Cellular Respiration Worksheet Key

How many carbon atoms are derived from glucose in one molecule of acetyl-CoA?

2

How many molecules of CO2 are generated by one turn of the citric acid cycle?

2

How many turns of the citric acid cycle can occur from the oxidation of one molecule of glucose?

2

How many carbon atoms are in one molecule of pyruvate? ____ How many molecules of pyruvate are made from one molecule of glucose? ____

3 and 2

How many carbon atoms are in one molecule of glucose?

6

Using the information in the above questions, how many molecules of ATP can be produced from the complete oxidation of one molecule of glucose?

Approximately 34 molecules of ATP are made from the complete oxidation of one molecule of glucose.

In which cellular compartment(s) does chemiosmosis occur? .

Chemiosmosis involves the intermembrane space and matrix

During oxidation of pyruvate, some high-energy electrons leave pyruvate. What do they make (and how much)?

Each pyruvate oxidized leads to the formation of one molecule of NADH. That's two NADH per glucose.

In which cellular compartment(s) does glycolysis occur?

Glycolysis occurs in the cytosol.

What puts electrons into the electron transport chain?

NADH and FADH2 put electrons into the electron transport chain.

How much (if any) ATP is hydrolyzed during chemiosmosis resulting from oxidation of one glucose molecule? How much (if any) ATP is made?

No ATP is hydrolyzed during chemiosmosis. Approximately 28 molecules of ATP are made: 25 from energy supplied by NADH, and 3 from energy supplied by FADH2.

How much (if any) ATP is hydrolyzed by the electron transport chain resulting from oxidation of one glucose molecule? How much (if any) ATP is made?

No ATP is hydrolyzed or made during electron transport.

How much (if any) ATP is hydrolyzed during oxidation of pyruvate derived from of one glucose molecule? How much (if any) ATP is made?

No ATP is hydrolyzed, and no ATP is produced during oxidation of pyruvate.

Thinking on a molecular level, why do we need O2 to live?

O2 is the final electron acceptor of the mitochondrial electron transport chain.

At the end of oxidation of pyruvate, where are the carbon atoms that used to be in pyruvate?

One carbon from each pyruvate ends up in CO2. The other two carbons, an acetyl group, are attached to coenzyme A to form acetyl-CoA. That's two CO2 and two acetyl- CoA per glucose.

How much (if any) ATP is hydrolyzed during the citric acid cycle resulting from oxidation of one glucose molecule? How much (if any) ATP is made?

One molecule of ATP is made per turn of the citric acid cycle. That's two ATP per glucose.

In which cellular compartment(s) does oxidation of pyruvate occur?

Pyruvate is oxidized in the matrix of mitochondria.

At the end of glycolysis, where are the carbon atoms that used to be in glucose?

The carbon atoms are divided between two molecules of pyruvate (three carbons per pyruvate molecule).

In which cellular compartment(s) does the citric acid cycle occur?

The citric acid cycle occurs in the mitochondrial matrix.

In which cellular compartment(s) does the electron transport chain occur?

The components of the mitochondrial electron transport chain are in the inner membrane, and changes occur in both the matrix and intermembrane space.

Where do the electrons end up when they leave the electron transport chain?

The electrons combine with molecular oxygen and protons to form water, H2O.

During glycolysis, some high-energy electrons leave glucose. What do they make (and how much)?

The high-energy electron that leave glucose during glycolysis end up in two molecules of NADH.

What is the main effect of moving electrons through the electron transport chain (what is created)?

The main effect of moving electrons through the electron transport chain is the creation of a proton gradient, a high concentration of protons in the intermembrane space.

Starting from pyruvate, neither lactic acid fermentation nor alcoholic fermentation produce any ATP. The cells cannot use lactic acid or alcohol as a carbon source (i.e., they are waste products), and potentially valuable high-energy electrons in NADH are lost in the process. What, then, is the point of performing fermentation?

The point of fermentation, whether it produces alcohol or lactic acid, is to produce more NAD+ from oxidation of NADH. Without NAD+, glycolysis cannot occur.

During the citric acid cycle, some high-energy electrons leave. What do they make (and how much)?

Three molecules of NADH and one molecule of FADH2 are made per turn of the citric acid cycle. That means six NADH and two FADH2 are made per glucose.

How much (if any) ATP is hydrolyzed during glycolysis of one glucose molecule? How much (if any) ATP is made?

Two molecules of ATP are hydrolyzed during glycolysis, and four molecules of ATP are produced. That's a net gain of two molecules of ATP per glucose molecule.

Why do we need oxygen?

it is the final electron acceptor of the electron mitochondrial electron transport chain