week 3 Flashcards
gram positive bacteria has?
teichoic acid
types of secretion systems
Type I - spans whole membrane/outer membrane
Type II - spans membrane/outer membrane BUT takes proteins from sec or tat transporter
Type V- only spans outer membrane and takes proteins from sec or tat
Type III - spans the whole membrane/outer membrane + membrane of another cell to inject a protein
Type IV - injects DNA into another host cell - horizontal gene transfer
Type VI - has a sheath that retracts and contracts to act like a needle and secrete protein into a host cell
S-layers
crystalline layer of glycoproteins outside of cell envelope
- provides protection against bacteriophages, low pH, lytic enzymes.
Capsules
really long polysaccharides
- provide protection against other bacteria, immune systems, desiccation etc..
Glycocalyx
LPS? teichoic acid
S-layer glycans
capsule
alginate
poly-N-acetylglucosamine
Enterobacterial common antigen
cellulose
all help with attachment or protect
what are pili made out of
made of protein
thin filamentous structures
what do pili do?
help in cell motility
- are retractable and can extend from the surface of the cell
where are pili found?
found in all gram negative bacteria and many gram positive bacteria
Types of pili
- fimbrae
- conjugation
- electrically conductive pili
- type IV pili (involved in motility, one of the secretion systems)
Motility on solid surfaces ?
a.) twitching
b.) gliding
motility on semi-solid surfaces
swarming
- uses flagella
- coordinated movement
swimming motility
- flagella
a.) peritrichous b. polar c. lophotrichous
flagella parts
- hollow tip that is built from the bottom
- rotor part that spins
- stationary part in peptidoglycan to anchor flagella
what does bacteria flagella use as a power source?
proton motor pump/force
CCW = ?
cell runs
CW = ?
cell tumbles
CW = ? (in reversible flagella)
cell reverses
chemotaxis
directed movement of bacteria in a chemical gradient
Archaea membranes
-no phosphate
- more stable
Archaea cell envelope
NO peptidoglycan !!
- some have pseudomurein which is similar
- some have S layer or protein sheath
Pseudomurein
has a lyzosozyme insensitive bond between the sugars. B(1,3)
has N-acetlyalosaminuronic acid for a sugar
Archaea flagella
smilar to bacteria flagella but uses ATP as energy source
Archaea hami
unique attachment structure
Lag phase
nutrients are being internalized
enzymes are being made
replication of cellular components
Exponential phase
population growth is doubling as fast as possible (optimal growth)
linear under log scale
stationary phase
running out of nutrients
growth slows
some cells die
NO net increase in cell numbers
- synthesis of endospores
death phase
rupture of plasma membrane
destruction of DNA
Asexual reproduction
binary fission
budding
fragmentation
cytokinesis
replication of cytoplasmic contents
- septation occurs (cross walls between daughter cells)
- site is selected by FtsZ (in center of cell)
- z ring is assembled
- linked to p. membrane
- constriction of cell and septum formation
e. coli divisome
10,000 FtsZ molecules polymerize into a ring in the center of the cell
- ring is tethereto P.M by ZipA and FtsA
- localizes peptidoglycan biosynthesis machinery to center of cell
how does the cell know where the centre is for Z ring formation?
MinCD prevnts Z ring from forming
- where MinE is = no MinCD = ring can fotm
- after septum forms - MinCD comes back
where does peptidogylcan synthesis occur?
in the middle of the cell- anchored by the FtsZ ring
Peptidogylcan biosynthesis
- synthesis of building blocks
- synthesis of disaccharide-peptide repeat unit
- translocation = cytoplasm to periplasm
- transglycosylation = formation of glycan linkages
- transpeptidation = peptide cross linkages
translocation
moving repeat building blocks from cytoplasm to periplasm
transglycosylation
= formation of glycan linkages
transpeptidation
= formation of = peptide cross linkages
