Chapter 24, Problem 24.22E

Interpretation Introduction

(a)

Interpretation:

The following equation ${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{CO}-\text{S}-\text{CoA}+\text{FAD}\to \text{\_\_\_}+\_\_\_$ is to be completed for one turn of the fatty acid spiral.

Concept introduction:

A fatty acid is a form of carboxylic acid that contains a long chain of hydrocarbon. It is the principal component of triglyceride and is used for the storage of energy in the body.

The synthesis of fatty acids takes place in the cytoplasm. The starting material of this synthesis is acetyl CoA.

Answer to Problem 24.22E

The complete reaction is shown below.

$\begin{array}{l}{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{CO}-\text{S}-\text{CoA}+\text{FAD}\to \\ \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CH}=\text{CH-CO-S-CoA}}+\underset{\_}{{\text{FADH}}_{\text{2}}}\end{array}$

Explanation of Solution

The incomplete equation is shown below.

${\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{CO}-\text{S}-\text{CoA}+\text{FAD}\to \text{\_\_\_}+\_\_\_$

It is the first step of the reaction; FAD helps to dehydrogenase the starting material. This results in the formation of a conjugated alkene. Therefore, the complete equation is shown below.

$\begin{array}{l}{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{CO}-\text{S}-\text{CoA}+\text{FAD}\to \\ \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CH}=\text{CH-CO-S-CoA}}+\underset{\_}{{\text{FADH}}_{\text{2}}}\end{array}$

Conclusion

The complete reaction is shown below.

$\begin{array}{l}{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}-\text{CO}-\text{S}-\text{CoA}+\text{FAD}\to \\ \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CH}=\text{CH-CO-S-CoA}}+\underset{\_}{{\text{FADH}}_{\text{2}}}\end{array}$

Interpretation Introduction

(b)

Interpretation:

The following equation $\text{\_\_\_}+{\text{H}}_{\text{2}}\text{O}\to \text{\_\_\_}$ is to be completed for one turn of the fatty acid spiral.

Concept introduction:

A fatty acid is a form of carboxylic acid that contains a long chain of hydrocarbon. It is the principal component of triglyceride and is used for the storage of energy in the body.

The synthesis of fatty acids takes place in the cytoplasm. The starting material of this synthesis is acetyl CoA.

Answer to Problem 24.22E

The complete reaction is shown below.

$\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CH}=\text{CH-CO-S-CoA}}+{\text{H}}_{\text{2}}\text{O}\to \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_2\text{CH}\left(\text{OH}\right){\text{CH}}_2\text{-CO-S-CoA}}$

Explanation of Solution

The incomplete equation is shown below.

$\text{\_\_\_}+{\text{H}}_{\text{2}}\text{O}\to \text{\_\_\_}$

It is the second step of the fatty acid spiral. The addition of water hydrates the conjugated alkene and forms a $\text{β-}$ hydroxy thioester. Therefore, the complete equation is shown below.

$\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CH}=\text{CH-CO-S-CoA}}+{\text{H}}_{\text{2}}\text{O}\to \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_2\text{CH}\left(\text{OH}\right){\text{CH}}_2\text{-CO-S-CoA}}$

Conclusion

The complete reaction is shown below.

$\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_{\text{2}}\text{CH}=\text{CH-CO-S-CoA}}+{\text{H}}_{\text{2}}\text{O}\to \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_2\text{CH}\left(\text{OH}\right){\text{CH}}_2\text{-CO-S-CoA}}$

Interpretation Introduction

(c)

Interpretation:

The following equation $\text{\_\_\_}+{\text{NAD}}^{+}\to \text{\_\_\_}+\text{\_\_\_}+\text{\_\_\_}$ is to be completed for one turn of the fatty acid spiral.

Concept introduction:

A fatty acid is a form of carboxylic acid that contains a long chain of hydrocarbon. It is the principal component of triglyceride and is used for the storage of energy in the body.

The synthesis of fatty acids takes place in the cytoplasm. The starting material of this synthesis is acetyl CoA.

Answer to Problem 24.22E

The complete reaction is shown below.

$\begin{array}{l}\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_2\text{CH}\left(\text{OH}\right){\text{CH}}_2\text{-CO-S-CoA}}+{\text{NAD}}^{+}\to \\ \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{COCH}}_2\text{-CO-S-CoA}}+\underset{\_}{\text{NADH}}+\underset{\_}{{\text{H}}^{+}}\end{array}$

Explanation of Solution

The incomplete equation is shown below.

$\text{\_\_\_}+{\text{NAD}}^{+}\to \text{\_\_\_}+\text{\_\_\_}+\text{\_\_\_}$

It is the third step of the fatty acid spiral. The oxidation of the $\text{β-}$ hydroxy thioester transforms the hydroxyl group into a ketone. The other products of this reaction are NADH and a hydrogen cation. Therefore, the complete equation is shown below.

$\begin{array}{l}\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_2\text{CH}\left(\text{OH}\right){\text{CH}}_2\text{-CO-S-CoA}}+{\text{NAD}}^{+}\to \\ \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{COCH}}_2\text{-CO-S-CoA}}+\underset{\_}{\text{NADH}}+\underset{\_}{{\text{H}}^{+}}\end{array}$

Conclusion

The complete reaction is shown below.

$\begin{array}{l}\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{CH}}_2\text{CH}\left(\text{OH}\right){\text{CH}}_2\text{-CO-S-CoA}}+{\text{NAD}}^{+}\to \\ \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{COCH}}_2\text{-CO-S-CoA}}+\underset{\_}{\text{NADH}}+\underset{\_}{{\text{H}}^{+}}\end{array}$

Interpretation Introduction

(d)

Interpretation:

The following equation $\text{\_\_\_}+\text{CoA}-\text{SH}\to \text{\_\_\_}+\text{\_\_\_}$ is to be completed for one turn of the fatty acid spiral.

Concept introduction:

A fatty acid is a form of carboxylic acid that contains a long chain of hydrocarbon. It is the principal component of triglyceride and is used for the storage of energy in the body.

The synthesis of fatty acids takes place in the cytoplasm. The starting material of this synthesis is acetyl CoA.

Answer to Problem 24.22E

The complete reaction is shown below.

$\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{COCH}}_2\text{-CO-S-CoA}}+\text{CoA}-\text{SH}\to \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{CO-S-CoA}}+\underset{\_}{{\text{CH}}_{\text{3}}\text{CO-S-CoA}}$

Explanation of Solution

The incomplete equation is shown below.

$\text{\_\_\_}+\text{CoA}-\text{SH}\to \text{\_\_\_}+\text{\_\_\_}$

It is the last step of the fatty acid spiral. The acetyl unit from the molecule is released as a molecule of acetyl CoA. This results in the formation of a fatty acid molecule, which is shortened by two carbon atoms. Therefore, the complete equation is shown below.

$\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{COCH}}_2\text{-CO-S-CoA}}+\text{CoA}-\text{SH}\to \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{CO-S-CoA}}+\underset{\_}{{\text{CH}}_{\text{3}}\text{CO-S-CoA}}$

Conclusion

The complete reaction is shown below.

$\underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}{\text{COCH}}_2\text{-CO-S-CoA}}+\text{CoA}-\text{SH}\to \underset{\_}{{\text{CH}}_{\text{3}}{\text{CH}}_{\text{2}}\text{CO-S-CoA}}+\underset{\_}{{\text{CH}}_{\text{3}}\text{CO-S-CoA}}$