How does the structure of a Gram-negative organism contribute to its virulence?

How does the structure of a Gram-negative organism contribute to its virulence?

Key Points. The outer membrane of Gram-negative bacteria contains lipopolysaccharides, proteins, and phospholipids. The lipopolysaccharide component acts as a virulence factor and causes disease in animals. More virulence factors are harbored in the periplasmic space between the outer membrane and the plasma membrane.

Do Gram-negative bacteria have Periplasm?

Gram-negative bacteria are surrounded by two membrane bilayers separated by a space termed the periplasm. The periplasm is a multipurpose compartment separate from the cytoplasm whose distinct reducing environment allows more efficient and diverse mechanisms of protein oxidation, folding, and quality control.

What determines if a bacteria is Gram-negative or Gram-positive?

In 1884, a bacteriologist named Christian Gram created a test that could determine if a bacterium had a thick, mesh-like membrane called peptidoglycan. Bacteria with thick peptidoglycan are called gram positive. If the peptidoglycan layer is thin, it’s classified as gram negative.

Which structure accounts for the different results of the Gram stain?

The two key features that lead to the differing visualization properties of Gram positive and Gram negative species are the thickness of the peptidoglycan layer and presence or absence of the outer lipid membrane.

Which of the following is the correct order of the use of the four reagents in a Gram stain?

The stains are applied to a smear of bacteria on a microscope slide in the following order: crystal violet, Gram’s iodine, decolorizing agent, and safranin. The color of Gram-negative and Gram-positive bacteria after the application of each reagent is presented in Table I.

What makes Gram-negative bacteria more virulent?

Gram-negative bacteria produce a variety of virulence factors, including toxins, fimbria, flagella, adhesins, invasins, and other secretory molecules, such as effectors and extracellular matrix, which are required for infection. Some virulence factors induce damage or death of host cells, while others …

Is periplasm in Gram-positive and Gram-negative?

The periplasm is a concentrated gel-like matrix in the space between the inner cytoplasmic membrane and the bacterial outer membrane called the periplasmic space in gram-negative bacteria. Using cryo-electron microscopy it has been found that a much smaller periplasmic space is also present in gram-positive bacteria.

Is periplasm Gram-positive or negative?

Gram-negative bacteria
Cellular component – Periplasm The periplasm is the space between the inner and outer membrane in Gram-negative bacteria. In Gram-positive bacteria a smaller periplasmic space is found between the inner membrane and the peptidoglycan layer.

What is the correct order of staining reagents in Gram staining?

How are Gram negative bacteria classified?

Gram-negative bacteria are classified by the color they turn after a chemical process called Gram staining is used on them. Gram-negative bacteria stain red when this process is used. Gram-positive bacteria. Gram-positive bacteria stain blue when this stain is applied to them.

Which sequence lists the steps of the Gram stain in order?

The performance of the Gram Stain on any sample requires 4 basic steps that include applying a primary stain (crystal violet) to a heat-fixed smear, followed by the addition of a mordant (Gram’s Iodine), rapid decolorization with alcohol, acetone, or a mixture of alcohol and acetone and lastly, counterstaining with …

What is correct order of Gram staining?

The stains are applied to a smear of bacteria on a microscope slide in the following order: crystal violet, Gram’s iodine, decolorizing agent, and safranin.