structure of prokaryotic cells and of viruses

Question 1

What are the distinguishing features of prokaryotic cells

Answer 1

● Cytoplasm lacking membrane-bound organelles
● So genetic material not enclosed in a nucleus

Question 2

Describe the general structure of prokaryotic cells

Answer 2

always
- cell surface membrane
- cell wall contains murein
- cytoplasm
- small ribosomes
- circular DNA free in cytoplasm not associated with proteins

sometimes
- capsule
- flagella
- plasmids

Question 3

Compare and contrast the structure of eukaryotic and prokaryotic cells

Answer 3

eukaryotic has membrane-bound organelles, prokaryotic has no membrane bound organelles
eukaryotic has a nucleus contraining DNA, prokaryotic has no nucleus DNA free in cytoplasm
eukaryotic DNA is long linear and associated with proteins, prokayotic DNA is short circular and not associated with proteins

Question 4

Explain why viruses are described as acellular and non-living

Answer 4

● Acellular - not made of cells
● Non-living - have no metabolism, cannot respire

Question 5

Describe the general structure of a virus particle

Answer 5

1. Nucleic acids surrounded by a capsid
   (protein coat)
2. Attachment proteins allow attachment
   to specific host cells
3. No cytoplasm, ribosomes, cell wall,
   cell-surface membrane etc.
4. Some also surrounded by a lipid
   envelope