MCB 3020 EXAM 2 QUESTIONS AND ANSWERS
First Law of Thermodynamics - Answers - energy can neither be created nor destroyed,
it can only be transformed or redistributed.
Total energy in universe remains constant
Second Law of Thermodynamics - Answers - entropy (disorder) in the universe is
constantly increasing
Standard reduction potential (Eo) - Answers - a measure of a reducing agent's tendency
to lose electrons
more negative Eo is better electron donor
Why does aerobic growth generate the highest amount of ATP? How does this play a
role in electron transport system - Answers - because oxygen is the terminal electron
acceptor with greatest Eo
ETC moves electrons from carriers with more negative Eo to carriers with a more
positive Eo
Compare Eo of aerobic and anaerobic respiration - Answers - aerobic is more efficient
because oxygen is terminal electron acceptor, creating the most ATP
Describe how enzymes are involved in chemical reactions - Answers - biological
catalyst that speeds up rate of reaction by lowering activation energy
Apoenzyme - Answers - protein component of the holoenzyme
Cofactor, significance? - Answers - non protein component of haloenzyme
can be prosthetic group which firmly attach to enzyme or can be loosely attached
coenzyme
How are enzymatic activities regulated or inhibited - Answers - via changes in
temperature, pH, or saturation of substrate molecule
Compare and contrast ribozymes and enzymes - Answers - ribozyme is RNA molecule
wtih catalytic activity
enzyme is a protein with catalytic activity
Allosteric Regulation VS Covalent Modification (ways to regulate enzyme activity) -
Answers - AR: small molecule binds reversibly to regulatory site away from catalytic
site, causing conformational change in enzyme, altering its activity
CM: chemical groups are added to or removed from the enzyme, affecting its activity
, Effects of environmental factors of enzymatic activities? How? - Answers - Saturation:
increases as concentration of substrate increases. at point of saturation, adding more
substrate will not increase the rate of reaction
Temperature: every enzyme has optimal temperature, any deviation decreases rate of
reaction. Increase in temp impacts H bonds and function
pH: every enzyme has optimal pH, any deviation decreases rate of reaction. change
also alters ionic properties and function
*may become denatured if temp or pH deviate too much*
Fermentation vs Respiration - Answers - F: inefficient method of producing energy,
involves only *substrate-level phosphorylation*. Yields less ATP, endogenous electron
receptor is reduced and then regenerated.
R: efficient method of producing energy that involves *oxidative phosphorylation*.
involves the oxidation of glucose and passage of electron down ETC. Energy released
is used to pump protons, creating PMF
Why does anaerobic respiration and fermentation make less ATP than aerobic? -
Answers - because fermentation relies on SLP to produce ATP and respiration
produces less ATP because it uses something other than Oxygen as the terminal
electron acceptor
Ex of eukaryotes that perform fermentation - Answers - They DO perform fermentation
ex: humans ferment lactic acid in muscles when oxygen levels are low
ex: single celled yeasts ferment ethanol
Important features of chemoorganotrophs.
Can they use the same compound as C source, energy source, and as source for
reducing power? Ex? - Answers - They are organisms that derive their energy and
electrons from organic molecules
Chemoorganoheterotrophs use same compound for all sources
Role of chemolithoautotrophs in acid mine drainage and in geochemical recycling? -
Answers - they oxidize ferrous iron to ferric iron and sulfide ions to sulfate ions. They
combine with pyrite in cole mines which leaches metals from the mines, turning river
acidic
GR: they consume such large amounts of inorganic material that they make important
contributions to the N, S, and Fe cycles
CO2 fixation means what? - Answers - process by which inorganic carbon dioxide is
converted to complex organic molecules
First Law of Thermodynamics - Answers - energy can neither be created nor destroyed,
it can only be transformed or redistributed.
Total energy in universe remains constant
Second Law of Thermodynamics - Answers - entropy (disorder) in the universe is
constantly increasing
Standard reduction potential (Eo) - Answers - a measure of a reducing agent's tendency
to lose electrons
more negative Eo is better electron donor
Why does aerobic growth generate the highest amount of ATP? How does this play a
role in electron transport system - Answers - because oxygen is the terminal electron
acceptor with greatest Eo
ETC moves electrons from carriers with more negative Eo to carriers with a more
positive Eo
Compare Eo of aerobic and anaerobic respiration - Answers - aerobic is more efficient
because oxygen is terminal electron acceptor, creating the most ATP
Describe how enzymes are involved in chemical reactions - Answers - biological
catalyst that speeds up rate of reaction by lowering activation energy
Apoenzyme - Answers - protein component of the holoenzyme
Cofactor, significance? - Answers - non protein component of haloenzyme
can be prosthetic group which firmly attach to enzyme or can be loosely attached
coenzyme
How are enzymatic activities regulated or inhibited - Answers - via changes in
temperature, pH, or saturation of substrate molecule
Compare and contrast ribozymes and enzymes - Answers - ribozyme is RNA molecule
wtih catalytic activity
enzyme is a protein with catalytic activity
Allosteric Regulation VS Covalent Modification (ways to regulate enzyme activity) -
Answers - AR: small molecule binds reversibly to regulatory site away from catalytic
site, causing conformational change in enzyme, altering its activity
CM: chemical groups are added to or removed from the enzyme, affecting its activity
, Effects of environmental factors of enzymatic activities? How? - Answers - Saturation:
increases as concentration of substrate increases. at point of saturation, adding more
substrate will not increase the rate of reaction
Temperature: every enzyme has optimal temperature, any deviation decreases rate of
reaction. Increase in temp impacts H bonds and function
pH: every enzyme has optimal pH, any deviation decreases rate of reaction. change
also alters ionic properties and function
*may become denatured if temp or pH deviate too much*
Fermentation vs Respiration - Answers - F: inefficient method of producing energy,
involves only *substrate-level phosphorylation*. Yields less ATP, endogenous electron
receptor is reduced and then regenerated.
R: efficient method of producing energy that involves *oxidative phosphorylation*.
involves the oxidation of glucose and passage of electron down ETC. Energy released
is used to pump protons, creating PMF
Why does anaerobic respiration and fermentation make less ATP than aerobic? -
Answers - because fermentation relies on SLP to produce ATP and respiration
produces less ATP because it uses something other than Oxygen as the terminal
electron acceptor
Ex of eukaryotes that perform fermentation - Answers - They DO perform fermentation
ex: humans ferment lactic acid in muscles when oxygen levels are low
ex: single celled yeasts ferment ethanol
Important features of chemoorganotrophs.
Can they use the same compound as C source, energy source, and as source for
reducing power? Ex? - Answers - They are organisms that derive their energy and
electrons from organic molecules
Chemoorganoheterotrophs use same compound for all sources
Role of chemolithoautotrophs in acid mine drainage and in geochemical recycling? -
Answers - they oxidize ferrous iron to ferric iron and sulfide ions to sulfate ions. They
combine with pyrite in cole mines which leaches metals from the mines, turning river
acidic
GR: they consume such large amounts of inorganic material that they make important
contributions to the N, S, and Fe cycles
CO2 fixation means what? - Answers - process by which inorganic carbon dioxide is
converted to complex organic molecules
