Bacterial cell structure
Laura Armstrong
Teacher
Recall Questions
This topic requires prior knowledge of animal and plant cell structures in order to contrast eukaryotic and prokaryotic cell organisation.
What is the function of the cell membrane?
To control the movement of substances into and out of the cell.
Where in the cell would you find most enzymes?
Cytoplasm
Give an example of a eukaryotic cell. Explain your choice.
Animal or plant cell because they contain a nucleus (and other membrane bound organelles).
Topic Explainer Video
Check out this @lauradoesbiology video that explains bacterial cell structure or read the full notes below. Once you've gone through the whole note, try out the practice questions!
Prokaryotic Cell Structure
Prokaryotic cells are smaller (about 10x smaller) and simpler than eukaryotic cells. Bacteria are examples of prokaryotic cells.
Prokaryotic cells do not contain a nucleus (or any membrane bound organelles).
They do contain the following sub-cellular structures:
Cell Wall
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Provides structural support and protection.
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Not made of cellulose. Made of murein (a different molecule).
Cell Surface Membrane
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Controls what enters and leaves the cell.
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Partially permeable.
Cytoplasm
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Contains enzymes for chemical reactions.
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No membrane-bound organelles are found in the cytoplasm.
Circular DNA
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Single loop of DNA, not enclosed in a nucleus.
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Carries genetic information.
Ribosomes
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Site of protein synthesis.
Plasmids (not always present)
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Small circular DNA molecules.
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Can be exchanged between bacterial cells
Capsule (not always present)
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Slimy outer layer.
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Protects the bacterium and helps it stick to surfaces.
Flagellum (not always present)
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Tail-like structure used for movement.
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Sperm cells are an example of an animal cell which has a flagellum.
Diagram of a Prokaryotic Cell
Key Term
- Prokaryotic – cell without a nucleus or membrane-bound organelles.
No answer provided.
Exam Tips
- Watch out! plasmids are NOT the main DNA – they are extra, smaller loops of DNA, and only some bacteria have plasmids, capsules and flagella.
- In ‘compare’ questions make sure you use comparative statements of the similarities and differences, to directly compare both types of cell.
No answer provided.
Practice Question
Compare the features of prokaryotic cells and eukaryotic cells. (4 marks)
Any four from:
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Eukaryotic cells have a nucleus, prokaryotic cells do not, the DNA is in a loop in the cytoplasm.
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Prokaryotic cells may have plasmids, eukaryotic cells do not.
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Eukaryotic cells have membrane bound organelles, like mitochondria and chloroplasts, prokaryotic cells do not
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Eukaryotic cells are larger than prokaryotic cells.
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Both have cytoplasm, cell membranes and ribosomes.
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Eukaryotic plant cells have a cell wall made out of cellulose, prokaryotes also have a cell wall but it is not made of cellulose.
More Practice
Try to answer these practice questions from the TikTok videos on your own, then watch the videos to see how well you did!