Question

Part A - Redox (oxidation-reduction) reactions in glycolysis

In glycolysis, as in all the stages of cellular respiration, the transfer of electrons from electron donors to electron acceptors plays a critical role in the overall conversion of the energy in foods to energy in ATP. These reactions involving electron transfers are known as oxidation-reduction, or redox, reactions.

Drag the words on the left to the appropriate blanks on the right to complete the sentences.

• 1. When a compound donates (loses) electrons, that compound becomes ________. Such a compound is often referred to as an electron donor.
• 2. When a compound accepts (gains) electrons, that compound becomes ________ . Such a compound is often referred to as an electron acceptor.
• 3. In glycolysis, the carbon-containing compound that functions as the electron donor is ________.
• 4. Once the electron donor in glycolysis gives up its electrons, it is oxidized to a compound called ________.
• 5. _________ is the compound that functions as the electron acceptor in glycolysis. 6. The reduced form of the electron acceptor in glycolysis is.

Answer 1

Concepts and reason

The concept used to solve the given problem is the knowledge of glycolysis reaction with redox reaction knowledge.

Fundamentals

Glycolysis is the metabolic pathway that involves converting hexose sugar glucose into smaller triose fragment pyruvic acid by several steps in which reduction and oxidation reaction occur.

Oxidation of any species involves the loss of electrons, while reduction involves the gain of electrons.

In glycolysis, the substrate glucose is converted into pyruvic acid by the action of several enzymes and oxidizing power $\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}$ which get reduced into the reducing power NADH.

Part 1

When any species is in its lower oxidation state and have a greater tendency to increase its oxidation state or number, then the oxidation reaction may occur.

To increase the oxidation number from the lower oxidation state to the higher oxidation state, there is a loss/ donation of electrons. The process of gaining a high oxidation state by the loss of electrons is known as oxidation. The product obtained after oxidation is the oxidized product.

Part 2

When any species is in its higher oxidation state, it tends to decrease its oxidation state or number. Then the reduction reaction may occur.

To decrease the oxidation number from the higher oxidation state to the lower oxidation state, there is again/acceptance of electrons. The process of gaining a lower oxidation state by the gain of electrons is known as reduction. The product obtained after reduction is a reduced product.

Part 3

During glycolysis, glucose acts as the substrate and undergoes several reactions to convert finally into pyruvate. This conversion involves several enzymes and oxidizing power to accomplish the glycolysis reaction.

The nutshell reaction of glycolysis is as follows:

$\mathrm{G}\mathrm{l}\mathrm{u}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{e}⟶\mathrm{o}\mathrm{x}\mathrm{i}\mathrm{d}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{P}\mathrm{y}\mathrm{r}\mathrm{u}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{e}$

As in the glycolytic pathway, glucose undergoes oxidation reaction hence the glucose here acts as the electron donor.

Part 4

During glycolysis, glucose acts as the substrate and undergoes several reactions to convert finally into pyruvate. This conversion involves several enzymes and oxidizing power to accomplish the glycolysis reaction.

The nutshell reaction of glycolysis is as follows:

$\mathrm{G}\mathrm{l}\mathrm{u}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{e}⟶\mathrm{o}\mathrm{x}\mathrm{i}\mathrm{d}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{P}\mathrm{y}\mathrm{r}\mathrm{u}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{e}$

As in the glycolytic pathway, glucose undergoes oxidation reaction hence the glucose here acts as the electron donor and result in the oxidized product pyruvate.

Part 5

During glycolysis, glucose acts as the electron donor and gets converted into pyruvate by loosing its electron.

The nutshell reaction of glycolysis is as follows:

$\mathrm{G}\mathrm{l}\mathrm{u}\mathrm{c}\mathrm{o}\mathrm{s}\mathrm{e}⟶\mathrm{o}\mathrm{x}\mathrm{i}\mathrm{d}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{P}\mathrm{y}\mathrm{r}\mathrm{u}\mathrm{v}\mathrm{a}\mathrm{t}\mathrm{e}$ + ${\mathrm{e}}^{-}$

As in the glycolytic pathway, glucose undergoes an oxidation reaction. There is oxidizing power, which itself undergoes reduction by accepting electrons released from glucose oxidation and promotes the oxidation of glucose.

The oxidizing power here in this glycolytic pathway is $\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}$ which functions as the electron acceptor and reduces itself.

The reaction involves in the reduction $\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}$ is as follows:

$\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}+{\mathrm{H}}^2\to \mathrm{N}\mathrm{A}\mathrm{D}\mathrm{H}+{\mathrm{H}}^{+}$

Part 6

During glycolysis, glucose acts as the electron donor and gets converted into pyruvate by loosing its electron.

The $\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}$ acts as oxidizing power accepts the electron get reduced itself and oxidizes other.

The oxidizing power here in this glycolytic pathway is $\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}$ which functions as the electron acceptor and reduces itself.

The reaction involves in the reduction $\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}$ is as follows:

$\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}+\mathrm{P}\mathrm{i}\to \mathrm{N}\mathrm{A}\mathrm{D}\mathrm{H}+{\mathrm{H}}^{+}$

Ans: Part 1

Part 1

Answer

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

Part 2

Part 2

Answer

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

Part 3

Part 3

Answer

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

Part 4

Part 4

Answer

Once the electron donor in glycolysis gives up its electrons, it is oxidized to a pyruvate compound.

Part 5

Part 5

Answer

The $\mathrm{N}\mathrm{A}{\mathrm{D}}^{+}$ is the compound that acts as electron acceptor in glycolysis

Part 6

Part 6

Answer

The reduced form of electron acceptor in glycolysis is $\mathrm{N}\mathrm{A}\mathrm{D}\mathrm{H}$ .