Question 1

The Calvin cycle is essentially

Accepted Answer

A)  started by the oxygen capture by Rubisco. 
B)  a reductive pentose phosphate cycle. 
C)  the reductive, or reverse, tricarboxylic acid cycle. 
D)  a pathway to synthesize fatty acids but not sugars. 
E)  a pathway that is used only when light is present. 
A)  started by the oxygen capture by Rubisco. 
B)  a reductive pentose phosphate cycle. 
C)  the reductive, or reverse, tricarboxylic acid cycle. 
D)  a pathway to synthesize fatty acids but not sugars. 
E)  a pathway that is used only when light is present.

Question 2

Nitrogenase is diagrammed below. This particular enzyme is shown in the format just before it begins a cycle of nitrogen reduction. This goal is accomplished in four steps. What is the first step?

Accepted Answer

A)  N₂ gas binds to the active site on the FeMo protein. 
B)  NADPH binds to the active site in order to reduce it prior to N₂ binding. 
C)  Two e - are transferred to the Fe protein and then to the FeMo protein, which are used to reduce H+ to H₂ prior to N₂ binding. 
D)  The preexisitng NH4+ is removed prior to N₂ binding. 
E)  Fe and Mo are bound to the active sites and then released prior to the next cycle. 
A)  N₂ gas binds to the active site on the FeMo protein. 
B)  NADPH binds to the active site in order to reduce it prior to N₂ binding. 
C)  Two e - are transferred to the Fe protein and then to the FeMo protein, which are used to reduce H+ to H₂ prior to N₂ binding. 
D)  The preexisitng NH4+ is removed prior to N₂ binding. 
E)  Fe and Mo are bound to the active sites and then released prior to the next cycle.

Question 3

Which of the following statements concerning glyceraldehyde-3-phosphate is FALSE?

Accepted Answer

A)  One G3P is produced by everything three turns of the cycle. 
B)  Two molecules of G3P condense to form a six-carbon sugar. 
C)  One more G3P condenses with a sugar to form a larger molecule used for biosynthesis. 
D)  PGA is reduced to G3P after the PGA moves out of the carboxysome. 
E)  G3P is reoxidized to carbon dioxide so that the cycle continues. 
A)  One G3P is produced by everything three turns of the cycle. 
B)  Two molecules of G3P condense to form a six-carbon sugar. 
C)  One more G3P condenses with a sugar to form a larger molecule used for biosynthesis. 
D)  PGA is reduced to G3P after the PGA moves out of the carboxysome. 
E)  G3P is reoxidized to carbon dioxide so that the cycle continues.

Question 4

The most ancient CO₂ fixation pathway in methanogens is the

Accepted Answer

A)  reverse TCA cycle. 
B)  3-hydroxypropionate cycle. 
C)  Calvin cycle. 
D)  reductive acetyl-CoA pathway. 
E)  Krebs cycle. 
A)  reverse TCA cycle. 
B)  3-hydroxypropionate cycle. 
C)  Calvin cycle. 
D)  reductive acetyl-CoA pathway. 
E)  Krebs cycle.

Question 5

Which amino acid is NOT one of the first amino acids produced by ancient cells?

Accepted Answer

A)  glutamate 
B)  tyrosine 
C)  glycine 
D)  valine 
E)  asparate 
A)  glutamate 
B)  tyrosine 
C)  glycine 
D)  valine 
E)  asparate

Question 6

Gene expression of nitrogenase through NtrC is downregulated in high concentrations of

Accepted Answer

A)  carbon dioxide. 
B)  nitrogen. 
C)  nitrate. 
D)  ammonium. 
E)  FeMo protein. 
A)  carbon dioxide. 
B)  nitrogen. 
C)  nitrate. 
D)  ammonium. 
E)  FeMo protein.

Question 7

Two strains of E. coli were developed, each of which overproduced an amino acid, either histidine or tryptophan. When grown together in medium with adequate amino acids, they grew but did not associate with each other. When these strains were grown together in medium without histidine and tryptophan, they grew and formed ________ in order to ________.

Accepted Answer

A)  carboxysomes; share the excess of the two amino acids 
B)  carboxysomes; provide ATP to each other to make the missing amino acids 
C)  nanotubes; share the excess of the two amino acids 
D)  nanotubes; provide ATP to each other to make the missing amino acids 
E)  heterocysts; share the excess of the two amino acids 
A)  carboxysomes; share the excess of the two amino acids 
B)  carboxysomes; provide ATP to each other to make the missing amino acids 
C)  nanotubes; share the excess of the two amino acids 
D)  nanotubes; provide ATP to each other to make the missing amino acids 
E)  heterocysts; share the excess of the two amino acids

Question 8

Industrial nitrogen fixation is achieved through the Haber process

Accepted Answer

A)  in which N₂ is reduced catalytically by H₂ at ambient temperature. 
B)  in which N₂ is hydrogenated by CH4 at extreme temperature and pressure. 
C)  in which nitrate and nitrite are chemically converted to NH at ambient temperature. 
D)  which requires little energy. 
E)  which is carried out by purified enzymes in a reactor. 
A)  in which N₂ is reduced catalytically by H₂ at ambient temperature. 
B)  in which N₂ is hydrogenated by CH4 at extreme temperature and pressure. 
C)  in which nitrate and nitrite are chemically converted to NH at ambient temperature. 
D)  which requires little energy. 
E)  which is carried out by purified enzymes in a reactor.

Question 9

Which of the following does NOT serve as an intermediate in the biosynthesis of amino acids?

Accepted Answer

A)  citrate 
B)  2-oxoglutarate 
C)  pyruvate 
D)  3-phosphoglycerate 
E)  pentose phosphate 
A)  citrate 
B)  2-oxoglutarate 
C)  pyruvate 
D)  3-phosphoglycerate 
E)  pentose phosphate

Question 10

What are polyalkanoates, and what are bacterially produced polyalkanoates used for? Why are they of ecological and medical interest?

Accepted Answer

Polyalkanoates are polyesters that are u

Question 11

Which of the following statements is NOT true about Rubisco?

Accepted Answer

A)  It catalyzes the addition of CO₂ to ribulose 1,5-bisphosphate. 
B)  It is present in all organisms that use the Calvin cycle to fix CO₂. 
C)  It is found in the carboxysomes of autotrophic bacteria. 
D)  All species contain the same number of large and small subunits. 
E)  Its structure is highly conserved across bacterial groups and chloroplasts. 
A)  It catalyzes the addition of CO₂ to ribulose 1,5-bisphosphate. 
B)  It is present in all organisms that use the Calvin cycle to fix CO₂. 
C)  It is found in the carboxysomes of autotrophic bacteria. 
D)  All species contain the same number of large and small subunits. 
E)  Its structure is highly conserved across bacterial groups and chloroplasts.

Question 12

How does the reductive (reverse) TCA cycle participate in carbon fixation?

Accepted Answer

A)  Some of the TCA reactions occur in reverse, assimilating small amounts of CO₂. 
B)  CO₂ assimilation uses up TCA intermediates for anabolic pathways. 
C)  Reverse TCA regenerates succinyl-CoA, which may enter gluconeogenesis. 
D)  A large amount of ATP is generated. 
E)  All reactions take place in a carboxysome. 
A)  Some of the TCA reactions occur in reverse, assimilating small amounts of CO₂. 
B)  CO₂ assimilation uses up TCA intermediates for anabolic pathways. 
C)  Reverse TCA regenerates succinyl-CoA, which may enter gluconeogenesis. 
D)  A large amount of ATP is generated. 
E)  All reactions take place in a carboxysome.

Question 13

Certain amino acids are more energetically expensive than others (tryptophan versus glutamate). Thus, when proteins are moved to the cell surface, extended outside the surface, or secreted out of the cell, there is a potential harm. Why is this potentially harmful, and what adaptations do bacteria have for this potential loss? Give an example.

Accepted Answer

With more "expensive" amino acids, more

Question 14

In anaplerotic reactions

Accepted Answer

A)  intermediates in a pathway are regenerated. 
B)  nutrients are imported from the environment. 
C)  molecules targeted for breakdown are salvaged for anabolism. 
D)  the reactions are thermodynamically impossible. 
E)  large amounts of ATP are generated. 
A)  intermediates in a pathway are regenerated. 
B)  nutrients are imported from the environment. 
C)  molecules targeted for breakdown are salvaged for anabolism. 
D)  the reactions are thermodynamically impossible. 
E)  large amounts of ATP are generated.

Question 15

Discuss evidence that supports the idea that glutamate, aspartate, alanine, glycine, and valine were the first amino acids produced by ancient cells.

Accepted Answer

These five amino acids are the amino aci

Question 16

The incorporation of NH₄⁺ into 2-oxoglutarate is the first step in nitrogen assimilation in bacterial cells. This reaction is catalyzed by the enzyme ________ and produces ________.

Accepted Answer

A)  glutamate dehydrogenase (GDH); glutamate 
B)  glutamine synthase (GS); glutamine 
C)  glutamate synthase (GOGAT); glutamate 
D)  2-oxoglutarate aminase (2-O
A) ; glutamine 
E)  2-oxoglutarate dehydrogenase (2-ODH); glutamine 
A)  glutamate dehydrogenase (GDH); glutamate 
B)  glutamine synthase (GS); glutamine 
C)  glutamate synthase (GOGAT); glutamate 
D)  2-oxoglutarate aminase (2-O
A) ; glutamine 
E)  2-oxoglutarate dehydrogenase (2-ODH); glutamine

Question 17

What methods do microorganisms NOT use to minimize energy for biosynthesis?

Accepted Answer

A)  inhibiting or killing competitors by making antimicrobials 
B)  loss of genes encoding enzymes for a nutrient that can be provided by the environment 
C)  regulation of gene expression so that molecules are not made if available 
D)  allosteric control of biosynthetic enzyme activity 
E)  transport of ATP from the environment into the cell to drive biosynthesis 
A)  inhibiting or killing competitors by making antimicrobials 
B)  loss of genes encoding enzymes for a nutrient that can be provided by the environment 
C)  regulation of gene expression so that molecules are not made if available 
D)  allosteric control of biosynthetic enzyme activity 
E)  transport of ATP from the environment into the cell to drive biosynthesis

Question 18

Which of the following molecules CANNOT freely cross biological membranes?

Accepted Answer

A)  O₂ 
B)  CO₂ 
C)  NH4+ 
D)  N₂ 
E)  H₂O 
A)  O₂ 
B)  CO₂ 
C)  NH4+ 
D)  N₂ 
E)  H₂O

Question 19

The amino acid biosynthetic pathways are designated as families. The ________ family generates only one amino acid.

Accepted Answer

A)  aspartate 
B)  serine 
C)  pyruvate 
D)  aromatic 
E)  histidine 
A)  aspartate 
B)  serine 
C)  pyruvate 
D)  aromatic 
E)  histidine

Question 20

Biological nitrogen fixation is energetically expensive. Assuming that NADPH is used as the reducing equivalent, how many ATPs are used in the enzymatic conversion of N₂ to NH₃?

Accepted Answer

A)  16 
B)  32 
C)  48 
D)  64 
E)  none; only GTP is used 
A)  16 
B)  32 
C)  48 
D)  64 
E)  none; only GTP is used

Exam 15: Biosynthesis

The Calvin cycle is essentially

Nitrogenase is diagrammed below. This particular enzyme is shown in the format just before it begins a cycle of nitrogen reduction. This goal is accomplished in four steps. What is the first step?

Which of the following statements concerning glyceraldehyde-3-phosphate is FALSE?

The most ancient CO₂ fixation pathway in methanogens is the

Which amino acid is NOT one of the first amino acids produced by ancient cells?

Gene expression of nitrogenase through NtrC is downregulated in high concentrations of

Industrial nitrogen fixation is achieved through the Haber process

Which of the following does NOT serve as an intermediate in the biosynthesis of amino acids?

What are polyalkanoates, and what are bacterially produced polyalkanoates used for? Why are they of ecological and medical interest?

Which of the following statements is NOT true about Rubisco?

How does the reductive (reverse) TCA cycle participate in carbon fixation?

In anaplerotic reactions

Discuss evidence that supports the idea that glutamate, aspartate, alanine, glycine, and valine were the first amino acids produced by ancient cells.

The incorporation of NH₄⁺ into 2-oxoglutarate is the first step in nitrogen assimilation in bacterial cells. This reaction is catalyzed by the enzyme ________ and produces ________.

What methods do microorganisms NOT use to minimize energy for biosynthesis?

Which of the following molecules CANNOT freely cross biological membranes?

The amino acid biosynthetic pathways are designated as families. The ________ family generates only one amino acid.

Biological nitrogen fixation is energetically expensive. Assuming that NADPH is used as the reducing equivalent, how many ATPs are used in the enzymatic conversion of N₂ to NH₃?

Microbial Life: Origin and Discovery

Observing the Microbial Cell

Cell Structure and Function

Bacterial Culture, Growth, and Development

Environmental Influences and Control of Microbial Growth

Viruses

Genomes and Chromosomes

Transcription, Translation, and Bioinformatics

Gene Transfer, Mutations, and Genome Evolution

Molecular Regulation

Viral Molecular Biology

Biotechniques and Synthetic Biology

Energetics and Catabolism

Electron Flow in Organotrophy, Lithotrophy, and Phototrophy

Food and Industrial Microbiology

Origins and Evolution

Bacterial Diversity

Archaeal Diversity

Eukaryotic Diversity

Microbial Ecology

Microbes in Global Elemental Cycles

Human Microbiota and Innate Immunity

The Adaptive Immune Response

Microbial Pathogenesis

Microbial Diseases

Antimicrobial Therapy

Clinical Microbiology and Epidemiology

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The incorporation of NH₄⁺ into 2-oxoglutarate is the first step in nitrogen assimilation in bacterial cells. This reaction is catalyzed by the enzyme and produces .