BCM Quiz 5 (Ch. 12, 13, 15)

How does energy affect the functioning of the Na+-K+ ATPase? Select all that apply. ATP provides energy for this pump to function. The pump maintains the proper cellular concentration of Na+ and K+. Without ATP, the pump would not be able to function. Without ATP, the pump transport only K+. The pump maintains only the proper cellular concentration of Na+.

ATP provides energy for this pump to function. The pump maintains the proper cellular concentration of Na+ and K+. Without ATP, the pump would not be able to function.

What is the differences between active and passive transport? Active transport requires an external energy source. Passive transport takes place when a molecule moves against its concentration gradient. Passive transport results in the generation of concentration gradients. Active transport takes place when a molecule moves down its concentration gradient. Passive transport is present only in the human cells.

Active transport requires an external energy source.

Metabolic processes are regulated by: transcriptional regulation of the amount of enzyme. allosteric control of enzyme activity. accessibility of substrates by compartmentalization. covalent modification of enzymes. All of the answers are correct.

All of the answers are correct.

How does SERCA regulate muscle activity? An increase in Ca2+ ions causes muscle constriction, and a decrease in Ca2+ ions causes muscle relaxation. A decrease in Ca2+ ions causes muscle constriction, and an increase in Ca2+ ions causes muscle relaxation. An increase in K+ ions causes muscle constriction, and a decrease in K+ ions causes muscle relaxation. A decrease in K+ ions causes muscle constriction, and an increase in K+ ions causes muscle relaxation. A increase in K+ ions causes muscle constriction, and an decrease in Ca2+ ions causes muscle relaxation.

An increase in Ca2+ ions causes muscle constriction, and a decrease in Ca2+ ions causes muscle relaxation.

Scurvy, a disease characterized by skin lesions and blood-vessel fragility, is caused by the deficiency of vitamin: A. B12. C. D. E.

C.

What is the ultimate product of oxidation in aerobic organisms? O2 H2O pyruvate CO2 lactate

CO2

What vitamin regulates calcium and phosphate metabolism? C B6 E D K

D

What is the major difference between eukaryotic and prokaryotic cells? Eukaryotic cell membranes consist of a single lipid bilayer. Prokaryotic cells do not have cell walls. Eukaryotic cells have membranes inside the cell that form internal compartments. Prokaryotic cells have periplasm. Prokaryotic cells have membranes that consist of two lipid bilayers.

Eukaryotic cells have membranes inside the cell that form internal compartments.

The electron carrier _______ is derived from the vitamin riboflavin.

FAD

The reduced form of flavin adenine dinucleotide is: FADH. FAD. FADH++. FADH2. FAD+.

FADH2.

What statement about fatty acids is INCORRECT? Fatty acid carbon atoms are numbered starting at the carboxyl terminus. A cis-Δ2 means that there is a cis double bond between carbon atoms 2 and 3. A double bond can be denoted by counting from the distal end, with the ω-carbon atom. Carbon atoms 2 and 3 are often referred to as α and β, respectively. Fatty acids in biological systems usually contain an odd number of carbon atoms.

Fatty acids in biological systems usually contain an odd number of carbon atoms.

_______ interactions are the major driving force for the formation of lipid bilayers.

Hydrophobic

What clues provide evidence of the mechanism of channel inactivation? Select all that apply. Inactivation can be restored by the addition of part of a missing peptide. Proteolysis of the cytoplasmic side leads to permanent open channel. Mutations in amino acid sequence leads to differences in inactivation kinetics. Peptide denaturation leads to permanent open channel. Proteolysis of the extracellular side leads to permanent open channel.

Inactivation can be restored by the addition of part of a missing peptide. Proteolysis of the cytoplasmic side leads to permanent open channel. Mutations in amino acid sequence leads to differences in inactivation kinetics.

How is NADPH different from NADH? Choose the statement that is correct for NADPH. The reactive part of NADH is its nicotinamide ring. The nitrogen atom carries a positive charge. NADPH carries high-potential electrons. Its adenosine moiety is esterified with phosphate. It is used primarily for the generation of ATP.

Its adenosine moiety is esterified with phosphate.

What statement about membranes is INCORRECT? Membranes are lipid bilayers. Membrane consists of peptides and lipids. Many membranes are electrically polarized. Membrane is an absolutely solid formation. Membrane lipids have both hydrophobic and hydrophilic properties.

Membrane is an absolutely solid formation.

What are the main features of simple diffusion? Molecules pass through a membrane from areas of lower to higher concentration. Only lipophilic molecules can easily pass through the membrane. Molecules pass through a membrane from areas of higher to lower concentration. Only hydrophilic molecules can easily pass through the membrane. Molecules pass through a membrane from areas of higher to lower concentration. Only lipophilic molecules can easily pass through the membrane. Molecules pass through a membrane from areas of lower to higher concentration. Only hydrophilic molecules can easily pass through the membrane. Molecules pass through a membrane from areas of lower to higher concentration. Only nonpolar molecules can easily pass through the membrane.

Molecules pass through a membrane from areas of higher to lower concentration. Only lipophilic molecules can easily pass through the membrane.

What substance serves as the electron donor for most reductive biosynthetic pathways? NADPH NADH FAD FMN NAD+

NADPH

An acetylcholine receptor is permeable for: Na+ and Ca2+. Na+ and K+. K+ and Ca2+. Mg2+. Cl-.

Na+ and K+.

What channels does tetrodotoxin isolated from the puffer fish bind to? Na+ channels K+ channels Na+ and Ca2+ K+ and Ca2+ channels anion channels

Na+ channels

Why can Na+ NOT pass through a potassium channel? The Na+ ion radius is larger than the K+ ion radius. The Na+ ion radius is larger than 3 Ǻ. The Na+ ion radius is smaller than the K+ ion radius. The Na+ ion radius is equal to 3 Ǻ. The Na+ ion radius is smaller than 3 Ǻ.

The Na+ ion radius is smaller than the K+ ion radius.

What are CORRECT statements about the binding sites of membrane pumps? Select all that apply. The external site can be open or closed while the internal site is open. The internal site can be open or closed while the external site is open. The external and internal sites are always open. The external site is open while the internal site is closed. The internal site is open while the external site is closed.

The external site is open while the internal site is closed. The internal site is open while the external site is closed.

Name the consequences of Na+-K+ pump inhibition. Select all that apply. The intracellular level of Na+ ions increases. Ca2+ extrusion slows down. An increase in the Ca2+ intracellular level leads to an increase in the ability of cardiac muscle to contract. The intracellular level of K+ decreases. The extracellular level of K+ decreases.

The intracellular level of Na+ ions increases. Ca2+ extrusion slows down. An increase in the Ca2+ intracellular level leads to an increase in the ability of cardiac muscle to contract.

What statement is consistent with the structure of biological membranes? All membrane proteins are integral and associate with the hydrophobic region of the membrane. Both proteins and lipids readily undergo transverse ("flip-flop") diffusion. Membranes are symmetric. The membrane lipids self-assemble to form the lipid bilayer. A biological membrane consists of proteins sandwiched between two layers of lipids.

The membrane lipids self-assemble to form the lipid bilayer.

Why does acetyl CoA have a high acetyl-group-transfer potential? Coenzyme A carries the terminal sulfhydryl group. Acetyl CoA carries an activated phosphoryl group. The transfer of the acetyl group is exergonic. The transfer of the acetyl group is endergonic. The transfer of the other groups is unfavorable.

The transfer of the acetyl group is exergonic.

What statement about "peripheral" membrane proteins is INCORRECT?? They are membrane proteins that interact with the polar head groups of the membrane lipids. They are membrane proteins that bind to the surfaces of integral proteins. They are membrane proteins that are anchored to the membrane by a covalently attached lipid molecule. Polar interactions of peripheral protein and polar head groups of the membrane lipids can be disrupted by adding salts or by changing the pH. They are membrane proteins that traverse the lipid bilayer.

They are membrane proteins that traverse the lipid bilayer.

A thermodynamically unfavorable reaction is driven by: a thermodynamically favorable reaction to which it is coupled. free energy. a catabolic reaction. a favorable reaction. an anabolic reaction.

a thermodynamically favorable reaction to which it is coupled.

The product of the second stage of catabolism is: acetyl CoA. ATP. CO2. H2O. O2.

acetyl CoA.

What molecules are responsible for sending nerve impulses? tetrodotoxin acetylcholine cobratoxin connexin cefazolin

acetylcholine

What term describes molecules that have both hydrophilic and hydrophobic moieties? amphoteric amphiprotic amphibian amphipathic amphiapomictic

amphipathic

What type of reactions requires energy? anabolic catabolic biochemical chemical spontaneous

anabolic

What channels do not transport ions at all? aquaporins acetylcholine receptors ligand-gated channels voltage-gated channels ABC transporters

aquaporins

Ion channels: are not selective. exist only in open state. can be selective and exist in open and closed states. are not selective and exist in open and closed states. can be selective and exist only in open state.

can be selective and exist in open and closed states.

Reaction pathways that exclusively transform fuels into cellular energy are: anabolic. catabolic. allobolic. amphibolic. metabolic.

catabolic.

Plant cells have: two membranes separated by a cell wall. membranes consisting of a single lipid bilayer. cell wall on the outside of the plasma membrane. cell wall surrounded by a plasma membrane. membrane consisting of proteins.

cell wall on the outside of the plasma membrane.

What substance is the key regulator of membrane fluidity in animals? cholesterol glycerol inositol phosphate cerebroside sphingomyelin

cholesterol

What proteins take part in receptor-mediated endocytosis? clathrin transferrin myoglobin hemocyanin proton pumps

clathrin

What compound serves as an acyl carrier in metabolism? FAD biotin thiamine pyrophosphate coenzyme A tetrahydrofolate

coenzyme A

The phosphoryl-transfer potential of ATP is lower than that of: pyrophosphate. creatine phosphate. 2,3-bisphosphoglycerate. glucose 1-phosphate. glucose 6-phosphate.

creatine phosphate.

What processes underlie the nerve impulse? depolarization of the membrane from -60 to -40mV, an increase in Na+ permeability, intracellular accumulation of Na+ ions repolarization of the membrane to +30mV, spontaneous permeability switch from K+ to Na+ the release of Na+ ions from the cell causes transition from the repolarization state to the polarization state the release of Cl- ions from the cell causes depolarization of membrane from -80 to - 120 mV the release of K+ ions from the cell causes transition from the repolarization state to the depolarization state

depolarization of the membrane from -60 to -40mV, an increase in Na+ permeability, intracellular accumulation of Na+ ions

What structure takes part in drug detoxification and the modification of proteins? nuclear envelope endoplasmic reticulum vesicle mitochondria peroxisome

endoplasmic reticulum

What process takes place right after the nerve impulse arrives at the end of the axon? binding of acetylcholine to the postsynaptic membrane depolarization of the presynaptic membrane export of acetylcholine vesicles into the synaptic cleft repolarization of the presynaptic membrane import of adrenaline vesicles into the postsynaptic membrane

export of acetylcholine vesicles into the synaptic cleft

Lateral diffusion is: spontaneous fast rotation of lipids from one face of a membrane to the other. fast diffusion of proteins and lipids across the membrane. diffusion of proteins across the membrane. spontaneous slow rotation of lipids from one face of a membrane to the other. slow diffusion of proteins and lipids across the membrane.

fast diffusion of proteins and lipids across the membrane.

What is the primary role of catabolism? generation of complex structures from simple ones generation of ATP generation of acetyl CoA degradation of biomolecules active transport

generation of ATP

What amino acid determines ion selectivity of the Ca2+ channel? aspartate glutamate lysine alanine glycine

glutamate

What membrane components contain carbohydrates? lipid-linked proteins cholesterol integral membrane proteins in contact with the cytoplasm phosphatidylserine glycolipids

glycolipids

What metabolic reaction type involves a cleavage of bonds by the addition of water? ligation isomerization group transfer oxidation-reduction hydrolyzation

hydrolyzation

Select all that apply. Amphipathic properties of membrane lipids are provided by a: hydrophilic hydrocarbon tale. hydrophobic head. hydrophobic hydrocarbon tale. hydrophilic head. nonpolar head.

hydrophobic hydrocarbon tale. hydrophilic head.

When an uncharged molecule moves against the concentration grade, the process is: at equilibrium. in need of energy resources. spontaneous. dependent on membrane potential. stopped anyway.

in need of energy resources.

What reactions rearrange particular atoms within a molecule while conserving the empirical formula? isomerization ligation group transfer oxidation-reduction hydrolysation

isomerization

The reaction of rearrangement of atoms to form isomers is: oxidation-reduction. group transfer. hydrolytic. isomerization. ligation requiring ATP cleavage.

isomerization.

What channel opens in response to binding of a particular molecule? voltage-gated ligand-gated active diffusion passive diffusion ABC transporter

ligand-gated

Select all that apply. Membranes are primarily comprised of: lipids. proteins. carbohydrates. metals. water.

lipids. proteins.

What enzymes catalyze reactions where carbon bonds are cleaved by means other than hydrolysis or oxidation? lyases catalases kinases phosphatases isomerases

lyases

What property is NOT a characteristic of the biological membranes? organization of biological membranes is described as a fluid mosaic model membrane has the transverse diffusion of its lipids membrane has the lateral diffusion of its components membranes are two-dimensional solutions of oriented lipids and globular proteins membrane is always impenetrable

membrane is always impenetrable

Fuels are degraded and large molecules are constructed step by step in a series of linked reactions. What type of reaction corresponds to this statement? cellular respiration photosynthesis catabolic reaction metabolic pathway oxidation

metabolic pathway

Arrange the following structures in order of increasing dimensions. micelle, lipid bilayer, vesicle vesicle, micelle, lipid bilayer lipid bilayer, vesicle, micelle micelle, vesicle, lipid bilayer lipid bilayer, micelle, vesicle

micelle, vesicle, lipid bilayer

What structure is surrounded by two membranes and is responsible for ATP synthesis? nuclear envelope mitochondria nucleus peroxisome endoplasmic reticulum

mitochondria

Where does fatty acid oxidation occur? the cytoplasm the Golgi apparatus mitochondria plastids lysosomes

mitochondria

Select all that apply. The ΔG of reactions depends on: temperature. enzymes. nature of the reactants. free energy. nature of the products.

nature of the reactants nature of the products.

Arrange the following fatty acids in order of increasing melting point: palmitic acid (C16, 1 double bond), stearic acid (C18, 0 double bond), oleic acid (C18, 1 double bond). palmitic acid, stearic acid, oleic acid oleic acid, palmitic acid, stearic acid stearic acid, palmitic acid, oleic acid The melting point of these fatty acids is equal. There is not enough data to determine the melting point.

oleic acid, palmitic acid, stearic acid

What is the ultimate electron acceptor in aerobic organisms? carbon dioxide NAD+ FAD oxygen succinate

oxygen

Which cellular process(es) require energy? performance of mechanical work facilitated diffusion degradation of biomolecules active transport performance of mechanical work and active transport

performance of mechanical work and active transport

What is the major class of membrane lipids? phospholipids glycolipids cholesterol sphingolipids ceramides

phospholipids

What kind of lipids consist of at least one fatty acid, a platform to which the fatty acids are attached, a phosphate, and an alcohol attached to the phosphate? phospholipids glycolipids cholesterol gangliosides sphingolipids

phospholipids

An external cell membrane of eukaryotic cells is called: endoplasmic reticulum. cell wall. plasma membrane. nuclear envelope. planar bilayer membrane.

plasma membrane.

The MOST fluid membrane would be a bilayer made of lipids with: polyunsaturated 18-carbon fatty acids. saturated 18-carbon fatty acids. saturated 16-carbon fatty acids. polyunsaturated 16-carbon fatty acids. polyunsaturated 20-carbon fatty acids.

polyunsaturated 16-carbon fatty acids.

Carbohydrate residues attached to the membrane lipids are almost always: positioned on the intracellular side of the membrane. positioned on the inside center of the bilayer. positioned on the extracellular side of the membrane. positioned equally on both sides of the membrane. also covalently attached to membrane proteins.

positioned on the extracellular side of the membrane.

Select all that apply. "Integral" membrane proteins are: proteins that traverse the lipid bilayer. membrane proteins that interact extensively with the hydrocarbon chains of membrane lipids. membrane proteins that can be released only by agents that compete for nonpolar interactions of the protein and the hydrocarbon chains of membrane lipids. proteins that connect with membrane lipids via polar interactions. proteins that are loosely bonded with the membrane.

proteins that traverse the lipid bilayer. membrane proteins that interact extensively with the hydrocarbon chains of membrane lipids. membrane proteins that can be released only by agents that compete for nonpolar interactions of the protein and the hydrocarbon chains of membrane lipids.

What molecule structures allow for permeability of biological membranes? Select all that apply. pumps carriers channels tubes tunnels

pumps carriers channels

What does ATP contain? ribose orthophosphate deoxyribose metal ions adenylate

ribose

In which processes does the membrane take part? Select all that apply. separating compartments joining compartments together transport of molecules release of molecules storage of molecules

separating compartments joining compartments together transport of molecules release of molecules

Transverse diffusion is: fast rotation of lipids from one face of a membrane to the other. flip-flop of membrane proteins. slow rotation of lipids from one face of a membrane to the other. fast diffusion of proteins and lipids across the membrane. slow diffusion of proteins and lipids across the membrane.

slow rotation of lipids from one face of a membrane to the other.

What group forms the reactive site of coenzyme A? sulfhydryl acyl amino carboxyl carbonyl

sulfhydryl

The total free-energy change for a chemically related series of reactions equals the: sum of the free-energy changes of individual steps. difference of the free-energy changes between each individual step. difference of the free-energy changes of all steps. free-energy changes of an individual step. maximum free energy.

sum of the free-energy changes of individual steps.

What accepts a hydrogen ion and two electrons in the oxidation of a substrate? the nicotinamide ring of NAD+ the reactive part of FAD FADH2 acetyl CoA ATP

the nicotinamide ring of NAD+

Select all that apply. Membrane potential is: the sum of concentrations and electric terms. electrochemical potential. the sum of charged and uncharged molecules passing through channels. the sum of all polar molecules passing through channels and back. the sum of all nonpolar molecules passing through channels and back.

the sum of concentrations and electric terms. electrochemical potential.

What bond attaches an acetyl group to coenzyme A? thioester bond anhydride bond phosphoanhydride bond covalent bond carbon bond

thioester bond

Carrier proteins: transport ions or molecules across the membrane without hydrolysis of ATP. mediate primary active transport. utilize the gradient of one ion to drive the transport of another ion down its concentration gradient. provide translocation across the membrane only for molecules. have two classes: uniporters and symporters.

transport ions or molecules across the membrane without hydrolysis of ATP.

What forces stabilize the lipid bilayers? Select all that apply. van der Waals interactions electrostatic bonding between the polar heads and surrounding water covalent bonds between the lipids and membrane proteins disulfide bridges between the membrane proteins hydrogen bonding between the polar heads and surrounding water

van der Waals interactions electrostatic bonding between the polar heads and surrounding water hydrogen bonding between the polar heads and surrounding water

Which structures are composed of aqueous compartments enclosed by a lipid bilayer and can be used to deliver chemicals to cells? micelle vesicle lysosome chloroplast ribosome

vesicle

What organic molecules are the sources of coenzymes in some higher animals? proteins lipids vitamins carbohydrates minerals

vitamins

What channel opens in response to membrane depolarization? ion-gated ligand-gated voltage-gated active diffusion passive diffusion

voltage-gated