Microbiology : Chapter 11 – Flashcards

Total of all chemical reactions occurring in cell

Breakdown of larger, more complex molecules into small, simpler ones. Energy is released and some is trapped and made available for work.

Synthesis of complex molecules from simpler ones with the input of energy

Involves the use of an electron transport chain

Final electron acceptor is oxygen

Final electron acceptor is different exogeneous acceptors such as NO-3, SO4-2 CO2 Fe+3 and SeO4-2

A type of potential energy that is generated and used to synthesize ATP

Uses an endogenous electron acceptor. Does not involve the use of an electron transport chain nor the generation of a proton motive force

In fermentation ATP is only synthesized by:

Large molecules

Small molecules

Two functions of organic energy sources

Pathways with enzymes that function catabolically and anabolically

Three common routes that breakdown glucose to pyruvate

The most common route to pyruvate

Also called EM Pathway. Occurs in cytoplasmic matrix of both procaryotes and eucaryotes

How many parts is the glycolytic pathway divided into?

Summary of Glycolysis

Synthesis of ATP from ADP by phosphorylation coupled with exergonic breakdown of high energy substrate molecules

Used by some soil bacteria and few other Gram negative bacteria

ED Pathways yield per glucose:

Also called hexose monophosphate pathway. Can operate at the same time as ED and EM pathway. Can operate aerobically or anaerobically. An amphibolic pathway

Function of Pentose Phosphate Pathway

What is the tricarboxylic acid cycle also called

What does the tricarboxylic acid cycle complete

What is TCA common in?

True or False TCA is an amphibolic pathway

For each Aceytl CoA molecule oxidized TCA cycle generates

Often used to transfer electrons from electron donors to electron acceptors

Electron donor

Electron acceptor

Equilibrium constant for an oxidation reduction reaction A measure of tendency of the reducing agent to lose electrons.

More negative the reduction potential

More positive the reduction potential

Series of electron carriers that operate together to transfer electrons from NADH to terminal electron acceptor. Electrons flow from carriers with more negative reduction potential to carriers with more positive reduction potential.

In the ETC, some released energy used to make ATP by __________________ phosphorylation

How many molecules of ATP are made per NADH using oxygen as acceptor?

How many molecules of ATP are made per FADH2 using oxygen as acceptor?

Electron transfer accompanied by proton movement across inner mitochondrial membrane

(located in plasma membrane); some resemble mitochondrial ETC, but many are different; different electron carriers, may be breached, may be shorter, may have lower P/O ratio

Most widely accepted explanation of oxidative phosphorylation

Postulates that energy released during electron transport used to establish a proton gradient and charge difference across membrane

What drives the formation of ATP

Enzyme that uses proton movement to catalyze ATP synthesis

Importance of PMF

True or False Oxygen is required for the regeneration of NAD from NADH.

What do the EM and ED pathways have in common? A. They are considered types of glycolytic pathways B. They require oxygen C. They are found only in obligate anaerobes D. All of the above

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

True or False Both ED and EM pathways are very common in bacteria.

True or False Aerobic respiration provides much more ATP than fermentation

Decrease in rate of sugar metabolism when microbe shifted from anaerobic to aerobic conditions. Occurs because aerobic process generates greater ATP per sugar molecules

Uses electron carriers other than O2. Generally yields less energy because reduction potential of electron acceptor is less positive than reduction potential of O2.

Use of nitrate as a terminal electron acceptor. The anaerobic reduction of nitrate makes it unavailable to cell for assimilation or uptake.

Reduction of nitrate to nitrogen gas. In soil, causes loss of soil fertility.

An energy yield process in which indigenous organic molecules serve as electron donors and acceptors *NADH is oxidized to NAD+ *The electron acceptor is pyruvate or pyruvate derivative

True or False. Oxygen is needed in microbial fermentation.

True or False. Oxidative phosphorylation occurs in microbial fermentation.

How is ATP formed in microbial fermentation

Many algae, some bacteria, fungi and protozoa ferment sugars to EtOH or CO2

Reduction of pyruvate to lactate. Found in bacteria, mold, algae, protozoa, and even in animal skeletal muscle.

All pyruvate is reduced to lactate, enzyme is lactate dehydrogenase.

Produce a substantial amount of products other than lactate from pyruvate

Formic acid fermentation

Are bacterias able to ferment amino acids?

Detects intermediate acetoin

Detects pH change in media caused by mixed acid fermentation

Why is Voges Proskauer Test and Methyl red test important

Oxidation of one amino acid with the use of the second amino acid as a electron acceptor

Converted to other sugars that enter glycolytic pathways

Cleaved by hydrolases or phosphorylase

Common sugars that have to be converted to glucose

Used as energy sources in the absence of external nutrients

Common energy sources. Hydrolyzed to glycerol and fatty acids by lipases.

Hydrolyzes proteins to amino acids

Removal of amino group from amino acid.

Transfer of amino group from one amino acid to an alpha-keto group.

Carried out by chemolithotrophs. Transferred to terminal electron acceptor by ETC ATP synthesized by oxidative phosphorylation

True or False. Chemolithotrophs are usually aerobic

Switches from chemolithotrophic metabolism to chemoorganotrophic metabolism

Which events are part of TCA cycle? A. Citrate reacts with oxaloacetate to form acetyl CoA B. Glucose is converted to fructose C. NAD is regenerated D. Carbon dioxide, reduced co-enzymes, and ATP (GTP) are produced

The number of ATP molecules generated per atom of oxygen that is reduced electrons are passed from NADH or reduced FAD (FADH) to dioxygen A. utilization ratio B. energy yield C. P/O ratio D. phosphorylation coefficient

Which liberates the most energy in the formation of ATP? A. Alcohol fermentation B. Sugar fermentation C. Aerobic respiration D. Anaerobic respiration

What occurs when a pyruvate molecule proceeds toward and through the Krebs cycle? A. H atom end up in NADH and FADH2, plus 3 carbon dioxides are formed B. Pyruvate converted to heat energy C. Fatty acids are synthesized D. Carbon dioxide combine with acetyl CoA and form oxaloacetate

The synthesis of ATP from ADP and Pi, when coupled with the exergonic enzymatic breakdown of a high energy molecule, is called __________ phosphorylation. A. chemiostatic B. oxidative C. substrate-level D. conformational change

In the TCA cycle, two carbons are removed from citric acid in the form of __________, thereby regenerating oxaloacetate to complete the cycle. A. acetyl-CoA B. ethanol C. carbon dioxide D. methanol

The major function(s) of the TCA cycle is(are) A. energy production B. provision of carbon skeletons for biosynthesis of cell components C. both energy production and provision of carbon skeletons for biosynthesis of cell components D. neither energy production nor provision of carbon skeletons for biosynthesis of cell components

The major function(s) of the TCA cycle is(are) A. energy production B. provision of carbon skeletons for biosynthesis of cell components C. direct oxidation of 4 and 5 carbon sugars during anaerobic growth D. energy production and provision of carbon skeletons for biosynthesis of cell components

Which of the following is NOT true regarding ATP synthases? A. They require proton motive force to make ATP. B. They span the inner membrane of mitochondria. C. The proton flow is outward during ATP synthesis. D. The subunits of ATP synthase undergo conformational changes during ATP production.

Which of the following statements concerning the proton motive force is correct? A. This takes place only in bacteria B. It reduces organic carbon compounds C. PMF is based on the differential concentration of the proton across the membrane D. All of the above

What takes place when pyruvate is converted to acetyl CoA? A. One molecule of carbon dioxide is given off B. One molecule of FADH2 is produced from FAD C. The conversion takes place in the cytoplasm D. All of the above E. Only A and C are correct.

What takes place when pyruvate is converted to acetyl CoA? A. One molecule of carbon dioxide is given off B. One molecule of FADH2 is produced from FAD C. The conversion takes place in the cytosol D. None of these

True or False During glycolysis, one molecule is converted to one molecule of pyruvate.

The electron transport chain, a series of membrane-associated electron carriers, loses most of the energy by driving several transmembrane: A. proton pumps B. electron pumps C. sodium, potassium pumps D. active transport pumps E. water pumps

Production of ATP using the energy liberated by the electron transport system is generally referred to as __________ phosphorylation. A. chemiosmotic B. oxidative C. substrate-level D. conformational change

Which of the following can be used as electron acceptors during anaerobic respiration? A. oxygen B. lactate C. ethanol D. sulfate

In the TCA cycle, two carbons in the form of _________ are added to oxaloacetate at the start of the cycle. A. acetyl-CoA B. ethanol C. carbon dioxide D. methanol

The net gain of ATP per molecule of glucose metabolized via the Embden-Meyerhoff pathway in procaryotes is A. 2 B. 36 C. 38 D. 85

The net gain of ATP per molecule of glucose metabolized anaerobically in eucaryotes is A. 2 B. 36 C. 38 D. 85

Which liberates the most energy in the formation of ATP? A. Alcohol fermentation B. Sugar fermentation C. Aerobic respiration D. Anaerobic respiration

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

In higher eucaryotes, most aerobically generated ATP comes from A. glycolysis B. the TCA cycle C. the electron transport chain D. all of these generate equal amounts of ATP

True or False Usually the last step in a metabolic pathway is a pacemaker reaction that is catalyzed by a regulatory enzyme.

Which of the following is not used as an electron carrier by living organisms? A. NAD+ B. NADP+ C. FAD D. ATP E. All of these are used as electron carriers by living organisms.

What happens to the oxygen that is used in cellular respiration? A. It is oxidized to from water B. It is lost C. It is reduced to form water D. It is converted to carbon dioxide.

How is ATP produced during respiratory metabolism? A. By glycolysis B. By the Krebs cycle C. By photophosphorylation D. A, B, and C E. A and B

How is ATP produced during the Emden-Meyerhof pathway? A. Substrate-level phosphorylation B. Fermentation C. Cyclic phosphorylation D. Oxidative phosphorylation

The standard reduction potential of a redox reaction is a measure of the tendency of the __________ to __________ electrons. A. reductant; gain B. reductant; lose C. oxidant; gain D. oxidant; lose

What do the TCA cycle, the tricarboxylic acid cycle, and the Krebs cycle have in common? A. They are forms of chemoautotrophy B. They are different types of substrate level phosphorylation C. They only occur during anaerobic respiration D. They are names for the same metabolic pathway E. A, B, and C are correct

True or False An organism does not use glycolysis and the pentose phosphate pathway simultaneously.

One of the most important coenzymes that accepts electrons/hydrogens is A. NAD+ B. NADH C. ATP D. NADPH E. ribozyme

An electron carrier that is used in harvesting energy from glucose molecules in a series of gradual steps in the cytoplasm is A. pyruvate B. cyclic AMP C. ATP D. NAD+ E. NADH

In oxidative respiration, energy is harvested from glucose molecules in a sequence of four major pathways. Which one of the following is not one of these four pathways? A. Krebs cycle B. glycolysis C. electron transfer through the transport chain D. beta oxidation E. pyruvate oxidation

The oxygen utilized in cellular respiration finally shows up as A. CO2 B. ATP C. new O2 D. H2O E. part of a sugar

Which of the following statements accurately reflects the process of glycolysis? A. Glycolysis is most likely one of the earliest of all biochemical reactions to evolve. Glycolysis uses molecular oxygen, however it occurs in anaerobic environments. B. Glycolysis is most likely one of the earliest of all biochemical reactions to evolve. Glycolysis uses no molecular oxygen. All reactions of glycolysis occur free in the cytoplasm. C. Glycolysis is most likely one of the earliest of all biochemical reactions to evolve. Glycolysis uses molecular oxygen, however it occurs in aerobic environments. D. Glycolysis is most likely one of the earliest of all biochemical reactions to evolve, Glycolysis uses molecular oxygen and occurs in the mitochondria.

Select the correct sequence concerning glucose catabolism. A. glycolysis → Pyruvate → Acetyl CoA → Electron Transport Chain → Kreb Cycle B. glycolysis → Pyruvate → Acetyl CoA → Kreb Cycle → Electron Transport Chain C. glycolysis → Acetyl CoA → Pyruvate → Electron Transport Chain → Kreb Cycle D. glycolysis → Acetyl CoA → Pyruvate → Kreb Cycle → Electron Transport Chain

The enzymes of the Krebs cycle in prokaryotic cell are located in the A. cytoplasm B. inter-membrane space of mitochondria C. periplasm D. outer membrane of the mitochondria E. matrix of the mitochondria

In the cyclic reaction sequence called the Krebs cycle, the following chemical events take place except A. the acetyl group is joined with a four carbon molecule, oxaloacetate B. the resulting six carbon molecule is oxidized C. electrons generated are used to produce NADH D. two carbons per cycle are made into CO2 molecules E. pyruvate molecules are restored to the cycle

What type of cell respiration occurs when an organic molecule accepts electrons? A. aerobic respiration B. anaerobic respiration C. fermentation D. catabolism E. digestion

In aerobic conditions, it takes __________ sugar to produce the same amount of ATP when compared to anaerobic conditions. A. more B. less C. the same amount of

The Kreb cycle occurs in the mitochondria. There are nine biochemical reactions involved in the Kreb cycle, and they are highly ordered. Select the correct order from the following choices. (Note: these are abbreviated and do not show NAD, ADP, ATP, or FAD.) A. acetyl CoA joins the Kreb cycle and unites with oxaloacetate → forming citrate → which forms beta-ketoglutarate → which forms succinylCoA → which forms succinate → which forms fumerate → which forms malate → which forms oxaloacetate B. acetyl CoA joins the Kreb cycle and unites with oxaloacetate → forming citrate → which forms alpha-ketoglutarate → which forms succinylCoA → which forms succinate → which forms fumerate → which forms malate → which forms oxaloacetate C. acetyl CoA joins the Kreb cycle and unites with oxaloacetate → which forms beta-ketoglutarate → forming citrate → which forms succinylCoA → which forms succinate → which forms fumerate → which forms malate → which forms oxaloacetate D. acetyl CoA joins the Kreb cycle and unites with oxaloacetate → forming citrate → which forms alpha-ketoglutarate → which forms succinylCoA → which forms succinate → which forms fumerate → which forms malate → which forms oxaloacetate

The most common pathway for conversion of glucose to pyruvate is A. Entner-Doudoroff B. Pentose phosphate C. Embden-Meyerhoff D. A and C

The pentose phosphate pathway provides A. ATP B. NADPH C. four or five carbon sugars for amino acid and nucleic acid synthesis D. all of these

True or False The electron transport systems in eucaryotes and procaryotes use different electron carriers.

Most ATP production in aerobic bacteria is via A. anaerobic respiration B. substrate-level phosphorylation C. oxidative phosphorylation via ATPases D. A and B

The proton gradient across bacterial membranes is involved in A. generation of ATP in the presence of an external electron acceptor B. active transport of some ions C. rotation of bacterial flagella D. all of the above E. none of the above

In the ETC, what is being "pumped" across the membrane? A. H+ B. e- C. NADHD D. ADP

Which of the following does not occur in the Krebs cycle? A. redox reactions B. production of NADH C. production of FAD+ D. production of carbon dioxide E. synthesis pf ATP

Which of the following terminal electron acceptors has the greatest potential to provide the largest amount of free energy? A. CO2 B. NO3 C. O2 D. Fe3+ E. SO4

All of the following are the end products of glycolysis except: A. Pyruvate B. ATP C. NAD D. NADH E. Energy

The series of enzymatic steps that fixes carbon dioxide into carbohydrates is called the __________. A. Pentose phosphate pathway B. Embden-Meyerhoff pathway C. Calvin cycle D. Entner-Doudoroff pathway

True or False The Voges-Proskauer test is positive for butanediol fermenters but negative for mixed acid fermenters.

True or False Metabolism of fats produces more ATP molecules per gram than metabolism of carbohydrates or proteins.

True or False The most efficient pathway for ATP production in animal cells is by glycolysis.

Amino acids are processed first by the removal of the amino group through A. deamination B. transamination C. either deamination or transamination D. neither deaminiation or transamination

During breakdown of fatty acids, carbons are removed __________ at a time as __________. A. one; carbon dioxide B. one; methane C. two; acetyl-CoA D. two; ethanol

In the absence of oxygen, eukaryotic cells are restricted to A. Chemiosmotic phosphorylation B. Cyclic photo phosphorylation C. Noncyclic photophosphorylation D. Oxidative phosphorylation E. Substrate level phosphorylation

Fatty acids are metabolized by the __________ pathway. A. alpha-oxidation B. beta-oxidation C. gamma-oxidation D. delta-oxidation

Production of ATP using the energy liberated when electrons from reduced chemical bonds are pass through the electron transport system is generally referred to as _________. A. chemiosmotic B. respiration C. substrate-level D. conformational change

True or False Oxygen is required for the regeneration of NAD from NADH.

What occurs during fermentation? A. A membrane bound system contains cytochromes to produce ATP B. Fermentation regenerates NAD as pyruvate is converted to ethanol or lactate C. Acetyl CoA is regenerated D. Citric acid is produced

Which test is used to detect a mixed acid fermentation such as E. coli? A. Catalase B. Voges-Proskauer C. Simmons citrate D. Indol E. Methyl red

In the absence of oxygen, hydrogen atoms generated by glycolysis and donated to organic molecules in a process called A. fermentation B. decarboxylation C. chemiosmosis D. electron transport chain reactions E. acetyl CoA formation

Which of the following may be used as sources of energy by chemolithotrophs? A. hydrogen gas B. ammonia C. elemental sulfur D. all of these

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

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

The Strickland reaction A. is an alternative glycolytic pathway B. is a fermentation reaction in which one amino acid is oxidized and a second amino acid is reduced C. is used to oxidize nucleotides D. results in production of high concentrations of intracellular glycerol, which can be used to counterbalance osmotic pressure

Mitochondrial electron transport takes place A. on the outer mitochondrial membrane B. on the inner mitochondrial membrane C. in the fluid matrix of the mitochondria D. both the inner and on the outer mitochondrial membrane

How might homolactic fermentation be distinguished from heterolactic fermentation A. Homolactic is aerobic; heterolactic is anaerobic B. Homolactic forms mostly lactic acid; heterolactic forms lactic acid, ethanol, and CO2 C. Homelactic produces ethanol; heterolactic does not D. Homolactic is carried out by Gram-positive organism; heterolactic by Gram negative

True or False Bacterial electron transport chains may be comprised of fewer components and have lower P/O ratios than mitochondrial transport chains.

Anaerobic respiration encompasses which of the following A. assimilatory nitrate reduction B. dissimilatory nitrate reduction C. denitrification D. both B and C

Which fermentation pathway is detected using in the methyl red test when differentiating among enteric bacteria? A. butanediol fermentation B. mixed acid fermentation C. ethanol fermentation D. lactic acid fermentation E. proprionic acid fermentation

The decarboxylation of pyruvate produces: A. NADH B. acetyl CoA C. CO2 D. ATP E. Only A, B, and C are correct