Question

which structure is unique to eukaryotic cells?
dna
cell membrane
ribosomes
nucleus

Explanation:

• DNA: Both prokaryotic and eukaryotic cells have DNA. In prokaryotes, it is usually in a circular form in the nucleoid region, while in eukaryotes, it is linear and enclosed in the nucleus. But the presence of DNA itself is not unique to eukaryotes.
• Cell membrane: All cells (prokaryotic and eukaryotic) have a cell membrane that acts as a barrier, controlling the movement of substances in and out of the cell.
• Ribosomes: Both prokaryotic and eukaryotic cells have ribosomes. Ribosomes are involved in protein synthesis. Prokaryotic ribosomes are smaller (\(70S\)) and eukaryotic ribosomes are larger (\(80S\)), but the presence of ribosomes is not unique to eukaryotes.
• Nucleus: Prokaryotic cells lack a true nucleus. Eukaryotic cells have a membrane - bound nucleus that houses the DNA. This is a key feature that distinguishes eukaryotic cells from prokaryotic cells.

Answer:

nucleus