Feb 5, Feb 7, Feb 10, 2-12, 2-14, 2-17, 2-19

What is the most likely means of getting pyruvate into a mitochondrion? A. Simple diffusion through the lipid bilayer B. Transporter-mediated process

B.

You follow a protocol that includes using chymotrypsin, an enzyme that cleaves all peptide bonds involving hydrophobic amino acids. What are you most likely trying to do? A. Probably preparing a protein for X-ray crystallography B. Probably preparing a protein for sequencing C. I am not sure but I saw a similar question in the exam

B.

The image below is an analogy of the experiment that allowed to determine: A. The sequence of carriers in the electron transport chain B. The number of ATPs produced by NADH and FADH2 C. The sequence of reactions in glycolysis D. The sequence of enzymes in the Krebs Cycle

A.

Which of the following groups of amino acids are most likely to be part of a transmembrane domain? A. Group 1 B. Group 2 C. Groups 1 and 2 could be part of a transmembrane domain

A

Acetyl-CoA is further oxidized in the _____, which occurs in the ______ A. Krebs cycle; mitochondrial matrix B. Glycolysis; mitochondrial membrane C. Krebs cycle; mitochondrial membrane D. Electron transport chain; mitochondrial matrix

A.

Adding more double bonds to this lipid bilayer would: A. Lower the transition temperature B. Increase the transition temperature C. Increase the ability of phospholipids to pack together D. A and B E. B and C

A.

Changes in the electric potential difference between the outside and the inside of the cell (membrane potential), triggers the opening of A. Voltage - gated B. Ligand - gated C. Mechano - gated

A.

Fluorescent Recovery After Photobleaching (FRAP) is a technique used to measure _____ A. Movement of membrane proteins B. Movement of cell organelles C. Recovery of cells after toxic stress D. Recovery of cell viability after temperature changes

A.

How does influx of Na+ ions change the membrane potential of a recently stimulated nerve cell? A. The interior becomes less negative B. The interior becomes more negative C. It does not change until more channels are open

A.

How is lactic acid (lactate) converted back to glucose? A. It is converted to pyruvate and then enters gluconeogenesis B. It is converted to pyruvate and then enters Krebs cycle C. It is converted to Acetyl-CoA and then enters gluconeogenesis D. It is converted to Acetyl-CoA and then enters the Krebs cycle

A.

If NADPH is utilized in anabolic pathways and NADH in catabolic pathways, which one will be favored in response to high energy availability in the cell? A. NADPH B. NADH

A.

Inhibiting ATP production eventually blocks glucose uptake from the luminal side of the intestine A. True B. False

A.

NADH electrons enter _____ and FADH2 electrons enter ___ in the electron-transport chain A. Complex I; Complex II B. Complex I; Complex III C. Complex II; Complex III D. Complex II; Complex I

A.

Slow-twitch muscle fibers ______ mitochondria, associating them with _____ production of ATP, which makes these fibers ______ to sustain exercise for longer periods of time. A. Have; Aerobic; Able B. Lack; Aerobic; Able C. Have; Anaerobic; Unable D. Lack; Anaerobic; Unable

A.

Some medications prevent heartburn by inhibiting the process of acid secretion in the stomach. One of them is Prilosec, which specifically inhibits ___ A. The H+/K+ ATPase B. The Na+/K+ ATPase C. The HCl ATPase D. The Na+/glucose contransporter

A.

Succinate dehydrogenase, the enzyme that catalyzes the transfer of electrons to FADH2 during the Krebs cycle, is part of Complex II in the electron transport chain A. True B. False

A.

The inside of an average mammalian cell is more negatively charged with respect to the outside. This is known as ______ A. Action potential B. Membrane potential C. Depolarization D. Synapse E. Neurotransmission

A.

The membrane of organism A is composed by mostly fatty acids with triple double bonds. The membrane of organism B is composed by mostly fatty acids with single double bonds. Both organisms are transferred to extremely cold temperatures. Which one is more likely to survive?

A.

The voltage difference inside and outside of the membrane of a nerve cell when it is not excited, is known as A. Resting potential B. Equilibrium C. Depolarization D. Action potential E. Reuptake

A.

Uncoupling glucose oxidation to ATP synthesis was once utilized to promote ____ A. Weight loss B. Memory loss C. Synthesis of Vitamin D D. Athlete endurance

A.

Which one of the following organisms has the highest percentage of unsaturated fatty acids? A. Antarctic fish B. Desert snake C. Human being D. Polar bear E. Thermophilic bacterium

A.

Which one of the three kinds of membrane associated proteins would be more difficult to study? A. Integral membrane proteins B. Peripheral proteins C. Lipid-anchored proteins

A.

_______ induce a rotation of 120° causing, the release of 1 ATP. A full rotation of the ring produces ___ ATPs A. Four protons; Three B. Three protons; Three C. Two protons; Four D. Three protons; Four

A.

Methane is ___ reduced than saturated fats. ____ energy is obtained from oxidizing 1g of methane than from oxidizing one 1g fat. A. More; Less B. More; More C. Less; Less D. Less; More

B

A cell's reservoir of NADPH composes its A. Oxidizing power B. Reducing power C. Structural stability D. Backbone reservoir

B.

Binding of neurotransmitters to to receptors on the postsynaptic membrane, opens _________ channels A. Voltage - gated B. Ligand - gated C. Mechano - gated

B.

Glucose oxidation starts in the _____, where glycolysis occurs. The end product of this pathway is _______ A. Cytoplasm; one pyruvate molecule B. Cytoplasm; two pyruvate molecules C. Nucleus; one pyruvate molecule D. Mitochondria; two pyruvate molecules

B.

Hydrolysis of ____ and binding of a phosphate (phosphorylation) induces a conformational change from E1 to E2. ________ and binding of a new _____ molecule induces the return of the protein back to E1 A. ATP; Dephosphorylation; ADP A. ATP; Dephosphorylation; ATP A. ADP; Dephosphorylation; ADP; B. ADP; Dephosphorylation; ATP

B.

If all hydrocarbon tails of phospholipids were saturated, ____ A. The bilayer would be more fluid B. The bilayer would be less fluid C. The bilayer would not be affected

B.

If the neurotransmitter triggers the opening of anion selective channels, this will induce a _____ membrane potential A. Less negative B. More negative

B.

If the outside concentration is 1000 times the inside concentration, then ΔG _____ A. ΔG = - 1.4 kcal/mol B. ΔG = - 4.2 kcal/mol C. ΔG = 1400 kcal/mol D. ΔG = - 0.0014 kcal/mol

B.

In most mammalian cells, there is a voltage difference across the membrane. At rest, how is the inside of the cell charged, relative to the outside of the cell? A. The inside is more positively charged B. The inside is more negatively charged

B.

In the following action potential diagram, the phases represented by 1, 2 and 3 are known as __, __ and __, respectively A. Membrane potential, Rep.olarization and Depolarization B. Resting potential, Depolarization and Repolarization C. Repolarization, Resting potential and Depolarization D. Depolarization, Repolarization and Resting potential

B.

Inhibiting ATP synthesis directly inhibits glucose uptake from the intestinal lumen A. True B. False

B.

Membranes contain a wide diversity of lipids, including A. Triglycerides, cholesterol and phosphoglycerides B. Cholesterol, phosphoglycerides and sphingolipids C. Phosphoglycerides, sphingolipids and triglycerides D. Cholesterol, triglycerides and sphingolipids

B.

Substance X is a charged molecule of small molecular weight. It is found at higher concentrations outside of cells than inside. How might substance X enter cells? A. Diffusion through the lipid bilayer B. Diffusion through a channel C. Active transport D. Cotransport

B.

Suppose you were culturing a population of bacteria at 37 °C and then lower the temperature of the culture to 15 °C . What effect do you think this might have on the fatty acid composition of the membrane? A. The level of saturation would decrease B. The level of saturation would increase

B.

The GPI-anchored linkage contains a few carbohydrate molecules linked to phosphatidylinositol (a type of lipid). Where do you expect to find this kind of linkage? A. On the cytoplasmic side of the plasma membrane B. On the extracellular side of the plasma membrane

B.

The changes between L, T and O conformations, are the result of A. Mechanical changes in the inner mitochondrial membrane B. Movement of protons that rotate the Fo subunit C. Opening of ligand-gated channels in the outer membrane D. Changes in voltage that change amino acid interactions in the F1 subunit

B.

The difference in H+ concentration across the membrane is responsible for the two components of the proton-motive force which are A. Membrane potential and Voltage B. pH and Voltage C. Cotransport and pH D. Active transport and passive diffusion E. Proton gradient and electron gradient

B.

To completely oxidize a 10C fatty acid, _____ cycles of beta-oxidation have to occur A. 3 B. 4 C. 5 D. 6 E. 10

B.

What is the main purpose of the Electron transport chain (ETC)? A. To pump electrons across the inner mitochondrial membrane B. To create an electrochemical gradient across the inner mitochondrial membrane C. To synthesize ATP utilizing the high energy electrons from NADH and FADH2 D. All of the above

B.

A second inhibitor, Antimycin A, acts between cytochromes b and c (4 and 5). The this second experiment would leave A. 1 to 5 reduced; 6 oxidized B. 1 to 5 oxidized; 6 reduced C. 1 to 4 reduced; 5 to 6 oxidized D. 1 to 4 oxidized; 5 to 6 reduced

C.

For every ATP hydrolyzed by the Na+ /K+ - ATPase, also known as the Na+ /K+ ____, the ratio of Na+ to K+ ions pumped is ____ A. Pump; 1:1 B. Channel; 1:1 C. Pump; 3:2 D. Channel; 3:2 E. Pump; 5:3

C.

Generally, transport of glucose molecules into the cell (from the bloodstream) occurs by: A. Active transport B. Simple diffusion through the lipid bilayer C. Facilitated diffusion D. Movement through ion channels

C.

Glycolipids, important in maintaining membrane integrity and facilitating cell-cell communication, are a type of A. Phosphoglyceride B. Phospholipid C. Sphingolipid D. Cholesterol

C.

Membrane proteins are distinguished by their relationship to the lipid bilayer. All of the following are a kind of membrane protein, except: A. Peripheral proteins B. Integral proteins C. Sugar-linked proteins D. Lipid-anchored proteins

C.

Membrane proteins that selectively allow cations such as Na+ to cross a membrane in response to changes in membrane potential, best describe A. Na+/K+ antiporters B. Na+/K+ symporters C. Voltage-gated cation channels D. Ligand-gated cation channels E. Ion leak channels

C.

Normal, differentiated cells rely primarily upon aerobic respiration to generate ATP, except when they experience decreased levels of oxygen. In contrast, cancer cells rely almost entirely upon glycolysis for producing ATP, regardless of the presence of oxygen. Cancer cells can increase the rate of glycolysis up to 200-fold, relative to normal cells. This phenomenon, is known as the Warburg effect. Which of the following properties of cancer cells would have provided evidence for the Warburg effect? • Their increased oxidation of pyruvate • Their increased release of CO2 • Their increased release of lactate

C.

Phosphofructokinase is a key enzyme in glycolysis. It's activity is inhibited by high levels of ___ and increased by high levels of _____

C.

Pyruvate later ____ a carbon, a process known as decarboxylation, producing ______, which continues the process of glucose oxidation A. Loses; Lactate B. Gains; Lactate C. Loses; Acetyl-CoA D. Gains; Acetyl-CoA

C.

The free energy change (ΔG) of moving an uncharged solute across the membrane depends on A. The intrinsic characteristics of the molecules B. The free energy of the substrates and the products C. The difference in concentration on both sides of the membrane D. The charge of the molecules E. The availability of ATP

C.

The movement of a substance from an area of high concentration to an area of lower concentration is known as ______ A. Denaturation B. Osmosis C. Diffusion D. Transport

C.

The net end products of glycolysis are A. Two ATP molecules B. Four ATP and two pyruvate C. Two ATP, two NADH and two pyruvate D. Two ATP, one NADH and one pyruvate E. Two ATP, two NADH and two acetyl CoA

C.

The temperature at which a lipid bilayer shifts from a fluid state to a frozen crystalline gel is called the _____ A. Temperature optimum B. Gelation temperature C. Transition temperature D. Breaking point E. Ideal temperature

C.

The transformation of Pyruvate to Acetyl-CoA is accomplished by a multienzyme complex that leads to the production of A. A 3-carbon product, ATP, and CO2 B. A 2-carbon product, NAD+ , and CO2 C. A 2-carbon product, NADH, and CO2 D. A 2-carbon product, NADH, and H2O

C.

Where do electrons that enter the electrontransport chain come from? A. Pyruvate and Acetyl CoA B. Acetyl CoA and NAD+ C. NADH and FADH2 D. NAD+ and FAD

C.

A K+ - transporting ion channel in the plasma membrane of animal cells that remains open even in a "resting" cell, best describes A. Cation-gated K+ channels B. Ligand-gated K+ channels C. Na+/K+ leak channels D. K+ leak channels E. Resting potential K+ channels

D.

After a period of prolonged fasting, some amino acids, known as glucogenic amino acids, can be transformed back into glucose. This process is known as A. Glycolysis B. Shikimate pathway C. Pentose phosphate pathway D. Gluconeogenesis E. Glycogenolysis

D.

Drugs such as prozac, cocaine and amphetamines affect synaptic transmission events by A. Altering the reuptake of neurotransmitters B. Increasing the release of neurotransmitters C. Extending the presence of neurotransmitters in the synaptic clefts of the limbic system D. All of the above are correct

D.

Enzymes involved in membrane remodeling in response to challenging environmental conditions include all of the following except: A. Acyl-transferases B. Phospholipases C. Desaturases D. Catalases

D.

Excitatory neurotransmitters open ____ channels while inhibitory neurotransmitters open ____ channels A. K+ ; ClB. Cl- ; K+ C. K+ ; Na+ and ClD. Na+ ; K+ and ClE. Na+ and K+ ;Cl

D.

Glycolysis is converted to pyruvate in 10 steps. How many steps are there in gluconeogenesis? A. 8 B. 9 C. 10 D. 11 E. 12

D.

How do drugs such as Prilosec and Zantac prevent heartburn? A. Prilosec is an irreversible inhibitor of the H+ /K+ - ATPase B. Zantac interferes with histamine-binding in the parietal cells C. Both Prilosec and Zantac inhibit the Na+ /K+ - pump D. A and B are correct

D.

How do mitochondria generate and store the energy used to produce most of the ATP made during aerobic respiration? A. By producing heat B. By generating a heat gradient C. By generating a concentration gradient D. By generating an electrochemical gradient E. By generating a Na+ ion gradient

D.

In the absence of oxygen, organisms such as yeasts produce ethanol because A. Ethanol is a source of energy for them B. To regenerate NAD from NADH+ C. They know we like wine D. A and B are correct

D.

Most of the functions of a cell membrane are performed by A. Glycolipids B. Cholesterol C. Carbohydrates D. Proteins E. Phospholipids

D.

Synthesis of ATP is driven by conformational changes in the β-subunits of the F1 head of ATP synthase that alternate between A. Open, Close and Bind B. β1, β2, β3 C. Open, Leak and Trap D. Open, Loose and Tight

D.

The refractory period occurs because: A. The neuron cannot fire again until the membrane potential returns to below threshold. B. Pre-synaptic inhibition prevents over-firing and cellular exhaustion. C. Sodium and potassium gradients across the membrane completely dissipate after every action potential D. Voltage-gated channels become inactivated for a short time following an action potential.

D.

Which of the following is NOT a function of the plasma membrane? A. Compartmentalization B. Responding to external signals. C. Scaffold for biochemical activities. D. Preventing flow of all molecules in and out of the cell. E. Energy transduction

D.

Which of the following is NOT a product of the anaerobic oxidation of pyruvate? A. Carbon dioxide B. Lactate C. Ethanol D. Acetyl CoA

D.

Which statement best describes how cholesterol affects cell membrane fluidity? A. Cholesterol increases fluidity at high temperatures and decreases fluidity at low temperatures. B. Cholesterol increases fluidity at high temperatures and increases fluidity at low temperatures. C. Cholesterol decreases fluidity at high temperatures and decreases fluidity at low temperatures. D. Cholesterol decreases fluidity at high temperatures and increases fluidity at low temperatures

D.

Hydrophobic portions of the integral proteins interact with the fatty acid chains of the membrane lipids to help stabilize the protein in the bilayer. These associations are mediated by ________ A. Covalent bonds B. Ionic bonds C. Hydrogen bonds D. van der Waals interactions E. Peptide bonds

D..

All of the following are high energy molecules that can be used as reducing agents by a cell, except A. FADH2 B. NADPH C. NADH D. NAD E. All of them are high energy molecules

E.

Hydropathy plots are graphical representations of ______ A. The length of a protein B. The number of α-helix and β-sheets in a protein C. The sequence of amino acids D. The location of a protein in the cell E. The hydrophobicity of portions of a protein

E.

Most of the ATP produced during aerobic cellular respiration is made by: A. Glycolysis B. Krebs cycle C.Fermentation D.Fatty acid cycle E. Oxidative phosphorylation

E.

The main components of the plasma membrane include lipids, proteins and carbohydrates. Which of the following is true about these carbohydrates? A. Most are in the outer leaflet of the plasma membrane B. Most are in the inner leaflet of the plasma membrane C. They are equally distributed on both sides of the bilayer D. They always face the cytoplasmic surface of the membrane E. They always face the extracellular surface of the membrane

E.

The movement of glucose from the bloodstream into cells is accomplished by A. Primary active transport B. Secondary active transport C. The Na+/glucose cotransporter D. Passive diffusion across the lipid bilayer E. Facilitated diffusion

E.

Transfer of the high energy electrons from NADH is associated with translocation of _____ H+, while FADH2 is associated with the translocation of _____ H+ A. 8; 10 B. 10; 8 C. 8; 6 D. 6; 8 E. 10; 6

E.

What property of membranes allows interactions to take place within the membrane, including the assembly of membrane protein clusters at particular sites and the formation of specialized structures? A. Membrane potential B. Membrane fluidity C. Hydrophobicity D. Electrostatic fluidity E. Their amphipathic nature

E.

Which of the following characteristics is NOT associated with the movement of ions through gated channels ? A. Passive diffusion B. Movement always occurs downhill C. Highly selective D. Formed by integral membrane proteins E. Energy-coupled

E.

Which of the following proteins would you expect to have a larger diffusion coefficient? A. A low molecular weight protein B. A large molecular weight protein C. A cytoplasmic protein D. A membrane-bound protein E. A and C are correct

E.

If your cells are now transferred from 15 °C to 37 °C , how would this affect the fatty acids and the activity of membrane desaturases? A. Saturation decreased, desaturases increase B. Saturation decreased, desaturases decrease C. Saturation increased, desaturases increase D. Saturation increased, desaturases decrease

a.

Na+ /K+ -ATPase pumps ___ ions from the cytoplasm to the extracellular space and ____ ions from the extracellular space into the cytoplasm A. 3 Na+ ; 2K+ B. 2 Na+ ; 3K+ C. 3 K+ ; 2 Na+ D. 2 K+ ; 3 Na+ E. 3 Na+ ; 3K+

a.

The product of anaerobic oxidation of pyruvate in muscle cells is ____, and in yeast cells is _____. A. Lactate; Ethanol B. Lactate; Glucose 6-P C. Acetyl CoA; Lactate D. Acetyl CoA; EthanoL

a.

The movement of substances against a concentration gradient is accomplished by A. Voltage-gated channels B. Ligand-gated channels C. Active transport D. Ionic channels E. Plasmolysis

c.

The picture below represents the movement of an uncharged solute across the membrane. Which of the following statements about this picture is/are true? A. This kind of transport does not require ATP B. This kind of transport requires ATP C. The ΔG of moving this solute is negative D. The ΔG of moving this solute is positive E. A and C F. B and D

c.