____.) Fill in the boxes with the three metabolic stages of respiration (a-c). Indicate whether the ATP is produced by substrate-level phosphorylation or oxidative phosphorylation (d-f). Label the arrows that show the flow of electrons via NADH.

____.) a. Fill in the table below by naming the sites of the respiratory stages and filling in the appropriate inputs and outputs of each respiratory stage.

b. After completing the table, complete the following ATP tally sheet for Eukaryotic Cellular Respiration.

c. Why is there a difference in the net yield of ATP per NADH produced in glycolysis versus the net yield of ATP per NADH produced in the Kreb’s Cycle?
NADH from glycolysis produced in cytoplasm must traverse mitochondrial membrane to be oxidized in ETC and this transport of NADH into mitochondria costs 1 ATP, so the net yield is 2 ATP/NADH. NADH from Kreb's is produced in the mitochondria so there is no cost for transport and the net yield is 3 ATP/NADH
d. Explain the difference in the number of ATP’s produced in prokaryotes versus eukaryotes during aerobic respiration. Be specific as to which step and site in the cell that this occurs.
Prokaryotes have no membrane-bound organelles - ETC occurs across a membrane. NADH produced in glycolysis of prokaryotes don't have to traverse mitochondrial membrane to be oxidized in ETC so each NADH from glycolysis yields 3 ATP's.

____.) In glycolysis: C
a. acetyl CoA is formed
b. NADH is oxidized
c. glucose is split to form to molecules of pyruvate
d. acetate is joined to oxaloacetate to form citrate
e. energized electrons are passed along the electron transport chain

____.) In glycolysis, glucose is broken down into 2 pyruvate molecules. Which of these molecules has a higher free energy? Why?
glucose - it is oxidized to form 2 pyruvates and some of the energy lost by glucose has been stored in NADH

____.) During the Pre-Kreb’s reaction, pyruvate is converted into acetyl CoA.
a. What is released during this reaction?
1 molecule of carbon dioxide and 1 NADH per pyruvate
b. Does pyruvate or acetyl CoA have more free energy? Why?
pyruvate - oxidized to form acetyl CoA and and lost energy in oxidation is stored in NADH
c. In this reaction, what is being reduced? What is the reducing agent?
NAD+ is reduced and pyruvate is the reducing agent

____.) What product from the pre-Kreb’s reaction crosses into the mitochondria to become a reactant in the Kreb’s cycle?
Acetyl CoA

____.) Glucose is catabolized to pyruvate, which is then converted to acetyl CoA before entering the Kreb’s cycle. Which of the following statements is true? D
a. Acetyl CoA is in more reduced form than glucose
b. Pyruvate is more energy rich than glucose
c. Pyruvate accepts electrons from lysed glucose
d. 2 molecules of acetyl CoA have less energy than in one molecule of glucose

____.)
a. List the following in order of highest energy content to the lowest energy content.
Pyruvate
Acetyl CoA
Oxaloacetate
Glucose
glucose > pyruvate > acetyl CoA > oxaloacetate
b. Since these molecules decrease in energy as they move through the respiration steps, what gains the energy and how?
reduced molecules gain energy as well as substrate-level phosphorylation

____.) One acetyl CoA molecule would produce how many of the following?
a. carbon dioxides = 2
b. NADH = 3
c. NAD+ = 3
d. ATP = 12
e. FADH2 = 1
f. FAD = 1

____.) In the following drawing:
a. Label the compartments and membranes of the mitochondria.
b. Fill in the appropriate blanks where FADH2 and NADH are oxidized.
c. Draw the pumping of the H+ across the membrane.
d. Draw the flow of electrons through the ETC.
e. Draw the flow of the H+ required to synthesize ATP.

____.) At which protein do the electrons have the most energy?
Protein 1

____.) What is the final electron acceptor in aerobic respiration?
oxygen

____.)
a. In order for the ETC to produce ATP, an ADP must be phosphorylated. Is this reaction endothermic or exothermic?
endothermic
b. What is the driving force for this reaction?
H+ flowing from intermembrane space to matrix through ATP synthase
c. How does the mitochondrial membrane generate and maintain an H+ gradient?
pumping of H+ from matrix to intermembrane space powered by the energy generated via the oxidation of NADH and FADH2
d. Chemiosmosis is said to be the coupling mechanism for oxidative phosphorylation. What processes does it couple? (HINT: Energy liberated from exothermic reactions is utilized to drive endothermic (non-spontaneous) reactions. Thus, these reactions must be coupled together.
Chemiosmosis is the ability of a membrane to use chemical energy to pump H+ and capture energy from the H+ gradient to do work. H+ gradient couples the redox reactions of ETC to ATP synthesis.

____.) The following equations are from the aerobic respiration pathways. Circle the molecules which are being reduced and put a box around the molecule which is being oxidized. Also, label the oxidizing agent with an ‘O’ and the reducing agent with an ‘R’.

____.) For each of the following pairs, circle the molecule with the greatest free energy. What is the connection between all of the molecules which you have circled?

____.)
a. During which stage(s) and where is NADH oxidized in aerobic respiration?
ETC
b. During which stage(s) and where is FAD reduced?
Kreb's

____.) What is the final electron acceptor(s) in prokaryotic anaerobic respiration?
forms of inorganic oxygen such as nitrate, sulfate, carbonate

____.) What is the net ATP yield for one glucose molecule undergoing anaerobic respiration?
10 - 26 ATP/glucose

____.) List two basic types of fermentation. What are the end products for each of these processes?
lactic acid fermentation produces lactic acid and alcohol fermentation produces ethanol

____.)
a. What is the final electron acceptor in lactic acid fermentation?
pyruvate
b. What is the final electron acceptor in alcohol fermentation?
acetaldehyde

____.)
a. What is the net ATP yield for one glucose molecule undergoing fermentation?
2 ATP
b. Is the ATP formed in fermentation by substrate phosphorylation or by oxidative phosphorylation?
substrate-level

____.) What is the determining factor that makes pyruvate undergo fermentation or proceed into aerobic metabolism in facultative anaerobes or muscle cells in eukaryotes?
the presence or absence of oxygen

____.) Discuss the similarities and differences between aerobic respiration and fermentation.
Refer to the appropriate pages in the textbook.

____.) Although NADH and FADH2 are energy rich molecules, why must they be converted to ATP?
active transport pumps recognize ATP only, so a cell depends on oxidizing energy rich molecules like NADH and FADH2 to convert them to ATP

____.) Suppose the electron carrier NAD+ reduced to NADH in glycolysis did not later give up electrons in fermentation. What would happen to the fermentation process?
NAD+ would not be regenerated so glycolysis would not be able to run, so no pyruvate would be produced so there are no reactants for fermentation to proceed.

____.) A century ago, Louis Pasteur, the great French biochemist, investigated the metabolism of yeast, a facultative anaerobe. He observed that the yeast consumed sugar at a much faster rate under anaerobic conditions than it did under aerobic conditions. Explain this Pasteur effect, as the observation is called (Campbell, 1996).
fermentation (anaerobic) yields 2 ATP/glucose while aerobic respiration yields 36 ATP/glucose; if the yeast require the same amount of energy per unit of time, then under anaerobic conditions it needs to comsume 18 times as much glucose

____.) In the 1940’s, some physicians prescribed low doses of a drug called dinitrophenol (DNP) to help patients lost weight. This unsafe method was abandoned after a few patients died. DNP uncouples the chemiosmotic machinery by making the lipid bilayer of the inner mitochondrial membrane leaky to H+. Explain how this causes weight loss (Campbell, 1996).
H+ might not flow through ATP synthase and the H+ gradient would not be maintained so ETC would not function properly and ATP would only be generated from glycolysis. When glucose supply is exhausted, the cell would start using fats and proteins to generae energy.

____.) Sitting here reading this question, your calf muscle consumes 216 ATP/hour.
a. How much glucose must be catabolized/hr to keep up with the energy demands of your calf muscles?
(1 glucose/36 ATP)(216 ATP/hr) = 6 glucose/hr
b. How many molecules of carbon dioxide does your calf muscle produce in the two hours you are sitting in class?
(2hr)(6 glucose/hr)(6 carbon dioxide/glucose) = 72 carbon dioxide molecules
c. How many water molecules does your calf muscle produce in two hours?
(2hr)(6 glucose/hr)(6 water/glucose) = 72 water molecules
d. How many oxygen molecules does your calf muscle require in the two hours?
(2hr)(6 glucose/hr)(6 oxygen/glucose) = 72 oxygen molecules
e. When the bell rings, you sprint to your car which of course is at least one mile away (parking stinks!). About halfway to your car, your calf muscles begin to get tight and hurt. Explain what has happened during your sprint to the car.
Sprinting causes an increase in energy demands of the calf muscle so oxygen is being consumed rapidly. The tightening occurs due to oxygen depletion and thus the calf muscle is undergoing lactic acid fermentation.
f. Your house is abut 30 minutes away from campus and by the time you get home your legs feel better and you are breathing normally. Explain what has happened during your drive home.
While you rest, the demand for ATP decreases and oxygen debt is "paid off." Lactic acid is converted back to pyruvate and aerobic respiration can resume.

____.) If oxygen is reduced in the atmosphere so that it can not keep up with the energy demands of the body:
a. What happens to the production of ATP in the ETC?
production of ATP in ETC decreases
b. What happens to the concentration of citrate, an intermediate in the Kreb’s cycle?
citrate increases - if electrons cannot be accepted by oxygen in ETC, a build up of inputs occurs so intermediates of Kreb's cycle will return to the cycle
c. If the citrate concentration increases, what happens to the activity of the enzyme phosphofructose kinase, an enzyme used to catalyze a reaction early in the glycolysis pathway?
the high levels of citrate would inhibit phosphofructose kinase
d. If citrate was used to reduce the enzyme activity of phosphofructose kinase, what type of inhibitor do you think it would be? Explain.
non-competitive
e. What type of inhibition is this (refer to part d)?
negative feedback inhibition
f. What product of aerobic respiration is also responsible for the inhibition of this enzyme?
ATP

____.) What is the net ATP yield of one acetyl CoA going into the Kreb’s cycle and through the ETC?
12

____.) In aerobic metabolism NAD+ are constantly being reduced to NADH in glycolysis and the Kreb’s cycle. What is the reason we do not run out of NAD+ and FAD?
NAD+ and FAD are regenerated through the oxidation of NADH and FADH2 in the ETC.

____.) Why do scientists think glycolysis is the most ancient of metabolic processes? List at least 3 reasons.
oxygen isn't necessary, most widespread metabolic pathway, and doesn't require membrane-bound organelles

____.) Why must a comatosed quadriplegic, who cannot possibly move, need to be fed intravenously? What is the energy needed for?
60% of the energy demands of a cell are needed to drive active transport - these are needed at all times even during sleep.