Describe and differentiate features unique to Gram negative and Gram positive ba
ID: 143402 • Letter: D
Question
Describe and differentiate features unique to Gram negative and Gram positive bacteria, the Mycoplasma and Mycobacteria. 1. 2. Describe the Gram stain and explain the mechanism 3. Identify the toxic components in Gram negative and Gram positive cell envelopes 4. Describe the structure of peptidoglycan, and explain the effects of both lysozyme and G- lactam antibiotics. 5. Describe the influence of the following features on virulence: flagella, fimbriae/pili, capsules, slime layer, endospores. Describe bacterial classifications based on O2 tolerance, and explain how O2 tolerance is conferred 6.Explanation / Answer
1 .Mycoplasma -
Mycobacterium -
2 . Gram stain - It is a technique to differentiate bacterias on the basis of their constituents of the cell wall .
Mechanism - the bacteria is stained with crystal violet stain and then a mordant is applied . Then it is washed with alcohol . The bacterial cells which have peptidoglycan , a special sugar present in the cell wall , will retain the stain and are called gram positive bacteria . The one that does not contain the peptidoglycan cannot retain the stain and the stain is washed off on washing with alcohol . These are called gram negative bacteria.
3. Toxic component in the gram negative cell envelope - It is the Lipoprotein that are present in the outer leaflet of the cell envelope .
Similarly , gram positive cell envelope have lipopolysaccharides which causes toxic reactions when attacked by the immune system .
4. Peptidoglycan (murein) is a polymer that is made up of amino acids and sugars , which forms a meshwork outside the cell membrane to form the cell wall .
Sugar components consists of N-acetyl glucosamine and N-acetylmuramic acid . There is a peptide of 3-5 amino acids that is attached to the N-acetylmuramic acid .
The peptidoglycan layer ls thicker in gram positive bacteria, as compared to gram negative bacteria.
Peptidoglycan comes under the target of lysozyme activity . They have a lytic activity on peptidoglycan by breaking the bonds in the meshwork .
On the other hand .Beta lactam antibiotics prevents the synthesis of the cell wall . They target the penicillin binding proteins which are the enzymes that are involved in the cross linking formation in the cell wall ,hence stopping the cell wall synthesis .
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.