Question

Microbiology Mini-Tutorial: Microbial Membrane Structure & Composition

Answer 1

Note: This is a reference for educational/studying purposes, not a question, please save all comments or questions for the end.

Answer 2

\({\bf{Gram-Positive}}\)

- membrane composed of techoic acids (carbohydrate chains attached to peptidoglycan) and lipotechoic acids (chains attached to the lipid not the peptidoglycan)
- thick peptidoglycan layer
- gram stain is purple
- examples: staph aureus, strep epidermis, listeria, anthrax
- more suspceptible to antibiotics that target peptidoglycan growth

\({\bf{Gram-Negative}}\)

- thin peptidoglycan layer
- membrane composed of lipopolysaccharides on the outer leaflet and lipoproteins embedded in the outer membrane layer
- lipopolyscharides composed of lipid A (an endotoxin), a polysaccharide core, and O-antigens
- porins
- ex. E. coli, Salmonella, Shigella, Pseudomonas
- gram stain is pink

Answer 3

peptidoglycan structure:

- two major components NAG (N-acetylglucosamine) and NAM (N-acetylmuramic acid) only synthesized by bacteria
- alternating between the two sugar residues in a meshlike structure
- MreB protein gives shape

- phosphatidylethyanolamine: major component of cell membranes, important in fusion, cytokinesis, and lipoprotein secretion
- 2-methyl hopanoids: steroid like molecule synthesized by bacteria to stabilize the cytoplasmic membrane
- membrane has viscosity of olive oil

Answer 4

Well this tutorial wasn't as long as I thought it would be but I hope it was helpful regardless. If you have any relevant questions I will address them to the best of my ability.