Upgrade to remove ads
Only $35.99/year

Microorganisms Lab Final

Terms in this set (134)

Agar
The most common solidifying agent used in culture media is agar.
Agar, which chemically is a polymer of the monosaccharide galactose, is extracted from marine algae and sold as a purified powder. Agar has properties which make it an ideal solidifying agent: (1) it is readily rehydrated; (2) it is easily sterilized by heating; (3) it is not digested by most species of bacteria; and (4) it can be incubated at a wide range of temperatures without melting. Because its melting point is 94oC, agar may be melted by placing it in boiling water. Once melted, agar will remain a liquid until its temperature cools to below 42oC. At this temperature, many types of bacteria can be added to liquid agar without harming them. Once solidified, agar will not liquify until heated to 94oC; this allows medium containing agar to be incubated at temperatures greater than 42oC without melting. Agar is usually used at a concentration of 1.5%, but the concentration can be varied to give media of different consistencies.
amoeboid movement -
move by means of cytoplasmic extensions known as pseudopodia. This type of motility is known as amoeboid movement
antibiotic-
Antibiotics, the second class of antimicrobial drugs, are produced by microorganisms and are lethal or inhibitory to other microorganisms.
antibody-
An antibody molecule is comprised of four polypeptides; two identical heavy chains and two identical light chains connected by a disulfide bond. An antibody molecule is Y-shaped, with two antigen binding sites at the tips of the Y. The light and heavy chains both contribute to the antigen binding sites. The areas on the antibody that recognize a unique antigen are called variable domains and are located at the amino-terminal end. The variable regions show considerable variation in the amino acid composition. The antibody base is composed of constant domains which are located at the carboxyl-terminal end.
The Y shape of an antibody can be divided into Fab and Fc regions. Fab regions contain the variable domain that binds to a specific antigen. The Fc regions contain a binding site for endogenous Fc receptors on the surface of lymphocytes, and is also the binding site for secondary antibodies
antigen-
AntigenThe antigen is a molecule that is capable of binding to the product of immune response, such as
antibodies. Immunogen is a molecule that is capable of binding to the components of an immune system and thereby triggering an immune response. Therefore, an immunogen is necessarily an antigen, but antigen may not necessarily be an immunogen.
antiseptic-
Antiseptics stop the growth of microorganisms but are mild enough to be used on living tissue
aseptic techniques -
The methods used to minimize contamination are known collectively as aseptic techniques. These methods require continual practice to become proficient enough that unnecessary contamination can be avoided. Throughout this course, you should follow instructions carefully and pay close attention during demonstrations, so that you can learn proper aseptic techniques.
Budding-
budding, which is a type of asexual reproduction. The parent cell forms a protuberance or bud, and after the parent cell's nucleus divides, one of the daughter nuclei migrates into the bud. As the bud enlarges, it will eventually separate from the parent cell and start to form its own bud.
catalase-
The enzyme catalase catalyzes the reaction of hydrogen peroxide into oxygen and water (H2O2 -> H2O + O2). Hydrogen peroxide is a harmful byproduct of respiration. Catalase serves to protect the cell from oxidative damage. It is present in most aerobic bacteria. The presence of catalase can be determined by the production of bubbles of gas when bacterial culture is added to hydrogen peroxide. No bubbles are produced in catalase-negative organisms.
cilia-
These microbes move by means of rhythmically beating, hairlike structures known as cilia. Cilia are shorter and more numerous than flagella. In addition to movement, cilia may also be used to sweep food into mouth-like openings of the cell. Ciliates are common in freshwater, have a variety of shapes and colors, and are cytologically very complex.
Colony-
A microbial colony is defined as a visible cluster of microorganisms growing on the surface of or within a solid medium, presumably cultured from a single cell.
contrast -
Contrast - What is the difference in lighting between adjacent areas of the specimen? Contrast is related to the illumination system and can be adjusted by changing the intensity of the light and the diaphragm/pinhole aperture. Also, chemical stains applied to the specimen can enhance contrast.
dilution blank-
Dilutions require the aseptic transfer of a known volume of a sample into a dilution blank containing a known volume of sterile buffer or water.
dimorphic-
Some fungi may exist in either the yeast form or the mold form depending on environmental conditions; these are referred to as dimorphic.
Disinfectant-
as disinfectants, if they are used to kill or stop the growth of pathogens on inanimate objects. They may not necessarily sterilize objects, but they reduce the number of microbes to safe levels
Other sets by this creator