Conversion of glucose 6-P requires ATP. Yet critically ill patients are given glucose solution intravenously instead of glucose 6-P. The reason for not giving glucose 6-P directly is

Options

A. Glucose 6-P is degraded very fast in the blood before it enters the cells
B. Commercial preparation of glucose 6-P is always contaminated with toxic chemicals
C. High cost of glucose 6-P
D. Cells cannot take up glucose 6-P.

Answer

To understand why critically ill patients are given glucose solution intravenously instead of glucose 6-phosphate, we can break down the reasoning into several steps:

### Step 1: Understanding Glucose and Glucose 6-Phosphate
- **Glucose** is a simple sugar that serves as a primary energy source for the body.
- **Glucose 6-Phosphate (G6P)** is a phosphorylated form of glucose that is produced when glucose is phosphorylated, which is a process that requires ATP (adenosine triphosphate).

### Step 2: The Role of ATP
- The conversion of glucose to glucose 6-phosphate requires ATP. This means that if we were to administer glucose 6-phosphate directly, it would not provide an immediate source of energy since ATP is needed for its formation.

### Step 3: Cellular Uptake of Glucose vs. Glucose 6-Phosphate
- Cells can easily take up glucose through specific transporters present in the cell membrane.
- However, glucose 6-phosphate cannot enter cells directly because it is charged due to the phosphate group, which prevents it from passing through the lipid bilayer of the cell membrane.

### Step 4: Implications for Critically Ill Patients
- In critically ill patients, there is a need for an immediate and readily available source of energy. Administering glucose allows for rapid uptake into cells, where it can then be phosphorylated to glucose 6-phosphate and utilized for energy production.

### Step 5: Conclusion
- Therefore, glucose is given intravenously instead of glucose 6-phosphate because cells cannot take up glucose 6-phosphate directly, making glucose a more effective option for providing energy to critically ill patients.

### Final Answer
The reason for not giving glucose 6-phosphate directly to critically ill patients is that **cells cannot take up glucose 6-phosphate directly**.

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