9.E: Microbial Metabolism (Exercises)
- Page ID
- 146540
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\( \newcommand{\dsum}{\displaystyle\sum\limits} \)
\( \newcommand{\dint}{\displaystyle\int\limits} \)
\( \newcommand{\dlim}{\displaystyle\lim\limits} \)
\( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)
( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\id}{\mathrm{id}}\)
\( \newcommand{\Span}{\mathrm{span}}\)
\( \newcommand{\kernel}{\mathrm{null}\,}\)
\( \newcommand{\range}{\mathrm{range}\,}\)
\( \newcommand{\RealPart}{\mathrm{Re}}\)
\( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)
\( \newcommand{\Argument}{\mathrm{Arg}}\)
\( \newcommand{\norm}[1]{\| #1 \|}\)
\( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)
\( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)
\( \newcommand{\vectorA}[1]{\vec{#1}} % arrow\)
\( \newcommand{\vectorAt}[1]{\vec{\text{#1}}} % arrow\)
\( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\( \newcommand{\vectorC}[1]{\textbf{#1}} \)
\( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)
\( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)
\( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)
\( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)
\(\newcommand{\longvect}{\overrightarrow}\)
\( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)
\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)9.1: Cellular Respiration
Cellular respiration begins when electrons are transferred from NADH and FADH2—through a series of chemical reactions to a final inorganic electron acceptor (either oxygen in aerobic respiration or non-oxygen inorganic molecules in anaerobic respiration). These electron transfers take place on the inner part of the cell membrane of prokaryotic cells or in specialized protein complexes in the inner membrane of the mitochondria of eukaryotic cells.
Multiple Choice
Which is the location of electron transports systems in prokaryotes?
- the outer mitochondrial membrane
- the cytoplasm
- the inner mitochondrial membrane
- the cytoplasmic membrane
- Answer
-
D
Which is the source of the energy used to make ATP by oxidative phosphorylation?
- oxygen
- high-energy phosphate bonds
- the proton motive force
- Pi
- Answer
-
C
A cell might perform anaerobic respiration for which of the following reasons?
- It lacks glucose for degradation.
- It lacks the transition reaction to convert pyruvate to acetyl-CoA.
- It lacks Krebs cycle enzymes for processing acetyl-CoA to CO2.
- It lacks a cytochrome oxidase for passing electrons to oxygen.
- Answer
-
D
In prokaryotes, which of the following is true?
- As electrons are transferred through an ETS, H+ is pumped out of the cell.
- As electrons are transferred through an ETS, H+ is pumped into the cell.
- As protons are transferred through an ETS, electrons are pumped out of the cell.
- As protons are transferred through an ETS, electrons are pumped into the cell.
- Answer
-
A
Which of the following is not an electron carrier within an electron transport system?
- flavoprotein
- ATP synthase
- ubiquinone
- cytochrome oxidase
- Answer
-
B
Fill in the Blank
The final ETS complex used in aerobic respiration that transfers energy-depleted electrons to oxygen to form H2O is called ________.
- Answer
-
cytochrome oxidase
The passage of hydrogen ions through ________ down their electrochemical gradient harnesses the energy needed for ATP synthesis by oxidative phosphorylation.
- Answer
-
ATP synthase
True/False
All organisms that use aerobic cellular respiration have cytochrome oxidase.
- Answer
-
True
Short Answer
What is the relationship between chemiosmosis and the proton motive force?
How does oxidative phosphorylation differ from substrate-level phosphorylation?
How does the location of ATP synthase differ between prokaryotes and eukaryotes? Where do protons accumulate as a result of the ETS in each cell type?
9.2: Fermentation
Fermentation uses an organic molecule as a final electron acceptor to regenerate NAD+ from NADH so that glycolysis can continue. Fermentation does not involve an electron transport system, and no ATP is made by the fermentation process directly. Fermenters make very little ATP—only two ATP molecules per glucose molecule during glycolysis. Microbial fermentation processes have been used for the production of foods and pharmaceuticals, and for the identification of microbes.
Multiple Choice
Which of the following is the purpose of fermentation?
- to make ATP
- to make carbon molecule intermediates for anabolism
- to make NADH
- to make NAD+
- Answer
-
D
Which molecule typically serves as the final electron acceptor during fermentation?
- oxygen
- NAD+
- pyruvate
- CO2
- Answer
-
C
Which fermentation product is important for making bread rise?
- ethanol
- CO2
- lactic acid
- hydrogen gas
- Answer
-
B
Which of the following is not a commercially important fermentation product?
- ethanol
- pyruvate
- butanol
- penicillin
- Answer
-
B
Fill in the Blank
The microbe responsible for ethanol fermentation for the purpose of producing alcoholic beverages is ________.
- Answer
-
yeast (Saccharomyces cerevisiae)
________ results in the production of a mixture of fermentation products, including lactic acid, ethanol and/or acetic acid, and CO2.
- Answer
-
Heterolactic fermentation
Fermenting organisms make ATP through the process of ________.
- Answer
-
glycolysis
Matching
Match the fermentation pathway with the correct commercial product it is used to produce:
| ___acetone-butanol-ethanol fermentation | a. bread |
| ___alcohol fermentation | b. pharmaceuticals |
| ___lactic acid fermentation | c. Swiss cheese |
| ___mixed acid fermentation | d. yogurt |
| ___propionic acid fermentation | e. industrial solvents |
- Answer
-
e; 2. a; 3. d; 4. b; 5. c
Short Answer
Why are some microbes, including Streptococcus spp., unable to perform aerobic respiration, even in the presence of oxygen?
How can fermentation be used to differentiate various types of microbes?
Critical Thinking
The bacterium E. coli is capable of performing aerobic respiration, anaerobic respiration, and fermentation. When would it perform each process and why? How is ATP made in each case?
9.3: Catabolism of Lipids and Proteins
Collectively, microbes have the ability to degrade a wide variety of carbon sources besides carbohydrates, including lipids and proteins. The catabolic pathways for all of these molecules eventually connect into glycolysis and the Krebs cycle. Several types of lipids can be microbially degraded. Triglycerides are degraded by extracellular lipases, releasing fatty acids from the glycerol backbone. Phospholipids are degraded by phospholipases, releasing fatty acids and phosphorylated head groups.
Multiple Choice
Which of the following molecules is not produced during the breakdown of phospholipids?
- glucose
- glycerol
- acetyl groups
- fatty acids
- Answer
-
A
Caseinase is which type of enzyme?
- phospholipase
- lipase
- extracellular protease
- intracellular protease
- Answer
-
C
Which of the following is the first step in triglyceride degradation?
- removal of fatty acids
- β-oxidation
- breakage of fused rings
- formation of smaller peptides
- Answer
-
A
Fill in the Blank
The process by which two-carbon units are sequentially removed from fatty acids, producing acetyl-CoA, FADH2, and NADH is called ________.
- Answer
-
β-oxidation
The NADH and FADH2 produced during β-oxidation are used to make ________.
- Answer
-
ATP by oxidative phosphorylation
________ is a type of medium used to detect the production of an extracellular protease called caseinase.
- Answer
-
Skim milk agar
Short Answer
How are the products of lipid and protein degradation connected to glucose metabolism pathways?
What is the general strategy used by microbes for the degradation of macromolecules?
Critical Thinking
Do you think that β-oxidation can occur in an organism incapable of cellular respiration? Why or why not?