Question

1 molecule of glucose on glycolysis produces (a) 2 molecule of pyruvic acid (b) 1 molecule of pyruvic acid (c) 2 molecule of \(\mathrm{CO}_{2}\) (d) 2 molecule of \(\mathrm{O}_{2}\)

Short answer

The correct answer is (a) 2 molecule of pyruvic acid. In the process of glycolysis, one molecule of glucose becomes two molecules of pyruvic acid.

Step-by-step solution

Understanding glycolysis

Glycolysis is a metabolic process that converts glucose (\(C_{6}H_{12}O_{6}\)), into pyruvate (\(C_{3}H_{4}O_{3}\)). The free energy released in this process is used to form the energy molecules ATP (adenosine triphosphate) and NADH (nicotinamide adenine dinucleotide).

Identifying the correct answer

In the process of glycolysis, one molecule of glucose is broken down into two molecules of pyruvate. Therefore, the correct answer is (a) 2 molecule of pyruvic acid. This is the product of a glucose molecule after the glycolysis process.

Key concepts

Pyruvate

Glycolysis is the first step in the breakdown of glucose to extract energy. When glucose is converted into pyruvate, it undergoes a ten-step process where various enzymes participate. During glycolysis, one molecule of glucose is split into two molecules of pyruvate. Each pyruvate molecule has three carbon atoms, which originate from the six-carbon glucose molecule.
Pyruvate plays a crucial role as it serves as a substrate for further energy-producing pathways inside cells, such as the citric acid cycle. It's important to understand that without forming pyruvate, cells would not be able to efficiently convert energy stored in glucose into usable forms.

ATP

ATP stands for adenosine triphosphate and is often referred to as the "energy currency" of the cell. During glycolysis, ATP is produced, providing immediate energy that cells use for various functions, such as muscle contractions and active transport. Glycolysis begins with an investment phase where two ATP molecules are used to break down glucose.
In the later stages of glycolysis, four ATP molecules are generated, giving a net gain of two ATP per glucose molecule. It's this production of ATP that makes glycolysis an essential part of cellular respiration, ensuring cells have a rapid source of energy to meet immediate demands. This quick supply of ATP is critical, especially in cells that have a high energy demand.

NADH

In addition to ATP, glycolysis also produces NADH, another crucial molecule in cellular metabolism. NADH stands for nicotinamide adenine dinucleotide (the reduced form) and acts as an electron carrier. As glucose is broken down into pyruvate, electrons are transferred to NAD+, converting it to NADH.
The role of NADH is significant in the process of cellular respiration as it transfers the electrons to the electron transport chain in mitochondria. This chain ultimately produces a large amount of ATP compared to glycolysis alone. Therefore, NADH not only helps in energy production but also links the processes in glycolysis to the continuation of aerobic respiration within cells. Without NADH, the efficiency of energy production in cells would diminish considerably.