Question : Bacteria are classified as Gram positive and Gram negative on the bas

Question

Question:

Bacteria are classified as Gram positive and Gram negative on the basis of the polysaccharide (primarily peptidoglycan) content of their cell walls. Explain the difference between the two types based on Gram staining character? Please note that Gram positive appear purple and Gram negative appear pink on microscopic examination is not an answer. Your answer must include a suitable explanation at the molecular level with reference to bacterial cell wall composition.

Explain the structural and functional advantages of quaternary association with reference to proteins? Your answer must include the definition of quaternary structure, at least two examples of proteins exhibiting quaternary structure, and at least three advantages of quaternary association.

A) Explaining the difference in Gram staining character supported by a suitable explanation at the molecular level with reference to bacterial cell wall composition (4 points); an appropriate example of Gram positive and Gram negative bacteria (0.5 points each). B) Definition of quaternary structure (1 point); two examples of proteins exhibiting quaternary structure (0.5 points each); three advantages of quaternary association (3 points).

Explanation / Answer

Gram positive bacteria : The cell wall of gram positive bacteria is thick.2 peptidoglycan layer is thick.3 Teichoic acid present in many.4 Emoticon produced by gram positive bacteria.

Gram negative bacteria : Cell wall is thin .2 Endotoxin and emoticon are produced by gram negative bacteria .3 Resistant to dying is low.4 Teichoic acid is absent.

Example of gram negative bacteria is: Escherichia coli.

Hmare positive bacteria example : Staphylococci aureus .

Advantages of quaternary association: 1. Arrangement of the subunit gives rise to stable structure.

2. Quaternary structure adda stability by decreasing the surface / volume ratio of smaller subunit.

3. Simplifies the construction of large molecules.

Definition of quaternary structure: two or more polypeptide chains may bind to each other to form a quaternary structure.

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