Glycolysis Process Overview

Study Notes

Glycolysis: Breaking Down Glucose

Glycolysis is a fundamental process of cellular respiration where cells break down glucose molecules into simpler compounds through a series of chemical reactions. In this process, one glucose molecule is split into two three-carbon fragments called pyruvate via a ten-step pathway. Let's delve deeper into each step of glycolysis.

Step 1: Phosphorylation of Glucose

The first step involves the addition of a phosphate group to glucose by enzyme hexokinase or glucokinase. This produces glucose-6-phosphate in animals or plants respectively.

Step 2: Isomerization

Glucose-6-phosphate is converted into fructose-6-phosphate using the enzyme phosphofructokinase.

Step 3: Second Phosphorylation

Fructose-6-phosphate undergoes another phosphorylation reaction to form fructose-1,6-bisphosphate with the help of kinase enzymes ATP Citrate Lyase and Fructose Biphosphatase.

Step 4: Splitting the Sugar

Fructose-1,6-bisphosphate splits into two three-carbon fragments called glyceraldehyde-3-phosphate and dihydroxyacetone phosphate, which go through more steps before being converted back into glyceraldehyde-3-phosphate.

Step 5: Third Phosphorylation

Glyceraldehyde-3-phosphate goes through another phosphorylation process to form 1,3-bisphosphoglycerate, using enzyme aldolase.

Step 6: Removal of Two Phosphates

Enzyme triose kinase removes two phosphates from 1,3-bisphosphoglycerate, forming glyceraldehyde-3-phosphate again and releasing a high energy compound, inorganic phosphate.

Steps 7-10: Generation of More Energy

In these final four steps, more energy compounds like ATP are generated.

By the end of glycolysis, two ATP molecules have been consumed, and four ATP molecules have been produced, resulting in a net gain of two ATP molecules per glucose molecule. Additionally, glycolysis also generates reduced nicotinamide adenine dinucleotide (NADH), which plays an important role in generating more ATP through cellular respiration.

Overall, glycolysis is essential for energy production in all living organisms, converting glucose into usable energy in the form of ATP while simultaneously producing NADH, which can be used in further stages of cellular respiration for additional energy generation.