Microbio Class Ch 11

The net gain of ATP per molecule of glucose metabolized to pyruvate using Entner-Doudoroff pathway is _________.

1

The net gain of ATP per molecule of glucose metabolized anaerobically via the Embden-Meyerhof pathway in prokaryotes is _________.

2

The theoretical maximum net gain of ATP per molecule of glucose metabolized aerobically in eukaryotes is _________.

32

Complete catabolism of lactose requires _________.

ATP, UTP, NAD, and appropriate enzymes

Indicate the products of aerobic respiration.

All choices are correct. water, CO2, ATP, NADH

The pentose phosphate pathway produces _________.

All of the choices are correct. CO2 NADPH glyceraldehyde 3-phosphate

Which of the following may be used as sources of energy by chemolithotrophs?

All of the choices are correct. Hydrogen gas Reduced nitrogen compounds Reduced sulfur compounds

Which of the following can be used as electron acceptors during anaerobic respiration?

All of the choices are correct. Nitrate Sulfate Carbon dioxide

Which of the following statements is true regarding the effect of electron transport chain length on energy production?

As electrons are passed from carrier to carrier, each oxidation releases enough energy to actively transport protons across a membrane, thus, the more carriers, the greater the proton motive force produced.

In the TCA cycle, two carbons are removed from citric acid in the form of __________, thereby regenerating oxaloacetate to complete the cycle.

CO2

A newly described bacterial species has been shown to use CO2 as its carbon source. Its energy source and its source of reducing power (electrons) are inorganic chemicals. Which term would best describe this nutritional type?

Chemolithoautotroph

Which nutritional classification would you predict to fit most of the well-known members of the human microbiome?

Chemoorganoheterotrophs

___________ refers to the removal of an amino group from an amino acid. One mechanism for this removal is __________, in which the amino group is transferred to an acceptor molecule.

Deamination; transamination

Which of the following produces the most ATP during aerobic respiration?

Electron transport chain and chemiosmosis

Which of the following is the major glycolytic pathway used by plants and animals?

Embden-Meyerhof pathway

The most common pathway for conversion of glucose to pyruvate is _________.

Embden-Meyerhoff

An organism can fit into only one nutritional pattern, such as photoheterotrophy, and cannot change if the environmental conditions change.

False

In the process of fermentation an organic substrate, such as glucose, is reduced and an intermediate of the pathway, such as pyruvate, is oxidized.

False

Many chemolithotrophs are able to produce more ATP from oxidation of their inorganic energy source than chemoheterotrophs produce from the aerobic oxidation of glucose.

False

Metabolic pathways can be either catabolic or anabolic but not both.

False

Nitrification of ammonia occurs when ammonia is first converted to nitrite and then is converted to nitrate by the nitrogen-fixing bacteria.

False

Oxygen is always required for the regeneration of NAD from NADH.

False

Some aerobic bacteria lack the Entner-Doudoroff and Embden-Meyerhoff pathways and instead use the pentose phosphate pathway for glycolysis.

False

The catabolism of glucose through a glycolytic pathway, followed by the TCA cycle and culminating in ATP production via the formation of a proton motive force in the electron transport chain, represents the overall reduction of glucose.

False

The pentose phosphate pathway is the major glycolytic pathway used by archaea.

False

How does a fermenter generate proton motive force (PMF) to drive active transport?

Fermenters can reverse the direction of the ATP synthase to generate PMF.

The oxidation of glucose to CO2 and H2O with the subsequent production of energy is best reflected in which of the following statements?

Glucose is oxidized in a stepwise fashion beginning with a glycolytic pathway and continuing with the TCA cycle where the remainder of the energy from the glucose is harnessed in reduced coenzymes, which transport electrons to an electron transport chain where ATP is made by oxidative phosphorylation.

Which of the following names refer to the tricarboxlic acid cycle?

Krebs Cycle, citric acid cycle

Which of the following is produced in largest numbers by the TCA cycle?

NADH

__________ is a two-step process that depends on the activity of at least two genera to carry out the oxidation of ammonia to nitrate.

Nitrification

The energy source for substrate-level phosphorylation (SLP) differs from that of oxidative phosphorylation (OP) in that __________.

OP is driven using energy provided by a proton motive force, whereas the energy to add a phosphate group to ADP during SLP comes from the direct transfer of a phosphate group from a molecule with a higher phosphate transfer potential than ATP

The number of ATP molecules generated per atom of oxygen that is reduced when electrons are passed from NADH or reduced FAD (FADH) to O2 is called the _________.

P/O ratio

How does the phosphorylation of galactose differ from the phosphorylation of glucose, mannose, and fructose prior to catabolism?

Phosphorylation of galactose requires UTP to phosphorylate galactose-1-phosphate

Although most metabolic reactions are freely reversible, a few irreversible catabolic steps are bypassed during biosynthesis with special enzymes that catalyze the reverse reaction in order to allow for independent regulation of catabolic and anabolic pathways.

True

An organism can take advantage of energy available from both light and from organic molecules and exhibit both phototrophy and chemoorganotrophy.

True

An organism may use glycolysis and the pentose phosphate pathway simultaneously.

True

Bacterial electron transport chains may be comprised of fewer components and have lower phosphate to oxygen (P/O) ratios than mitochondrial transport chains.

True

Fermentation involves the use of pyruvate and/or other organic molecules as electron acceptors.

True

Glycolysis and the TCA cycle are two of the most important catabolic pathways in chemoorganotrophs.

True

In addition to being used in the making of ATP, a proton motive force is used directly to power the rotation of bacterial flagella.

True

Most chemolithotrophs have electron transport chains that terminate with O2 as the final electron acceptor.

True

Oxidative decarboxylation takes place when pyruvate from the glycolytic pathway is oxidized, producing acetyl-CoA along with one CO2 and one NADH.

True

Prokaryotes may use several different terminal oxidases for the electron transport system.

True

Reduction of nitrate to nitrite by Paracoccus denitrificans is an example of anaerobic respiration.

True

The catabolism of glucose begins with one or more of the glycolytic pathways that yield pyruvate.

True

The electron transport systems in eukaryotes and prokaryotes use different electron carriers.

True

The major difference between aerobic and anaerobic respiration is the final electron acceptor at the end of the electron transport chain.

True

The terms Krebs cycle, tricarboxylic acid cycle, and citric acid cycle all refer to the same process.

True

Very few Gram-positive bacteria utilize the Entner-Doudoroff glycolytic pathway.

True

In higher eukaryotes, most aerobically generated ATP is produced by _________.

a membrane-bound proton translocating ATP synthase during oxidative phosphorylation

In the TCA cycle, two carbons in the form of __________ are added to oxaloacetate at the start of the cycle.

acetyl-CoA

The pyruvate dehydrogenase complex oxidizes and cleaves pyruvate to form one CO2 and _________.

acetyl-CoA

____________ ____________ is a process that can completely catabolize an organic energy source to CO2 using the glycolytic pathways and TCA cycle with O2 as the terminal electron acceptor for an electron transport chain.

aerobic respiration

__________ pathways are those that function both catabolically and anabolically.

amphibolic

Fatty acids are metabolized by the __________ pathway.

beta-oxidation

The six carbons of the glucose molecule that enter the cell respiration pathway end up in/as _______ ______ by the end of the process.

carbon dioxide

In most cases, fueling reactions are __________ reactions.

catabolic

The hypothesis that proton motive force drives ATP synthesis is called the __________ hypothesis.

chemiosmotic

The most commonly accepted hypothesis for the production of ATP that results from electron transport system is called the __________ hypothesis.

chemiosmotic

Aerobic respiration, anaerobic respiration, and fermentation are the three basic types of _________.

chemoorganoheterotrophic metabolism

Select the terms that describe an organism's carbon source.

chemotroph, autotroph

The TCA cycle is located in the _________ of bacteria, and in the _________ of eukaryotes.

cytoplasm; mitochondrial matrix

Amino acids are processed first by the removal of the amino group through _________.

deamination or transamination

When cells of a facultative anaerobe such as Paracoccus denitrificans are growing under anaerobic conditions and using nitrate as the terminal electron acceptor, ___________ nitrate reduction is occurring.

dissimilatory

When nitrate is used as a final electron acceptor by bacteria growing in anoxic soils, the nitrogen is no longer available for the construction of precursor metabolites. This is referred to as _________.

dissimilatory nitrate reduction

The terms phototroph and chemotroph refer to an organism's source of _________.

energy

The major function(s) of the TCA cycle is(are) _________.

energy production and provision of carbon skeletons for biosynthesis of cell components

Processes that supply ATP, reducing power, and precursor metabolites are collectively referred to as ____________ reactions.

fueling

Organisms that form lactate, ethanol, and CO2 as end products of glucose metabolism are called __________ fermenters.

heterolactic

Consider the metabolism of a chlorophyll-based phototroph. In oxidative phosphorylation during cell respiration, the source of energy is _________ whereas in photophosphorylation the source of energy is __________.

highly reduced organic compounds; light

Organisms that directly reduce almost all of their pyruvate to lactate are called __________ fermenters.

homolactic

Disaccharides and polysaccharides can be processed as nutrients after first being cleaved to monosaccharides by either __________ or __________.

hydrolysis; phosphorolysis

Large external polysaccharides are degraded by bacteria and archaea using ________ ________, which they secrete outside the cell.

hydrolytic enzymes

The substances that donate electrons to the electron transport chains of chemolithotrophs are ___________.

inorganic compounds

Chemolithotrophs obtain their energy from __________.

inorganic molecules that are oxidized, providing electrons to create a proton motive force that drives oxidative phosphorylation

In aerobic conditions, it takes __________ sugar to produce the same amount of ATP when compared to anaerobic conditions.

less

The amount of ATP produced during anaerobic respiration is _________ that produced during aerobic respiration, because the difference in the standard reduction potential between NADH and the final electron acceptor is __________.

less than; smaller

The total of all chemical reactions occurring in a cell is called _________.

metabolism

TCA cycle enzymes are found in the __________ _________ of eukaryotic cells.

mitochondrial matrix

Mitochondrial electron transport takes place _________.

on the inner mitochondrial membrane

Indicate the processes below that represent the basic types of chemoorganotrophic metabolism.

photosynthesis, oxidation-reduction

A ________ hydrolyzes a protein into its constituent amino acid monomers and a _________ enzyme removes amino groups from the amino acids.

protease, deaminase

Proteins are catabolized by hydrolytic cleavage to amino acids by the action of enzymes called __________.

proteases

What enzymes hydrolyze proteins, releasing amino acids?

proteases

The Embden-Meyerhof, Entner-Doudoroff and pentose phosphate pathways all bring about the reduction of coenzymes (either NAD+ or NADP+). The reduced coenzymes __________.

provide reducing power to fuel subsequent reactions

The TCA cycle __________.

provides reducing power in the form of NADH and FADH2, and precursor molecules for anabolic reactions

After glycolysis, pyruvate is oxidized to one CO2 and the two-carbon molecule acetyl-CoA by a multienzyme system called the ________ ________ complex.

pyruvate dehydrogenase

The TCA cycle begins when __________.

pyruvate from the glycolytic pathway is oxidized to acetyl-CoA, which is added to oxaloacetate

Whereas the Embden-Meyerhof pathway produces two molecules of pyruvate (net) for each glucose, the Entner-Doudoroff pathway produces one molecule each of ___________ and ____________.

pyruvate; glyceraldehyde

Production of ATP using the energy liberated when electrons from reduced chemical bonds are passed through the electron transport system is generally referred to as _________.

respiration

The synthesis of ATP from ADP and Pi, when coupled with an exergonic chemical reaction is called __________ phosphorylation.

substrate-level

During glycolysis, ATP is produced when 1,3 bisphosphoglycerate transfers a phosphate to ADP forming ATP. This is an example of _________.

substrate-level phosphorylation

When mitochondria pass electrons donated by NADH through the electron transport chain to molecular oxygen, a theoretical maximum of __________ molecules of ATP can be made per oxygen molecule reduced.

three

The TCA cycle generates all of the following from each acetyl-CoA molecule oxidized except _________.

two ATP or GTP molecules

During breakdown of fatty acids, carbons are removed __________ at a time with each turn of the cycle, and two carbon units are released as __________.

two; acetyl-CoA

Which of the following are consequences of anaerobic respiration? (Check all that apply.)

Some bacteria are able to readily survive in both well-oxygenated as well as anoxic environments. Some bacteria may cause denitrification. Bacteria are able to reduce the levels of NO3− in sewage plant effluents.

How is ATP produced during fermentation?

Substrate-level phosphorylation

Differences between mitochondrial and E. coli electron transport chains include which of the following?

The E. coli chain contains a different array of cytochromes.

In order for a substance to transfer a phosphate to ADP in a substrate-level phosphorylation reaction, which of the following must be true?

The phosphate donor must have a higher phosphate transfer potential than ATP.

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

The presence of an electron transport chain

Which of the following is NOT true regarding ATP synthases?

The proton flow is outward during ATP synthesis.