2.3

Question 1

how many bacteria contain cell wall

Answer 1

the vast majority
rare to not have one

Question 2

primary functions of cell wall

Answer 2

-prevent cell from bursting due to osmotic pressure
-[solutes] high inside cell

-provides shape and rigidity

Question 3

gram positive vs gram negative cell wall

Answer 3

G+ - thick cell wall and no outer membrane
G- thin cell wall and have an outer membrane

Question 4

what cells have peptidoglycan

Answer 4

bacteria only

Question 5

peptidoglycan

Answer 5

lattice like structure formed from chains of glycans linked together by peptide bridges

Question 6

components of peptidoglycan

Answer 6

sugar backbone and peptide crosslinks

Question 7

sugar backbone of peptidoglycan

Answer 7

alternating N- Acetylglocosamine (NAG) and N acetylmuramic acid (NAM)

Question 8

peptide crosslinks

Answer 8

-short peptide chains attached to NAM covalently linked to peptide from adjacent link
-attached to other chain via peptide bond

Question 9

glycan chains in peptidoglycan

Answer 9

N-Acetylglocosamine and N- acetylmuramic acid alternating but connected by beta(1,4) linkage

Question 10

beta(1,4) linkage

Answer 10

glycosidic bond

Question 11

peptide composed of what amino acids

Answer 11

D isomer amino acids
different from aa that proteins are made of

Question 12

peptide crosslinks names and positions

Answer 12

peptide bonds
between position 3 and position 4

Question 13

gram negative bacteria cell wall features

Answer 13

-1-3 peptidoglycan layers 2-7 nm thick
-flexible, porous, and strong
-additional strength provided by outer membrane

Question 14

gram positive cell wall

Answer 14

thick peptidoglycan layer- 15+ layers

Question 15

what heps connect peptidoglycan layers in gram positive bacteria

Answer 15

interbridges

Question 16

polypeptide peptide sequence

Answer 16

-different for given bacterium
-not random
-specific sequences in diff organisms

Question 17

teichoic acids

Answer 17

in Gram Positive cell wall
long polymers comprised of glycerol phosphate or ribitol phosphate with attached D- glucose or/and D- alanine

Question 18

what is teichoic acid attached to

Answer 18

peptidoglycan or cytoplasmic membrane

Question 19

teichoic acids attached to cytoplasmic membrane called

Answer 19

lipoteichoic acids

Question 20

function of teichoic acids

Answer 20

-provide cell strength through ionic interactions b/w neighbor strains w metal ion bridge
- help trap divalent metal ions(like Mg2+ (has negative charge)
- barrier and attachment functions

Question 21

wall associated proteins functions

Answer 21

-gram positive bacteria- associate with cell wall covalently or not
-cell adhesion
-interact with teichoic acids, breaking down proteins

Question 22

cell wall permeability

Answer 22

it is porous but not a permeability barrier–> except to large molecules like proteins and protein complexes

Question 23

is cell wall dynamic?

Answer 23

not stagnant, constantly being synthesized, degraded and remodelled, lots of this happens during cell growth

Question 24

gram positive staining

Answer 24

peptidoglycan dehydrated and pores close, this prevents escape of crystal violet dye

Question 25

gram negative staining

Answer 25

decolorizing agent degrades outer membrane, thin peptidoglycan does not retain purple, cells are counterstained w safranin

Question 26

gram staining process

Answer 26

1) crystal violet iodine
2) decolorized w alcohol
3) counterstaining w safranin

Question 27

exception to all bacteria having cell wall

Answer 27

mycoplasma pneaumoniae
lives in host cell where there is minimal osmotic pressure, stable environment and dont need CW