Exam 1 Lecture 4 Flashcards
(26 cards)
Structure in order from outside to inside of Gram-negative bacteria?
- LPS
- Outer Membrane has Porins-beta barrels(Ompf) and non-specific channels
- Brauns Lipoprotein (connects outer membrane to the wall)
- Cell wall- a single layer of peptidoglycan
- Inner Membrane
LPS structure from outside to in?
- O-antigen polysaccharide (can change to avoid immune system) up to 200 sugars also called the repeating unit
- Core polysaccharide varies with species 5-10 sugars
- Lipid A- tails embedded in outer membrane has 2 parts
a. disaccharide diphosphate
b. 6 fatty acid tails
Name 1 good and 1 bad function of LPS?
- Resistant to phagocytosis
- Can act as a receptor for virus/phages
Basic characteristics of mycobacteria cell envelope?
Thick waxy and hydrophobic
Slow growing
Basic structure from inside to out?
- Cell membrane
- Peptidoglycan layers
3 Arabinogalactan layer (Galactan then Arabinam)
- Mycomembrane (mycolic acids, has porins)
- Capsule (sugar mycolates then glycolipids)
What is an S-layer?
Surface Layer composed of protein and glycoproteins
Highly ordered crystalline sheet with 2-8 nm large pores
Often lost in lab in Rich media
What does and S-Layer do?
Protection and structural stability
(not needed in a media-rich lab environment so often lost)
Who has an S-layer?
A lot of archaea and some bacteria
What does S-layer link to?
Archaea- pseudo PG or membrane
Gram-pos- PG
Gram-neg- LPS
What is the glycocalyx?
A polysaccharide (some protein) layer outside the cell wall
Either Capsule or Slime
Who has a glycocalyx and what does it do?
Most Prokaryotes
- Attachment and adhesion to substrates (plaque)
- Protection against desiccation and phagocytosis
Difference between Slime and capsule?
Capsule is discreet and contained, slime is loose
Does a capsule have a role in pathogenesis?
Yes, many bacteria need the capsule for protection for their ability to infect host cells.
Experiment- living non-capsulated bacteria injected = no death
Living non-capsulated bacteria and dead capsulated bacteria injected = death
Living bacteria took capsules from dead and infected
Examples of pathogenic bacteria that require a capsule to be pathogenic?
- Streptococcus pyogenes*
- Streptococcus pneumonia*
- Yersinia pestis*
- Bacillus anthracis*
- Neisseria meningitidis*
Types of flagella systems?
Peritrichious
Lophotrichous
Monotrichious
What do archaea have that is like a flagellum?
Archaellum
different evolution
Describe peritrichous flagella?
Randomly distributed around the body
bundle together when swimming forward
Describe lophotrichous flagella?
Only at ends of cell
Describe monotrichous?
Single flagellum
What is the flagellar motor evolved from?
Type III Secretion system
Where does the energy come from to power the flagella?
PMF
How long are flagella?
~10-15 microns long
What are flagella made up of?
FliC proteins ~20 K subunits
Where are flagella in spirochetes?
In the periplasm, gives the bacteria a corkscrew shape
Whole corkscrew bacteria turns to propel it forward
