Acetyl CoA is the key intermediate between the Krebs cycle of glycolysis. After glycolysis, the glucose converts to pyruvic acid which is a three-carbon molecule. It is converted into acetyl coenzyme a by oxidative decarboxylation This, Acetyl CoA enters the Krebs cycle and along with oxaloacetic acid forms the citric acid which is a 6C compound.

The key intermediate compound linking glycolysis to the Krebs cycle is Acetyl CoA.

Glycolysis is the initial step in the breakdown of glucose, where glucose is converted into two molecules of pyruvate. This process occurs in the cytoplasm and generates a small amount of ATP and NADH.

The next step is the conversion of pyruvate into Acetyl CoA, which takes place in the mitochondria. This process is known as pyruvate oxidation.

Here is a detailed explanation of the conversion of pyruvate to Acetyl CoA and its role in linking glycolysis to the Krebs cycle:

1. Pyruvate Decarboxylation:
- Pyruvate produced from glycolysis enters the mitochondrial matrix.
- It undergoes a series of enzymatic reactions known as pyruvate decarboxylation.
- During this process, pyruvate loses a carbon dioxide molecule, and the remaining two-carbon molecule combines with coenzyme A (CoA) to form Acetyl CoA.
- This reaction is catalyzed by the enzyme pyruvate dehydrogenase complex.

2. Linking Glycolysis to the Krebs Cycle:
- Acetyl CoA is a key intermediate that connects glycolysis to the Krebs cycle.
- Acetyl CoA enters the Krebs cycle by combining with a four-carbon molecule called oxaloacetate.
- This combination forms a six-carbon molecule called citrate, which initiates the Krebs cycle.
- The Krebs cycle, also known as the citric acid cycle or the tricarboxylic acid (TCA) cycle, is a series of enzymatic reactions that generate energy in the form of ATP and reduce electron carriers such as NADH and FADH2.

3. Role of Acetyl CoA:
- Acetyl CoA serves as the fuel for the Krebs cycle.
- It provides the acetyl group necessary for the condensation reaction with oxaloacetate, initiating the Krebs cycle.
- Acetyl CoA is also an important molecule in other metabolic pathways, such as fatty acid synthesis.

In conclusion, Acetyl CoA is the key intermediate compound that links glycolysis to the Krebs cycle. It is formed through the conversion of pyruvate in the mitochondria and serves as the entry molecule for the Krebs cycle, providing the acetyl group necessary for its initiation.