Ch 11: Catabolism, Energy Release and Conservation

Chapter 11 Homework Questions

Products of the pentose phosphate pathway:

NADPH, CO₂, glyceraldehyde 3-phosphate

For one acetyl-CoA, how much NADH is produced in the TCA cycle?

3 NADH

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

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

energy

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

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

What enzymes hydrolyze proteins, releasing amino acids?

Proteases

True/False: Reduction of nitrate to nitrite by Paracoccus denitrificans is an example of anaerobic respiration.

TRUE

T/F: Metabolic pathways can be either catabolic or anabolic but not both.

False

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

FALSE

T/F: The electron transport systems in eukaryotes and prokaryotes use different electron carriers.

True

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

True

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

The E. coli chain contains a different array of cytochromes

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

hydrolysis, phosphorolysis

_________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

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

Phosphate donor must have a higher phosphate transfer potential than ATP

Organisms that form lactate, ethanol, and CO2CO2 as end products of glucose metabolism are called _________ fermenters.

heterolactic

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

Hydrogen gas, reduced nitrogen compounds, and reduced sulfur compounds

After glycolysis, pyruvate is oxidized to one  CO2CO2 and the two-carbon molecule acetyl-CoA by a multienzyme system called the _________ _________ complex

pyruvate dehydrogenase

The most common pathway for conversion of glucose to pyruvate is:

Embden-Meyerhoff

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

32

T/F: Prokaryotes may use several different terminal oxidases for the electron transport system.

TRUE

What terms are used to describe an organism’s carbon source?

heterotroph, autotroph

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

deamination or transamination

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

carbon dioxide

The pyruvate dehydrogenase complex oxidizes and cleaves pyruvate to form one CO2 and _____

acetyl-CoA

T/F: 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

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.

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

1

T/F: 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

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

3

T/F: Very few Gram-positive bacteria utilize the Entner-Doudoroff glycolytic pathway

TRUE

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

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 substances that donate electrons to the electron transport chains of chemolithotrophs are ___

inorganic compounds

T/F: The major difference between aerobic and anaerobic respiration is the final electron acceptor at the end of the electron transport chain

True

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

cytoplasm; mitochondrial matrix

Chemolithotrophs obtain their energy from ___

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

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

chemoorganoheterotrophs

Consequences of anaerobic respiration

• some 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

T/F: Oxidative decarboxylation takes place when pyruvate from the glycolytic pathway is oxidized, producing acetyl-CoA along with one CO2CO2 and one NADH.

T

T/F: Most chemolithotrophs have electron transport chains that terminate with O2O2 as the final electron accepto

T

The TCA cycle

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

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

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

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

two ATP or GTP molecules

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

P/O ratio