Question

which cellular structure is associated with eukaryotic cells but not with prokaryotic cells?
○ cell wall
○ cell membrane
○ dna
○ ribosomes
○ nucleus

Explanation:

1. Analyze each option:

• Cell wall: Some prokaryotes (e.g., bacteria) have a cell wall, and some eukaryotes (e.g., plants, fungi) also have a cell wall. So it is not unique to eukaryotes.
• Cell membrane: Both prokaryotic and eukaryotic cells have a cell membrane as it is essential for controlling the movement of substances in and out of the cell.
• DNA: Both prokaryotic and eukaryotic cells contain DNA as genetic material (prokaryotes have circular DNA in the nucleoid, eukaryotes have linear DNA in the nucleus).
• Ribosomes: Both prokaryotic and eukaryotic cells have ribosomes for protein synthesis (prokaryotic ribosomes are smaller, 70S; eukaryotic are 80S, but they are present in both).
• Nucleus: Eukaryotic cells have a true nucleus (a membrane - bound organelle that contains the genetic material), while prokaryotic cells do not have a nucleus (their genetic material is in the nucleoid region without a membrane around it).

Answer:

nucleus (the option with the text "nucleus")