BioChem Exam 2 Material (From Mastering Chemistry)
Studied by 0 people
Learn
Practice Test
Spaced Repetition
Match
Flashcards1/123
There's no tags or description
Looks like no tags are added yet.
Name | Mastery | Learn | Test | Matching | Spaced |
|---|
No study sessions yet.
124 Terms
Please match the correct term on the left with the appropriate structural feature of proteins listed on the right.
1) primary structure
A) the interaction between two separate protein strands
2) secondary structure
B) the sequence of AA
3) tertiary structure
C) small sections of organized protein structure, such as helices
4) quaternary structure
D) the overall fold of a single protein strand, such as the globulin fold
-1:B; 2:A; 3:D; 4:C
-1:C; 2:D; 3:A; 4:B
-1:D; 2:C; 3:B; 4:A
-1:B; 2:C; 3:D; 4:A
-1:B; 2:C; 3:D; 4:A
Match the following characteristics to α helices, β sheets, or both.
1) 5.4Å/turn
A) α helices
2) antiparallel arrangement
B) β sheets
3) large dipole moment
C) both
4) extensive H-bonding network
-1:B; 2:B; 3:A; 4:A
-1:A; 2:C; 3:A; 4:B
-1:A; 2:A; 3:C; 4:B
-1:A; 2:B; 3:A; 4:C
-1:A; 2:B; 3:A; 4:C
A short 8-residue sequence of a polypeptide is determined to have φ angles ranging from -65 degrees to -80 degrees and ψ angles ranging from -40 degrees to -50 degrees. What conclusion can be drawn from this data?
a) This segment has helical content.
b)This segment is mostly β sheet.
c) The sequence has no defined secondary structure.
d) No conclusion can be drawn.
a) This segment has helical content.
Which of the following statements about globular proteins are true?
1) The protein folds to make itself as compact as possible.
2) The packing of the protein is such that hydrophilic residues appear on the surface where they can interact with an aqueous environment.
3) Irregularities of the protein's surface allow for the formation of clefts, which are often where the protein promotes a chemical transformation.
4) Regions of secondary structures folding on one another are examples of the protein's tertiary structure.
-Only statements 1, 2, and 4 are correct.
-Only statements 2, 3, and 4 are correct.
-Only statements 1, 2, and 3 are correct.
-All of the listed statements are correct.
-All of the listed statements are correct.
Determine whether each term describes the primary, secondary, or tertiary structure of proteins (or forces relating to the primary, secondary, or tertiary structure of proteins).
-Amide bond
-alpha helix
-beta-pleated sheet
-disulfide bond
-salt bridge
-Amide bond: Primary
-alpha helix: Secondary
-beta-pleated sheet: Secondary
-disulfide bond: Tertiary
-salt bridge: Tertiary
Which of the following statements regarding the folding of proteins is NOT true?
a) Hydrophobic residues pack together because the side chains are attracted to each other through weak Van der Waals interactions.
b)Van der Waals interactions have a stabilizing, cumulative effect.
c) Internal H bonds stabilize the fold.
d) Salt bridges stabilize the fold.
a) Hydrophobic residues pack together because the side chains are attracted to each other through weak Van der Waals interactions.
Protein folding is a thermodynamically favorable process under physiological conditions because:
a) no intermediate stage disulphide bonds form during the folding process.
b) there is an increase in entropy associated with protein folding.
c) of the large negative enthalpy change associated with many noncovalent interactions.
d) there is a decrease in entropy of the solvent by burying hydrophobic groups within the molecule.
e) all of the above.
c) of the large negative enthalpy change associated with many noncovalent interactions.
Which of the following statements about protein quaternary structure are correct?
1) It involves a complex of two or more proteins interacting with each other.
2) The subunits of the structure can be either identical or different.
3) The interactions between subunits can give rise to indefinite growth of polymeric complexes.
4) Most assemblies of protein subunits have one or more defined axis of rotation.
-Only statements 1, 3, and 4 are correct.
-Only statements 2, 3, and 4 are valid.
-Only statements 1, 2, and 3 are valid.
-All of the listed statements are correct.
-All of the listed statements are correct.
Proteins are polymers of _____.
-glycerol
-nucleotides
-amino acids
-hydrocarbons
-CH2O units
-amino acids
What type of bond joins the monomers in a protein's primary structure?
-peptide
-ionic
-S - S
-hydrophobic
-hydrogen
-peptide
The secondary structure of a protein results from _____.
-hydrophobic interactions
-ionic bonds
-peptide bonds
-hydrogen bonds
-bonds between sulfur atoms
-hydrogen bonds
Tertiary structure is NOT directly dependent on _____.
-hydrophobic interactions
-peptide bonds
-ionic bonds
-bonds between sulfur atoms
-hydrogen bonds
-peptide bonds
_________ structure is the sequence of amino acids in a protein.
Primary
___________ structure describes the alpha-helices and beta-sheets that are formed by hydrogen bonding between backbone atoms located near each other in the polypeptide chain.
Secondary
____________ structure is the result of two or more protein subunits assembling to form a larger, biologically active protein complex.
Quaternary
__________ structure is achieved when a protein folds into a compact, three-dimensional shape stabilized by interactions between side-chain R groups of amino acids
Tertiary
Glycine and proline are both non-polar amino acids, and both are very likely to be found at the surface of proteins. What physical characteristic of each is responsible for this observation?
1) Both glycine and proline are small.
2) Glycine is small, and proline is rigid.
3) The side chains of both these amino acids make favorable interactions with molecules near the surface of proteins.
4) Both amino acids make strong interactions with each other and therefore are likely to be found next to each other in a protein.
-Only statement 2 is correct.
-Only statements 1 and 2 are correct.
-Only statements 2, 3, and 4 are correct.
-Only statements 1, 2, and 3 are correct
-Only statement 2 is correct.
Which of the following statements represents the difference between a nucleoside and a nucleotide?
-Nucleosides contain glycosidic linkages.
-Nucleotides contain 5′ phosphate groups.
-Nucleosides contain pyrimidine bases, whereas nucleotides contain purine bases.
-Nucleosides contain purine bases, whereas nucleotides contain pyrimidine bases.
-Nucleotides contain 5′ phosphate groups.
Which of the following statements is NOT true of polynucleotides?
-All polynucleotides have directionality.
-For DNA specifically, the genetic information is stored in the primary structure of the polynucleotide chain.
-All phosphodiester links are between the 3′ phosphate and 5′ hydroxyl groups.
-Every polynucleotide chain has individuality.
-All phosphodiester links are between the 3′ phosphate and 5′ hydroxyl groups.
If a strand of DNA has the nitrogen base sequence 5'-ATTTGC-3', what will be the sequence of the matching strand?
-3'-ATTTGC-5'
-3'-GCAAAT-5'
-3'-TUUUCG-5'
-3'-TAAACG-5'
-3'-UAAACG-5'
-3'-TAAACG-5'
If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain?
-200
-150
-50
-25
-75
75
The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.
-covalent bonds
-hydrogen bonds
-ionic bonds
-S—S bonds
-hydrophilic interactions
-hydrogen bonds
A nucleotide is composed of a(n) _____.
-sulfhydryl group, a nitrogen-containing base, and a five-carbon sugar
-phosphate group, a nitrogen-containing base, and a hydrocarbon
-amino group, a nitrogen-containing base, and a five-carbon sugar
-phosphate group, a nitrogen-containing base, and a five-carbon sugar
-glycerol, a nitrogen-containing base, and a five-carbon sugar
-phosphate group, a nitrogen-containing base, and a five-carbon sugar
Which of the following statements about DNA are true?
1) The bases are located inside the helix formed from two polynucleotide strands.
2) The grooves all have the same dimensions.
3) The two strands run in the same direction.
4) Within experimental error, the mole percent adenine was always the same as the mole percent thymine, while the mole percent guanine was always the same as that of cytosine.
-Only statements 1 and 3 are correct.
-Only statements 1 and 4 are correct.
-Only statements 1, 2, and 4 are correct.
-All of the listed statements are correct.
-Only statements 1 and 4 are correct.
The abbreviated name below is short for which of the following biologically important fatty acids?
18:3cΔ9,12,15
-cis,cis,trans-9,12,15-Octadecatrienoic acid
-all-cis-9,12,15-Eicosatetraenoic acid
-all-cis-9,12,15-Octadecatrienoic acid
-cis,cis,trans-9,12,15-Eicosatetraenoic acid
-all-cis-9,12,15-Octadecatrienoic acid
Which statements about the makeup of biological membranes are true?
1) They are composed of bilayers in which the polar head group of the lipid is oriented toward solvent and the lipophilic tails are pointed inward toward the interior of the membrane.
2) All fatty acids can form micelles.
3) The major classes of lipids that make up membranes are glycerophospholipids, sphingolipids, glycosphingolipids, and glycoglycerolipids.
4) The hydrophobic interior is typically twice as thick as the polar, hydrophilic head groups.
-Statements 2, 3, and 4 are true.
-Statements 1, 2, and 3 are true.
-Statements 1, 2, and 4 are true.
-All of the listed statements are true.
-All of the listed statements are true.
Match each lipid with its correct components or description.
1) glycerophospholipids
A) built on sphingosine
2) cerebrosides
B) anionic phospholipids containing one or more sialic acid residues
3) gangliosides
C) lipids with phosphate-containing head groups
4) sphingolipids
D) fatty acid linked through an amide bond to the sphingosine C(2)-amine
-1:C; 2:D; 3:B; 4:A
-1:D; 2:A; 3:C; 4:B
-1:C; 2:B; 3:A; 4:D
-1:A; 2:C; 3:D; 4:B
-1:C; 2:D; 3:B; 4:A
Membrane proteins often have unique characteristics relative to globular proteins that function in largely aqueous environments. Which of the following does NOT describe a trait of a membrane protein?
-They can form membrane receptors, such as integrins (or LDL receptor), located on the surface of cells.
-They can often contain common motifs, such as seven transmembrane α-helical proteins or β-barrels.
-Membrane proteins typically have hydrophilic residues situated on the surface in contact with membrane lipids and hydrophobic residues buried in the interior of the protein core.
-They often have high hydrophobic content.
-Membrane proteins typically have hydrophilic residues situated on the surface in contact with membrane lipids and hydrophobic residues buried in the interior of the protein core.
Which of the following is an example of a monosaccharide?
-Maltose
-Amylose
-Galactose
-Lactose
-None of the above
-Galactose
What is the structural relationship between glucose and galactose?
-They are anomers.
-They are both aldopentoses.
-They are epimers.
-They are enantiomers.
-They are epimers.
Which of the following monosaccharides are ketoses?
1) xylulose
2) idose
3) tagatose
4) psicose
-Answers 1, 2, and 3 are ketoses.
-Answers 1, 3, and 4 are ketoses.
-Answers 1, 2, and 4 are ketoses.
-All of the listed answers are ketoses.
-Answers 1, 3, and 4 are ketoses.
lyceraldehyde has a chiral carbon so has two stereoisomers, which are called diastereomers.
-True
-False
False
Pentoses and hexoses can form stable ring structures by internal hemiacetal formation.
-True
-False
True
N-linked glycans are attached to proteins through N-acetylglucosamine or N-acetyl galactosamine to the amide side chain of:
-histidine.
-glutamine.
-asparagine.
-arginine.
-lysine.
-asparagine.
Which of the following are distinguishing features of different disaccharides?
1) the arrangement of different monomer units
2) the configuration of the anomeric hydroxyl group of each residue
3) the two specific sugar molecules and their stereoconfigurations
4) the carbons involved in the linkage
-Only 1, 2, and 3 are features.
-Only 1, 2, and 4 are features.
-Only 2, 3, and 4 are features.
-All of the listed items are features.
-All of the listed items are features.
Which sugar molecule listed below has the following name?
β-D-galactopyranosyl(1→ 4)β-D-glucopyranose
-sucrose
-lactose
-gentiobiose
-maltose
-lactose
Which storage polysaccharide has the following characteristics?
is a polymer of glucose
has α(1→ 4) linkages
is largely helical in its structure
-glycogen
-amylose
-cellulose
-amylopectin
-amylose
Select the statement that is incorrect.
-Polysaccharides are carbohydrates.
-All carbohydrates have the general formula Cn(H2O)n.
-Simple sugars are carbohydrates.
-Simple sugars, disaccharides, and polysaccharides contain only carbon, oxygen, and hydrogen atoms.
-All carbohydrates have the general formula Cn(H2O)n
. A simple sugar is composed of equal parts carbon and water, which gave rise to the general name of any sugar as a _______________
Carbohydrate
A _____________ cannot be hydrolyzed any further.
Monosaccharide
Lactose, the sugar in milk, is a ______________, because it can be split into two monosaccharides.
Disaccharide
A carbohydrate that yields many monosaccharides when hydrolyzed is a __________
Polysaccharide
Why is a type O individual considered a universal blood donor?
-A type O individual produces both lactose synthase and mutarotase and hence, can donate blood to any recipient without experiencing any negative health effects.
-A type O individual produces both the antigenic A and B oligosaccharides and hence, can donate blood to any recipient without stimulating an immune reaction.
-A type O individual does not produce the antigenic A or B oligosaccharides and hence, can donate blood to any recipient without stimulating an immune reaction.
-A type O individual does not produce lactose synthase or mutarotase and hence, can donate blood to any recipient without experiencing any negative health effects.
-A type O individual does not produce the antigenic A or B oligosaccharides and hence, can donate blood to any recipient without stimulating an immune reaction.
Why is a type AB individual considered a universal acceptor?
-A type AB individual carry neither A nor B oligosaccharides, and therefore will recognize both
A and B as familiar in donated blood.
-A type AB individual carry neither A nor B oligosaccharides, and therefore will not recognize either A or B as foreign in donated blood.
-A type AB individual carries both A and B oligosaccharides, and therefore will recognize both A and B as familiar in donated blood.
-A type AB individual carries both A and B oligosaccharides, and therefore will not recognize either A or B as foreign in donated blood.
-A type AB individual carries both A and B oligosaccharides, and therefore will not recognize either A or B as foreign in donated blood.
The side chain of histidine has a typical pKa value in the range of 6.5-7.4. However, when analyzing the pKa values in a particular protein, scientists determined that one particular His residue has an unusually low pKa value of 4.8. Which of the following statements correctly explain this anomaly?
1) The microenvironment around a residue can impact its pKa value.
2) A positively charged amino acid must be in close proximity to this residue.
3) A negatively charged amino acid must be in close proximity to this residue.
4) This residue must be located on the surface of the protein.
-Statements 1, 2, and 4 are correct.
-Statements 1 and 2 are correct.
-Statements 1 and 4 are correct.
-Statements 2, 3, and 4 are correct.
-Statements 1 and 2 are correct.
The most critical substance in stimulating muscle contraction is:
-tropomyosin.
-troponin C.
-ATP.
-troponin T.
-Ca2+.
-Ca2+.
Which of the following bands of the sarcomere does NOT change size during muscle contraction?
-the A band
-the H zone
-the sarcomere
-the I band
-the A band
Which step of cross-bridge cycling is considered the power stroke?
-when the ADP is released and the myosin cross-bridge moves to the right in the animation
-when the phosphate is released and the myosin cross-bridge forms
-when ATP binds to the myosin head and releases it from the thin filament
-when ATP is hydrolyzed and the myosin head moves to the left in the animation
-when the ADP is released and the myosin cross-bridge moves to the right in the animation
Why is Ca2+ important to the process of sarcomere shortening?
-Ca2+ binds to the phosphate and helps to remove it from the myosin head.
-Ca2+ binds to the troponin complex, which results in exposure of the myosin binding sites on actin.
-Ca2+ moves the tropomyosin molecule, which results in exposure of the myosin binding sites on actin.
-Ca2+ is a cofactor in the binding and hydrolysis of ATP.
-Ca2+ binds to the troponin complex, which results in exposure of the myosin binding sites on actin.
If ATP was removed from the cell, would the muscle be stiff or flaccid?
-It would be flaccid because ATP is needed for muscle contraction.
-It would be stiff because the lack of ATP would cause Ca2+ levels to rise, resulting in contraction.
-It would be stiff because the myosin head would be unable to release the actin binding site.
-It would be flaccid because without ATP hydrolysis, the step when phosphate is released and the myosin head binds, the actin could not occur.
-It would be stiff because the myosin head would be unable to release the actin binding site.
When is the force of contraction of the muscle strongest?
-when the sarcomeres are stretched the most and the potential for shortening is the greatest
-when there is maximal overlap between the thick and thin filaments
-when Ca2+ levels are highest, ensuring maximal actin/myosin interaction
-when ATP levels are highest
-when there is maximal overlap between the thick and thin filaments
The heavy chain of the muscle form of myosin:
-has two covalently bound light chains.
-forms a coiled-coil structure with a globular head domain.
-is a complex of 540 kDa.
contains the motor domain
-within the C-terminal region.
-binds ATP near the C-termini.
-forms a coiled-coil structure with a globular head domain.
Which of the following statements about muscle contraction is TRUE?
-ATP hydrolysis releases myosin from actin.
-Muscle contraction occurs as ATP is hydrolyzed.
-ATP hydrolysis results in strong binding of myosin to actin.
-ATP hydrolysis causes a conformational change in the myosin head.
-ATP hydrolysis must occur before the actin-binding site closes.
-ATP hydrolysis causes a conformational change in the myosin head.
Calcium regulates muscle contraction by binding to:
-troponin T.
-actin.
-myosin.
-tropomyosin.
-troponin C.
-troponin C.
Which of the following statements about α-keratins is FALSE?
-Individual molecules are α-helical.
-There is a strip of contiguous hydrophobic surface making a shallow spiral around the helix.
-They include a small globular regions covalently linked to the surface.
-They include a major class of protein that comprises hair, fingernails and animal skin.
-Pairs of α-helices twist about each other in a coiled-coil structure held together entirely by hydrophobic interactions.
-Pairs of α-helices twist about each other in a coiled-coil structure held together entirely by hydrophobic interactions.
The protein that makes up about a third of the total protein mass in animals is:
-α-keratin.
-hemoglobin.
-collagen.
-β-keratin.
-myoglobin.
-collagen.
Tropocollagen is a double helix of two left-handed polypeptide chains.
True
False
False
Match the appropriate cells with the correct immune response.
1) T lymphocytes
A) adaptive immune response
2) B lymphocytes
B) humoral immune response
3) macrophages
C) cellular immune response
4) immunoglobulins
-1:C; 2:B; 3:B; 4:B
-1:B; 2:B; 3:C; 4:C
-1:B; 2:A; 3:C; 4:B
-1:C; 2:A; 3:B; 4:C
-1:C; 2:B; 3:B; 4:B
Which of the following definitions are correct?
1) An antigen is the substance that elicits an immune response.
2) An epitope is a portion on the surface of an invading particle to which specific antibodies bind.
3) An antibody is a specific immunoglobulin that binds to an antigen.
-Only definitions 2 and 3 are correct.
-Only definitions 1 and 3 are correct.
-Only definitions 1 and 2 are correct.
-All of the listed definitions are correct.
-All of the listed definitions are correct.
Which of the following statements about antibody structure is NOT true?
-The variable domain has different tertiary structure in both the heavy and light chains.
-Each immunoglobulin consists of two identical heavy chains and two identical light chains.
-The constant domains are located at the ends of the Y-like fork of the antibody, where they form two identical binding sites for antigens.
-The different tertiary structure of the variable domain is responsible for the antigen binding specificity.
-The constant domains are located at the ends of the Y-like fork of the antibody, where they form two identical binding sites for antigens.
Which statements regarding shape and charge complementarity are true?
1) Charge complementarity occurs when specific noncovalent binding interactions occur between two contacting surfaces.
2) The "charge" interactions can be charge-charge, H-bonding, or van der Waals interactions.
3) Shape complementarity refers to the intimate contact made between an antibody and its target antigen.
4) Shape and charge complementarity explain exclusively the interactions between an antibody and its target antigen.
-Only statements 2, 3, and 4 are true.
-Only statements 1, 2, and 3 are true.
-Only statements 1, 2, and 4 are true.
-All of the listed statements are true.
-Only statements 1, 2, and 3 are true.
The specific interaction between an antibody and antigen occurs by virtue of both shape and ________ complementarity.
charge
Which of the following is unlikely to be a characteristic of a membrane protein?
-α-helical membrane-spanning motifs.
-β-sheet membrane-spanning motifs
-Symmetric orientation across the membrane
-Covalently attached lipid moities
-Largely hydrophobic transmembrane segments
-Symmetric orientation across the membrane
Membrane proteins often have unique characteristics relative to globular proteins that function in largely aqueous environments. Which of the following does NOT describe a trait of a membrane protein?
-They often have high hydrophobic content.
-They can form membrane receptors, such as integrins (or LDL receptor), located on the surface of cells.
-They can often contain common motifs, such as seven transmembrane α-helical proteins or β-barrels.
-Membrane proteins typically have hydrophilic residues situated on the surface in contact with membrane lipids and hydrophobic residues buried in the interior of the protein core.
-Membrane proteins typically have hydrophilic residues situated on the surface in contact with membrane lipids and hydrophobic residues buried in the interior of the protein core.
When molecules move down their concentration gradient, they move from where they are _________________ to where they are ________________.
More concentrated to where they are less concentrated
Diffusion across a biological membrane is called _______
passive transport
Facilitated diffusion is a type of _______.
-pinocytosis
-phagocytosis
-active transport
-passive transport
-passive transport
Which of the following represent(s) facilitated diffusion across a membrane?
-carriers, such as ionophores
-permeases, such as GLUT1, a glucose transporter found on erythrocytes
-transport through protein pores
-All of the listed choices represent facilitated diffusion.
-All of the listed choices represent facilitated diffusion.
Which of the following statements is NOT true with respect to potassium ion channels?
-External influences, such as a change in pH or the binding of an appropriate ligand, alter the conformation of the channel protein, opening or closing it as appropriate.
-The binding of the first potassium ion induces a conformational change in the channel protein that allows it to selectively bind only additional potassium ions.
-The channels have closed and open conformations.
-The hinge region of the proteins that move as a result of external influences has Gly residues, which facilitates protein movement, given its small size.
-The binding of the first potassium ion induces a conformational change in the channel protein that allows it to selectively bind only additional potassium ions.
Passive facilitated cotransport can move some substrate across a membrane against its concentration gradient.
True
False
True
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.
-The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane.
-The diffusion of Na+ ions into the cell is impeded by the electrical gradient across the plasma membrane.
-The diffusion of K+ ions out of the cell is impeded by the K+ concentration gradient across the plasma membrane.
-The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane.
-The electrochemical gradient is larger for Na+ than for K+.
-The diffusion of Na+ ions into the cell is facilitated by the Na+ concentration gradient across the plasma membrane.
-The diffusion of K+ ions out of the cell is impeded by the electrical gradient across the plasma membrane.
-The electrochemical gradient is larger for Na+ than for K+.
A signal transduction pathway is initiated when a _____ binds to a receptor.
-tyrosine kinase
-G protein
-signal molecule
-calmodulin
-cyclic AMP
-signal molecule
A signal molecule is also known as a(n) _____.
-protein
-ligand
-receptor
-initiator
-key
-ligand
Which of these is the second of the three stages of cell signaling?
-gene activation
-reception
-binding of a neurotransmitter to a plasma -membrane receptor
-transduction
-cell response
-transduction
Which of the following is NOT a secondary messenger?
cAMP
nitric oxide
sn-1,2-diacylglycerol
inositol 1,4,5-trisphosphate
-inositol 1,4,5-trisphosphate
-sn-1,2-diacylglycerol
-cAMP
-nitric oxide
-nitric oxide
Which statement about G proteins is NOT true?
-Most G proteins are trimeric in nature.
-Activated G protein moves along the membrane to reach an effector molecule, such as adenylate cyclase.
-Several bacterial toxins, such as that from V. cholerae, can inactivate the GTPase activity of G proteins.
-G proteins possess very active GTPase activity.
-G proteins possess very active GTPase activity.
Which of the following are characteristics of G protein-coupled receptors?
1) They typically have seven transmembrane domains that are embedded in the cell membrane.
2) They carry hydrophilic portions of protein that extend into the extracellular matrix as well as the cytosol.
3) The receptor region is located on the extracellular portion of the protein.
4) Most work in concert with G proteins.
-1, 2, and 4 are characteristics of G protein-coupled receptors.
-1, 2, and 3 are characteristics of G protein-coupled receptors.
-Only 1 and 2 are characteristics of G protein-coupled receptors.
-All of the listed statements are characteristics of G protein-coupled receptors.
-All of the listed statements are characteristics of G protein-coupled receptors.
Which of the following is an extracellular messenger involved in signal transduction?
-Ca2+
-Rhodopsin
-Cyclic GMP
-Diacylglycerol
-Epinephrine
-Epinephrine
Receptor tyrosine kinases are membrane-spanning proteins with an intrinsic tyrosine kinase domain on the extracellular side of the membrane.
True
False
False
Match each function with the name of a major enzyme class.
1) transfer functional groups between molecules
A) oxidoreductases
2) catalyze intramolecular rearrangements
B) transferases
3) catalyze redox chemistry
C) hydrolases
4) catalyze the joining of two molecules together
D) lyases
E) isomerases
F) ligases
-1:B; 2:C; 3:D; 4:F
-1:C; 2:E; 3:D; 4:F
-1:B; 2:F; 3:C; 4:D
-1:B; 2:E; 3:A; 4:F
-1:B; 2:E; 3:A; 4:F
In general, enzymes are what kinds of molecules?
-lipids
-nucleic acids
-minerals
-carbohydrates
-proteins
-proteins
Enzymes work by _____.
-adding energy to a reaction
-adding a phosphate group to a reactant
-decreasing the potential energy difference between reactant and product
-reducing EA
-increasing the potential energy difference between reactant and product
-reducing EA
An enzyme _____.
-is a source of energy for endergonic reactions
-increases the EA of a reaction
-is an organic catalyst
-is a inorganic catalyst
-can bind to nearly any molecule
-is an organic catalyst
What name is given to the reactants in an enzymatically catalyzed reaction?
-EA
-products
-active sites
-substrate
-reactors
-substrate
As a result of its involvement in a reaction, an enzyme _____.
-loses energy
-permanently alters its shape.
-loses a phosphate group
-is unchanged
-is used up
-is unchanged
Which of the following describes a mechanism that enzymes use to achieve their rate enhancement of reactions?
-preferential binding to the transition state through complementary non-covalent interactions
-altering the reaction pathway to include intermediate states
-distortion of the substrate or active site, which, in effect, lowers the energy of activation
-All of the listed choices describe mechanisms used by enzymes to achieve their rate enhancement of reactions.
-All of the listed choices describe mechanisms used by enzymes to achieve their rate enhancement of reactions.
Considering both of the mechanisms proposed for catalysis by lysozyme, which of the following rate-enhancing features does lysozyme use to increase the rate of the hydrolysis reaction it catalyzes?
1) general acid-base catalysis
2) electrostatic catalysis
3) distortion of substrate
4) covalent catalysis
-Only choices 1, 2, and 4 are correct.
-Only choices 1, 3, and 4 are correct.
-Only choices 1 and 2 are correct.
-All of the listed choices are correct
-All of the listed choices are correct
Consider a situation in which the enzyme is operating at optimum temperature and pH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?
-Increase the pH.
-Increase the temperature.
-Increase the enzyme concentration.
-Increase the substrate concentration.
-Increase the enzyme concentration.
Consider the following reaction:
A → B
Which of the following statements about this reaction are correct?
1) If you double the concentration of reagent A, you will double the rate.
2) The reaction rate (or velocity) is dependent only on the concentration of A.
3) The units for the first-order rate constant are M s- 1.
4) A plot of the log[A] versus time yields an inverse hyperbola.
-Only statements 2 and 4 are correct.
-Only statements 1, 3, and 4 are correct.
-Only statements 1, 2, and 3 are correct.
-Only statements 1 and 2 are correct.
-Only statements 1 and 2 are correct.
Consider a situation in which the enzyme is operating at optimum temperature and pH, and has been saturated with substrate. What is your best option for increasing the rate of the reaction?
-Increase the pH.
-Increase the temperature.
-Increase the enzyme concentration.
-Increase the substrate concentration.
-Increase the enzyme concentration.
The lock and key model of substrate binding and enzymatic catalysis explains:
-the catalytic mechanism.
-structural changes that occur on substrate binding.
-the release of product.
-formation of a transition state.
-substrate specificity.
substrate specificity.
Which of the following amino acid residues are often involved in proton transfers in enzyme-catalyzed reactions?
-Glutamine, asparagine, lysine, and tyrosine
-Serine, tyrosine, arginine, and cysteine
-Histidine, aspartate, glutamate, arginine, and lysine
-Histidine, aspartate, lysine, and serine
-Histidine, aspartate, serine, and cysteine
-Histidine, aspartate, glutamate, arginine, and lysine
Electrostatic catalysis proceeds via covalent bonding interactions.
True
False
False
1) Would you expect an "enzyme" designed to bind to its target substrate as tightly as it binds the reaction transition state to show a rate enhancement over the uncatalyzed reaction?
-yes
-no
2) Explain why not.
-because the temperature would be identical for both the catalyzed and uncatalyzed reactions
-because the protein is a very strong inhibitor and it slows the reaction
-because the activation energy would be identical for both the catalyzed and uncatalyzed reactions
-because the entropy would be identical for both the catalyzed and uncatalyzed reactions
no
-because the activation energy would be identical for both the catalyzed and uncatalyzed reactions
Match each of the following terms from the Michaelis-Menten equation to its correct definition.
1) V max
A) substrate concentration at 0.5 V max
2) k cat
B) rate of a reaction when enzyme is saturated with substrate
3) k cat/K M
C) enzyme efficiency
4) K M
D) number of substrate molecules turned over by enzyme
-1:B; 2:D; 3:C; 4:A
-1:D; 2:B; 3:A; 4:C
-1:B; 2:C; 3:D; 4:A
-1:C; 2:D; 3:A; 4:B
-1:B; 2:D; 3:C; 4:A
A Lineweaver-Burk plot can be used to determine KM using initial-rate data for an enzyme-catalyzed reaction.
True
False
True
A (n) ______________ inhibitor has a structure that is so similar to the substrate that it can bond to the enzyme just like the substrate.
Competitive
A (n) ______________ inhibitor binds to a site on the enzyme that is not the active site.
noncompetitive
Usually, a(n) _______________ inhibitor forms a covalent bond with an amino acid side group within the active site, which prevents the substrate from entering the active site or prevents catalytic activity.
irreversible
The competitive inhibitor competes with the substrate for the __________ on the enzyme.
active site
Note 
Flashcards (32)