Chapter 5: 5.1 Prokaryotic Cell Walls and External Structures Flashcards
Bacteria are ubiquitous, what does this mean?
They can be found anywhere
What are bacteria cell walls composed of?
A large polymer called peptidoglycan
* Made up of polysaccharides and amino acids
What are the two different groups that bacteria?
- Gram-positive (stains purple)
- Gram-negative (stains pink)
What are characteristics of Gram-positive bacteria?
- Thick layer of peptidoglycan surrounding the plasma membrane
- No outer membrane
- Stain purple
What are characteristics of Gram-negative bacteria?
- Thin layer of peptidoglycan surrounding the plasma membrane
- Outer membrane
- Stain pink
What kind of bonds do bacterial membrane lipids have?
Ester bonds
Archaea are often…
Extremophiles
Define:
Extremophiles
Live in extreme environments such as extremely high temperatures, salt concentration etc.
Describe:
Archaea Cell Walls
Cell walls are composed of pseudo-peptidoglycan
* Membrane lipids have ether bonds
Describe:
Capsule
(3 points)
- 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
Describe:
Slime
- Secreted outer layer of polysaccharides as well
- Flexible and relatively permeable
- Used for hydration and motility on surfaces
True or False:
Capsule is relatively inflexible
True, capsule is relatively inflexible or rigid and impermeable
What is slime used for?
Used for hydration and motility on surfaces
What is capsule used for?
- Protection against external harm (e.g. immune cells, desiccation, antibiotics)
- Adhering to surfaces
What happens to cells when conditions are harsh?
They enter a state of dormancy to protect themselves
When cells enter a dormant stage:
What happens to the cell?
Cells are not dividing
* Form an endospore which is relatively resistant to all external conditions
Cells can enter a state of dormancy to protect themselves and re-activate when conditions are good. What is this process called?
Sporulation
List:
The stages of sporulation
(3 steps)
- DNA replication occurs and the new DNA is encased in a cell membrane layer
- Early endospore formation: DNA is encapsulated in a cell wall of its own
- Cell wall around the DNA thickens and the original cell wall disintegrates
Define:
Pilus
Plural: Pili
Small thin rods that protrude out of the cell
Are pili retractable?
Yes, they are
What are the function(s) of pili?
- Transport of extracellular DNA known as plasmids (F pili)
- Attachment to surfaces (fimbriae)
Define:
Flagella
Tail-like structure that normally extends out from one end but some bacteria can have multiple tails at various ends
What are flagella for?
For swimming and moving around
