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Cell BiologyHighereukaryotic cellsprokaryotic cellscell structure

AQA GCSE · Question 05.2 · Cell Biology

Figure 7 shows the malarial protist. The malarial protist is a eukaryotic cell. Describe three ways the structure of the malarial protist is different from the structure of a prokaryotic cell. Do not refer to size in your answer.

How to approach this question

Recall the key structural differences between eukaryotic cells (like protists, fungi, plants, animals) and prokaryotic cells (like bacteria). Focus on the nucleus, other organelles, and the form of the genetic material.

Full Answer

1. The protist (eukaryote) has a true nucleus containing its genetic material, whereas a prokaryote has its genetic material (a single DNA loop and plasmids) free in the cytoplasm. 2. The protist has membrane-bound organelles such as mitochondria, whereas prokaryotes do not. 3. The protist has linear chromosomes, while prokaryotes have a circular main chromosome.
Eukaryotic and prokaryotic cells have fundamental structural differences: 1. **Nucleus:** Eukaryotic cells, like the malarial protist, have a true nucleus, which is a membrane-bound organelle containing the cell's genetic material (DNA) in the form of linear chromosomes. Prokaryotic cells do not have a nucleus; their genetic material consists of a single, circular loop of DNA located in the cytoplasm in a region called the nucleoid. 2. **Membrane-Bound Organelles:** Eukaryotic cells contain various membrane-bound organelles, such as mitochondria (for respiration), endoplasmic reticulum, and Golgi apparatus. Prokaryotic cells lack all of these. 3. **Plasmids:** Prokaryotic cells often contain small, circular rings of DNA called plasmids, which are separate from the main chromosome. Eukaryotic cells do not have plasmids. (Note: While many prokaryotes have a cell wall, and this protist does not, not all prokaryotes have one, and some eukaryotes do, so this is a less universal distinction than the nucleus and organelles).

Common mistakes

✗ Referring to size, as the question explicitly forbids it. ✗ Stating that prokaryotes have no DNA. They do, it's just not in a nucleus. ✗ Confusing cell walls and cell membranes.

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