Chapter 5: 5.1 Prokaryotic Cell Walls and External Structures

Question 1

Bacteria are ubiquitous, what does this mean?

Answer 1

They can be found anywhere

Question 2

What are bacteria cell walls composed of?

Answer 2

A large polymer called peptidoglycan
* Made up of polysaccharides and amino acids

Question 3

What are the two different groups that bacteria?

Answer 3

1. Gram-positive (stains purple)
2. Gram-negative (stains pink)

Question 4

What are characteristics of Gram-positive bacteria?

Answer 4

• Thick layer of peptidoglycan surrounding the plasma membrane
• No outer membrane
• Stain purple

Question 5

What are characteristics of Gram-negative bacteria?

Answer 5

• Thin layer of peptidoglycan surrounding the plasma membrane
• Outer membrane
• Stain pink

Question 6

What kind of bonds do bacterial membrane lipids have?

Answer 6

Ester bonds

Question 7

Archaea are often…

Answer 7

Extremophiles

Question 8

Define:

Extremophiles

Answer 8

Live in extreme environments such as extremely high temperatures, salt concentration etc.

Question 9

Describe:

Archaea Cell Walls

Answer 9

Cell walls are composed of pseudo-peptidoglycan
* Membrane lipids have ether bonds

Question 10

Describe:

Capsule

(3 points)

Answer 10

• Secreted outer layer of polysaccharides or sugars
• Relatively inflexible or rigid and impermeable
• Used for protection against external harm (e.g. immune cells, desiccation, antibiotics) and used for adhering to surfaces

Question 11

Describe:

Slime

Answer 11

• Secreted outer layer of polysaccharides as well
• Flexible and relatively permeable
• Used for hydration and motility on surfaces

Question 12

True or False:

Capsule is relatively inflexible

Answer 12

True, capsule is relatively inflexible or rigid and impermeable

Question 13

What is slime used for?

Answer 13

Used for hydration and motility on surfaces

Question 14

What is capsule used for?

Answer 14

• Protection against external harm (e.g. immune cells, desiccation, antibiotics)
• Adhering to surfaces

Question 15

What happens to cells when conditions are harsh?

Answer 15

They enter a state of dormancy to protect themselves

Question 16

When cells enter a dormant stage:

What happens to the cell?

Answer 16

Cells are not dividing
* Form an endospore which is relatively resistant to all external conditions

Question 17

Cells can enter a state of dormancy to protect themselves and re-activate when conditions are good. What is this process called?

Answer 17

Sporulation

Question 18

List:

The stages of sporulation

(3 steps)

Answer 18

1. DNA replication occurs and the new DNA is encased in a cell membrane layer
2. Early endospore formation: DNA is encapsulated in a cell wall of its own
3. Cell wall around the DNA thickens and the original cell wall disintegrates

Question 19

Define:

Pilus

Plural: Pili

Answer 19

Small thin rods that protrude out of the cell

Question 20

Are pili retractable?

Answer 20

Yes, they are

Question 21

What are the function(s) of pili?

Answer 21

1. Transport of extracellular DNA known as plasmids (F pili)
2. Attachment to surfaces (fimbriae)

Question 22

Define:

Flagella

Answer 22

Tail-like structure that normally extends out from one end but some bacteria can have multiple tails at various ends

Question 23

What are flagella for?

Answer 23

For swimming and moving around