General Microbiology - are referred to as"cocci"...

Info icon This preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon
General Microbiology GENERAL Bacteria are unicellular microorganisms having a variety of characteristics allowing their classification. One major classification scheme is based upon their staining properties using the "Gram stain" procedure. In this procedure, heat-killed bacteria are exposed to the purple dye crystal violet and iodine. This combination forms a dye complex in the bacterial cell wall. Treatment of the stained bacteria with a decolorizer like ethanol will wash away the dye complex from some bacteria but not others. Bacteria that retain the crystal violet-iodine complex appear purple and are called "Gram-positive". Bacteria that lose the dye complex can be counterstained with the red dye saffranin so that they appear red. These bacteria are called "Gram-negative". The basis of the Gram reaction lies within the structure of the cell wall, described below . Bacteria also come in many different shapes. Spherical shapes
Image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 2
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: are referred to as "cocci" while elongated cylinders are called "bacilli" or "rods". Some bacteria are slightly elongated cocci and these are referred to as "coccobacilli". Even other bacteria have a corkscrew-like appearance; these spiral forms are often called "spirochetes". Individual cells may also be arranged in pairs or clusters or chains. Thus, may morphologies are possible and these can be useful for the identification of bacterial genera. ( Click here to see a bacterial classification flowchart ). The ability of a bacterium to cause disease is known as its virulence. Factors involved in determining virulence potential are discussed here . In terms of the medical aspects of bacterial structure , we are most interested in those features that interact with the host. These features are found predominantly on the outer surface of the bacterial cell. This page will describe some of these features....
View Full Document

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

    Student Picture

    Kiran Temple University Fox School of Business ‘17, Course Hero Intern

  • Left Quote Icon

    I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern