Question

1.I need short answer of the questions?

1. What is the major difference between gram postive and negetive bacteria.

2. What are endospores?

3. what are the name of 4 phase of bacterial growth?

4. name three ways DNA can be transfered from one bacteria to other.

5. What is LPS ( lipopoly saccharide) which types of bacteria have them and where? What is Capsule?

6. what is Fimbrae?

What is Pilli?

Answer 1

1) The major difference between gram positive bacteria and gram negative is the difference in the thickness of peptidoglycan layers surrounding the plasma membrane .In gram negative , the peptidoglycan is only few nanometers thick and it contain one to a few layers .Gram positive , the peptidoglycan is 30-100 nm thickness and contain many layers.

Another difference is gram positive retain the crystal violet color even after they washed and it appears purple colour .Gram negative do not retain the stain color even after they are washed appears pink colour.

2) Endospore is a tough , non reproductive dormant structure produced by the small no of bacteria .The function is to ensure the survival of a bacterium through the periods of environmental stress.

3)   * Lag phase

* Log phase /exponential phase

* stationary phase

* Death​​​​​​

4) There are 3 ways of horizontal gene transfer in bacteria , transformation , transduction and conjugation .

5) LPS (lipo polysaccharides) or lipoglycans and endotoxins , they are large molecule consisting of a lipid and a polysaccharide contain o -antigen they are found in the outer membrane of gram -negative bacteria .This is localized in the outer layer of the membrane and in non capsulated strains , exposed on cell surface.

Capsule - is a virulence factor because it enhance the ability of bacteria to cause disease .The capsule can protect cell from engulfment by eukaryotic cells .

6) Fimbriae and the pilli are thin protein tubes originating from the cytoplasmic membranes of bacteria .They are found in all gram negative bacteria but not in many gram positive bacteria .It composed of a protein called pilin.

A pili is a hair like appendage on surface of bacteria.

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