BIO282 Lab 10 Notes

Which of the following does NOT store potential energy that is usable by a cell?

CO2

Artificial sweeteners taste sweet because their chemical structures often resemble that of glucose or other sugars, tricking the tongue into sending "tastes sweet" signals to the brain. However, to help a person lose weight, what else needs to be true of artificial sweeteners?

Cells would be unable to use them to make ATP. Correct! If the sweetener could not be used to make ATP, the person would have to make ATP from other foods or from stored fats. If the sweetener still made the person feel like they had a full stomach, so they don't eat as much real food overall, this could lead to the person losing weight.

Complex I transfers electrons to Q (coenzyme Q) in one of the reactions in the electron transport chain. Which molecule is reduced and which is oxidized in this reaction?

Complex I is oxidized. Q is reduced

Recall that in cellular respiration, the processes of glycolysis, pyruvate processing, and the citric acid cycle precede the electron transport chain. What is produced by these three prior processes that is used by the electron transport chain?

Each of the processed produce NADH, which carries potential energy to the ETC

Which statement about energy and ATP is correct?

Energy is released when ATP is converted to ADP plus Pi. Correct! The conversion of ATP into ADP releases stored potential energy. The ATP molecule is not transformed into energy.

What happens to the ETC when oxygen is withheld for longer and you keep trying to transfer electrons from NADH and FADH2 to the ETC?

Eventually, the ETC cannot oxidize(i.e., accept electrons from_ any additional NADH or FADH2.

Energetically, what would happen if NADH transferred electrons directly to Complex II (or later), instead of Complex I?

Fewer protons would be pumped, so less of the energy stored in NADH would be transferred to ATP. Correct! If NADH entered the ETC after Complex I, fewer protons would be pumped, and some of the energy stored in NADH would be wasted(not used to make ATP).

Which of the following would decrease the number of ATP molecules generated per NADH molecule in the electron transport chain?

Having NADH transfer its electrons to Complex III instead of Complex I.

NADH and FADH2

In cellular respiration, these two molecules serve as carriers of potential energy, via their electrons. They store less energy than glucose, but more than ATP

The antibiotic antimycin A causes electrons to become stuck to Q, so that they are unable to ever reach Complex IV. Which of the following scenarios you explored in this tutorial is MOST SIMILAR to the effects of antimycin A?

Lack of oxygen (electrons don't leave the ETC)

Suppose your classmate says, "In respiration, glucose is transformed into energy and ATP." Is this statement correct? Why?

No, because cells use the energy stored in glucose to make ATP from ADP and phosphate.

Which of the following could be an effective treatment for severe cyanide poisoning?

None of the above

Based on your results, what key role does oxygen appear to be playing in cellular respiration?

Oxygen allows the cyclist to go farther on less glucose.

O2

Oxygen is required for an organism to make maximum use of the energy in glucose.

What is the role of oxygen in the ETC?

Oxygen keeps the ETC running by removing electrons from Complex IV.

For which of the following is potential energy INCREASING?

Protons moving from the mitochondrial matrix to the intermembrane space

CO2

The carbon atoms in glucose are eventually incorporated into carbon dioxide molecules.

Suppose that an individual has a mutation where Q transfers electrons to Complex IV(instead of Complex III). How would cellular respiration be affected in this individual?

The person would still make more ATP from one NADH molecule than from one FADH2 molecule. Correct! NADH would still cause protons to be pumped by Complexes I and IV, while FADH2 would only cause protons to be pumped by Complex IV.

ATP

The ultimate product of respiration.

As ATP is created, protons are moving back into the matrix through ATP synthase. What happens to the potential energy of these protons?

Their potential energy is transferred to ATP.

Initially, when the ETC is deprived of oxygen and you attempt to transfer electrons from NADH and FADH2 to the ETC, what is the result?

There is not that much, if any, of an immediate effect.

When your body uses glucose for energy during exercise, you weigh less afterward. Why?

You weigh less because glucose is transformed into carbon dioxide and water that is lost through exhaling and sweat.

What would happen to you metabolically, if all your mitochondria were destroyed?

You would have much less ATP available to think, move muscles, etc.

Yeast have mitochondria and can perform cellular respiration. What would you expect to be consumed and produced during the process of cellular respiration in yeast?

cells transfer some of the energy stored in glucose's chemical bonds to ATP

Some students have the misconception that during cellular respiration, the matter in glucose is somehow turned into energy. Consider that when we exercise, we burn glucose and also lose mass. Why does this happen?

our cells convert glucose into CO2 and water, which is eliminated from our body during exercising