Unit 1 Review
What is the fold difference in [H+] between pH 5 and pH 7?
A) 2
B) 1000
C) 100
D) 10
C) pH 5 is 100 times the concentration of H+ ions
Remember pH = - log [H+]
Which of the following enzymes in involved in both glycolysis and gluconeogenesis?
A) Hexokinase
B) PEP carboxykinase
C) Glucose-6-phosphatase
D) Triosephosphate isomerase
D) Triosephosphate isomerase
Which statement regarding the citric acid cycle is FALSE?
A) Its role is strictly limited to energy conservation during the catabolism of the acetyl group.
B) provides reducing equivalents under aerobic condition
C) provides intermediates for biosynthesis
D) uses most of the oxygen required under aerobic conditions.
A) Its role is strictly limited to energy conservation during the catabolism of the acetyl group.
AND
D) uses most of the oxygen required under aerobic conditions.
ARE FALSE --> If you got one of these you get points, If you got both you get double points
Other true statements
Part of the chemical logic behind it involves the conversion of the relatively unreactive methyl group of acetyl-CoA to a more reactive methylene group.
The carbon atoms that feed into the cycle as acetyl-CoA do not leave as CO2 during their first turn in the cycle.
It is found in the mitochondria of eukaryotes.
it operates in different directions under aerobic and aerobic conditions.
Which statement(s) is/are correct about Rubisco?
A) Uses CO2 as a substrate
B) Uses Ribulose1,5P2 as a substrate
C) Does not require input of energy
D) Is the most abundant protein on Earth
All are true, if you said more than 1 of these, you get additional points. (per correct answer)
A) Uses CO2 as a substrate
B) Uses Ribulose1,5P2 as a substrate
C) Does not require input of energy
D) Is the most abundant protein on Earth
Which of your TAs is the youngest (Y)? The oldest (O)?
A) Y-Bri O-Chris
B) Y-Chris O-Jacob
C) Y-Chris O-Marian
D) Y-Marian O-Bri
C) Y-Chris O-Marian
Which statement is true about hemoglobin and myoglobin binding carbon monoxide (C≡O) and molecular oxygen (O=O)?
A) Both oxygen and carbon monoxide bind equally tightly to the heme part of
these proteins.
B) If it were not for the protein moiety of hemoglobin and myoglobin, C≡O would be more toxic to humans because binding would be even tighter
C) Oxygen fits much better into the hydrophobic binding site of hemoglobin
and myoglobin.
D) C≡O only binds to the heme tightly when its partial pressure (concentration) in the air is higher than that of oxygen
B) If it were not for the protein moiety of hemoglobin and myoglobin, C≡O would be more toxic to humans because binding would be even tighter
Which of the following are differences between the isoforms of hexokinase I-IV.
A) Hexokinase IV has a high Km for glucose
B) Hexokinase I-III is found in the liver
C) Hexokinase I-III are inhibited by glu-6-P
D) Hexokinase IV is essentially unregulated in the liver
A) Hexokinase IV has a high Km for glucose
AND
C) Hexokinase I-III are inhibited by glu-6-P
if you guessed either of these you get points
Hexokinase I-III: Found in muscle, Low Km for glucose, product inhibited by glu-6-P (important to trap Glu in cells)
Hexokinase IV: Found in liver, regulated by sequestration, High Km for glucose, not product inhibited by glu-6-P (liver has Glu-6-phosphatase)'
Note: Differences in catalytic activity and cell location is one reason why isoenzymes are so important for metabolism
The glycosylase activity of debranching enzyme in the muscle acts on which bond?
A) β1-4 glycosidic bond
B) β1-6 glycosidic bond
C) α1-6 glycosidic bond
D) α1-4 glycosidic bond
C) α1-6 glycosidic bond
Which of the following combinations is the correct ultimate electron acceptor of ETC and product of OXPHOS?
A) CO2 and Water
B) O2 and Water
C) O2 and Sugar
D) CO2 and Sugar
B) O2 and Water
Which of your TAs are now doctors? (Select all that you think are true)
A) Jacob
B) Bri
C) Chris
D) Marian
A) Jacob
AND
B) Bri
What is the pI of this protein (Ser – Phe – Arg – Gly – Ala - Pro) as well as its net charge at pH 4.0
A) pI = ~5.6 Net Charge @ pH 4 = 0
B) pI = ~7.2 Net Charge @ pH 4 = +1
C) pI = ~5.6 Net Charge @ pH 4 = +1
D) pI = ~10.8 Net Charge @ pH 4 = 0
C) pI = ~5.6 Net Charge @ pH 4 = +1
3 pKas: Ser-N = 9.15, Arg-R = 12.48, Pro-C = 1.99
pI = pKa1 + pKa2 / 2 -- the pKa you choose are the ones that are immediately above and below the pH where net charge = 0 (remember that pI = net charge of zero)
1.99 + 9.15 / 2 = ~5.57
To determine the net charge you need to determine the pKas of the dissociable groups in the peptide and then compare pH to pKa. pH<pKa = Acid form, pH>pKa = Base form, pH=pKa = 50:50 acid:base
pH 4 < pKa Ser-N and Arg-R so +2
pH > pKa Pro-C = -1
+2 + (-1) = +1
How would the following impact membrane fluidity: increasing the degree of unsaturation within a fatty acid tail within the membrane?
A) Decrease fluidity, because they do not pack well into membrane making it less rigid
B) Increase fluidity, because they do not pack better into membrane making it less rigid
C) Decrease fluidity, because they pack better into membrane making it more rigid
D) Increase fluidity, because they pack better into membrane making it more rigid
B) Increase fluidity, because they do not pack well into membrane making it less rigid
Glucagon is an activator of ___ in the _________:
A) Glycogen phosphorylase / muscle
B) Glycogen synthase/ muscle
C) Glycogen phosphorylase / liver
D) Glycogen synthase /liver
C) Glycogen phosphorylase / liver
Which of the following combination has both the source of the carbon in the sugar that is produced by photosynthetic organisms during photosynthesis and the correct electron donor for photosynthetic electron transport?
A) Carbon dioxide AND Water
B) Water AND Water
C) Carbon dioxide AND Rubisco
D) Water AND Rubisco
A) Carbon dioxide AND Water
Note: The oxygen produced in photosynthesis comes from water
What was your TAs favorite unit to teach?
A) Unit 1
B) Unit 2
C) Unit 3
D) Unit 4
ALL ANSWERS GET POINTS - You all make it more enjoyable by engaging with us and with the material but we also like all the BIOCHEMISTRY we cover in this class too.
A) Unit 1
B) Unit 2
C) Unit 3
D) Unit 4
Enzymes are added to an unfavorable reaction in a cell, which of the following statements are true regarding the role of this enzyme and how unfavorable reactions can occur in a cell?
A) Enzyme speeds up reaction so that it becomes favorable in the cell (i.e. negative delta G)
B) Enzymatic regulation keeps the cellular reaction running at close to equilibrium even when substrate concentration is normally higher than product concentration at equilibrium
C) Speeds up reaction even though the reaction remains unfavorable so other means such as reaction coupling or keeping the substrate concentrations low can then also be used by cells to promote the progression of this reaction in cells
D) Speeds up reaction even though the reaction remains unfavorable so other means such as reaction coupling or keeping the product concentrations low can then also be used by cells to promote the progression of this reaction in cells
D) Enzyme speeds up reaction even though the reaction remains unfavorable so other means such as reaction coupling or keeping the product concentrations low are also needed to promote the progression of this reaction in cells
Remember that enzymes primarily function to speed up reactions, largely through reducing activation energy. However, this does not impact concentrations of substrate and product at equilibrium and will not influence overall delta G. Also, keep in mind that when comparing [substrate] and [product] how this influence delta G will only be swayed at equilibrium conditions (and enzymes don't impact equilibrium concentrations.) (i.e., also Q does not equate to equilibrium conditions). While enzymatic activity can be regulated, this typically helps us to understand there kinetics rather than their thermodynamics. Lastly, the two major ways the ΔG of an unfavorable reaction can be made favorable (i.e., occur) under cellular conditions is to (1) Couple a reaction with the hydrolysis of ATP, a very exergonic reaction. or (2) Create an environment such that Q is very low (i.e. the concentration of products is much lower than the concentration of substrates)
If cells were unable to efficiently remove Fructose-2,6-BP from the cell, what effect might this have on the cell?
A) An increase in Fru-2,6-BP will increase flux through glycolysis and decrease flux through gluconeogenesis
B) An increase in Fru-2,6-BP will not impact metabolic flux at all
C) An increase in Fru-2,6-BP will increase flux through gluconeogenesis and decrease flux through glycolysis
D) Changes in metabolic flux in this condition might cause cell to rely on energy production through anaerobic processes
A) An increase in Fru-2,6-BP will increase flux through glycolysis and decrease flux through gluconeogenesis
AND
If you said D IN ADDITION TO A, you get DOUBLE POINTS
D) Changes in metabolic flux in this condition might cause cell to rely on energy production through anaerobic processes
--> May not actually happen, but in theory it could be possible
The Malate dehydrogenase reaction is has a ∆G⁰’ = +23.7 kJ/mol. while the citrate synthase reaction of has a ∆G⁰’ = -32.2 kJ/mol. What does this tell us about the coordination of the TCA cycle?
A) Malate dehydrogenase reaction is coupled to citrate synthase reaction and since the citrate synthase reaction is very favorable, this pulls the Malate dehydrogenase reaction toward the right.
B) Malate dehydrogenase reaction is followed by the citrate synthase reaction in the cell
C) In the cell [Oxaloacetate] must very low, while [citrate] is relatively high
D) Oxaloacetate is an important gluconeogenic precursor and is a metabolite that can be shuttled into or out of the TCA cycle
ALL ARE CORRECT -- If you did not raise all cards, unfortunately, you do not get points.
A) Malate dehydrogenase reaction is coupled to citrate synthase reaction and since the citrate synthase reaction is very favorable, this pulls the Malate dehydrogenase reaction toward the right.
B) Malate dehydrogenase reaction is followed by the citrate synthase reaction in the cell
C) In the cell [Oxaloacetate] must very low, while [citrate] is relatively high
D) Oxaloacetate is an important gluconeogenic precursor and is a metabolite that can be shuttled into or out of the TCA cycle
How would ATP production and Oxygen consumption change in the presence of the following inhibitors: (1) Inhibitor of Complex I and (2) Inhibitor of Complex III?
A) Both decrease to essentially zero because there is now no proton gradient, in either case this could be lethal
B) Both decrease but inhibition of complex III will be more severe than inhibition of complex I because complex III will prevent all proton flow from both NADH and FADH2 whereas complex I inhibition only impacts flow from FADH2
C) In either case cells will likely become hypoxic due to lack of useable oxygen
D) Both decrease but inhibition of complex III will be more severe than inhibition of complex I because complex III will prevent all proton flow from both NADH and FADH2 whereas complex I inhibition only impacts flow from NADH
C) In either case cells will likely become hypoxic due to lack of useable oxygen
AND
D) Both decrease but inhibition of complex III will be more severe than inhibition of complex I because complex III will prevent all proton flow from both NADH and FADH2 whereas complex I inhibition only impacts flow from NADH
NEED BOTH TO GET POINTS HERE
Raise your hand if you went to at least 1 TAs offices hours this semester.
A) How many people in your group raised your hand?
B) Keep your hand raised if you go to multiple TAs office hours?
C) Keep your hand raised if you regularly go to multiple TAs office hours? (i.e. at least 2 weeks for each unit)
D) Now everyone put your hands down, raise your hands if you found what your TAs offered helpful for this class (ex. in office hours, in recitation, etc..) - no need to specify what you thought was helpful
A) If no one in your group raised your hand, you do not get points for this question. If at least one person in your group raised your hand for this question, you get points for this question.
B) If no one in your group raised your hand, you do not get points for this question. If at least one person in your group keeps their hands raised for this question, you get another set of points for this question.
C) If no one in your group raised your hand, you do not get points for this question. If at least one person in your group keeps their hands raised for this question, you get another set of points for this question.
D) If no one in your group raised your hand, you do not get points for this question. If at least one person in your group has their hands raised for this question, you get another set of points for this question.
The reaction that converts NADP+ to NADPH is a highly unfavorable reaction (ΔG°’= 220 kJ/mol). What is the half-equation for this reaction and what provides the energy for the reaction to occur?
A) NADP+ + 2 e- + 2 H+ --> NADPH + H+ AND the sun
B) NADP+ --> NADPH + 2 e- + 2 H+ AND the electron transport chain
C) NADP+ + 2 e- -> NADPH + H+ AND the sun
D) NADP+ + 2 e- + 2 H+ --> NADPH + H+ AND the electron transport chain
A) NADP+ + 2 e- + 2 H+ --> NADPH + H+ AND the sun
Which of the following explains the importance of the Cori cycle.
A) The Cori Cycle is important to move liver lactate to the muscle because liver needs to lose lactate to undergo gluconeogenesis
B) The Cori Cycle is important to move muscle lactate to the liver because liver needs lactate to undergo gluconeogenesis
C) Lactate dehydrogenase is typically reversible in the muscle but not in the liver
D) Lactate dehydrogenase is typically reversible in the liver but not in the muscle
B) The Cori Cycle is important to move muscle lactate to the liver because liver needs lactate to undergo gluconeogenesis
AND
D) Lactate dehydrogenase is typically reversible in the liver but not in the muscle
--> Lactate is a metabolic dead-end in the muscle
BOTH ARE NEEDED TO GET POINTS HERE
If the pyruvate dehydrogenase complex is inactivated, what will be the effect on:
Lactate production, mitochondrial matrix pH, and citrate production?
A) Increase, increase, decrease
B) increase, decrease, decrease
C) Increase, decrease, increase
D) Decrease, increase, decrease
B) increase, decrease, decrease
Pyruvate + NAD + + CoA → Acetyl-CoA + NADH + CO2 (pyruvate dehydrogenase complex reaction)
Note: changes in pyruvate, acetyl-CoA, and citrate levels will regulate the activities of other metabolic enzymes.
One person in the class gets to answer... so choose wisely.
The same uncoupler is introduced to both chloroplasts and mitochondria, how would you describe its effect?
Another person in the class gets to answer... so choose wisely.
Why are herbicides good to use on plants while simultaneously being relatively unproblematic for animals?
The uncoupler would probably impact the membranes of both organelles similarly. It is likely to be able to move across both membranes equally well. --> If you got this correct everyone gets the points. AND the group who volunteered to answer gets DOUBLE POINTS.
Remember that proteins have specificities and there are differences between the structure and function of plant and animal proteins that dictate how they interact with drugs/chemicals like herbicides. Targeting one specifically will only impact the one that is targeted. --> If you got this correct everyone gets the points. AND the group who volunteered to answer gets DOUBLE POINTS.
Raise your hand if you have already filled out the course evaluation.
If no one in your group raised your hand, you do not get points for this question.
If at least one person in your group raised your hand for this question, you get points for this question.