from a late endosome
You are researching a cytoplasmic protein associated with a nerve disorder. The native form of the enzyme appears to be globular protein; however, when a sample of the purified protein is treated with a chemical that reduces disulfide bonds, the enzymatic activity decreases dramatically and multiple globular proteins can be detected in the sample. What does this tell you about the protein? -The primary and secondary structure of the protein depends on disulfide bonds. -The protein is most likely composed of \alpha helices that are held together by disulfide bonds. -The protein is most likely composed of \beta sheets that are held together by disulfide bonds. -The protein is most likely composed of multiple polypeptide chains that are held together by disulfide bonds. -The primary structure of the protein contains multiple cysteine residues that are hydrolyzed by the chemical reductant.
The protein is most likely composed of multiple polypeptide chains that are held together by disulfide bonds.
Suggest one advantage that ultracentrifugation has over centrifugation. -Ultracentrifugation allows to separate biomolecules based on their size, shape, and/or density, whereas separation in a conventional centrifugation is based on molecular mass only. -Ultracentrifugation is capable of much higher speeds and hence much greater centrifugal force than conventional centrifugation. -Ultracentrifugation allows to separate mixtures containing charged molecules, whereas conventional centrifugation separates neutral biomolecules only. -Ultracentrifugation allows to separate biomolecules with different physical properties, whereas conventional centrifugation precipitates all the biomolecules.
Ultracentrifugation is capable of much higher speeds hence much greater centrifugal force than conventional centrifugation.
Which of the following model organisms contributed the most to connecting the genetic strand and the biochemical strand of modern cell biology through the use of genetic techniques and biochemical techniques to show molecules interacting in vivo? -Mutants of Drosophila melanogaster allowed for the mapping of genetic traits to particular chromosomes. -Pea plants illustrated the behavior of trait inheritance between generations. -Yeast mutants and yeast two-hybrid systems allow for the characterization of genetic mutants and determination of how specific proteins interact within a living cell. -Yeast was used to isolate enzymes into a cell-free extract that could carry out fermentation.
Yeast mutants and yeast two-hybrid systems allow for the characterization of genetic mutants and determination of how specific proteins interact within a living cell.
A cellular structure that is visible with an electron microscope but not with a light microscope is -a mitochondrion. -a nucleus. -a chloroplast. -a ribosome.
a ribosome
Which of the following is an example of a prosthetic group? -carboxypeptidase A -a zinc ion -a polypeptide chain -a hydrogen ion -a glycine residue
a zinc ion
Which of the following would be attributed to a peroxisomal dysfunction? -accumulation of glucocerebroside -accumulation of very long chain fatty acids -accumulation of ganglioside GM2 -accumulation of complex sugars -accumulation of N-acetylglucosamine phosphotransferase
accumulation of very long chain fatty acids
EA
activation energy
Active transport is the protein-mediated movement of substances __________. -against a concentration gradient -in response to membrane potential -toward thermodynamic equilibrium -coupled to ATP synthesis
against a concentration gradient
Radioisotopes have been important in the study of biochemical pathways because they __________. -allow scientists to view individual molecules -allow scientists to trace the fate of specific molecules -provide an important energy source for all organisms -are major natural components of all cells
allow scientists to trace the fate of specific molecules.
Which of these illustrates the secondary structure of a protein?
alpha and beta sheets are characteristic of a protein's secondary structure.
An enzyme _____. -is a inorganic catalyst -is a source of energy for endergonic reactions -can bind to nearly any molecule -increases the EA of a reaction -is an organic catalyst
an organic catalyst
Which of the following is a mechanism of substrate activation? -electron transfer -proton transfer -neutron transfer -bond distortion -bond distortion, proton transfer, and electron transfer
bond distortion, proton transfer, and electron transfer
_____ is/are identical in structure to centrioles.
basal bodies
A slice of raw apple placed in a concentrated sugar solution will -become turgid as water is drawn out of its cells. -become turgid as water is drawn into its cells. -become flaccid as water is drawn out of its cells. -become flaccid as water is drawn into its cells.
become flaccid as water is drawn out of its cells. flaccid=in hypertonic solution less tight cell turgid=full of water
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Hoppe-Seyler isolates the protein hemoglobin in crystalline form (1864).
biochemical
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Lehninger demonstrates that oxidative phosphorylation depends for its immediate energy source on the transport of electrons in the mitochondrion (1957).
biochemical
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Lipmann postulates the central importance of ATP in cellular energy transactions (1940).
biochemical
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Ostwald proves that enzymes are catalysts (1893).
biochemical
Which type of microscopy enhances and amplifies slight changes in the phase of transmitted light? -differential interference contrast microscopy -digital video microscopy -both differential interference contrast microscopy and phase contrast microscopy -fluorescence microscopy -phase-contrast microscopy
both differential interference contrast microscopy and phase contrast microscopy
cytoskeleton:
cell shape and movement of organelles
Which of the following types of light microscopy improves the resolution of thick specimens by illuminating one plane of the specimen at a time? -phase-contrast microscopy -brightfield microscopy -differential interference contrast microscopy -confocal microscopy -fluorescence microscopy
confocal microscopy
chromoplast:
contains pigments in flowers
Scanning electron microscopy (SEM) is especially suited to -creating a sense of depth. -examining internal cellular structure. -simultaneously observing living specimens, examining internal cellular structure, and creating a sense of depth. -both observing living specimens and creating a sense of depth. -observing living specimens.
creating a sense of depth.
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Davson and Danielli postulate a model for the structure of cell membranes (1935).
cytological
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Ko¨llicker describes "sarcosomes" (now called mitochondria) in muscle cells (1857).
cytological
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Palade, Porter, and Sjøstrand each develop techniques for fixing and sectioning biological tissue for electron microscopy (1952-1953).
cytological
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Claude isolates the first mitochondrial fractions from rat liver (1940). (2 possible)
cytological and biochemical
pyrimidines
cytosine, thymine, uracil single ring structure
When the size of a cell increases, the surface area/volume ratio -decreases initially and then begins to increase. -remains the same. -increases. -decreases -increases initially and then begins to decrease.
decreases
DNA and RNA differ in the type of pentose sugar each possesses (DNA has __________; RNA has __________) and in one base (DNA has _______; RNA has ______).
deoxyribose, ribose thymine, uracil
Insulin does not enter a target cell but instead binds to a specific membrane receptor on the external surface of the membrane, thereby activating the enzyme adenylyl cyclase on the inner membrane surface. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
detection of signals (insulin)
peroxisome:
detoxification of hydrogen peroxide
The nucleic acid of a virus is composed of -DNA only. -RNA only. -both DNA and RNA. -either DNA or RNA but not both.
either DNA or RNA but not both.
Which type of microscopy has the greatest resolving power? -fluorescence microscopy -phase-contrast microscopy -digital video microscopy -confocal scanning microscopy -electron microscopy
electron microscope
The phosphorylation of glucose to generate glucose-6-phosphate is catalyzed by the enzyme hexokinase. This enzyme, however, is allosterically inhibited by its own product, glucose-6-phosphate. This is an example of __________. -feedback regulation -competitive inhibition -covalent modification -irreversible inhibition
feedback regulation
_____ are surface appendages that allow a bacterium to stick to a surface. -Ribosomes -Cell walls -Flagella -Mitochondria -Fimbriae
fimbriae
Communication between animal cells is facilitated by -gap and adhesive junctions. -plasmodesmata. -adhesive junctions. -tight junctions. -gap junctions.
gap junctions
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Avery, MacLeod, and McCarty demonstrate that bacterial transformation is attributable to DNA, not protein (1944).
genetic
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Haeckel postulates that the nucleus is responsible for heredity (1868).
genetic
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Beadle and Tatum formulate the one gene-one enzyme hypothesis (1940). (2 possible)
genetic and biochemical
Indicate whether it belongs mainly to the cytological, biochemical, or genetic strand in the historical development of cell biology. -Muller discovers that X-rays induce mutations (1927).
genetics
Each of the following molecules move across membranes by simple diffusion except -fatty acids. -glucose. -water. -carbon dioxide. -oxygen.
glucose
Which of the following processes would be most likely to occur in the Golgi complex? -synthesis of DNA -detoxification of drugs -synthesis of steroids -production and packaging of lipids -glycosylation of proteins
glycosylation of proteins
To which of the following classes of sugars does glucose belong? -heptose -hexose -pentose -triose -tetrose
hexose
If the surface area of a cell increases by a factor of 100, the volume of that cell will -remain the same. -increase by a factor of 100. -increase by a factor of 1000. -increase by a factor of 10. -decrease by a factor of 100.
increase by a factor of 1000. *
Raffinose
indigestible oligosaccharide made of 3 monosaccharides (galactose-glucose-fructose)
As a result of its involvement in a reaction, an enzyme _____. -is used up -is unchanged -loses a phosphate group -permanently alters its shape. -loses energy
is unchanged
Proline is referred to as the "helix breaker" because -its only found in the L form, which is incompatible with helical protein structure. -it lacks a charged functional groups for ionic bonding. -it is hydrophobic. -it has a polar functional group. -it lacks the hydrogen atom needed for hydrogen bonding.
it lacks the hydrogen atom needed for hydrogen bonding.
Z-DNA
left handed helix
Cytological Strand of Cell Biology
light microscopy/electron microscopy, transmission electron microscopy/scanning electron microscopy
The smooth endoplasmic reticulum functions in synthesis of -DNA. -proteins. -polysaccharides -lipids. -lipids, polysaccharides, proteins, and DNA.
lipids
When cells are disrupted and fractionated into subcellular components, the enzyme cytochrome is recovered with the endoplasmic reticulum fraction. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
localization of function
Photosystems and are embedded in the thylakoid membrane of the chloroplast. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
localization of function (chloroplast)
If you were shown an electron micrograph of a section of a cell and were asked to identify the cell as plant or animal, one thing you might do is -look for plastids or Golgi complex. -look for plastids or a large vacuole. -look for plastids or mitochondria. -look for plastids or ribosomes.
look for plastids or a large vacuole.
One reason that it might be difficult to separate lysosomes from peroxisomes by centrifugation techniques is that -lysomsomes and peroxisomes are similar in size -lysosomes are smaller than peroxisomes -lysosomes are larger than peroxisomes -lysosomes are bound to peroxisomes
lysomsomes and peroxisomes are similar in size
Which of the following groups of organelles contain acid hydrolase, catalase, and detoxifying enzymes for drugs, respectively? -mitochondria, rough endoplasmic reticulum, smooth endoplasmic reticulum -lysosome, mitochondria, Golgi complex -nucleus, peroxisome, rough endoplasmic reticulum -lysosome, peroxisome, smooth endoplasmic reticulum
lysosome (acid hydrolase), peroxisome (catalase), smooth endoplasmic reticulum (detoxifying enzymes for drugs)
Which of the following is characteristic of eukaryotic cells? -70S ribosomes -peptidoglycan cell wall -membrane-bounded nucleus -binary fission -smaller than 5 μm in diameter
membrane bound nucleus
Which of the following is characteristic of eukaryotic cells? -membrane-bounded nucleus -peptidoglycan cell wall -70S ribosomes -binary fission -smaller than 5 μm in diameter
membrane-bounded nucleus
Which of the following fundamental properties of life do viruses not possess? -ability to reproduce -irritability -metabolism -metabolism and irritability -irritability and ability to reproduce
metabolism and irritability
what provides the cell with structural support?
microfilaments which are a part of the cytoskeleton
Which of these are hollow rods that shape and support the cell? -microfilaments -microtubules -plasma membrane -peroxisomes -chloroplasts
microtubules
The major structural elements of the cytoskeleton are
microtubules, microfilaments, and intermediate filaments.
Ribosomal subunits are manufactured by the _____.
nucleolus
glucose sodium cotransporter
outside of the cell has high Na+ concentration, and low glucose concentration (vice versa on the inside) both glucose and Na+ move into the cell together Na moves down it's electricochemical gradient glucose moves against its concentration gradient
An example of an irreversible inhibitor is -a competitive inhibitor. -angiotensin converting enzyme (ACE) inhibiting drugs. -a noncompetitive inhibitor. -penicillin. -isoleucine.
penicillin
What type of bond joins the monomers in a protein's primary structure?
peptide bonds
Which of the following organelles has only a single membrane around it? -mitochondrion -nucleus -peroxisome -chloroplast -ribosome
peroxisome
Which type of microscope can detect density differences and thereby see organelles in living cells? -fluorescence -phase contrast -TEM -SEM
phase contrast
Enzymes work by _____. -increasing the potential energy difference between reactant and product -adding a phosphate group to a reactant -adding energy to a reaction -reducing EA -decreasing the potential energy difference between reactant and product
reducing EA
Lipid rafts are -important regions of membrane structure comprised of phospholipids. -regions where greater concentrations of sphingolipids are on the inner side of the membrane. -rafts of lipids inside of the cell that serve to store energy. -regions of the membrane that are high in sphingolipids, which facilitate communication with the external environment of the cell. -regions not typically associated with signal transduction.
regions of the membrane that are high in sphingolipids, which facilitate communication with the external environment of the cell.
The interior of a membrane consists primarily of the hydrophobic portions of phospholipids and amphipathic proteins. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
regulation of transport
The inner mitochondrial membrane contains an carrier protein that couples outward movement to inward movement. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
regulation of transport (mitochondrial)
The membrane of a plant root cell has an ion pump that exchanges phosphate inward for bicarbonate outward. -permeability barrier -localization of function -regulation of transport -detection of signals -intercellular communication
regulation of transport (plant root)
nucleolus:
ribosome production
In a bacterium, where are proteins synthesized? -ribosomes -nucleus -peroxisome -nucleoid region -capsule
ribosomes
_____ are the sites of protein synthesis.
ribosomes
Which of these manufactures cellular membranes by adding membrane proteins andphospholipids to its own membrane? -nucleolus -ribosomes -Golgi apparatus -rough endoplasmic reticulum -lysosomes
rough endoplasmic reticulum
Several environments in which you are more likely to find archaea than bacteria are -fresh water, hot springs, basic environments, and phosphorus-containing environments. -salt water, hot springs, acidic environments, and sulfur-containing environments. -salt water, hot springs, acidic environments, and phosphorus-containing environments. -fresh water, hot springs, basic environments, and sulfur-containing environments.
salt water, hot springs, acidic environments, and sulfur-containing environments.
Dextrans
secreted by some bacteria to form slime layers - biofilms polymers of α-D-glucose linked by α(1 → 6) glycosidic bonds, with frequent α(1 → 3) branching. Choose the correct portion of a dextran, including one branch point.
Which of the following organelles is not part of the endomembrane system? -Golgi apparatus -lysosome -secretory vesicle -endoplasmic reticulum -ribosome
secretory vesicle
genetic strand
sequencing of a genome/bioinformatics, nucleic acid hybridization/DNA sequencing
where is calcium stored?
smooth endoplasmic reticulum -In addition to storing calcium, the smooth ER also plays a role in detoxification and lipid synthesis.
smooth endoplasmic reticulum:
steroid synthesis
lysosome:
storage of hydrolase
The Michaelis constant, Km, refers to the __________ at which a reaction proceeds at __________ of the maximum velocity. This constant most accurately reflects __________. -substrate concentration; one-half; the affinity of the substrate-enzyme interaction -substrate concentration; one-fourth; pH optimum of the enzyme -enzyme concentration; one-half; temperature optimum of the enzyme -product concentration; one-half; structure of the substrate
substrate concentration; one-half; the affinity of the substrate-enzyme interaction
What name is given to the reactants in an enzymatically catalyzed reaction? -reactors -substrate -products -EA -active sites
substrates
70s
the size of prokaryotic ribosomes.
Which of the following is NOT true concerning the six classes of lipids? -Which of the following is NOT true concerning the six classes of lipids? -They participate in membrane structure. -One or more of the lipid classes can be used by the cell as energy storage molecules. -They can be involved in transmission of signals within a cell. -They are responsible for expression of genetic information.
they are responsible for expression of genetic information.
order of transcription to secretion
transcription 1. The RNA transcript is transported from the nucleus to the cytoplasm. 2. The RNA message associates with a ribosome and begins synthesis of the desired protein on the surface of the rough ER. 3. The protein is partially glycosylated within the lumen of the ER. 4. The protein passes across the ER membrane into the lumen of a Golgi cisterna. 5. The final sugar groups are added to the protein in the Golgi complex. 6. The protein is packaged into a secretory vesicle and released from the Golgi complex. 7. The secretory vesicle arrives at and fuses with the plasma membrane.
central vacuole:
turgor pressure
Which of the following is INCONSISTENT with the cellular basis of life? -The nuclear and mitochondrial DNA of a cell contains all of the information necessary for cellular reproduction. -Viruses are living, acellular parasites. -Cellular function is intimately linked to cellular structure. -All anatomical structures and physiological processes of an organism are consequences of emergent properties of cellular structures and cellular processes.
viruses are living, acellular parasites
Which of the following is a terpene? -estrogen -vitamin A -glycerol -chitin -testosterone
vitamin A
A cell in a hypertonic solution _________. The result of this will be __________. -will take up water; a decrease in the molar concentration of all solutes in the cell -maintains its volume; a higher concentration of total solutes in the cell than in the external medium -will decrease in volume; an increase in the molar concentration of all solutes in the cell -will decrease in volume; a lower concentration of each solute in the cell than in the external medium
will decrease in volume; an increase in the molar concentration of all solutes in the cell
