Structure Unique To Bacteria Flashcards
What is the cell wall of bacteria made from
Peptidoglycans (glycan polymers)
Muramic acid and n acetyl glucosamine linked with peptide cross bridges via transpeptidase
Name 3 ways peptidoglycan cell wall is important
1- target from antibiotics like penecillin
2- keeps osmotic pressure stable
3- protection from cell lysis (which happens due to b lactam)
Explain the gram +ve cell wall
They have large peptidoglycan wall over their single layer membrane
What are the anionic polymers called in the cell walls of gram +ve
Teichoic acids
What are teichoic acids important for in gram +ve
Needed for bacteria survival
Also are antigenic so produce an immune response
How is the cell wall different in gram negative
They have a thin peptidoglycan cell wall embedded between a double cell membrane
What is the structure in gram negative which contains both the peptidoglycan cell wall and inner membrane
Periplasm
What is found on the outer membrane of gram negative
Lipopolysaccharide layer with lipid A and polysaccharides
What is lipid A on the outer membrane for in gram negative
It produces pyrogenic toxins which cause a fever in infected cells
How is the lipopolysaccharide layer important in gram negative defence mechanism
They can shed and add a new one which is unrecognised by our immune system
What is a crystalline protein lattice called on the outer layer of all bacteria and archaea
Proteinaceous s layer
What is the proteinaceous s layer for
It acts as a selective sieve for protection
What is the capsule made of and how is it attached to the cell wall
It’s a polysaccharide which is covalently attached to the cell wall peptidoglycan
Why is the capsule important to bacteria
It helps defend immune system in phagocytosis
Is the capsule immunogenic (forms immune response like teichoic acids)
Yes sometimes it is
What are the appendages called on bacteria used for attachment and adhesion
Pili and fimbriae
What is pili and fimbriae made from
Protein polymers
What process is pili and fimbriae needed for
Pathogenesis (adhesion to cells to stop being washed away)
And cell conjugation (sex pili)
What kind of movement does pili and fimbriae facilitate
Twitches
Which structure is needed for rotary movement especially in chemotaxis where it changes direction
Flagella
What happens flagella rotation
H+ flow into mot proteins embedded in the inner membrane of gram negative
Which rings are rotated on flagella due to mot proteins and H flow
The C and MS ring
Are pili and Fimbriae also immunogenic like the capsule
Yes we detect them
What are endospores needed for
Cellular survival in bad conditions eg resistant to heat
What do spores get engulfed by in sporulation
Vegetative cells which are in harsh conditions
What happens in sporulation
Vegetative cells engulf spores and start to asymmetrically divide and then release the spore in germination
What are biofilms and which other structure helps build them
Communities of motile cells helped produced by capsule
What happens in biofilm development
Motile cells attach to surfaces which become SESSILE
These then cluster into a matrix made of polysaccharides, proteins and nucleus acids
The matrix biofilm starts growing
The cells can then disperse due to a trigger
What are biofilms for
Adhesion
And resistance to antibiotics
Give an example of a biofilm
Plaque build up
