Question 1

Describe how modular enzymes function in polyketide biosynthesis. Why might this be of use medically?

Accepted Answer

Modular enzymes consist of multiple modu

Question 2

The catalytic site of Rubisco is located in

Accepted Answer

A)  the large subunit. 
B)  the small subunit. 
C)  a cavity that forms between an LSU and an SSU. 
D)  the chloroplast. 
E)  the chlorosome. 
A)  the large subunit. 
B)  the small subunit. 
C)  a cavity that forms between an LSU and an SSU. 
D)  the chloroplast. 
E)  the chlorosome.

Question 3

Which molecules use 5-phosphoribosyl-1-pyrophosphate (PRPP) in their biosynthesis?

Accepted Answer

A)  amino acids 
B)  nucleotides 
C)  fatty acids 
D)  tetrapyrrole 
E)  nonribosomal peptide antibiotics 
A)  amino acids 
B)  nucleotides 
C)  fatty acids 
D)  tetrapyrrole 
E)  nonribosomal peptide antibiotics

Question 4

How is fatty acid biosynthesis regulated in bacteria?

Accepted Answer

Because fatty acid biosynthesis consumes

Question 5

The cell diagrammed below provides an overview of some regulation of the Calvin cycle. Which of the following is NOT involved in this regulation?

Accepted Answer

A)  Several different transport mechanisms are used for $ \mathrm{CO}_{2} $ and $ \mathrm{HCO}_{3}- $. 
B)  $ \mathrm{CO}_{2} $ and $ \mathrm{HCO}_{3}^{-} $are sequestered inside a carboxysome. 
C)  Rubisco is sequestered inside a carboxysome. 
D)  Carbonic anhydrase is used to convert $ \mathrm{CO}_{2} $ to $ \mathrm{HCO}_{3}^{-}{ }^{-} $and thus trap it. 
E)  Proteins are used to block light and thus the light reactions. 
A)  Several different transport mechanisms are used for $ \mathrm{CO}_{2} $ and $ \mathrm{HCO}_{3}- $. 
B)  $ \mathrm{CO}_{2} $ and $ \mathrm{HCO}_{3}^{-} $are sequestered inside a carboxysome. 
C)  Rubisco is sequestered inside a carboxysome. 
D)  Carbonic anhydrase is used to convert $ \mathrm{CO}_{2} $ to $ \mathrm{HCO}_{3}^{-}{ }^{-} $and thus trap it. 
E)  Proteins are used to block light and thus the light reactions.

Question 6

Which of the following are unique in that they fix CO₂ as their sole carbon source?

Accepted Answer

A)  organotrophs and iron oxidizers 
B)  photoheterotrophs and chemiolithotrophs 
C)  photoautotrophs and lithotrophs 
D)  heterotrophs and methanogens 
E)  methanogens and photoheterotrophs 
A)  organotrophs and iron oxidizers 
B)  photoheterotrophs and chemiolithotrophs 
C)  photoautotrophs and lithotrophs 
D)  heterotrophs and methanogens 
E)  methanogens and photoheterotrophs

Question 7

The enzyme nitrogenase is inhibited by oxygen. Which of the following does NOT protect nitrogenase from oxygen?

Accepted Answer

A)  special thick-walled cells (heterocysts) in filamentous cyanobacteria, such as Anabaena 
B)  special nitrogenase-protecting proteins in Azotobacter species 
C)  temporal separation of nitrogen fixation (at night) and photosynthesis (during the day) in some species of cyanobacteria 
D)  growth under aerobic conditions 
E)  growth under anaerobic conditions 
A)  special thick-walled cells (heterocysts) in filamentous cyanobacteria, such as Anabaena 
B)  special nitrogenase-protecting proteins in Azotobacter species 
C)  temporal separation of nitrogen fixation (at night) and photosynthesis (during the day) in some species of cyanobacteria 
D)  growth under aerobic conditions 
E)  growth under anaerobic conditions

Question 8

The most ancient CO₂ fixation pathway in anaerobic phototrophic bacteria and archaea is the

Accepted Answer

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

Question 9

It is thought that the Calvin cycle appeared after the divergence of the three domains of life. What supports this hypothesis?

Accepted Answer

The full Calvin cycle is only found in b

Question 10

Briefly discuss how carbon molecules of different sizes can be made for biosynthesis. What else is needed and how is it obtained?

Accepted Answer

Molecules with varying numbers of carbon

Question 11

Which of the following is NOT correct regarding nitrogen assimilation into biomass?

Accepted Answer

A)  Different oxidation states of nitrogen require different amounts of reducing energy. 
B)  It is easy for living organisms to assimilate nitrogen due to its great stability. 
C)  Nitrogen forms must be fully reduced to NH3. 
D)  Only bacteria and archaea can assimilate elemental nitrogen. 
E)  It is expensive, requiring reducing energy and ATP. 
A)  Different oxidation states of nitrogen require different amounts of reducing energy. 
B)  It is easy for living organisms to assimilate nitrogen due to its great stability. 
C)  Nitrogen forms must be fully reduced to NH3. 
D)  Only bacteria and archaea can assimilate elemental nitrogen. 
E)  It is expensive, requiring reducing energy and ATP.

Question 12

In the mechanism of nitrogen reduction, ________ directly takes the place of the H₂ in the FeMo subunit of the enzyme nitrogenase.

Accepted Answer

A)  NH3 
B)  N₂ 
C)  HN=NH 
D)  H₂N-NH₂ 
E)  NADPH 
A)  NH3 
B)  N₂ 
C)  HN=NH 
D)  H₂N-NH₂ 
E)  NADPH

Question 13

The enzyme that carries out this reaction shown in the diagram below is ________, and the end product is ________.

Accepted Answer

A)  3-phosphoglycerate synthetase; added to another carbon dioxide 
B)  3-phosphoglycerate synthetase; reduced to glyceraldehyde-3-phosphate 
C)  nitrogenase; reduced to glyceraldehyde-3-phosphate 
D)  Rubisco; reduced to glyceraldehyde-3-phosphate 
E)  Rubisco; added to another carbon dioxide 
A)  3-phosphoglycerate synthetase; added to another carbon dioxide 
B)  3-phosphoglycerate synthetase; reduced to glyceraldehyde-3-phosphate 
C)  nitrogenase; reduced to glyceraldehyde-3-phosphate 
D)  Rubisco; reduced to glyceraldehyde-3-phosphate 
E)  Rubisco; added to another carbon dioxide

Question 14

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

Accepted Answer

A)  two 
B)  three 
C)  four 
D)  five 
E)  six 
A)  two 
B)  three 
C)  four 
D)  five 
E)  six

Question 15

Rubisco catalyzes which of the following reactions?

Accepted Answer

A)  $ \mathrm{CO}_{2}+ $ ribulose 1,5 -bisphosphate $ \rightarrow 2,3 $-phosphoglycerate 
B)  $ \mathrm{HCO}_{3}{ }^{-}+ $acetyl-CoA $ \rightarrow $ malonyl-CoA + NADPH $ \triangle 3 $-hydroxypropionate 
C)  $ \mathrm{H}_{2} \mathrm{~S}+ $ light $ \rightarrow \mathrm{S}^{0}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} $ 
D)  Ribulose-1,5-bisphosphate $ +\mathrm{CO}_{2}{ }^{-} \rightarrow $ Fructose- 1,6 -bisphosphate 
E)  2-carboxy-3-ketoarabinitol-1,5-bisphosphate $ \rightarrow $ G3P 
A)  $ \mathrm{CO}_{2}+ $ ribulose 1,5 -bisphosphate $ \rightarrow 2,3 $-phosphoglycerate 
B)  $ \mathrm{HCO}_{3}{ }^{-}+ $acetyl-CoA $ \rightarrow $ malonyl-CoA + NADPH $ \triangle 3 $-hydroxypropionate 
C)  $ \mathrm{H}_{2} \mathrm{~S}+ $ light $ \rightarrow \mathrm{S}^{0}+2 \mathrm{H}^{+}+2 \mathrm{e}^{-} $ 
D)  Ribulose-1,5-bisphosphate $ +\mathrm{CO}_{2}{ }^{-} \rightarrow $ Fructose- 1,6 -bisphosphate 
E)  2-carboxy-3-ketoarabinitol-1,5-bisphosphate $ \rightarrow $ G3P

Question 16

Which of the following is NOT a tetrapyrrole?

Accepted Answer

A)  cytochrome 
B)  chlorophyll 
C)  vitamin B12 
D)  tryptophan 
E)  hemoglobin 
A)  cytochrome 
B)  chlorophyll 
C)  vitamin B12 
D)  tryptophan 
E)  hemoglobin

Question 17

Denitrification is the

Accepted Answer

A)  conversion of nitrate or nitrite to N₂ by anaerobic respirers. 
B)  oxidation of NH4+ to nitrate or nitrite by lithotrophs. 
C)  conversion of N₂ to NH4+. 
D)  removal of nitro groups from organic molecules. 
E)  removal of amino groups from organic molecules. 
A)  conversion of nitrate or nitrite to N₂ by anaerobic respirers. 
B)  oxidation of NH4+ to nitrate or nitrite by lithotrophs. 
C)  conversion of N₂ to NH4+. 
D)  removal of nitro groups from organic molecules. 
E)  removal of amino groups from organic molecules.

Question 18

Based on the number of enzymes involved in its biosynthesis, which of the following is the most complex amino acid specified by the genetic code?

Accepted Answer

A)  tryptophan 
B)  tyrosine 
C)  phenylalanine 
D)  leucine 
E)  isoleucine 
A)  tryptophan 
B)  tyrosine 
C)  phenylalanine 
D)  leucine 
E)  isoleucine

Question 19

Which of the following is NOT correct about fatty acid biosynthesis?

Accepted Answer

A)  It involves successive condensations of malonyl-ACP. 
B)  A dehydratase is used to generate an unsaturated bond. 
C)  It is regulated by the stringent response of carbon starvation. 
D)  NADPH is generally involved in hydrogenation. 
E)  Many single-component enzymes are involved. 
A)  It involves successive condensations of malonyl-ACP. 
B)  A dehydratase is used to generate an unsaturated bond. 
C)  It is regulated by the stringent response of carbon starvation. 
D)  NADPH is generally involved in hydrogenation. 
E)  Many single-component enzymes are involved.

Question 20

An association between two Antarctic microorganisms is pictured below. It provides an interaction that supplies ________, made by the ________, to the ________.

Accepted Answer

A)  amino acids; diatom; bacterium 
B)  fixed nitrogen; diatom; bacterium 
C)  fixed nitrogen; bacterium; diatom 
D)  vitamin B12; diatom; bacterium 
E)  vitamin B12; bacterium; diatom 
A)  amino acids; diatom; bacterium 
B)  fixed nitrogen; diatom; bacterium 
C)  fixed nitrogen; bacterium; diatom 
D)  vitamin B12; diatom; bacterium 
E)  vitamin B12; bacterium; diatom

Exam 15: Biosynthesis

Describe how modular enzymes function in polyketide biosynthesis. Why might this be of use medically?

The catalytic site of Rubisco is located in

Which molecules use 5-phosphoribosyl-1-pyrophosphate (PRPP) in their biosynthesis?

How is fatty acid biosynthesis regulated in bacteria?

The cell diagrammed below provides an overview of some regulation of the Calvin cycle. Which of the following is NOT involved in this regulation?

Which of the following are unique in that they fix CO₂ as their sole carbon source?

The enzyme nitrogenase is inhibited by oxygen. Which of the following does NOT protect nitrogenase from oxygen?

The most ancient CO₂ fixation pathway in anaerobic phototrophic bacteria and archaea is the

It is thought that the Calvin cycle appeared after the divergence of the three domains of life. What supports this hypothesis?

Briefly discuss how carbon molecules of different sizes can be made for biosynthesis. What else is needed and how is it obtained?

Which of the following is NOT correct regarding nitrogen assimilation into biomass?

In the mechanism of nitrogen reduction, ________ directly takes the place of the H₂ in the FeMo subunit of the enzyme nitrogenase.

The enzyme that carries out this reaction shown in the diagram below is ________, and the end product is ________.

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

Rubisco catalyzes which of the following reactions?

Which of the following is NOT a tetrapyrrole?

Denitrification is the

Based on the number of enzymes involved in its biosynthesis, which of the following is the most complex amino acid specified by the genetic code?

Which of the following is NOT correct about fatty acid biosynthesis?

An association between two Antarctic microorganisms is pictured below. It provides an interaction that supplies ________, made by the ________, to the ________.

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

Filters

The enzyme that carries out this reaction shown in the diagram below is , and the end product is .

An association between two Antarctic microorganisms is pictured below. It provides an interaction that supplies , made by the , to the .