Question

Microbiology Questions??

1. Which of the following statements is true about the bacterial DNA represented at arrows "A" and "B" in in this image?

   		The DNA at B is not essential for the cell to grow and function.
   		The DNA at B is the cell's nucleus.
   		The DNA at B may contain genes that make the bacteria resistant to penicillin.
   		The DNA at A is the cell's nucleus.
   		The DNA at B is packaged using histone proteins
   		The DNA at B contains the cell's genes for normal operation of the cell.

QUESTION

One striking difference between the prokaryotic and eukaryotic plasma membrane is:

		Production of ATP via the Electron Transport Chain occurs on the prokaryotic plasma membrane, but not the eukaryotic plasma membrane.
		Prokaryotic plasma membranes contain peptidoglycan, and eukaryotic plasma membranes do not.
		Prokaryotic membranes do not contain phospholipids, and eukaryotic membranes are composed primarily of phospholipids.
		Regulation of transport of substances into and out of the cell occurs at the prokaryotic membrane, but not at the eukaryotic plasma membrane.

QUESTION

Which of the following is true regarding the gram-positive and gram-negative cell walls.

		Only gram-positive cells have teichoic acid and only gram-negative cells have porins.
		Both gram-positive and gram-negative cells have an outer cell membrane.
		Only gram-positive cells have peptidoglycan and only gram-negative cells have lipopolysaccharide.
		Both gram-positive and gram-negative cells have a thick layer of peptidoglycan.

Answer 1

2) The correct answer is-

b- Prokaryotic plasma membranes contain peptidoglycan, and eukaryotic plasma membranes do not.

This is because both the prokaryotic and eukaryotic cells have a plasma membrane which is a double layer of lipids that separates the cell interior from the outside environment. In prokaryotes, along with plasma membrane, there is a peptidoglycan layer which is absent in the eukaryotes.

3) The correct answer is-

c- Only gram-positive cells have peptidoglycan and only gram-negative cells have lipopolysaccharide.

In the Gram-negative Bacteria, which do not retain the crystal violet stain, the cell wall is composed of a single layer of peptidoglycan surrounded by a membranous structure called the lipopolysaccharide. In the Gram-positive Bacteria, which retains the crystal violet stain, consists of several layers of peptidoglycan.

1)- The diagram is not given