BIOC 431-EXAM IV QUESTIONS AND
ANSWERS
List the similarities and differences between the mitochondrial electron transport chain
and the photosynthetic electron transport chain. - Answer-*Mitochondrial ETC
Starts with NADH, ends by turning O2 into H2O.
Exists on a partially enclosed membrane
(porins)
"Downhill" scheme
Strongest redox carriers NADH and O2.
Energy stored primarily as delta psi
Has glutathione
*Photosynthetic ETC
Starts by taking electrons from H2O to make O2.
Exists on a completely enclosed membrane
(inside permeability barrier)
"Z scheme"
Strongest redox carriers chlorophyll and
activated chlorophyll.
Energy stored primarily as delta pH
Has many, diverse groups of antioxidants
*BOTH
Give five general classes of electron carriers that function in both mitochondrial
electron transfer to O2 and photosynthetic electron transfer. - Answer-Other e‐ carriers
similar
Similar electron transport chains: lipid soluble and aqueous soluble steps, 3 protein
complexes.
Both store energy across the membrane
Generates reactive oxygen species (ROS)
Some photosynthetic bacteria contain the protein bacteriorhodopsin, which absorbs light
and pumps protons out of the cell directly. Briefly describe how such a cell could use
bacteriorhodopsin and an H+ATPase to make ATP using light. - Answer-On exposure to
light, bacteriordopsin would pump protons out of the cell, establishing a proton gradient.
This proton gradient could be used by H+ ATPase to generate ATP.
During photophosphorylation in plants, electrons flow through a series of carriers in the
chloroplast. What is the ultimate donor of electrons, and what is the ultimate acceptor?
What provides the energy to move those electrons?
, Page - Answer-1) H2O
2) NADP+
3) light
Which one of the following statements about photophosphorylation is false?
A) It can be uncoupled from electron flow by agents that dissipate the proton gradient.
B) The difference in pH between the luminal and stromal side of the thylakoid
membrane is 3 pH units.
C) The luminal side of the thylakoid membrane has a higher pH than the stromal side.
D) The number of ATPs formed per oxygen molecule is about three.
E) The reaction centers, electron carriers, and ATP-forming enzymes are located in
the thylakoid membrane. - Answer-C
What is the major dietary source of N and S? - Answer-In our diets, almost all of our
nitrogen and sulfur comes from
ingested protein.
Why is it important that proteases are produced as zymogens? - Answer-So that the
proteases (which degrade proteins) do not degrade themselves. Because proteases are
produced as zymogens, they are inactive enzymes until needed.
Why are multiple proteases and low pH required for hydrolysis of dietary proteins? -
Answer-elaborate mechanism- inactive precursors protects the exocrine cells from
destructive proteolytic attack
What are other sources of proteins besides dietary? - Answer-amino acids
What types of reactions is PLP important for? How can transamination be split into two
reactions? - Answer-1) aminotransferases, also known as transaminases
2) Through extreme resonance structures, water adds across the bond, proton is added,
amino acid amine exchanged for C=O
Want more on imine hydrolysis? http://www.masterorganicchemistry.com/reaction‐
guide/imine‐hydrolysis/
What amino acids accumulate NH3 for transport? How are these amino acids related to
TCA cycle intermediates? How /where are each loaded? - Answer-Glutamate and
Glutamine
Glutamate is intermediate of TCA cycle (Glutaminase to turn glutamine into glutatmate)
What portion of the final Urea molecule are generated by Carbamoyl phosphate
synthetase I? - Answer-This will become the first amine in urea
What TCA cycle intermediate is the role of ornithine similar to? - Answer-??
Ornithine is a common amino acid not found in proteins
Ornithine transcarbamoylase does not require ATP, therefore it is a transferase
ANSWERS
List the similarities and differences between the mitochondrial electron transport chain
and the photosynthetic electron transport chain. - Answer-*Mitochondrial ETC
Starts with NADH, ends by turning O2 into H2O.
Exists on a partially enclosed membrane
(porins)
"Downhill" scheme
Strongest redox carriers NADH and O2.
Energy stored primarily as delta psi
Has glutathione
*Photosynthetic ETC
Starts by taking electrons from H2O to make O2.
Exists on a completely enclosed membrane
(inside permeability barrier)
"Z scheme"
Strongest redox carriers chlorophyll and
activated chlorophyll.
Energy stored primarily as delta pH
Has many, diverse groups of antioxidants
*BOTH
Give five general classes of electron carriers that function in both mitochondrial
electron transfer to O2 and photosynthetic electron transfer. - Answer-Other e‐ carriers
similar
Similar electron transport chains: lipid soluble and aqueous soluble steps, 3 protein
complexes.
Both store energy across the membrane
Generates reactive oxygen species (ROS)
Some photosynthetic bacteria contain the protein bacteriorhodopsin, which absorbs light
and pumps protons out of the cell directly. Briefly describe how such a cell could use
bacteriorhodopsin and an H+ATPase to make ATP using light. - Answer-On exposure to
light, bacteriordopsin would pump protons out of the cell, establishing a proton gradient.
This proton gradient could be used by H+ ATPase to generate ATP.
During photophosphorylation in plants, electrons flow through a series of carriers in the
chloroplast. What is the ultimate donor of electrons, and what is the ultimate acceptor?
What provides the energy to move those electrons?
, Page - Answer-1) H2O
2) NADP+
3) light
Which one of the following statements about photophosphorylation is false?
A) It can be uncoupled from electron flow by agents that dissipate the proton gradient.
B) The difference in pH between the luminal and stromal side of the thylakoid
membrane is 3 pH units.
C) The luminal side of the thylakoid membrane has a higher pH than the stromal side.
D) The number of ATPs formed per oxygen molecule is about three.
E) The reaction centers, electron carriers, and ATP-forming enzymes are located in
the thylakoid membrane. - Answer-C
What is the major dietary source of N and S? - Answer-In our diets, almost all of our
nitrogen and sulfur comes from
ingested protein.
Why is it important that proteases are produced as zymogens? - Answer-So that the
proteases (which degrade proteins) do not degrade themselves. Because proteases are
produced as zymogens, they are inactive enzymes until needed.
Why are multiple proteases and low pH required for hydrolysis of dietary proteins? -
Answer-elaborate mechanism- inactive precursors protects the exocrine cells from
destructive proteolytic attack
What are other sources of proteins besides dietary? - Answer-amino acids
What types of reactions is PLP important for? How can transamination be split into two
reactions? - Answer-1) aminotransferases, also known as transaminases
2) Through extreme resonance structures, water adds across the bond, proton is added,
amino acid amine exchanged for C=O
Want more on imine hydrolysis? http://www.masterorganicchemistry.com/reaction‐
guide/imine‐hydrolysis/
What amino acids accumulate NH3 for transport? How are these amino acids related to
TCA cycle intermediates? How /where are each loaded? - Answer-Glutamate and
Glutamine
Glutamate is intermediate of TCA cycle (Glutaminase to turn glutamine into glutatmate)
What portion of the final Urea molecule are generated by Carbamoyl phosphate
synthetase I? - Answer-This will become the first amine in urea
What TCA cycle intermediate is the role of ornithine similar to? - Answer-??
Ornithine is a common amino acid not found in proteins
Ornithine transcarbamoylase does not require ATP, therefore it is a transferase
