Pellet 1 contains nuclei from differential centrifugation

Steps:

• Recall differential centrifugation separates cell components by size and density, with pellet 1 at lowest speed containing largest structures: nuclei.
• Identify nuclei as site of transcription where DNA is transcribed to mRNA.
• Match function to choices: synthesis of mRNA occurs in nucleus.
• Eliminate other options based on their organelle locations.

Why C is correct:

• mRNA synthesis (transcription) happens in the nucleus, per central dogma of molecular biology.

Why the others are wrong:

• A: Digestion of organelles occurs in lysosomes, pelleted later.
• B: ATP production happens in mitochondria, pelleted at higher speeds.
• D: Protein synthesis occurs on ribosomes, in cytosolic supernatant or microsomal pellet.

Final answer: C