BIL 150: Exam 3 pt. 2

**Motor proteins provide for molecular motion in cells by "walking" along cytoskeletal elements. Which of the following cytoskeletal proteins does the motor protein Kinesin walk along?
microfilaments
intermediate filaments
actin
microtubules
plasmodema

microtubules

Which of the following statements about the cytoskeleton is a false statement?
chemicals that block the assembly of the cytoskeleton proteins could result in the loss of cellular shape
- microtubules are mostly rigid and resist compression, whereas microfilaments provide tension
- the smooth endoplasmic reticulum is responsible for the assembly of the cytoskeleton.
- cytoskeletal function is made possible by the assembly and disassembly of a globular cellular proteins into complex linear aggregates
- movement of cilia and flagella is the result of motor proteins, as dynein, causing microtubules to move relative to each other

the smooth endoplasmic reticulum is responsible for the assembly of the cytoskeleton.

Which of the following membrane activities requires the nucleotide GTP?
1) Na+ ions moving out of a mammalian cell in exchange for K+ ions
2) movement of carbon dioxide out of a chloroplast
3) closure of Gap Juntions in plant cells
4) activation of a G-protein in a cell
5) facilitated diffusion of Cl- ions across the membrane through a chloride channel

activation of a G-protein in a cell

When a nerve cell responds to a neurotransmitter that has been released by another nerve cell, that results in the opening gated of ion channels in another neuron, the neurotransmitter is serving as which part of a Signal-Transduction Pathway?
GPCR (G Protein Coupled Receptor)
1) a signal molecule
2) a receptor protein
3) a cascade kinase enzyme
4) a transducer

a signal molecule

Of the following processes which would most likely include all of the other processes listed?
passive transport
1) diffusion of a solute across a membrane
2) osmosis
3) movement of an ion down a concentration gradient through a channel protein
4) facilitated diffusion

passive transport

In general, a signal transmitted via a phosphorylation cascade of a series of proteins?
brings a conformational change to a series of proteins.
1) requires phosphorylase activity.
2) cannot occur in yeasts because they lack protein phosphatases.
3) allows target cells to change their shape and therefore their activity.
4) requires binding of a hormone to a cytosol receptor.

brings a conformational change to a series of proteins.

**You are working on a team that is designing a new signal molecules to function as a drug. In order for this drug to work, it must enter the cytoplasm of specific target cells. Which of the following would be a factor that might best determine whether your molecule could selectively enter into these target cells?

1)a high affinity for a specific receptor protein in the cell's membranes.
2)the hydrophilicity of the drug molecule.
3)a lack of charge on the drug molecule.
4) the lipid composition of the target cells' plasma membrane.
5)the blood or tissue type of the patient.

a high affinity for a specific receptor protein in the cell's membranes.

A type of localized signaling in which a cell secretes a signal molecule that affects just neighboring cells is best described as which of the following signaling?
insulin signaling.
paracrine signaling
hormonal signaling
isotonic signaling.
cell-cell contact-dependent signaling

paracrine signaling

Binding of a specific signal molecules, as epinepherine, to its receptor is most likely to activate which of the following molecules?
microtubules
insulin
an ion-gated Na channel
a series of protein kinases
the breakdown of mRNA molecules

a series of protein kinases

An inhibitor of the enzyme phosphodiesterase activity would likley have which of the following effects?
to prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm.
directly block the response of of the signal molecule epinephrine
decrease the amount of cAMP in the cytoplasm
block the binding of epinepherine to its receptor.
add 3 phosphate molecules to a protein kinase

to prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm.

**Living organisms increase in complexity as they grow, resulting in a decrease in the entropy of the organism. How does this relate to the second law of thermodynamics?

- Life obeys the second law of thermodynamics because the decrease in entropy as the organism grows is exactly balanced by an increase in the entropy of the whole universe.
- Living organisms do not follow the laws of thermodynamics.
- Living organisms are able to directly transform energy into entropy.
- Living organisms do not obey the second law of thermodynamics, which states that entropy must increase with time.
- As a consequence of growing, organisms may still cause a greater increase in entropy in the total environment (internal and external) of the cell can show a decrease in entropy while the cell grows in complexity.

As a consequence of growing, organisms may still cause a greater increase in entropy in the total environment (internal and external) of the cell can show a decrease in entropy while the cell grows in complexity.

A young puppy has never had much energy. He is brought to a veterinarian for help and and testing discovers that its mitochondria do not process glucose readily for ATP production and the puppy's cells produce more lactate than normal. Which of the following might likley be a good explanation of this puppy's weakened energy state?

1)the puppy's cells readily move the FADH2 made in glycolysis into the mitochondria.
2)the puppy's mitochondria could lack a transport protein that would move pyruvate across the inner mitochondrial membrane into the mitoplasm.
3)His cells have a defective pyruvate dehydrogenase that makes glucose rather than lactate.
the puppy's cells contain something that inhibits glycolysis from making pyruvate in its muscle cells.
4)The puppy's cells lack the enzyme in glycolysis that directly makes lactate.

the puppy's mitochondria could lack a transport protein that would move pyruvate across the inner mitochondrial membrane into the mitoplasm.

GTPase-phosphatase activity is involved in the regulation of signal transduction because it?
1) converts cGMP to GTP
2) increases the available concentration of phosphate
3) decreases the amount of G-protein in the membrane
4) hydrolyzes the GTP bound to a G-protein
5) phosphorylates protein kinases

hydrolyzes the GTP bound to a G-protein

Signal molecules can result in a phosphorylation cascade by?

1) initiating conformational changes in a series of many different proteins
2) altering the length of microtubular cilia proteins
3) inhibiting the action of protein kinase enzyme
4) binding of a hormone to a nuclear membrane receptor

initiating conformational changes in a series of many different proteins

**In a liver cell mitochondria where are the ATP synthase complexes located?

1) in between the inner and out mitochondrial membrane only.
2) in the outer mitochondrial membrane only.
3) in both the inner and outer mitochondrial membranes.
4) in the plasma (cell) membrane only.
5) in the inner mitochondrial membrane only.

in the inner mitochondrial membrane only.

During a chemcial reaction, you determine that the conversion of A to B by an enzyme has a standard free energy [ ∆G0'] of -20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the ∆G0' for the new reaction?
- 20 kcal/mol
0 kcal/mol
+ 20 kcal/mol
+ 40 kcal/mol
- 40 kcal/mol

- 20 kcal/mol

During glycolysis, for each molecule of glucose oxidized to pyruvate?

1) Thirty-six molecules of ATP are used and six molecules of ATP are produced
2) two molecules of ATP are consumed and two molecules of ATP are produced
3) four molecules of ATP are consumed and two molecules of ATP are produced
4) two molecules of ATP are consumed and theirty-six molecules of ATP are produced
5) two molecules of ATP are consumed and four molecules of ATP are produced

two molecules of ATP are consumed and four molecules of ATP are produced

You measure the pH of the inner mitoplasm (matrix) and the pH of the space between the inner and out membranres of a mitochondria. Which, if any, of the following relationships of pH would you expect to find?

1) The pH within the mitoplasm is lower than that of the perimitochondrial space.
2) The pH of the perimitochondrial space and mitoplasm are equal.
3) The pH of the mitoplasm is the same as the pH of the cell's cytoplasm.
4) The pH of the perimitochondrial space is basic and above 9.3.
5) none of these is a viable pH relationship.

none of these is a viable pH relationship.

Among the differences in between all the cellular ribonucleotides ATP, TTP, CTP, GTP, and UTP we find?

1) that there is no difference in the free energy content of all these ribonucleotides.
2) that only UTP can occur in a cyclic configuration.
3) that there is no nitrogen-containing bases in TTP and UTP.
4) that the number of phosphates in GTP and ATP is different than in TTP, CTP, and UTP.
5) that the sugar molecule is different in all of them.

that there is no difference in the free energy content of all these ribonucleotides.

The mathematical expression that describes the change in Gibbs free energy of a chemcial system is ΔG = ΔH - TΔS. Which of the following statements is correct concerning the free energy equation?

ΔS is the change in enthalpy, which is a measure of the change in heat content.
ΔH is the change in entropy, a measure in the degree of reandomness of a reaction.
ΔG is always positive in chemcial reactions.
ΔH, the change in enthalpy of a reaction, and is considerd neglible in cellular reactions.
ΔG, the change in free energy, is always a negatve (-) value in cellular reactions.

ΔH, the change in enthalpy of a reaction, and is considerd neglible in cellular reactions.

The ATP made during glycolysis is generated by?

substrate-level phosphorylation.
oxidation of NADH to NAD+
chemiosmosis.
photophosphorylation.
electron transport.

substrate-level phosphorylation.

The oxygen that is consumed during cellular respiration is involved directly in which of the following processes or events?

the phosphorylation of ADP to form ATP.
the oxidation of pyruvate to acetyl CoA.
accepting electrons at the end of the mitochondrial electron transport chain.
the reduction of NADP+ to NADPH.
glycolysis.

accepting electrons at the end of the mitochondrial electron transport chain.

Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose 6-phosphate to fructose 1,6-bisphosphate, an early step of glycolysis. In the presence of oxygen an increase in the amount of ATP in a cell would be expected to?

1) feedback inhibit phosphofructokinase and thus slow the rates of glycolysis and the citric acid cycle.
2) activate phosphofructokinase stop substrate phosphorylation.
3) inhibit phosphofructokinase and thus increase the rate of the dark reaction of sugar synthesis in photosynthesis.
4) activate phosphofructokinase and thus enhance the rates of glycolysis and the citric acid cycle.
5) inhibit the phosphofructokinase, which would increase the rates of the citric acid cycle.

feedback inhibit phosphofructokinase and thus slow the rates of glycolysis and the citric acid cycle.

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction?

loses electrons and gains potential energy.
gains electrons and gains potential energy.
neither gains nor loses electrons, but gains or loses potential energy.
gains electrons and loses potential energy.
loses electrons and loses potential energy.

loses electrons and loses potential energy.

Most CO2 that is released during cellular respiration is released during which of the following processes?

the Krebs citric acid cycle.
the oxidation of pyruvate to acetyl-CoA.
non-cyclic photophosphorylation.
glycolysis.
lactate fermentation.

the Krebs citric acid cycle.

In the individual reaction shown above of the Krebs Citric Acid Cycle, which of the following types of reactions is taking place?

acylation
oxidation - reduction
decarboxylation
choose this choice if all of the above occur during this reaction
choose this choice if only two of the above occurs during this Krebs cycle reaction.

choose this choice if only two of the above occurs during this Krebs cycle reaction.

Which cellular respiration pathway is common to both anaerobic and aerobic celluar respiration?

the citric acid cycle.
the electron transport chain.
glycolysis.
pyruvate dehydrogeanse complex.
choose this choice if none of these pathways are common to both aerobic and anaerobic cell respiration.

glycolysis

A key function of both alcohol fermentation and lactic acid fermentation is to?

oxidize NADH to NAD+.
reduce NAD+ to NADH.
reduce FAD+ to FADH2.
reduce FADH2 to FAD+.
release CO2.

oxidize NADH to NAD+.

The enzyme ATP synthase transports protons across the inner mitochondrial membranes of mitochondria with the existing concentration gradient. Which domain of the ATP synthase is directly responsible for the diffusive movent of protons through the inner mitochondrial membrane?

F0
F1
neither F0 or F1, the protons diffuse directly through the inner mitochondrial membrane
the Na pump

F0

Inside an active mitochondrion, most electrons follow which of the following pathway?

pyruvate → citric acid cycle → ATP → NADH → oxygen.
citric acid cycle → FADH2 → electron transport chain → ATP.
citric acid cycle → NADH → electron transport chain → oxygen.
electron transport chain → citric acid cycle → ATP → oxygen.
glycolysis → NADH → oxidative phosphorylation → ATP → oxygen.

citric acid cycle → NADH → electron transport chain → oxygen.

In mitochondria, exergonic redox reactions ________.

decrease the entropy of all cell rspiration reactions
reduce carbon atoms to carbon dioxide
are coupled via phosphorylated intermediates to endergonic processes
are the source of energy driving prokaryotic ATP synthesis
provide the energy that establishes the proton gradient

provide the energy that establishes the proton gradient

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is ________.

pyruvate
O2
NADH
NAD+
water

O2

In mechanism, photophosphorylation is most similar to ________.

oxidative phosphorylation in cellular respiration
substrate-level phosphorylation in glycolysis
carbon fixation
photorepiration
reduction of NADP+

oxidative phosphorylation in cellular respiration

How is photosynthesis similar in C4 plants and CAM plants?

Both types of plants make most of their sugar in the dark.
Both types of plants make sugar without the Calvin cycle.
C4 plants use NADH, while CAM plants use NADPH to fix CO2
In both cases, PEP carboxylase is used to fix carbon in the initial reaction.
In both cases, only photosystem I is used.

In both cases, PEP carboxylase is used to fix carbon in the initial reaction.

The light reactions of green plant photosynthesis supply the Calvin cycle with ________.

H2O and ATP
ATP and NADPH
glucose and fructosse
CO2 and NADPH
light energy

ATP and NADPH

Which of the following enzymes is central to the ability of C4 plants to perform photosynthesis?
PEP carboxylase
phosphofructokinase
pyruvate kinase
catalase
pyruvate dehydrogenase

PEP carboxylase

Where are the enzymes of the Calvin cycle localized?

chloroplasm (stroma) of the chloroplast
thylakoid membrane
mitoplam (matrix) of the mitochondria
interior of the thylakoid (thylakoid space)
outer membrane of the chloroplast

chloroplasm (stroma) of the chloroplast

In the following signal transduction pathway... epinephrine → G protein-coupled receptor → G protein → adenyl cyclase → cAMP → glycogen phophorylase. identify the second messenger.

GTP
ATP
cyclic AMP
G protein
glycogen phosphorylase

cyclic AMP

Motor proteins provide for molecular motion within cells by interacting with which of the following intracellular structures?

components of the cytoskeleton
cellulose fibers in the plant cell wall
free ribosomes and ribosomes attached to the ER
membrane proteins of the inner nuclear envelope
lysosomes

components of the cytoskeleton

Which of the following structures is independent, not involved with, the endomembrane system in eukaryotic cells?

chloroplast
nuclear envelope
Golgi apparatus
plasma membrane
choose this choice is all of above are directly involved with the endomembrane system

chloroplast