All about cell wall of bacteria and structure of peptidoglycan layer

Today we discussed about Shalini’s project that she performed with gram positive bacteria by using SDS gel technique
Here we discussed about
• What is cell wall of bacteria made up of?

  • It’s peptidoglycan layer, this layer will be think in gram positive bacteria and thin in gram negative* bacteria
    • In gram positive bacteria there are many layers of peptidoglycan so what is peptidoglycan made up of?
  • Peptidoglycan is made from long chain of 2 sugars i.e., NAG (N-Acetyl glucosamine) & NAM (N-acetylmuramic acid)
    • How are NAG and NAM bonded together?
  • They are bonded by glycosidic bond as they are sugars to be more specific… Beta 1,4- glycosidic bond
    • What is alpha and beta bond?

• What is alpha and beta bond?

  • For this we look at OH group on 1st carbon atom of any sugar so if OH is below the plane then we call it alpha molecule and if OH is above then we call it as beta molecule

• Why we call them peptidoglycan?

  • Here NAG & NAM are *sugars bonded with glycosidic bond so glycan is used but 2 NAM of 2 different chains are bonded together by pentapeptides so use peptido here, together it becomes peptidoglycan
    • Also, what would happen in we break cell wall & how do we break it?
  • For breaking cell wall 1st, we will break the link between m-DAP & D-Ala, we can break this bond by using an endopeptidase
    So, this was about cell wall inside cell wall we have cell membrane made up of phospholipid bilayer and some protein so at the end Shalini was trying to say something about this but her voice wasn’t clear

• How does penicillin breaks cell wall of bacteria?..
So, if we are culturing any bacteria on agar plate and by any chance spore of fungus enters the agar plate and grows into fungus that produces penicillin then what would happen?

  • Penicillin might act like an endopeptidase here and will break the bond between m-DAP & D-Ala

• How will penicillin break cell wall of bacteria and kill them?


Fantastic so much content being discussed in a Hands-on context.