Learning Quizes!
Polymers of polysaccharides, fats and proteins are all synthesized from monomers by which process? a.The removal of water (dehydration) b.The formation of disulfide bridges between monomers c.The addition of water to each monomer (hydrolysis) d.Connecting monosaccharides together e.Ionic bonding of monomers
The removal of water (dehydration)
The energy of electron transport serves to translocate protons to the intermembrane space of mitochondria. How does this help mitochondria produce energy? a.The protons are transferred to oxygen in an energy-releasing reaction b.The protons pick up electrons from the electron transport chain on their way through the inner mitochondrial membrane. c.The translocation of protons sets up the gradient that drives ATP synthesis in the mitochondria via ATP Synthase. d.The protons receive electrons from the NAD+ and FAD that are accepted by the electrons in glycolysis and the Citric Acid Cycle
The translocation of protons sets up the gradient that drives ATP synthesis in the mitochondria via ATP Synthase.
Which of the following happens when a G-protein-coupled receptor activates a G protein? a.The β subunit exchanges its bound GDP for GTP b.The α subunit exchanges its bound GDP for GTP c.It activates the α subunit and inactivates the βγ complex d.The GDP bound to the α subunit is phosphorylated to form bound GTP
The β subunit exchanges its bound GDP for GTP
Which of the following about intermediate filaments is not true? a.They are found in the cytoplasm of all eukaryotic cells b.All of these are true c.They are grouped into different classes based on the cell types or locations in which they are found d.They lack the intrinsic polarity of microtubules and microfilaments e.They are the most stable of the cytoskeleton filaments
They are found in the cytoplasm of all eukaryotic cells
Which of the following is true for anabolic pathways? a.They consume energy to build up polymers from monomers b.Only plants carry out anabolic pathways c.They do not depend on enzymes d.They release energy as they degrade polymers to monomers
They consume energy to build up polymers from monomers
Which of the following statements concerning unsaturated fats is true? a.They contain more hydrogen than saturated fats having the same number of carbon atoms b.They have double bonds in the carbon chains of their fatty acids c.They are generally solids at room temperature d.They are more common in animals than in plants e.All of these are true statements
They have double bonds in the carbon chains of their fatty acids
In a plant cell, where are ATP synthase complexes found? a.Inner membrane of the chloroplast and inner mitochondrial membrane b.Thylakoid membrane c.Inner mitochondrial membrane d.Plasma membrane e.Thylakoid membrane and inner mitochondrial membrane
Thylakoid membrane and inner mitochondrial membrane
You have grown a culture of human cells and discover that it is heavily contaminated with bacteria. Which of the following procedures will most likely eliminate the bacteria without killing the human cells? a.Treating the culture with a detergent that destroys cell membranes b.Treating the culture with a drug that dissolves cell walls c.Diluting a small portion of the contaminated culture with 1000 times as much fresh nutrient broth and then regrowing the cells d.Treating the culture with a drug that causes the endoplasmic reticulum to fall apart e.Treating the culture with a drug that damages DNA
Treating the culture with a drug that dissolves cell walls
The oxygen produced by photosynthetic plants comes from_______. a.Water b.The electrons from NADPH c.Carbon dioxide d.Glucose
Water
The sodium potassium pump is: a.A lipid that pumps potassium into the cell and sodium out of the cell b.A lipid that pumps potassium out of the cell and sodium into the cell c.A protein that pumps potassium out of the cell and sodium into the cell d.A protein that pumps potassium into the cell and sodium out of the cell
A protein that pumps potassium into the cell and sodium out of the cell
What is a nuclear localization signal? a.A stretch of amino acids that directs a protein to the nucleus b.A stretch of amino acids that directs proteins from the nucleus to the ER c.A signal that prevent proteins from diffusing out of the nucleus d.A component of the nuclear pore complex e.A molecule that is attached to nuclear protein so that they are retained inside the nucleus
A stretch of amino acids that directs a protein to the nucleus
Which of the following is most likely to diffuse unaided through the plasma membrane? a.Chloride ion b.Glucose c.An amino acid d.CO2
CO2
The activation of receptor tyrosine kinase by signal binding is most immediately characterized by a.GTP hydrolysis b.Channel protein conformational changes c.Dimerization and phosphorylation d.Cyclic AMP formation e.Activation of trimeric G protein
Dimerization and phosphorylation
Which of the following is false? a.Dolly the sheep was created using the somatic cell nuclear transfer (SCNT) technique b.During the somatic cell nuclear transfer (SCNT) technique, the nucleus of a somatic cell is transferred to an egg that has had its nucleus removed c.Embryonic stem cells can only give rise to a few types of cells in the body d.Embryonic stem cells are derived from the blastocyst stage during embryonic development
Embryonic stem cells can only give rise to a few types of cells in the body
Which of the following statements is true? a.Extracellular signal molecules that are large and polar must bind to a cell-surface receptor so as to signal a target cell b.Cortisol (a steroid) generates a signal response by binding to a cell-surface receptor c.All of these are true d.A cell-surface receptor capable of binding only one type of signal molecule can mediate only one kind of cell response e.To function, all extracellular signal molecules must be transported by their receptor across the plasma membrane into the cytosol
Extracellular signal molecules that are large and polar must bind to a cell-surface receptor so as to signal a target cell
What is the main role of the photosystem pigment molecules in the thylakoid membrane? a.Synthesize ATP b.Harvest photons and transfer light energy to the reaction-center chlorophyll c.Split water and release oxygen to the reaction-center chlorophyll d.Transfer electrons to NADPH
Harvest photons and transfer light energy to the reaction-center chlorophyll
Triacylglycerol is a a.Molecule formed from three alchohols by dehydration reactions b.Lipid that makes up phospholipids c.Protein with tertiary structure d.Carbohydrate with three sugars joined by glycosidic linkages e.Lipid made with three fatty acids and glycerol
Lipid made with three fatty acids and glycerol
efer to the figure showing step 8 in the citric acid cycle. Which statement concerning the reaction is correct? a.NAD+ is more reduced than NADH b.Oxaloacetate is more reduced than malate c.Malate is more reduced than oxaloacetate d.Malate is more oxidized than oxaloacetate
Malate is more reduced than oxaloacetate
Which of the following statements about the function of the centrosome is false? a.Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome. b.Centrosomes contain γ-tubulin that is important for microtubule nucleation c.Centrosomes in animal cells typically contain a pair of centrioles d.Centrosomes are the major microtubule-organizing center in animal cells
Microtubules emanating from the centrosome have alternating polarity such that some have their plus end attached to the centrosome while others have their minus end attached to the centrosome.
Which of the following is not a fundamental property of carbon? a.Carbon-containing molecules are diverse b.Carbon has a valence of 4 c.Carbon-containing molecules may form stereoisomers d.Carbon-containing molecules are stable e.Molecules made of only Carbon and Hydrogen often hydrogen bond with other molecules
Molecules made of only Carbon and Hydrogen often hydrogen bond with other molecules
During electron transport in mitochondria, electrons move along the electron-transport chain coupled to the pumping of protons into the intermembrane space. What is the final result of these electron transfers? a.pyruvate is oxidized to CO2 b.OH- is oxidized to O2 c.H- is converted to H2 d.O2 is reduced to H2O
O2 is reduced to H2O
You disrupt all hydrogen bonds in a protein. What level of structure will be preserved? a.Primary structure b.Quaternary structure c.Secondary structure d.No structure is preserved e.Tertiary structure
Primary!
Enzymes are biological catalysts. Which of the following is not true when comparing an uncatalyzed reaction to the same reaction with a catalyst? a.The catalyzed reaction will be faster b.The catalyzed reaction will have a different change in free energy between reactants and products c.The catalyzed reaction will have lower activation energy d.The catalyzed reaction will not consume the catalyst
The catalyzed reaction will have a different change in free energy between reactants and products
Which of the following statements about glycolysis is false? a.Glycolysis has steps involving oxidation-reduction reactions b.Glycolysis makes ATP exclusively through substrate-level phosphorylation c.Glycolysis can operate in the complete absence of O2 d.The end products of glycolysis are CO2 and H2O e.The enzymes of glycolysis are located in the cytosol of the cell
The end products of glycolysis are CO2 and H2O
The movement of a substance through a transport protein as it follows its concentration gradient across a cell membrane is an example of a.Active transport b.Facilitated diffusion c.Diffusion d.Osmosis
facilitated diffusion
Life is possible because living cells maintain themselves in a steady state, with most of their reactions a.conserving energy b.conserving matter c.far from equilibrium d.at equilibrium
far from equilibrium!
Membrane lipids are capable of many different types of movement. Which of these movements is least likely to occur in biological membranes? a.Rotation b.Flexing of hydrocarbon chains c.Flipping between lipid layers d.Lateral movement
flipping between lipid layers
Suppose you discovered a new amino acid. Its R-group contains only hydrogen and carbon atoms. What type of tertiary bond would you expect your new amino acid to participate in? a.Hydrogen bond b.Disulfide bond c.Ionic bond d.Hydrophobic interaction e.Alpha helix
hydrophobic interaction
In eukaryotes, pyruvate is converted to acetyl CoA a.in the cytosol b.in the space between the two mitochondrial membranes c.in the mitochondrial matrix d.during passage through the mitochondrial outer membrane e.during passage through the inner mitochondrial membrane
in the mitochondrial matrix
A peptide bond a.is a covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen of a second amino acid. b.is a covalent bond between adjacent glucose molecules in a peptide. c.is a covalent bond between the NH group of one polypeptide and the CO group of another polypeptide. d.is a covalent bond between the functional R groups of adjacent amino acids. e. is a noncovalent bond that dictates the tertiary structure of a protein.
is a covalent bond between the carboxyl carbon of one amino acid and the amino nitrogen of a second amino acid.
The general name for an enzyme that transfers phosphate groups from ATP to a protein is a.Phosphorylase b.Protease c.Phosphatase d.Kinase e.ATPase
kinase
A vesicle that travels from the cell's interior towards the plasma membrane might travel on microtubules driven by the motor ___. a.kinesin b.tropomyosin c.dynein d.myosin
kinesin
What unit of length would you generally use to give the measurements of a typical human cell?
micrometers!
Which of the three major classes of cytoskeletal elements is stabilized by a GTP cap?
microtubules
Which of the following organelles is not part of the endomembrane system? a.Endoplasmic reticulum b.Lysosomes c.All of these are part of the endomembrane system d.Mitochondria e.Golgi apparatus
mitochondria
Lipid droplets are composed of a phospholipid _______ that surrounds a core filled with ______
monolayer, lipids
A polar covalent bond can form when a.there is the gain of one or more electrons from one atom to another atom of the same molecule b.two atoms of a molecule attract the electrons equally c.one of the atoms has a greater affinity for neutrons than the other atom of the same molecule d.one of the atoms has a greater affinity for electrons than the other atom of the same molecule e.there is the loss of one or more electrons from one atom to another atom of the same molecule
one of the atoms has a greater affinity for electrons than the other atom of the same molecule
A bacterium is suddenly expelled from a warm human intestine into the cold world outside. Which of the following adjustments might the bacterium make to maintain the same level of membrane fluidity? a.produce lipids with hydrocarbon tails that are longer and have fewer double bonds b.produce lipids with hydrocarbon tails that are shorter and have more double bonds c.produce fewer glycolipids d.produce more glycolipids
produce lipids with hydrocarbon tails that are shorter and have more double bonds
The metabolism of sugars by glycolysis a.occurs in mitochondria b.occurs only in aerobic organisms c.consumes NADH as a source of energy d.produces a net gain of ATP e.generates carbon dioxide
produces a net gain of ATP
After isolating the rough endoplasmic reticulum from the rest of the cytoplasm, you purify the RNAs attached to it. Which of the following proteins do you expect the RNA from the rough endoplasmic reticulum to encode? a.Proteins that will be secreted b.Cytosolic proteins c.Nuclear proteins d.Ribosomal proteins e.Mitochondrial proteins Feedback
proteins that will be secreted
Fermentation directly a.produces acetyl CoA b.generates ATP c.produces ADP d.regenerates NAD+ from NADH e.regenerates FADH2 from FAD
regenerates NAD+ from NADH
If a protein that is synthesized in the ER has a KDEL sequence, that protein will ____. a.be transported to the mitochondria b.act as a receptor on the plasma membrane c.reside in the ER d.be excreted from the cell e.enter the nucleus through the nuclear pores
reside in the ER
G-protein coupled receptors all have a similar structure and pass through the membrane __ times. a.three b.two c.five d.seven e.one
seven
During the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and phosphoenolpyruvate, a phosphate group is added to ADP to generate ATP. The mechanism for ATP production in this reaction is a.glycolytic phosphorylation b.product-level phosphorylation c.oxidative phosphorylation d.anabolic phosphorylation e.substrate-level phosphorylation
substrate-level phosphorylation
An example of a hydrogen bond is the bond between a.the H of one water molecule and the O of another water molecule b.the two hydrogen atoms of two different water molecules c.the two oxygen atoms of two different water molecules d.C and H in methane (CH4) e.Na+ and Cl- in salt
the H of one water molecule and the O of another water molecule
What is the major structural difference between starch and glycogen? a.the amount of branching that occurs in the molecule b.the types of monosaccharide subunits in the molecules c. whether glucose is in the α or β form d.the type of glycosidic linkages in the molecule e.all of these are differences between starch and glycogen
the amount of branching that occurs in the molecule
Where are proteins in the nucleus synthesized? a.The endoplasmic reticulum b.The nucleus c.In both the cytosol and the nucleus d.The cytosol
the cytosol
Proteins that are fully translated in the cytosol do not end up in _______. a.The nucleus b.The cytosol c.The Golgi d.They can end up in any of these locations e.The mitochondria
the golgi
Phosphorylation cascades, such as those found in the MAP Kinase pathway, involve a series of protein kinases. These cascades are useful for cellular signal transduction because a.they amplify the original signal manyfold b.None of these are useful features of signaling cascades c.they always lead to the same cellular response d.they counter the harmful effects of phosphatases e.the number of molecules used is small and fixed
they amplify the original signal manyfold
All of the following are functions of the citric acid cycle except a.release of carbon dioxide b.production of FADH2 c.transfer of electrons to oxygen to create water d.production of NADH e.production of GTP Feedback
transfer of electrons to oxygen to create water
A protein that forms an ion channel through a membrane is most likely to be a.An enzyme b.A peripheral protein c.A transmembrane protein d.A phospholipid
transmembrane protein
Actin may assemble onto one end while disassembling from the other end of the same microfilament simultaneously in a process known as a. treadmilling b.dynamic instability c.oligomerization d.catastrophe e.nucleation
treadmilling
Which of the following is smallest? a.a typical protein b.a ribosome c.a virus d.a prokaryotic cell e.a mitochondrion
typical protein
How do proteins become embedded in the membrane of the endoplasmic reticulum? a.by complete passage through the ER pore b.by protein chaperones that insert polypeptides into the ER membrane c.via transit sequences that target polypeptides made in the cytosol for the ER membrane d.by splicing of proteins on either side of the ER membrane e.via stop- and start-transfer sequences that stop and start translocation of a polypeptide through the ER membrane
via stop- and start-transfer sequences that stop and start translocation of a polypeptide through the ER membrane
What is the "default" destination for proteins translated on ribosomes in the cytosol? a.Endoplasmic reticulum b.Cytosol c.Nucleus d.Mitochondria e.Golgi apparatus
cytosol
Which of the following correctly represents the flow of electrons during photosynthesis? a.NADPH --> chlorophyll --> Calvin cycle b.H2O --> NADPH --> Calvin cycle c.photosystem I --> photosystem II --> O2 d.NADPH --> electron transport chain --> O2 e.NADPH --> O2 --> CO2
H2O --> NADPH --> Calvin cycle
Rank carbon, hydrogen, nitrogen and oxygen in terms of the number of bonds each typically forms (least to most):
HONC
Cells use membranes to help maintain set ranges of ion concentrations inside and outside the cell. Which of the following ions is the most abundant inside a typical mammalian cell? a.Na+ b.K+ c.Ca2+ d.Cl-
K+
Starting with one molecule of glucose, the "net" products of glycolysis are a.2 ATP and 2 pyruvate b.2 NAD+, 2 pyruvate, 2 ATP c.2 NADH, 2 pyruvate, 2 ATP d.2 NADH, 2 pyruvate, 4 ATP e.2 FADH2, 2 pyruvate, 4 ATP
2 NADH, 2 pyruvate, 2 ATP
The light reactions of photosynthesis supply the Calvin cycle with a.Light energy b.H2O and NADPH c.CO2 and ATP d.Sugar and O2 e.ATP and NADPH
ATP and NADPH
A pluripotent cell is a.Not able to divide b.Can only be produced in the lab c.Able to divide to make any type of cell in the body d.Able to divide to make only one type of cell
Able to divide to make any type of cell in the body
Which of the following statements about the cytoskeleton is true? a.The three cytoskeletal filaments perform distinct tasks in the cell and act completely independently of one another b.The cytoskeleton provides a rigid and unchangeable structure important for the shape of the cell c.All of these are true d.All eukaryotic cells have actin, microtubules, and intermediate filaments in their cytoplasm e.Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end
Actin filaments and microtubules have an inherent polarity, with a plus end that grows more quickly than the minus end
Which of the following statements is false? a.All cells arise from preexisting cells b.The cell is the basic unit of structure for all organisms c.All organisms consist of one or more cells d.All cells have a membrane-bound nucleus e.Cells come in a wide variety of sizes and shapes
All cells have a membrane-bound nucleus
Where does the Calvin cycle take place? a.Thylakoid lumen b.Cytosol c.Mitochondrial matrix d.Chloroplast stroma
Chloroplast stroma
What type of interaction is directly responsible for the formation of protein secondary structure? a.Hydrophobic interactions between side chains of amino acids b.Peptide bonds between adjacent amino acids c.Peptide bonds between nonadjacent amino acids d.Hydrogen bonds between sections of the polypeptide backbone e.Hydrogen bonds between side chains of amino acids
Hydrogen bonds between sections of the polypeptide backbone
Where does most new membrane synthesis take place in a eukaryotic cell? a.In the plasma membrane b.On ribosomes c.In the Golgi d.In the endoplasmic Reticulum e.In the nucleus
In the ER
Which of the three major classes of cytoskeletal elements supports and strengthens the nuclear envelope?
Intermediate filaments
The 3 stages of cell signaling are: a.Paracrine, local and synaptic stages b.Alpha, beta and gamma stages c.Signal reception, signal transduction and cellular response d.Signal reception, changes in gene expression, behavioral response e.Signal reception, cellular response, cell division
Signal reception, signal transduction and cellular response
This figure shows the organization of a protein that normally resides in the ER membrane. The box labeled 1 is the ER signal sequence, and the box labelled 2 is the stop transfer sequence. Given this diagram, which of the following statements must be TRUE? a.none of these answers are correct b.The N-terminus of this protein is in the ER lumen c.The mature version of this protein will span the membrane twice, with both the N- and C-terminus in the cytoplasm d.The N-terminus of this protein is cytoplasmic e.The mature version of this protein will span the membrane twice, with both the N- and C-terminus in the ER lumen
The N-terminus of this protein is in the ER lumen
To what does the 9 + 2 arrangement of microtubules, typical of cilia and flagella, refer? a.The relationship between the basal body and dynein arms b.The arrangement of microtubules in the axoneme c.The length of the microtubules d. The arrangement of dynein arms with respect to each microtubule
The arrangement of microtubules in the axoneme
The components of a nucleotide are a.a six-carbon sugar, an ester linkage, and a four-ringed hydrocarbon. b.two six-carbon sugars attached with an α(1→4) glycosidic bond. c.a carboxyl group, an amine group, and a variable R group. d.a three-carbon alcohol with a hydroxyl group on each carbon and three fatty acids. e.a five-carbon sugar, a phosphate group, and a nitrogen-containing base.
a five-carbon sugar, a phosphate group, and a nitrogen-containing base.
Epithelial growth factor (EGF) stimulates the proliferation of skin cells. The receptor that binds EGF is a receptor tyrosine kinase (RTK), and many tumor cell lines have mutations in the gene that encodes this receptor. Which of the following types of mutation would be expected to promote uncontrolled cell proliferation in skin cells? a.a mutation that prevents dephosphorylation of the activated receptor b.a mutation that destroys the kinase activity of the receptor c.a mutation that prevents dimerization of the receptor d.a mutation that prevents the ability of EGF to bind to the receptor
a mutation that prevents dephosphorylation of the activated receptor
Which of the three major classes of cytoskeletal elements has a monomer that binds ATP?
actin
Which of the three major classes of cytoskeletal elements is abundant in the leading edge (lamellipodia) of a crawling cell?
actin
Acetylcholine binds to a GPCR on heart muscle, making the heart beat more slowly. The activated receptor stimulates a G protein, which opens a K+ channel in the plasma membrane, as shown in the figure below. Which of the following would enhance this effect of the acetylcholine? a.mutations in the acetylcholine receptor that weaken the interaction between the receptor and acetylcholine b.addition of a high concentration of an analog of GTP that can't be hydrolyzed to GDP c.mutations in the acetylcholine receptor that weaken the interaction between the receptor and the G protein d.addition of a drug that prevents the α subunit from exchanging GDP for GTP
addition of a high concentration of an analog of GTP that can't be hydrolyzed to GDP
Proteins destined to enter the endoplasmic reticulum ____. a.all remain within the endoplasmic reticulum b.cross the ER membrane in a folded state c.begin to cross the ER membrane while still being synthesized d.are transported across the ER membrane after their synthesis is complete e.are synthesized in their entirety on free ribosomes in the cytosol
begin to cross the ER membrane while still being synthesized
Consider this pathway: adrenaline --> G-protein coupled receptor --> G protein --> adenylyl cyclase --> cAMP. Identify the second messenger. a.Adrenaline b.Adenylyl cyclase c.G protein d.GPCR e.cAMP
cAMP
The breakdown of glucose to pyruvate by a cell is an example of what type of reaction? a.catabolic b.synthetic c.apoptotic d.aerobic e.anabolic
catabolic
Unlike soluble, cytosolic proteins, membrane proteins are more difficult to purify. Which of the following substances is most commonly used to help purify a membrane protein? a.Detergent b.High salt solution c.Something that will change the pH d.Sucrose
detergent
The composition of lipids in the outer and inner monolayers of the cell membrane lipid bilayers is a.identical in each monolayer b.highly random for each monolayer c.the same for all cell plasma membranes but different from the composition in mitochondrial and chloroplast membranes d.different in each monolayer e.twice as concentrated in the inner monolayer as in the outer monolayer Feedback
different in each monolayer
