Question

What is the purpose of hexokinase? A. Phosphorylate glucose-6-phosphate to glucose-1, 6- bisphosphate B. Phosphorylate glucose-6-phosphate to fructose-1, 6- bisphosphate C. Isomerize glucose-6-phosphate to fructose-6-phosphate D. Phosphorylate glucose to glucose-6-phosphate

Short answer

D. Phosphorylate glucose to glucose-6-phosphate

Step-by-step solution

Understand the Function of Enzymes

Enzymes are biological catalysts that speed up chemical reactions in the body without being consumed in the process. Each enzyme is specific to a particular substrate and reaction.

Identify the Substrate of Hexokinase

The substrate for hexokinase is glucose. Hexokinase is one of the first enzymes involved in glycolysis, the metabolic pathway that breaks down glucose to produce energy.

Determine the Reaction Catalyzed by Hexokinase

Hexokinase catalyzes the conversion of glucose to glucose-6-phosphate by transferring a phosphate group from ATP to glucose.

Match the Reaction to the Given Choices

Review the multiple-choice options and find the one that describes the phosphorylation of glucose to glucose-6-phosphate: A. Phosphorylate glucose-6-phosphate to glucose-1,6-bisphosphate - Incorrect B. Phosphorylate glucose-6-phosphate to fructose-1,6-bisphosphate - Incorrect C. Isomerize glucose-6-phosphate to fructose-6-phosphate - Incorrect D. Phosphorylate glucose to glucose-6-phosphate - Correct

Key concepts

enzyme specificity

Enzymes are remarkable biological molecules that act as catalysts for various biochemical reactions in living organisms. Each enzyme is highly specific, meaning it can only accelerate a particular type of reaction with a specific substrate.
This specificity is due to the unique three-dimensional structure of the enzyme, which provides an active site precisely shaped to bind to its corresponding substrate.
For hexokinase, the key substrate is glucose. The enzyme's active site binds glucose and facilitates its conversion to glucose-6-phosphate by transferring a phosphate group from ATP.
This high level of specificity ensures that the enzyme catalyzes only the intended reaction, leading to efficient regulation of metabolic pathways.
The relationship between hexokinase and glucose showcases how enzyme specificity is vital for proper cellular function. By selectively targeting glucose, hexokinase ensures that glucose is adequately processed within the cell, contributing to energy production and various biosynthetic processes.

glycolysis

Glycolysis is a fundamental metabolic pathway essential for energy production in nearly all living cells. This process breaks down one molecule of glucose into two molecules of pyruvate, generating energy in the form of ATP and NADH.
Glycolysis occurs in the cytoplasm and can function both aerobically and anaerobically.
The glycolytic pathway includes ten enzyme-catalyzed steps, beginning with glucose phosphorylation by hexokinase. This initial step is crucial because it traps glucose within the cell and prepares it for subsequent breakdown.
The conversion of glucose to glucose-6-phosphate also sets the stage for later steps in glycolysis, which collectively yield a net gain of two ATP molecules per glucose molecule.
Understanding glycolysis helps explain how cells harness and use energy from glucose, emphasizing the importance of enzymes like hexokinase in this energy-generating process.

glucose phosphorylation

Glucose phosphorylation is the process where a phosphate group is added to glucose, forming glucose-6-phosphate. This reaction is catalyzed by the enzyme hexokinase during the first step of glycolysis.
The phosphorylation of glucose is vital because it effectively traps the glucose molecule inside the cell, as glucose-6-phosphate cannot easily cross the cell membrane.
Additionally, this modification prepares glucose for further breakdown along the glycolytic pathway.
Hexokinase facilitates this reaction by transferring a phosphate group from ATP (adenosine triphosphate) to glucose.
This not only prepares glucose for subsequent metabolic reactions but also regulates glucose uptake in cells, ensuring that cells have a steady supply of glucose for energy production.
The efficiency and control provided by glucose phosphorylation highlight the importance of hexokinase in cellular metabolism and energy regulation.