3.2.1.2 Structure of prokaryotic cells and of viruses

Question 1

What makes prokaryotic cells different from eukaryotic cells?

Answer 1

Prokaryotic cells such as bacteria are smaller and simpler than eukaryotic cells.

Question 2

What does the cytoplasm of a prokaryotic cell lack?

Answer 2

The cytoplasm of a prokaryotic cell has no membrane-bound organelles.

Question 3

What type of ribosomes do the cytoplasm of a prokaryotic cell contain?

Answer 3

The cytoplasm contains ribosomes which are smaller than those in eukaryotic cells. 70 s ribosomes

Question 4

What controls the movement of substances in and out of a prokaryotic cell?

Answer 4

The plasma membrane controls the movement of substances into and out of the cell and is mainly made of lipids and proteins.

Question 5

What is the cell wall of prokaryotic cells made of?

Answer 5

The cell wall is made of a polymer called murein.

Question 6

What is murein?

Answer 6

Murein is a glycoprotein.

Question 7

What is the role of a capsule in some prokaryotes?

Answer 7

The capsule helps to protect bacteria from attack by cells of the immune system.

Question 8

What are plasmids?

Answer 8

Plasmids are small loops of DNA that aren’t part of the main circular DNA molecule. Prokaryotic cells can have several plasmids.

Question 9

What can plasmids do?

Answer 9

Plasmids contain genes for things like antibiotic resistance and can be passed between prokaryotes.

Question 10

What is a flagellum?

Answer 10

A flagellum is a long hair-like structure that rotates to make the prokaryotic cell move.

Question 11

How does the DNA differ in a prokaryotic cell compared to a eukaryotic cell?

Answer 11

The DNA floats free in the cytoplasm in a prokaryotic cell and is circular.

Question 12

What are viruses made up of?

Answer 12

Viruses are just nucleic acids surrounded by protein.

Question 13

What is the protein coat around the core of a virus called?

Answer 13

The protein coat around the core is called the capsid.

Question 14

What are attachment proteins?

Answer 14

Attachment proteins stick out from the edge of the capsid and let the virus cling on to a suitable host cell.

Question 15

What is the genetic material in viruses?

Answer 15

The genetic material in viruses is either DNA or RNA.

Question 16

How do prokaryotic cells replicate?

Answer 16

Prokaryotic cells replicate by binary fission.

Question 17

What happens to the DNA during binary fission?

Answer 17

The circular DNA and plasmids replicate.

Question 18

What happens after the DNA has replicated in binary fission?

Answer 18

The cell gets bigger and the DNA loops move to opposite poles of the cell.

Question 19

What happens to the cytoplasm during binary fission?

Answer 19

The cytoplasm begins to divide and new cell walls begin to form.

Question 20

What is produced at the end of binary fission?

Answer 20

The cytoplasm divides and two daughter cells are produced each with one copy of the circular DNA.

Question 21

What do viruses need to replicate?

Answer 21

Viruses need a host cell to replicate and use the host cell’s machinery to replicate the viral particles.

Question 22

Why can some viruses only infect one type of cell?

Answer 22

Different viruses have different attachment proteins and therefore require different receptor proteins on host cells.

Question 23

How do viruses replicate?

Answer 23

Viruses inject their DNA or RNA into the host cell and use the cell’s machinery to replicate the viral particles.