Mod 2 L3 - bacterial sturcture Flashcards
Coccus diameter and examplez
0.5-1 micormeters
Staphulococcus
Streptococcus
Rod bact size and examples
<8x0.5 micrometres
E.coli
Vibrio cholerae
What are spirochetes
flexible, helical
e.g. treponema pallidium
Walsbys square bactefium
Square and flat bacteria
haloquadratum walsbyi
Biggest bacteria and its size
Thiomargerita nambiensis
0.75mm
What are 3 arrangements of bacteria
chains
Pairs
Clusters
Steps of gram stain
heat fix
Crys violet
Grams iodine -fixes violet stain
Ethanol/acetone
Safranin
functions of peptidoglycan
structure
protection from osmotic lysis
- withstands high internal osmotic pressure e.g. gram +ve have thicker walls cuz higher pressure
how can the peptglyc wall be a weakness
can be a target for attack on the cell,
e.g. by antibiotics or bacteriophages, which destroy peptglyc wall to destroy cell
in bact that dont have peptglyc wall (mycoplasma) , what stabilises it
sterols in cell memb
the 2 amino sugars that alternate to make up peptglyc wall
N-acetyl glucosamine (NAG)
N-acetyl muramic acid (NAM)
how many peptides in chain link covalently to glycan chain
4 - tetrapeptide
which residue will the tetrapeptide always bind to
NAM residue
in gram -ve, between which 2 peptides are cross links formed
3 on one and 4 on the other
peptides are more variable in gram +ve, what is the bit in the middle called
interbridge
