Prokaryotic Cells and Viruses

Question 1

In a prokaryote what is the structure and function of the cell wall?

Answer 1

The cell wall supports the cell and prevents it from changing shape. It’s made of a polymer called murein. Murein is a glycoprotein.

Question 2

In a prokaryote what is the structure and function of the capsule?

Answer 2

Made up from secreted slime it helps protect the cell from attack

Question 3

In a prokaryote what is the structure and function of the plasmids?

Answer 3

Small loops of DNA that aren’t part of the main circular DNA molecule. They contain gene for things like antibiotic resistance and can be passed between prokaryotes. Some prokaryotes don’t have any plasmids whilst others have several

Question 4

In a prokaryote what is the structure and function of the DNA?

Answer 4

Prokaryotes don’t have a nucleus, the DNA floats free in the cytoplasm. It’s circular DNA, present as one long coiled up strand, not attached to any histone proteins

Question 5

In a prokaryote what is the structure and function of the flagellum?

Answer 5

A long, hair-like structure that rotates to make the cell move. Not all prokaryotes have flagella, some have more than one

Question 6

Viruses are acellular, explain

Answer 6

They are just nucleic acids surrounded by a protein. They’re smaller than bacteria. All viruses invade and reproduce inside the cells of other organisms, these cells are known as host cells

Question 7

How do prokaryotic cells replicate?

Answer 7

Binary Fission

Question 8

Explain binary fission

Answer 8

1. The circular DNA and plasmids replicate. The main DNA loop I replicated once but plasmids can be replicated lots of times
2. The cell gets bigger and the DNA loops move to opposite poles of the cell
3. The cytoplasm begins to divide and a new cell wall begins to form
4. The cytoplasm divides and two daughter cells are produced - each daughter cell has one copy of the main circular DNA, but can have varying numbers of plasmids

Question 9

How do viruses replicate?

Answer 9

Viruses use their attachment proteins to bind to complimentary receptor proteins on the surface of host cells. They inject their DNA or RNA into the host cell - the host cell then uses it’s own machinery to replicate the viral particles