1.7 prokaryotic cells

What are prokaryotes?

Prokaryotes are single-celled organisms  made up of prokaryotic cells. They are much smaller than eukaryotic cells and do not contain a nucleus or membrane-bound organelles.

Name the structures that may be found in botheukaryotic and prokaryotic cells.

1. Cell wall

2. Cytoplasm 

3. Cell surface membrane or plasma membrane

4. Ribosomes 

Some, but not all, eukaryotic cells may have cell walls (like plant cells or fungus cells).

How is a prokaryotic cell wall different to a plant cell wall?

A prokaryotic cell wall is made up of murein or peptidoglycan, while a plant cell wall is made up of cellulose.

How are ribosomes different in eukaryotic cells and prokaryotic cells?

Ribosomes in eukaryotic cells are 80S and larger, while ribosomes in prokaryotic cells are 70S and smaller.

What is a capsule and what does it do?

A capsule is an extra layer around the cell wall made up of polysaccharides.

It protects the cell from attack by antibiotics or white blood cells. 

What is a plasmid and what does it do?

A plasmid is a small loop of DNA separate from the main DNA. 

It contains genes for antibiotic resistance and can be passed from one prokaryotic cell to another. 

What is a flagellum and what does it do?

A flagellum is a long, hair-like structure attached to the cell membrane. 

It rotates to push the cell through its environment so it can swim.

What are pili and what do they do?

Pili are short, hair-like structures on the cell surface. 

They are used for attaching the cell to other cells or surfaces. 

Describe the similarities between eukaryotes and prokaryotes. 

1. Both can be unicellular

2. Both contain cytoplasm

3. Both contain cell-surface membranes  or plasma membranes

4. Both contain ribosomes 

5. May contain a cell wall 

Describe the differences between eukaryotes and prokaryotes.

1. Eukaryotes can be multicellular, prokaryotes cannot 

2. Eukaryotes are larger 

3. Eukaryotic DNA is in the nucleus, prokaryotic DNA is in the cytoplasm 

4. Eukaryotes have larger ribosomes 

5. Eukaryotes contain membrane-bound organelles, prokaryotes do not 

6. Eukaryotic cell walls are made of cellulose or chitin, prokaryotic cell walls are made of murein