Which description correctly contrasts DNA location and organelle presence?

• A. Prokaryotes lack a nucleus and membrane-bound organelles and have circular DNA; eukaryotes have a nucleus with linear DNA and many membrane-bound organelles.
• B. Prokaryotes have a nucleus and linear DNA; eukaryotes lack a nucleus.
• C. Prokaryotes have circular DNA within a nucleus.
• D. Prokaryotes have circular DNA located in mitochondria.

Answer: (C)

DNA location and organelle presence differ between the two cell types. Prokaryotes lack a nucleus and membrane-bound organelles, and their DNA is circular and resides in the cytoplasm in a region called the nucleoid. Eukaryotes have a nucleus containing linear DNA organized into chromosomes, and they possess many membrane-bound organelles. The best description combines these ideas: prokaryotes have circular DNA in the cytoplasm and no nucleus, while eukaryotes have linear DNA in a nucleus and contain membrane-bound organelles. The description that places prokaryotic DNA inside a nucleus is inconsistent with the basic difference between these cell types.