Organization of the Bacterial Cell pt.3 Flashcards
what antibiotic only works on mycobacteria
ethambutol blocks synthesis of arabinan
why do mycobacteria grow super slowly
the waxy envelope is way less permeable to everything including nutrients
what is the S-layer / what does it do
is the protein/glycoprotein component of the cell envelope / has large pores to allow a lot of things into the cell
what is the S-layer linked to in gram-positive cells / gram negative cells
peptidoglycan / LPS
what is a slime layer
a glycocalyx that is loosely associated with the cell wall
what is a capsule
a glycocalyx that is a discrete layer outside the cell wall
what do capsules and slime layers do
they assist with attachment & adhesion, protect from desiccation, protect from phagocytosis
why are capsules required for disease
because they protect the bacterial cell from phagocytosis
how do peritrichous flagella move
they bundle together behind the swimming cell (kinda like a ponytail)
how do flagella move
in a circular rotation movement - only in a clockwise or counterclockwise fashion
how is the energy required for the flagella made
generated though proton motive force
what is chemotaxis
is the biased random walk that bacterium do - when spinning counterclockwise the cell is running (towards attractants), clockwise the cell is tumbling and changes direction
how do chemoreceptors influence the biased random walk
they trigger the flagellum to go either clockwise or counterclockwise (can sense the attractants)
what are pili used for
adherence and twitching mobility
how do bacteria grow
have to increase in length/mass before can separate and divide into two identical daughter cells (binary fission)
what is the rate of bacterial growth / how do cells have a growth rate that is faster than their replication rate
exponential / in fast growing cells replication can start before termination of the previous round
what regulates cell division
DNA replication
how does bacteria replication begin
the origin of replication replicates
where is the terminator sequence located
in the center of the cell
what is the Z-ring / what triggers its formation
the septum that divides the two daughter cells / the replication of the terminator sequence
what two things direct synthesis of new peptidoglycan to the division site
transglycosylases and transpeptidases
what occurs before a cell may divide / what is used for it
elongation of the cell / through new peptidoglycan being added along the wall
what is the difference between MreB and FtsZ
MreB forms around the entire rod of bacterium & FtsZ is only at the division site
what is the cause of dispersed zonal growth
MreB forms a spiral around the cell so it new peptidoglycan is added in stripes along the cell
how many zones of growth are in a circular cell
one because there is only FtsZ
what is polar growth
when new peptidoglycan is only added at one pole
what two parts determine the shape of the cell
the cytoskeleton sue to addition of peptidoglycan and the turgor pressure on the cell wall
