Cells: Prokaryotic cells and viruses

Question 1

What is the size of a prokaryote

Answer 1

Between 0.1 and 5.0 micrometres in diameter

Question 2

State a difference between prokaryotic cells and eukaryotic cells relative to their size

Answer 2

Prokaryotic cells are much smaller than eukaryotic cells

Question 3

State ALL the differences between prokaryotic cells and eukaryotic cells

Answer 3

• Prokaryotic cells are much smaller than eukaryotic cells
• Prokaryotic cells have a cytoplasm that lacks membrane bound organelles
• Prokaryotic cells have smaller [70S] ribosomes
• Prokaryotic cells have no nucleus; they have a single circular DNA that is free to move around in the cytoplasm
• Prokaryotic cells have a cell wall that contains murein (a glycoprotein)
• Prokaryotic cells may have plasmids, a capsule or flagellum

Question 4

State a difference between prokaryotic cells and eukaryotic cells relative to their organelles

Answer 4

Prokaryotic cells have a cytoplasm that lacks membrane bound organelles e.g Golgi apparatus, [Smooth/Rough] endoplasmic reticulum

Question 5

State a difference between prokaryotic cells and eukaryotic cells relative to their DNA

Answer 5

• Prokaryotic cells have no nucleus; they have a single circular DNA that is free to move around in the cytoplasm and contains plasmids
• Whereas eukaryotic cells have a nucleus containing DNA that is linear

Question 6

State and describe the features of prokaryotic cells

Answer 6

• Cytoplasm - contains no membrane bound organelles
• [70S] ribosomes - smaller than those in the eukaryotic cell (still used for protein synthesis)
• Circular free floating DNA - Not attached to any histone proteins [presenting as one long coiled-up strand]
• Plasmids - Small loops of DNA separate from the circular DNA not always found in prokaryotic cells
• Cell wall - Made of a polymer called murein (a glycoprotein)
• Slime capsule - Made up of secreted slime
• Flagellum - Long hair like structure that rotates to make the prokaryotic cell move

Question 7

State the role of plasmids

Answer 7

Contain genes for things like antibiotic resistance

Question 8

State what the slime capsule is made from

Answer 8

• Made up of secreted slime

Question 9

State the role of the slime capsule

Answer 9

It protects the bacteria from being attacked my cells of the immune system

Question 10

State the role of the cell wall in prokaryotic cells

Answer 10

It supports the cells and prevents it from changing shape

Question 11

State what the cell walls in prokaryotic cells are made from

Answer 11

Murein (a glycoprotein)

Question 12

State a difference between prokaryotic cells and viruses relarive to their size

Answer 12

Viruses are smaller than prokaryotic cells

Question 13

What are prokaryotes

Answer 13

Single celled organisms whose cells don’t contain membrane bound organelles

Question 14

What are eukaryotes

Answer 14

Multi-cellular organisms whose cells contain a nucleus and other membrane-bound organelles

Question 15

Viruses are acellular, what does this mean

Answer 15

It means that viruses are non-living

Question 16

Name the structures found in viruses

Answer 16

• Core of genetic material
• Protein coat
• Attachment proteins

Question 17

State the difference between prokaryotic cells and viruses relative to their organelles

Answer 17

Viruses lack a plasma membrane, a cytoplasm and ribosomes

Question 18

Define host cells

Answer 18

A living cell which harbours an infectious agent

Question 19

How do prokaryotic cells replicate

Answer 19

Via Binary fission

Question 20

Outline the stages of binary fission in prokaryotic cells

Answer 20

• Circular DNA and plasmid[s] replicate (The pain DNA replicates once, but plasmids can be replicated many times)
• The cell gets bigger and the DNA loops move to opposite pole of the cell
  *The cytoplasm begins to divide (and new cell walls begin to form)
• The cytoplasm divides and two daughter cells are produced - each with one copy of the circular DNA, but with variable numbers of the plasmid[s]

Question 21

How do viruses replicate

Answer 21

• By using host cells

Question 22

Outline the stages to how viruses use host cells to replicate themselves

Answer 22

• They use their attachment proteins to bind to complementary receptor proteins on the surface of host cells
• Then they inject their DNA or RNA into the host cell - using the cells own machinery (e.g enzymes, ribosomes) to do the work and replicate the viral particles

Question 23

Wy can some viruses only infect one type of cell while others can infect a lot of different cells

Answer 23

Different virues have different attachment proteins and therefor require a different receptor proteins on host cells