Question

In which of the following organelles are the enzyme pyruvate dehydrogenase complex and the glycolytic pathway located?

• A. Cytosol and Mitochondria
• B. Cytosol and chloroplast
• C. Golgi bodies and ER
• D. Microsomes and ribosomes

Hint:

Glycolysis needs no organelle, while the pyruvate dehydrogenase step needs the mitochondrial matrix.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept.
Cell respiration happens in stages, and each stage is carried out in a specific part of the cell.

Step 2: Key Fact.
Glycolysis, the breakdown of glucose into pyruvate, happens in the cytosol, the fluid part of the cell outside the organelles, it needs no oxygen and no membrane-bound organelle. The pyruvate dehydrogenase complex converts pyruvate into acetyl-CoA, and this step happens inside the mitochondrial matrix, right before the Krebs cycle.

Step 3: Detailed Explanation.
Together, glycolysis is located in the cytosol and the pyruvate dehydrogenase complex is located in the mitochondria, matching option 1. Option 2 wrongly places one of these in the chloroplast, but chloroplasts run photosynthesis, not glycolysis or the pyruvate dehydrogenase step. Options 3 and 4 name locations (Golgi bodies, ER, microsomes, ribosomes) used for protein and lipid processing or protein synthesis, not for glycolysis or pyruvate oxidation.

Step 4: Final Answer.
Glycolysis occurs in the cytosol, and the pyruvate dehydrogenase complex works in the mitochondria. \[ \boxed{\text{Cytosol and Mitochondria}} \]