Question

Which of the following statements is/are true regarding the effect of the concentration of metabolic intermediates on glycolysis in erythrocytes?

• A. Increased AMP levels stimulate glycolysis
• B. Increased citrate inhibits glycolysis
• C. Increased glucose 6-phosphate inhibits glycolysis
• D. Increased fructose 1,6-bisphosphate stimulates glycolysis

Hint:

In glycolysis, key intermediates regulate the pathway to ensure that it is active when the cell needs energy and inhibited when energy is plentiful.

Answer 1

The Correct Option is A, B, D

Step 1: Understand the regulatory role of intermediates in glycolysis.

AMP (A): Increased AMP levels signal low energy in the cell, which stimulates glycolysis to produce more ATP. This is correct, as AMP is a positive allosteric regulator of phosphofructokinase-1 (PFK-1), a key enzyme in glycolysis.

Citrate (B): Increased citrate levels, indicating high energy status, inhibit glycolysis via feedback inhibition at the PFK-1 step. This is correct, as citrate is a negative allosteric regulator of PFK-1.

Glucose 6-phosphate (C): High levels of glucose 6-phosphate can inhibit hexokinase, but in erythrocytes, regulation of glycolysis mainly involves PFK-1 rather than hexokinase. Therefore, this is not a correct regulatory point in erythrocytes.

Fructose 1,6-bisphosphate (D): Increased levels of fructose 1,6-bisphosphate stimulate glycolysis by activating PFK-1. This is correct and reflects a positive feedback mechanism in glycolysis.

Step 2: Conclusion.
The correct regulatory statements related to glycolysis in erythrocytes are: (A), (B), and (D).

Final Answer:
The correct answer is \( \boxed{(A), (B), (D)} \).