Micro- The Methods of Microbiology

Set: Micro- The Methods of Microbiology

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All 57 Terms

	Term	Definition
	microscopy	the construction and use of microscopes. it began in the 17th century with Antony van Leeuwenhoek and his little hand held microscopes. since its begining, there have been many spectacular advances
	culture	provide microorganisms with suitable conditions for their growth and multiplication
	magnification	enlargement of the image....one of the factors that we depend on microscopes for
	contrast	refers to the difference in light intensity, this is created by light absorption
	stains	dyes that increase contrast by binding selectively to certain cells or certain parts of them in order to obtain enough contrast to obtain useful images of bacteria and most microorganisms.
	resolution	the ability to destinguish detail within an image. this is a property of the lens system used to view the specimen
	resolving power	the closest that two points can be to one another and still be distinguished as being separate. this is the way that resolution is measured. three factors that determin the ___ of the microscope are: the size of its objective lens ( the microscopes first magnifying lens), the wavelength of the light passing through the specimen, and the refractive index of the material between the objective lens and the specimen.
	compound microscopes	microscopes that have two lenses, an ocular lens and a corrected lens (several individual lenses bonded together)
	basic dye	an ionic dye that has a positive charge and is attracted to microorganisms that carry a slightly negative charge
	acidic dye	an ionic dye that has a negative charge and are attracted to positively charged parts of the cell...like proteins
	mordant	a compound that is not a dye, but is important to the some staining procedures. It intesifies staining by increasing a cell's affinity for a dye. sometimes they are used to coat appendages, making them thicker and therefor more readily visible when stained.
	simple stain	use of basic dyes to make cells visible. they stain all cells that absorb that cell the same color.
	differential stain	this is a stain intended to distinguish between two types of microorganisms. three steps: primary staining, destaining, and counterstaining....a mordant may also be applied. two stains that are used extensively in microbiology are the Gram stain and the acid-fast stain.
	primary staining	the same as simple staining and the first step in differential staining
	destaining	a treatment that removes stains from certain cells, the second step in differential staining
	counterstaining	the application of another dye to reveal the cells or parts of cells that have been destained, the third step in differential staining.
	gram stain	the stain that leaves gram-positive bacteria purple from the gentian violet, gram negative bacteria lose their purple color because of the safranin and become red or pink, and the mordant that is used is iodine
	acid-fast bacteria	the bacteria, mycobacterium tuberculosis, which are stained by the acid-fast stain. all other bacteria and host tissues become destained, but their presence in a specimen can be detected by counter-staining. These bacteria resist destaining because they have a waxlike material in their cell envelop.
	acid-fast stain	the stain that leaves all cells red, until the mordant (heating all cells for 5 minutes) drives the color into the cells, HCl removes red dye from all cells except for the acid-fast bacteria, and the counterstain methylene blue colors all the bacterial cells and host tissues
	flagella stain	this stain reveals the number and arrangement of flagella on bacteria, which is vital for identification. this specific part of a microbial cell is too thin to be visible by light microscopy, but flagella staining renders them visible by adding material that sticks to them. the thickened structure is then stained with dye. This process helps reveal the number and the arrangement fo flagella on bacteria, which helps to identify the species.
	negative stain	staining that is intended for bacteria which contain a capsule. a capsule is colorless and invisible if unstained. The capsule is identified because only it remains uncolored. the india ink that is added consists of carbon paticle which are unable to penetrate the capsule, so it blackens the entire background
	culture	to cultivate, to do experiments with microorganisms
	pure culture	a common culture that consists of a single type of microorganism derived from a single cell...they rarely exist this way in nature, this must be obtained artificially
	mixed culture	often found in the natural environment, there are many different microorganisms living together
	clone	descendents of a single organism
	sterilization	elimination of all organisms, necessary when trying to obtain a pure culture
	medium	the liquid or solid material that supplies nutrients to the culture
	Moist heat sterilization	sterilization by steam. more effective than dry heat.
	Dry heat sterilization	heating in an over or over direct heat in order to sterilize something
	autoclave	a pressurized container designed to sterilize materials with moist heat. this resembles a larger version of an ordinary home pressure cooker.
	streak plate method	the easiest and most commonly used method of diluting microbial populations. a population is picked up with a sterile wire inoculation loop, and is dilluted by moving the loop back and forth on the surface of the agar-solidified medium in a petri dish or plate. as the loop is streaked back and forth over the surface, fewer and fewer microorganisms are deposited on the surface. then the loop is sterilized in the flame and used to streak the plate again. this time the streaks will overlap the first set of streaks so that some of the microbial cells are dragged onto a freash, sterile region of the surface. repeating this process several times sufficiently dilutes the microbial population so that individual cells are deposited separately on the agar surface.
	incubate	to grow in a warm suitable place....used on plates in order to form colonies out of the individual cellsserial dilutions
	multistep dillution	the preactical step to ensuring that the dilution for your pour and spread plate methods to ensure that you do not have a suspension with over 10^9 cells per mililiter.
	saline	salt; the solution that is used in the dilution process. 1 mL of cells is added to 9 mL of this solution. this process is repeated several times...twice for dilluted 100-fold, six it has been diluteda million fold (10^6)
	pour plate method	the method in which the dilluted sample is added to melter agar containing medium, mixed, and poured into a petri dish. there is no assurance that these cultures will be pure. this as well as the spread plate methods usually produce more isolated colonies than the streak plate method...there fore they are preferred when isolating a minority strain from a mixed population
	spread plate method	the method in which the diluted sample is poired onto the surface of an agar-solidified medium in a plate and spread evenly with a sterile glass rod. there is no assurance that these cultures will be pure. this as well as the pour plate methods usually produce more isolated colonies than the streak plate method...there fore they are preferred when isolating a minority strain from a mixed population
	defined medium	a medium that is prepared from pure chemicals, so its exact chemical composition is known. a specific type of this media is known as a minimal medium which has just enough ingredients to support growth/
	complex medium	a medium that is made from extracts of natural materials, such as beed, blood, casein (milk protein), yeast, and soybeans. These extracts all contain large numbers of components, so their precise chemical composition is not known.
	broth	a liquid complex medium
	peptone	partially hydrolyzed casein
	nutrient broth	one of the most often used complex medium broths that contains hundreds of mixtures and is already formulated into specific complex media.
	nutrient agar	a solidified form of one of the most often used complex mediums that contain hundreds of mixtures and is already formulated into specific complex media
	selective media	media which favors the growth of particular microorganisms. they are used to isolate or detect the favored species in a complex mixture of other microorganisms. some contain toxic chemicals which inhibit the growth of some microorganisms but not others. other selevtive media employ an extreme pH value or an unusual carbon source to favor growth of a particular microorganism
	differential media	media that are used to identiufy microorganisms by the appearance of their colonies. example: streptococcus pyogenes (the bacteria that causes strep throat) can be identified by blood agar because on this medium, S. pyogenes colonies are surrounded by a clear zone because they lyse (destroy by bursting) nearby red blood cells
	selective-differential media	media that are both selective and differential, MacConkey agar is an example, detects strains of Salmonella and Shigella. it is selective because it contains crystal violet and bile salts, which inhibit the growth of many bacteria, but not coliform bacteria and species of Salmonella and Shigella. it is differential because it contains neutral red (a pH indicator) and lactose (milk sugar). coliform bacteria make acid from lactose and the acid turns neutral red (which seems colorless at the normal pH), so colonies of coliform bacteria become brick red. whereas the colonies of salmonella and shigella remain uncolored.
	enrichment culture	a medium which is used to isolate a particular microorganism or type of microorganism from a large, complex natural population. environmental biologists often use enrichment cultures
	strict aerobes	cannot grow without oxygen
	strict anaerobes	cannot grow in the presence of oxygen. for them, oxygen is toxic
	facultative anaerobe	can grow with or without oxygen
	aerotolerant anaerobes	anaerobes that can tolerate oxygen, but prefer not to have it around. they do not use oxygen
	microaerophile	it needs oxygen, but can only tolerate low concentrations of it.
	thioglycolate	a chemical medium that allows many anaerobes to grow readily in certain test tubes. these chemicals react with oxygen, keeping the lower part of the tube oxygen-free.
	stock culture	cultures that are maintained for study and reference
	desiccation	one form of preserving a culture which involves the removal of all water
	lyophilization	freeze-drying....a common way to desiccate a stock culture. a liquid culture of the microorganism is poired into a small test tube, skim milk is often added to protect the cells during the drying process. then the mixture is frozen with dry ice and exposed to a vacuum. the test tube is tightly sealed by fusing the neck shut with a flame. once the process is complete, the culture can be stored at room temperature
	ultra-deep freeze	a freezer that is capable of maintaining especially low temperature, which is used to preserve stock cultures by low-temp storage. The substance is often mixed with substances that minimize freeze-killing (skim milk, glycerol, dimethyl sulfoxide). the test tube is then sealed amd stored below -50 C....this can also occur in liquid nitrogen
	tissue cultures	cultures of animal cells that are used because the organism cannot be grown without the living tissue. the ricksettsia and chlamydia bacterial families and viruses can be cultured only within a living cell. and Treponema pallidum (syphilis) and Mycobacterium leprae (leprosy) need to grow in rabbits and armadillos respectively.

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Terms	57
Creator	nicholhm
Created	September 14, 2007
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nicholhm : Changed facultative anaerobes → can grow with or without oxygen to facultative anaerobe → can grow with or without oxygen

nicholhm : Changed differential stain → use are stains intended to distinguish between two types of microorganisms. three steps: primary staining, destaining, and counterstaining....a mordant may also be applied. two stains that are used extensively in microbiology are the Gram stain and the acid-fast stain. to differential stain → this is a stain intended to distinguish between two types of microorganisms. three steps: primary staining, destaining, and counterstaining....a mordant may also be applied. two stains that are used extensively in microbiology are the Gram stain and the acid-fast stain.

nicholhm : Changed mixed cultures → often found in the natural environment, there are many different microorganisms living together to mixed culture → often found in the natural environment, there are many different microorganisms living together

nicholhm : Changed mordants → a compound that is not a dye, but is important to the some staining procedures. It intesifies staining by increasing a cell's affinity for a dye. sometimes they are used to coat appendages, making them thicker and therefor more readily visible when stained. to mordant → a compound that is not a dye, but is important to the some staining procedures. It intesifies staining by increasing a cell's affinity for a dye. sometimes they are used to coat appendages, making them thicker and therefor more readily visible when stained.

nicholhm : Changed disiccation → one form of preserving a culture which involves the removal of all water to desiccation → one form of preserving a culture which involves the removal of all water

nicholhm : Changed microaerophiles → need ovygen, but can only tolerate low concentrations of it. to microaerophile → it needs oxygen, but can only tolerate low concentrations of it.

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