BIO 106 Set 3

For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle.

2

How many NADH are produced by glycolysis?

2

In glycolysis there is a net gain of _____ ATP.

2

For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle

6

In glycolysis, what starts the process of glucose oxidation?

ATP

Suppose that a cell's demand for ATP suddenly exceeds its supply of ATP from cellular respiration. Which statement correctly describes how this increased demand would lead to an increased rate of ATP production?

ATP levels would fall at first, decreasing the inhibition of PFK and increasing the rate of ATP production.

How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)

Both electron transport and ATP synthesis would stop.

What are the net outputs of acetyl coa formation?

CO2, acetyl coa, and NADH (In acetyl CoA formation, pyruvate (a product of glycolysis) is oxidized to acetyl CoA, with the reduction of NAD+ to NADH and the release of one molecule of CO2.)

Which of these is NOT a product of glycolysis?

FADH2

NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons from an FADH2 molecule.

Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron dono

A substrate-level phosphorylation occurs in the Krebs cycle when _____.

GDP is phosphorylated to produce GTP

During strenuous exercise, anaerobic conditions can result if the cardiovascular system cannot supply oxygen fast enough to meet the demands of muscle cells. Assume that a muscle cell's demand for ATP under anaerobic conditions remains the same as it was under aerobic conditions. What would happen to the cell's rate of glucose utilization?

Glucose utilization would increase a lot.

What are the net inputs of glycolysis?

Glucose, NAD+ and ADP

Substrate level phosphorylation...

In substrate-level phosphorylation, an enzyme transfers a phosphate group from one molecule (an intermediate in the breakdown of glucose to pyruvate) to ADP to form ATP. This is very different from the mechanism of ATP synthesis that takes place in oxidative phosphorylation.

Under anaerobic conditions (a lack of oxygen), the conversion of pyruvate to acetyl CoA stops. Which of these statements is the correct explanation for this observation?

In the absence of oxygen, electron transport stops. NADH is no longer converted to NAD+, which is needed for the first three stages of cellular respiration.

Use your knowledge of the first three stages of cellular respiration to determine which explanation is correct. More ATP is produced per CO2 released in cyclic processes than in linear processes. It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA. Redox reactions that simultaneously produce CO2 and NADH occur only in cyclic processes. Cyclic processes, such as the citric acid cycle, require a different mechanism of ATP synthesis than linear processes, such as glycolysis.

It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.

Match each product of pyruvate metabolism with the condition under which it is produced. Fermentation in human muscle, fermentation in yeast and bacteria, aerobic oxidation

Lactate: fermentation in human muscle Ethanol: fermentation in yeast and bacteria acetyl coa: aerobic oxidation

_____ is the compound that functions as the electron acceptor in glycolysis.

NAD+

What are the net outputs of oxidative phosphorylation?

NAD+, water, and ATP (In oxidative phosphorylation, the NADH and FADH2 produced by the first three stages of cellular respiration are oxidized in the electron transport chain, reducing O2 to water and recycling NAD+ and FAD back to the first three stages of cellular respiration. The electron transport reactions supply the energy to drive most of a cell's ATP production.)

The reduced form of the electron acceptor in glycolysis is ___.

NADH (in the net reaction for glycolysis, glucose (the electron donor) is oxidized to pyruvate. The electrons removed from glucose are transferred to the electron acceptor, NAD+, creating NADH.)

During electron transport, energy from _____ is used to pump hydrogen ions into the _____.

NADH and FADH2 ... intermembrane space

Which of the following statements about the electron transport chain is true?

NADH and FADH2 donate their electrons to the chain

What are he net inputs of oxidative phosphorylation?

NADH, ADP and O2

What are the net outputs of glycolysis?

NADH, ATP and pyruvate (In glycolysis, the six-carbon sugar glucose is converted to two molecules of pyruvate (three carbons each), with the net production of 2 ATP and 2 NADH per glucose molecule. There is no O2 uptake or CO2 release in glycolysis.)

Sort the following items according to whether they are reactants or products in the anaerobic reduction of pyruvate during lactic acid fermentation. NADH NAD+ Pyruvate Lactate

Products: NAD+ and lactate Reactants: NADH and pyruvate

What are the net inputs of acetyl coa formation?

Pyruvate, NAD+ and coenzyme A

Two ATP molecules are expended in the energy investment phase of glycolysis. Why is this energy needed to begin the process of glucose catabolism?

Some energy must be invested to make the glucose molecule unstable and begin the process of catabolism.

Where does glycolysis occur?

The cytosol

On NAD+ and NADH...

The main coupling among the stages of cellular respiration is accomplished by NAD+ and NADH. In the first three stages, NAD+ accepts electrons from the oxidation of glucose, pyruvate, and acetyl CoA. The NADH produced in these redox reactions then gets oxidized during oxidative phosphorylation, regenerating the NAD+ needed for the earlier stages.

Why might adding inorganic phosphate to a reaction mixture where glycolysis is rapidly proceeding help sustain the metabolic pathway?

The metabolic intermediates of glycolysis are phosphorylated.

What job does the electron transport chain accomplish in order to drive the formation of ATP?

The proteins in the electron transport chain pump protons from the matrix of the mitochondria to the intermembrane space, thus establishing an electrochemical gradient.

Which of these enters the citric acid cycle? G3P pyruvate acetyl CoA glucose NADH + H+

acetyl coa

which of these is NOT a product of the citric acid cycle? FADH2 acetyl CoA ATP CO2 NADH + H+

acetyl coa

What are the net inputs of the citric acid cycle?

acetyl coa, nad+ and ADP

Into which molecule are all the carbon atoms in glucose ultimately incorporated during cellular respiration?

carbon dioxide

what are the net outputs of the citric acid cycle?

coenzyme A, CO2, NADH, and ATP (In the citric acid cycle, the two carbons from the acetyl group of acetyl CoA are oxidized to two molecules of CO2, while several molecules of NAD+ are reduced to NADH and one molecule of FAD is reduced to FADH2. In addition, one molecule of ATP is produced.)

Which stage of glucose metabolism produces the most ATP?

electron transport and chemiosmosis

Which process is not part of the cellular respiration pathway that produces large amounts of ATP in a cell?

fermentation

In glycolysis, the carbon containing compound that functions as the electron donor is ___.

glucose

Which molecule is metabolized in a cell to produce energy for performing work?

glucose

Which step of the cellular respiration pathway can take place in the absence of oxygen?

glycolysis

where does oxidative phosphorylation occur?

inner mitochondrial membrane

The proximate (immediate) source of energy for oxidative phosphorylation is _____.

kinetic energy that is released as hydrogen ions diffuse down their concentration gradient

Where does acetyl coa formation occur?

mitochondrial matrix

where does the citric acid (krebs) cycle occur?

mitochondrial matrix

In cellular respiration, most ATP molecules are produced by _____.

oxidative phosphorylation

When a compound donates (loses) electrons, that compound becomes ____. Such a compound is often referred to as an electron donor.

oxidized

The final electron acceptor of cellular respiration is ____

oxygen

once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called _____.

pyruvate

Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?

pyruvate, ATP, and NADH

When a compound accepts (gains) electrons, that compound becomes ____. Such a compound is often referred to as an electron acceptor.

reduced

In glycolysis, ATP molecules are produced by _____.

substrate-level phosphorylation

In the citric acid cycle, ATP molecules are produced by _____.

substrate-level phosphorylation

In mitochondrial electron transport, what is the direct role of O2?

to function as the final electron acceptor in the electron transport chain

True or false? The potential energy in an ATP molecule is derived mainly from its three phosphate groups.

true

True or false? The reactions that generate the largest amounts of ATP during cellular respiration take place in the mitochondria.

true