Cell Structure - Prokaryotic Cells And Viruses

Question 1

How is a prokaryotic cell different to a eukaryotic cell?

Answer 1

The cell is smaller and doesn’t have a nucleus or a nuclear envelope

Question 2

What is the size of bacteria?

Answer 2

0.1 - 10um in length

Question 3

What is the cell wall of bacteria made of and how do some bacteria further protect themselves?

Answer 3

It’s made of muerin which is a polymer of polysaccharides and peptides.
Many bacteria further protect themselves by secreting a capsule of mucilaginous slime around the cell wall

Question 4

What type of ribosomes are found in the cytoplasm?

Answer 4

70s ribosomes

Question 5

How do bacteria store food reserves?

Answer 5

As glycogen granules and oil droplets

Question 6

What is the genetic material in bacteria in the from of?

Answer 6

Circular pieces of dna which are plasmids

Question 7

What do plasmids do?

Answer 7

They can reproduce themselves independently and may give the bacterium resistance to harmful chemicals like antibiotics

Question 8

Give 5 differences between eukaryotic and prokaryotic cells

Answer 8

• eukaryotic cells have a distinct nucleus with a nuclear envelope while prokaryotic cells have no nucleus and only have an area where DNA is found
• eukaryotic cells have membrane bound organelles like mitochondria but prokaryotic cells have no membrane bound organelles
• eukaryotic cells have the larger 80S ribosomes but prokaryotic cells have the smaller 70S ribosomes
• in eukaryotic cells when present the cell wall is made of mainly cellulose or chitin while in prokaryotic cells the cell wall is made of murein
• eukaryotic cells have no capsule while some prokaryotic cells do

Question 9

What structures does a bacterial cell contain and for each structure explain its role

Answer 9

• cell wall = a physical barrier that excludes certain substances and protects against mechanical damage and osmotic lysis
• the capsule= protects bacterium from other cells and helps groups of bacteria stick together for further protection
• cell surface membrane = acts as a differentially permeable layer which controls the entry and exit of chemicals
• circular DNA = possess the genetic information for the replication of bacterial cells
• plasmid = contains genes which may aid the survival of bacteria in adverse conditions e.g. it produces enzymes that break down antibiotics

Question 10

What are viruses?

Answer 10

Acellular, non living particles

Question 11

What do viruses consist of?

Answer 11

Genetic material wrapped in protein

Question 12

How big are viruses?

Answer 12

20-300nm

Question 13

How are viruses sensitive?

Answer 13

Because they have attachment proteins, which extend from the lipid envelope and if this isn’t preset the capsid, and they are essential to allow the virus to identify and attach to a host cell

Question 14

What type of genetic material do viruses contain?

Answer 14

They contain either DNA or RNA and either could be single stranded or double stranded

Question 15

What is the genetic material of a virus encased in?

Answer 15

The capsid which is a protein coat

Question 16

What are the steps to virus replication?

Answer 16

1. The virus attaches to a host cell and injects genetic material
2. The genetic material is then used as a code to synthesise more nucleic acids and proteins
3. New virus particles are assembled
4. The virus then destroys the host cell as it bursts out of it