Micro 303 Exam queries and answers
well graded A+
Metabolism - ANS✅✅Sum of all biochemical reactions that occur in a cell
A syntrophic bacterium runs the following reaction: butyrate + H2O-> acetate + H+ + H2
This reaction is unfavourable (ΔG = +48.2 kJ) unless a methanogen is present that uses hydrogen.
Explain why this reaction becomes favourable. - ANS✅✅The methanogen decreases the
concentration of the H2 which decrease Keq which then makes delta G more negative and therefore
more favourable
Of the following half reactions, which has the most potential energy?
2H+ + 2e- -> H2 (meV = -420)
cytochrome c (Fe3+) + e- -> cytochrome c (Fe2+) (meV = 254)
NAD(P)+ + 2H+ +2e- -> NAD(P)H + H+ (meV = -320)
NO3- + 6H+ + 5e- -> ½N2 + H2O (meV = 740) - ANS✅✅2H+ + 2e- -> H2 (meV = -420)
More negative meV = greater potential energy
2H2+O2-> 2H2O
What is the electron potential drop in MeV?
Is the reaction favorable?
What is the potential E in kJ released?
deltaG (kj) = -nFdeltaE
F=96.485 kj/Vg
deltaE = V
,n= Greatest common factor of electrons transferred
2H+ + 2e- -> H2 (meV = -420)
O2 + 4H+ +4e- -> 2H2O (meV=815) - ANS✅✅2H+ + 2e- -> H2 (meV = 420) is reversed so meV = 420
420 + 815 = 1235 meV
-4(96.485)(1.235) = -477 kj
favorable
When yeast are used in bread making and beer making, they grow on the sugar provided to them.
The process they carry out is - ANS✅✅Aerobic and then mostly anaerobic
You carefully prepare your malt, mash it and then make a wort. Happy yeast are added to the
fermentation vessel, and it seems to proceed normally, however it gets stuck, as the alcohol
concentration stops at about 3 % (Commercial beer will be about 4 to 7% alcohol, and you were
hoping for 5%). Propose reasons you think this may happen. Be as biochemically detailed as you can.
- ANS✅✅Not enough oxygen to oxidize NADH and allow for further fermentation via alcohol
fermentation
Catabolism (4) - ANS✅✅Break down of complex substrates into simpler ones with the release of E
and reducing power.
• Breaks lipid apart at the glycerol backbone via glycolysis
• Fatty acids are broken down via B-oxidation
• Reuse Component: When possible a cell will reuse a carrier, co-factor, or enzyme
• Funneling: Cells try to reuse common pathways, common substrates will be converted to
metabolites and funneled through existing pathways
Anabolism - ANS✅✅How you synthesize biomolecules you need for life. Synthesis of complex
molecules from simpler ones and requires E and often reducing power
, How does the free energy of a reaction relate to the favorability of a reaction? - ANS✅✅An
increase in entropy (S) causes the free energy (delta G) to be more negative. As a result, this
increases the favorability of reaction.
-Catabolic reactions are favorable
How does the concentration of substrates and products affect a reaction? - ANS✅✅Le chatlier's
principle
• Increase in concentration of reactants causes delta G to become more negative which leads to a
more favorable reaction
• Also, a low concentration of product also pushes reaction forward
What is a redox reaction? Give several examples. - ANS✅✅Oxidation reduction reactions
• Harvesting energy from electron donors through electron transfers
• More negative reduction potential will donate electrons to redox reactions with more positive
potentials
• If the reaction is reversed, the sign is changed
• Example: NAD+ and FAD gain or lose electrons in the ETC
• Example: Breakdown of glucose: gets oxidized to form CO2
ATP? Role in Metabolism? - ANS✅✅ATP: energy currency of the cell, stores energy
• Involved with the breakdown of glucose via glycolysis
Product of cellular respiration and fermentation
• Able to be recycled ATP -> ADP
•After ATP is hydrolyzed, energy can be used to do work
•Energy that is stored is found in the phosphate bond
NADH? Role in Metabolism - ANS✅✅NADH: Electron carrier for metabolic processes
• Donates electrons to the ETC to make ATP
• Gets oxidized to NAD+
• One NADH helps in the formation of 3 ATP
• Mostly found in the inner matrix of mitochondria
well graded A+
Metabolism - ANS✅✅Sum of all biochemical reactions that occur in a cell
A syntrophic bacterium runs the following reaction: butyrate + H2O-> acetate + H+ + H2
This reaction is unfavourable (ΔG = +48.2 kJ) unless a methanogen is present that uses hydrogen.
Explain why this reaction becomes favourable. - ANS✅✅The methanogen decreases the
concentration of the H2 which decrease Keq which then makes delta G more negative and therefore
more favourable
Of the following half reactions, which has the most potential energy?
2H+ + 2e- -> H2 (meV = -420)
cytochrome c (Fe3+) + e- -> cytochrome c (Fe2+) (meV = 254)
NAD(P)+ + 2H+ +2e- -> NAD(P)H + H+ (meV = -320)
NO3- + 6H+ + 5e- -> ½N2 + H2O (meV = 740) - ANS✅✅2H+ + 2e- -> H2 (meV = -420)
More negative meV = greater potential energy
2H2+O2-> 2H2O
What is the electron potential drop in MeV?
Is the reaction favorable?
What is the potential E in kJ released?
deltaG (kj) = -nFdeltaE
F=96.485 kj/Vg
deltaE = V
,n= Greatest common factor of electrons transferred
2H+ + 2e- -> H2 (meV = -420)
O2 + 4H+ +4e- -> 2H2O (meV=815) - ANS✅✅2H+ + 2e- -> H2 (meV = 420) is reversed so meV = 420
420 + 815 = 1235 meV
-4(96.485)(1.235) = -477 kj
favorable
When yeast are used in bread making and beer making, they grow on the sugar provided to them.
The process they carry out is - ANS✅✅Aerobic and then mostly anaerobic
You carefully prepare your malt, mash it and then make a wort. Happy yeast are added to the
fermentation vessel, and it seems to proceed normally, however it gets stuck, as the alcohol
concentration stops at about 3 % (Commercial beer will be about 4 to 7% alcohol, and you were
hoping for 5%). Propose reasons you think this may happen. Be as biochemically detailed as you can.
- ANS✅✅Not enough oxygen to oxidize NADH and allow for further fermentation via alcohol
fermentation
Catabolism (4) - ANS✅✅Break down of complex substrates into simpler ones with the release of E
and reducing power.
• Breaks lipid apart at the glycerol backbone via glycolysis
• Fatty acids are broken down via B-oxidation
• Reuse Component: When possible a cell will reuse a carrier, co-factor, or enzyme
• Funneling: Cells try to reuse common pathways, common substrates will be converted to
metabolites and funneled through existing pathways
Anabolism - ANS✅✅How you synthesize biomolecules you need for life. Synthesis of complex
molecules from simpler ones and requires E and often reducing power
, How does the free energy of a reaction relate to the favorability of a reaction? - ANS✅✅An
increase in entropy (S) causes the free energy (delta G) to be more negative. As a result, this
increases the favorability of reaction.
-Catabolic reactions are favorable
How does the concentration of substrates and products affect a reaction? - ANS✅✅Le chatlier's
principle
• Increase in concentration of reactants causes delta G to become more negative which leads to a
more favorable reaction
• Also, a low concentration of product also pushes reaction forward
What is a redox reaction? Give several examples. - ANS✅✅Oxidation reduction reactions
• Harvesting energy from electron donors through electron transfers
• More negative reduction potential will donate electrons to redox reactions with more positive
potentials
• If the reaction is reversed, the sign is changed
• Example: NAD+ and FAD gain or lose electrons in the ETC
• Example: Breakdown of glucose: gets oxidized to form CO2
ATP? Role in Metabolism? - ANS✅✅ATP: energy currency of the cell, stores energy
• Involved with the breakdown of glucose via glycolysis
Product of cellular respiration and fermentation
• Able to be recycled ATP -> ADP
•After ATP is hydrolyzed, energy can be used to do work
•Energy that is stored is found in the phosphate bond
NADH? Role in Metabolism - ANS✅✅NADH: Electron carrier for metabolic processes
• Donates electrons to the ETC to make ATP
• Gets oxidized to NAD+
• One NADH helps in the formation of 3 ATP
• Mostly found in the inner matrix of mitochondria
