Question 1

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 2

How does the reductive or reverse TCA cycle differ from the regular TCA cycle?

Accepted Answer

Most of the individual reactions of the

Question 3

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

Question 4

Which pair is NOT matched correctly?

Accepted Answer

A)  NtrC-regulates nitrogenase gene expression in response to NH4+ concentration 
B)  NtrB-phosphorylates NtrC when NH4+ concentration is low 
C)  NifL-forms a two-component signal transduction system with NtrC 
D)  NifA-acts in concert with factor σ -54 
E)  NifHDKTY-components of nitrogenase 
A)  NtrC-regulates nitrogenase gene expression in response to NH4+ concentration 
B)  NtrB-phosphorylates NtrC when NH4+ concentration is low 
C)  NifL-forms a two-component signal transduction system with NtrC 
D)  NifA-acts in concert with factor σ -54 
E)  NifHDKTY-components of nitrogenase

Question 5

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 6

What are nonribosomal peptide antibiotics? How are they synthesized?

Accepted Answer

Some microorganisms synthesize a large n

Question 7

The bacterial enzyme nitrogenase performs the reduction of N₂ gas using a large amount of energy and reducing power. Describe the nitrogen reduction steps during nitrogenase activity and write the overall reaction.

Accepted Answer

Nitrogenase catalyzes four reduction cyc

Question 8

Why do most fatty acids contain an even number of carbon atoms?

Accepted Answer

A)  The priming reaction involves condensation of the acetyl-CoA with ACP. 
B)  A C3-intermediate (malonyl-Co
A)  is carboxylated during chain elongation to yield an even number of carbons. 
C)  Fatty acid biosynthesis incorporates succinyl-CoA. 
D)  Fatty acids do not have an even number of carbons. 
E)  It is now easier to add double bonds. 
A)  The priming reaction involves condensation of the acetyl-CoA with ACP. 
B)  A C3-intermediate (malonyl-Co
A)  is carboxylated during chain elongation to yield an even number of carbons. 
C)  Fatty acid biosynthesis incorporates succinyl-CoA. 
D)  Fatty acids do not have an even number of carbons. 
E)  It is now easier to add double bonds.

Question 9

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 10

What techniques and technical advances allowed Melvin Calvin to study carbon fixation? Why did he choose the unicellular alga Chlorella?

Accepted Answer

Melvin Calvin and his group used ¹⁴C, wh

Question 11

Rubisco catalyzes which of the following reactions?
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

Accepted Answer

The answer of Rubisco catalyzes which of the following reactions?
a....

Question 12

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 13

What technique was used to demonstrate that gene expression of the CO₂-concentrating mechanism (CCM) transporters is induced by low levels of CO₂? Briefly explain the basis of the technique.

Accepted Answer

The technique used was reverse transcrip

Question 14

Which technique did Melvin Calvin use to elucidate the intermediates of phototrophic carbon fixation in the chloroplasts of Chlorella?

Accepted Answer

A)  HPLC 
B)  gel electrophoresis 
C)  paper chromatography 
D)  column chromatography 
E)  mass spectroscopy 
A)  HPLC 
B)  gel electrophoresis 
C)  paper chromatography 
D)  column chromatography 
E)  mass spectroscopy

Question 15

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 16

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 17

Which of the following molecules links glycolysis with the TCA cycle, and also serves as a precursor for many biosynthetic products?

Accepted Answer

A)  malate 
B)  citrate 
C)  oxaloacetate 
D)  acetyl-CoA 
E)  succinate 
A)  malate 
B)  citrate 
C)  oxaloacetate 
D)  acetyl-CoA 
E)  succinate

Question 18

Which of the following molecules provides a way to simultaneously assimilate one carbon atom and one nitrogen atom during purine biosynthesis?

Accepted Answer

A)  acetyl-CoA 
B)  acetyl-ACP 
C)  malonyl-ACP 
D)  carbamoyl phosphate 
E)  NADPH 
A)  acetyl-CoA 
B)  acetyl-ACP 
C)  malonyl-ACP 
D)  carbamoyl phosphate 
E)  NADPH

Question 19

How many turns of the Calvin cycle does it take to provide one molecule of glyceraldehyde-3-phosphate into the biosynthesis of glucose?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  6 
E)  5 
A)  1 
B)  2 
C)  3 
D)  6 
E)  5

Question 20

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.

Exam 15: Biosynthesis

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

How does the reductive or reverse TCA cycle differ from the regular TCA cycle?

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?

Which pair is NOT matched correctly?

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?

What are nonribosomal peptide antibiotics? How are they synthesized?

The bacterial enzyme nitrogenase performs the reduction of N₂ gas using a large amount of energy and reducing power. Describe the nitrogen reduction steps during nitrogenase activity and write the overall reaction.

Why do most fatty acids contain an even number of carbon atoms?

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

What techniques and technical advances allowed Melvin Calvin to study carbon fixation? Why did he choose the unicellular alga Chlorella?

Industrial nitrogen fixation is achieved through the Haber process

What technique was used to demonstrate that gene expression of the CO₂-concentrating mechanism (CCM) transporters is induced by low levels of CO₂? Briefly explain the basis of the technique.

Which technique did Melvin Calvin use to elucidate the intermediates of phototrophic carbon fixation in the chloroplasts of Chlorella?

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

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

Which of the following molecules links glycolysis with the TCA cycle, and also serves as a precursor for many biosynthetic products?

Which of the following molecules provides a way to simultaneously assimilate one carbon atom and one nitrogen atom during purine biosynthesis?

How many turns of the Calvin cycle does it take to provide one molecule of glyceraldehyde-3-phosphate into the biosynthesis of glucose?

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

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