MCB 3020 EXAM 2 QUESTIONS AND ANSWERS
List the laws of thermodynamic and describe their relevance in the chemical reactions -
Answers - Energy can not be created/destroyed. Total universal energy is constant.
Energy may be redistributed.
Entropy - requires energy to put molecules together.
Define the standard reduction potential. - Answers - Equilibrium constant for an
oxidation-reduction reaction. Measures the tendency of the reducing agent to lose
electrons.
Why does aerobic growth generate the highest amount of energy (ATP)? How does this
value plays a role in organization of electron transport system? - Answers - Aerobic
growth generates the highest ATP because glucose is the donor and oxygen is the
electron acceptor. These pass the electrons along during the ETS.
Compare Eo of aerobic and anaerobic respiration. - Answers - Aerobic has better/more
extremely positive and negative Eo - so better donors and acceptors.
Describe the flow of electron in fermentation and respiration. What happened to the
electron in each of the above processes? - Answers - Fermentation:
Respiration:
Describe how enzymes are involved in chemical reactions. (activation energy, lowering
Eo) - Answers - Enzymes lower activation energy b/c they lower the Eo by increasing
concentration of substrate at active site and orienting the substrates properly.
Define apoenzyme and cofactor. What is the significance of cofactors? - Answers -
Apoenzyme: protein component of enzyme
Cofactor: non-protein component of enzyme. They are either firmly attached prosthetic
groups or loosely attacked carriers/transporters around the cell called coenzymes.
How are enzymatic activities are regulated or inhibited? - Answers - Inhibition:
Competitive (direct competition with binding substrate), Noncompetitive (binds enzyme
at site other than active site to change enzyme's shape), feedback inhibition (also called
endproduct inhibition, final product slows down its producing pathway)
List/describe the effects of environmental factors on enzymatic activities. How? -
Answers - Substrate concentration, pH (affects hydrogen bond), temperature (affects
ionic bond).
Compare respiration and fermentation - Answers - Final electron acceptor: oxygen for
aerobic. Anaerobic uses NO3-, CO2, organic acceptors, fumarates. Fermentation uses
endogenous acceptors like NAD+ which must be regenerate.
, Electron donor is glucose always.
Both make ATP from ADP but respiration makes 38 from 1 glucose. Fermentation
makes 2.
Respiration has electrons pass through ETC to final acceptor and proton motive force
(PMF) is generated to make ATP. Uses oxydative phosphorylation for ATP.
Fermentation doesnt use ETC or PMF. ATP synthesized by substrate level
phosphorylation.
What are the important features of Chemoorganotrophs - Answers - derive their energy
from electrons and organic molecules.
List groups of organisms based on their energy source, carbon source and the source
of electrons - Answers -
Compare respiration and fermentation; ATP synthesis, pathways, ETS, Electron donor,
electron carriers, electron acceptors, and amount of ATP produced - Answers - Major
electron carriers = NAD, FAD, NADP
Define, describe, and explain proton gradient, proton motive force. - Answers -
Electrons are passed down ETC and protons are pumped from low to high
concentration. This creates the proton gradient. Potential energy from the proton
gradient is harnessed as the protons move across the membrane. This is the proton
motive force.
Define and list the different forms of phosphorylation. Which one is associated with
glycolysis, Krebs cycle, and electron transport system? - Answers - Substrate-level
phosphorylation creates ATP from another high-energy compound. Glycolysis and
krebs cycle.
Oxydative phosphorylation involves the creation of ATP from scratch using the proton
motive force. Electron transport system.
Define and list amphibolic pathways - Answers - Function as both catabolic and
anabolic. Include Embden-Meyerhof pathway (aka gylcolysis), pentose phosphate
pathway, and tricarboxylic acid (TCA) cycle
List and describe and compare three common routes of glucose conversion to pyruvate
- Answers - Embden-Meyerhof pathway (glycolysis):
Pentose phosphate pathway: uses a phosphate shunt, synthesizes pentose sugars and
oxidized glucose. Aerobic or anaerobic.
Entner-Doudoroff pathway: Yields 1 NADH, 1 NADPH, 1 ATP per glucose used. Rare.
List the laws of thermodynamic and describe their relevance in the chemical reactions -
Answers - Energy can not be created/destroyed. Total universal energy is constant.
Energy may be redistributed.
Entropy - requires energy to put molecules together.
Define the standard reduction potential. - Answers - Equilibrium constant for an
oxidation-reduction reaction. Measures the tendency of the reducing agent to lose
electrons.
Why does aerobic growth generate the highest amount of energy (ATP)? How does this
value plays a role in organization of electron transport system? - Answers - Aerobic
growth generates the highest ATP because glucose is the donor and oxygen is the
electron acceptor. These pass the electrons along during the ETS.
Compare Eo of aerobic and anaerobic respiration. - Answers - Aerobic has better/more
extremely positive and negative Eo - so better donors and acceptors.
Describe the flow of electron in fermentation and respiration. What happened to the
electron in each of the above processes? - Answers - Fermentation:
Respiration:
Describe how enzymes are involved in chemical reactions. (activation energy, lowering
Eo) - Answers - Enzymes lower activation energy b/c they lower the Eo by increasing
concentration of substrate at active site and orienting the substrates properly.
Define apoenzyme and cofactor. What is the significance of cofactors? - Answers -
Apoenzyme: protein component of enzyme
Cofactor: non-protein component of enzyme. They are either firmly attached prosthetic
groups or loosely attacked carriers/transporters around the cell called coenzymes.
How are enzymatic activities are regulated or inhibited? - Answers - Inhibition:
Competitive (direct competition with binding substrate), Noncompetitive (binds enzyme
at site other than active site to change enzyme's shape), feedback inhibition (also called
endproduct inhibition, final product slows down its producing pathway)
List/describe the effects of environmental factors on enzymatic activities. How? -
Answers - Substrate concentration, pH (affects hydrogen bond), temperature (affects
ionic bond).
Compare respiration and fermentation - Answers - Final electron acceptor: oxygen for
aerobic. Anaerobic uses NO3-, CO2, organic acceptors, fumarates. Fermentation uses
endogenous acceptors like NAD+ which must be regenerate.
, Electron donor is glucose always.
Both make ATP from ADP but respiration makes 38 from 1 glucose. Fermentation
makes 2.
Respiration has electrons pass through ETC to final acceptor and proton motive force
(PMF) is generated to make ATP. Uses oxydative phosphorylation for ATP.
Fermentation doesnt use ETC or PMF. ATP synthesized by substrate level
phosphorylation.
What are the important features of Chemoorganotrophs - Answers - derive their energy
from electrons and organic molecules.
List groups of organisms based on their energy source, carbon source and the source
of electrons - Answers -
Compare respiration and fermentation; ATP synthesis, pathways, ETS, Electron donor,
electron carriers, electron acceptors, and amount of ATP produced - Answers - Major
electron carriers = NAD, FAD, NADP
Define, describe, and explain proton gradient, proton motive force. - Answers -
Electrons are passed down ETC and protons are pumped from low to high
concentration. This creates the proton gradient. Potential energy from the proton
gradient is harnessed as the protons move across the membrane. This is the proton
motive force.
Define and list the different forms of phosphorylation. Which one is associated with
glycolysis, Krebs cycle, and electron transport system? - Answers - Substrate-level
phosphorylation creates ATP from another high-energy compound. Glycolysis and
krebs cycle.
Oxydative phosphorylation involves the creation of ATP from scratch using the proton
motive force. Electron transport system.
Define and list amphibolic pathways - Answers - Function as both catabolic and
anabolic. Include Embden-Meyerhof pathway (aka gylcolysis), pentose phosphate
pathway, and tricarboxylic acid (TCA) cycle
List and describe and compare three common routes of glucose conversion to pyruvate
- Answers - Embden-Meyerhof pathway (glycolysis):
Pentose phosphate pathway: uses a phosphate shunt, synthesizes pentose sugars and
oxidized glucose. Aerobic or anaerobic.
Entner-Doudoroff pathway: Yields 1 NADH, 1 NADPH, 1 ATP per glucose used. Rare.
