MBI 201 Exam 2 QUESTIONS - Miami University Fall 2022

in glycolysis, ATP is produced when 1,3-bisphosphate transfers a phosphate to ADP forming ATP. This is an example of ___

substrate-level phosphorylation

which line illustrates an enzyme-catalyzed reaction?

lower

In the EMP pathway (glycolysis), the cofactor ___ serves as a temporary electron carrier when glyceraldehyde 3-phosphate (G3P) is _____ to 1,3-bisphosphoglycerate (1,3PG).

NAD+

oxidized

a ___ is an enzyme that catalyzes the transfer of phosphate groups from high-energy, phosphate-donating molecules such as ATP to specific substrates

kinase

fermentation products can include compounds such as lactic acid and ethanol, but many other products like acetic acid and succinic acid are also possible because ___

these products arise to complete the catabolism of glucose and regenerate NAD+ from NADH

The conversion of glyceraldehyde 3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP) in the glycolysis is catalyzed by a ______.

isomerase

In the pentose phosphate shunt, glucose 6-phosphate is oxidized to 6-phosphogluconate, which is then decarboxylated to ribulose 5-phosphate. What is the main metabolic role of this pathway

production of NADPH and C5 carbohydrate for synthesis of nucleotides

the TCA cycle generates all the following from each oxidized acetyl-CoA moelcule EXCEPT:

3 NADH

2 CO2

2 ATP or GTP

1 FADH2

2 ATP or GTP molecules

what is the distinguishing feature characterizes aerobic and anaerobic respiration but does not play a role in fermentation pathways?

the presence of an electron transport chain

Using the same amount of glucose, less energy is produced from fermentation compared to aerobic respiration because

respiration completely oxidizes glucose to CO2, resulting in greater generation of NADH and thus ATP.

the six carbons of the glucose molecule that enter the cell respiration pathway are oxidized into CO2 during the process of ___

pyruvate oxidation and the TCA cycle

for each CO2 that is released in the TCA cycle, the carboxylic acid group of the intermediate is ___ and the electrons are extracted to generate ___

oxidized

NADH

what can be used as electron acceptors during anaerobic respiration?

nitrate and Fe3+

reduction potentials of a chemical is defined as ___

the tendency to accept electrons

which of the following is true regarding prokaryotic metabolism?

The use of organic compounds as electron donors is known as aerobic respiration

Chemolithotrophy refers to the use of organic molecules as electron sources

Oxygen serves as the terminal electron acceptor during photolysis

Electrons can be obtained from inorganic chemicals such as H2S by some lithotrophic bacteria.

Oxygen can serve as an electron donor during chemolithotrophy

Electrons can be obtained from inorganic chemicals such as H2S by some lithotrophic bacteria.

which of the following is not a redox pair?

fumarate/succinate

NADP+/NADH

S/H2S

Q/QH2

FAD+/FADH2

NADP+/NADH

an unknown bacterium can use hydrogen to reduce carbon dioxide into methane. this bacterium performs the metabolism called ___ and, given its source of electrons, it is a ___

methanogenesis

chemolithotroph

in ecoli ETCs, the electron transfer process between the NADH oxidation and O2 reduction is connected by the mobile electron carrier ___

quinol

the following groups of molecules are components of the electron transport systems except:

heme b

iron-sulfur clusters

quinones

FMN

acetyl-CoA

acetyl-CoA

in bacterial and archaeal cells, the electron transport chain is located in the ___ whereas, in eukaryotic cells, the electron transport chain is located in the ___

plasma membrane

inner mitochondrial membrane

Choose the TRUE statement regarding the difference between mitochondrial and E. coli electron transport chains.

The E. coli electron transport chain contains an additional proton pump.

In the mitochondrial electron transport chain, energy released from oxidation reactions is harvested to pump more protons.

When NADH is oxidized, higher proton motive force is observed in E. coli electron transport chain.

The fundamental principles on which they operate are different.

The electron transport chain does not involve membranes in E. coli.

In the mitochondrial electron transport chain, energy released from oxidation reactions is harvested to pump more protons.

which of the following may be used as a source of energy by chemolithotrophs?

hydrogen gas

methane

reduced nitrogen compounds

reduced sulfur compounds

all options

chemolithotrophs generally derive ___ ATP fom oxidation of inorganic substrates because the reduction potentials of those substrates are much more ___ than the reduction potential of organic substrates

less

positive

in cyanobacteria, ___ is the electron source for the light reactions, and when it's oxidized, ___ is produced

H2O

O2

in the process of linear electron flow in photosynthetic cyanobacteria, ___

both photosystems I and II are required

the ATP/NADPH ratio generated by the linear electron flow in oxygenic photosynthesis is not enough to support carbon fixation in the calvin cycle. the additional ATP requirement is generally fulfilled by ___

cyclic electron flow

Based on their standard reduction potentials, arrange the following electron carriers in the electron transport chain so electrons flow in the right direction.

Cytochroms a3 (Fe3+) + e- ---> Cytochrome a3 (Fe2+) Eo (volts) = 0.35Ubiquinone + 2H+ + 2e- ---> Ubiquinol Eo (volts) = 0.10Cytochrome a (Fe3+) + e- ---> Cytochrome a (Fe2+) Eo (volts) = 0.29Cytochrome c (Fe3+) + e- ---> Cytochrome c (Fe2+) Eo (volts) = 0.25

ubiquinol - cytochrome c- cytochrome a- cytochrome a3

which of the following is false regarding dehalorespiration?

it is a type of hydrogenotrophy

Cl- can be removed from toxic compounds

carbon dioxide is a by-product

halogenated organic molecules serve as electron acceptors

hydrogenotrophs can be used in bioremediation

carbon dioxide is a by-product

bacteriorhodopsin ___

absorbs light and goes through a photocycle involving excitation and relaxation and ultimately resulting in the pumping of one H+

methanotrophs ___

are organisms that use methane as their electron source

in many bacteria, the electron carrier ___ is fed into the electron transport system, whereas ___ is used for biosynthesis

NADH

NADPH

during the utilization of iron by Acidithiobacillus ferrooxidans for ATP production, ___

the PMF drives reverse electron flow through the NAD(P)H dehydrogenase complex to produce NAD(P)H for biosynthesis

Which of the following pathways are (2) NOT a route for CO2 assimilation?

reductive EMP pathway

reductive acetyl-CoA pathway

reductive pentose phosphate pathway

3-hydroxylpropionate cycle

reverse TCA cycle

eductive ED pathway

reductive EMP pathway and reductive ED pathway

which of the following is not correct about fatty acid biosynthesis?

it involves successive condensations of malonyl-ACP

many intermediates from glycolysis are involved

dehydratase is used to generate an unsaturated bond

NADPH is consumed

Many intermediates from glycolysis are involved in the fatty acid synthesis.

which of the following statements is NOTtrue about rubisco?

it catalyzes the addition of CO2 to R1,5BP

plants, algae, and cyanobacteria use rubisco to fix CO2

rubisco also reacts with O2, leading to improved carbon fixation

present in all organisms that use the calvin cycle

found in carboxysomes of cyanobacteria

reacts with O2, leading to improved carbon fixation

what is the order of phases of the calvin-benson cycle, starting with the entry of ribulose 1,5-bisphosphate

carboxylation

regeneration

reduction

In the reductive TCA cycle, three ATPs are used to produce one oxaloacetate. How many molecules of CO2 are fixed in this cycle?

4

in the fatty acid synthesis, ___

malonyl-ACP is continuously added to the growing fatty acid chain to yield an even number of carbons

which of the following does not serve as an intermediate in the biosynthesis of amino acids?

citrate

3-phosphoglycerate

2-oxoglutarate

pentose phosphate

pyruvate

citrate

purines and pyrimidines are precursors for synthesis of ___

nucleic acids

The molecule shown below carries energy in the cell but it needs to be stabilized. It is a ________ molecule and is stabilized when it ________.

ATP; complexes with Mg2+

The enzyme pyruvate kinase catalyzes the conversion of phosphoenolpyruvate to pyruvate; the phosphate group is transferred to ADP to form ATP. This reaction is an example of

ATP synthesis by substrate-level phosphorylation.

A bacterium uses hydrogen as the electron source to fix carbon dioxide into methane. It thus performs a type of metabolism called ________ and, given its sources of electrons, it is performing ________.

methanogenesis; hydrogenotrophy

The greatest amount of NADH is produced during which stage of aerobic respiration of glucose molecules?

tricarboxylic acid cycle

The spontaneity of a reaction is determined by ___________ and the reaction is further accelerated by ___________.

negative Gibbs free energy change; enzymes

E. coli was grown aerobically in batch cultures. Assuming it takes 4 H+ to produce 1 ATP using ATP synthase, _______ ATPs are produced from the breakdown of 1 glucose molecule during aerobic respiration. Out of these ATPs, ____ is from substrate-level phosphorylation.

26; 4

Which of the following substrates is an electron donor in organotrophy?

Succinate

NO2

H2O

H2

Fe2+

Succinate

What is the chromophore group in bacteriorhodopsin?

retinal

Which of the following is NOT a terminal electron acceptor in anaerobic respirations?

hydrogen sulfide

nitrite

sulfate

nitrate

hydrogen sulfide

Electron donors for anoxygenic photosystem I in green sulfur bacteria include the following, EXCEPT

Succinate

Fe2+.

H2O.

H2.

H2S.

Succinate

Cyanobacteria are believed to generate the majority of oxygen gas in Earth's atmosphere. What allows them to produce oxygen?

photosynthesis in which water photolysis produces H+, e-, and O2

Which one of the following molecules from the TCA cycle can be used to synthesize amino acids?

fumarate

succinate

isocitrate

succinyl-CoA

2-oxoglutarate

2-oxoglutarate

In fatty acid (FA) synthesis, ___________

malonyl-ACP (C3 intermediates) is continuously added to the growing FA chain to yield an even number of carbons.

ATP is produced during fermentation through ___________.

substrate-level phosphorylation

In the process of linear electron flow in oxygenic photosynthesis,

Photosystems I and II are both required.

Electrons from water flow through electron transport chains resulting in synthesis of ATP and NADPH.

Water is split to form oxygen.

All of the choices are correct.

All of the choices are correct.

What types of bacteria does NOT perform the reductive pentose phosphate cycle to fix CO2?

heterotrophs

Which of the following reactions is catalyzed by Rubisco?

CO2 + ribulose 1,5-bisphosphate --> 3-phosphoglycerate

The Calvin cycle

involves some intermediates from the EMP pathway

The ________ pathway is utilized for carbon fixation in plant chloroplasts and cyanobacteria.

3-hydroxypropionate cycle

What is the role of reverse electron flow in lithoautotrophic bacteria?

It can be used to generate NADPH by coupling with the PMF.

In oxygenic photosynthesis, the cyclic electron flow

is used to generate more ATP but not NADPH by recycling electrons from ferredoxin back to plastoquinone.

In the mitochondrial electron transport chain, the electron transfer process between complex III and complex IV is connected by the mobile electron carrier______.

cytochrome c