Microbial Structure & Motility Flashcards
Major functions of the PM in Bacteria?
- Permeability barrier
- Energy conservation
- Acts as anchor for proteins.
Structure of cell membrane in (EU)bacteria
Phospholipid bilayer
No cholesterol
Cell membrane in Archaea Bacteria
Mix of lipid monolayer and bilayer. Phytanyl chains substitutes for fatty acids.
What is the cell wall in bacteria made of?
Murein (peptidoglycan layer)
How is the cell wall modified?
- Opening made in cell wall by autolysins
- Bactoprenol adds new material to opening
- Transglycosylases links compound together
How do gram-negative bacteria differ?
Peptidoglycan layer is within the membrane. It is thin.
Which structure helps bacteria ‘swim’?
Flagella
Can flagella be seen through a light microscope?
No, staining is required.
What is taxis?
Directed movement in response to stimuli
What is run and tumble?
Method that flagella use to move.
How does a bacterium respond to stimuli?
Receptor sends signal to flagellum motor for it to initiate movement.
What other component of the bacterial cell control motility?
Fimbriae and Pili
Which structure is longer; Fimbriae or Pili?
Pili
Function of Fimbriae
Adhesion
Function of Pili
Genetic exchange
What is the slime layer?
Gel-like substances surrounding the cell wall. Made of psac
What is the capsule and glycocalyx made of?
- Capsule is made of psac and ppeptide
- Glycocalyx is made of thin psac and glycoprotein.
Function of slime/capsule?
- Protect against dehydration
- Protects from pathogens
Function of glycocalyx?
Responsible for attachment
Where are endospores found?
In extremophiles
What is the role of the cell wall?
- Provide strength to cell
- Protects against mechanical and osmotic stress
What keeps the peptidoglycan layer rigid?
Glycosidic bonds ad peptide bonds.
What is the role of a transpeptidase?
To make peptide links between acetylmuramic residues.
What is difference between the cell wall in EU and Archaea bacteria?
Archaea bacteria is made of Pseudo-murein, NOT peptidoglycan. Difference is there isn’t acetylmuramic acid. It is subbed for acetyltalosaminuronic acid
What is peptidoglycan made of?
N-acetylmuramic acid and N-acetylglucosamine
