Chapter 2- Tools Of The Lab

Question 1

Define media.

Answer 1

A nutrient used to grow organisms outside of their natural habitat.

Question 2

Define inoculation

Answer 2

The implantation of micro organisms into or upon culture media

Question 3

Define culture

Answer 3

The visible accumulation of micro organisms and or on a nutrient medium. Also the propagation of micro organisms with various media.

Question 4

Define incubator

Answer 4

To isolate a sample cultural and a temperature controlled environment to encourage growth.

Question 5

Give examples of clinical specimens that can be used as an inoculum’s

Answer 5

Blood Cerebrospinal fluid sputum urine feces

Question 6

What temperature range is ideal for most pathogens?

Answer 6

Between 20°C and 45°C

Question 7

What is the difference between pure cultures, mixed cultures and contamination?

Answer 7

A pure culture is a container of medium that grows only a single known species or type of micro organism.

A mixed culture is a container that holds two or more identified, easily differentiated species of micro organisms, not unlike a garden plot containing both carrots and onions.

A contaminated culture was once pure or mixed but has since had contaminants or unwanted microbes of uncertain identity introduced into it.

Question 8

Media is classified by what three properties?

Answer 8

Physical state, chemical composition, and functional type or purpose.

Question 9

Define broth and agar

Answer 9

Agar is A polysaccharide found in seaweed and commonly used to prepare solid culture media

Question 10

What are the properties of agar that allow for it successful use in the microbiology laboratory?

Answer 10

Auger is flexible and moldable, and provide the basic framework to hold moisture and nutrients, though it is not itself a digestible nutrient for most micro organisms.

Question 11

Define chemically defined media and complex media. Give examples of each.

Answer 11

Chemically defined media can come in many forms. Some media such as minimal media for fungi, containing nothing more than a few essential compounds such as thoughts and amino acids dissolved in water. Others contain a variety of defined organic or Inorganic chemicals

Complex media contain at least one ingredient that is not chemically definable – not a simple, pure compound and not represented by an exact chemical formula. (Blood, serum, etc)

Question 12

Describe general-purpose media

Answer 12

Grows a broad spectrum, nutrient agar/broth BHI, TSH

Question 13

Describe minimal media

Answer 13

Has few Esencial compounds – salts, amino acids – some defined organic and in organic chemicals

Question 14

Describe enriched media

Answer 14

Fastidious microbes – it needs growth factors/nutrients

Question 15

Describe enrichment media

Answer 15

It encourages growth of desired microbes

Question 16

Describe selective and differential media

Answer 16

Selective media suppresses unwanted microbes, it encourages desired microbes

Differential media distinguishes colonies of different microbes it has a pH indicators

Question 17

Describe reducing media

Answer 17

Contains a substance that absorbs oxygen

Question 18

Describe carbohydrate fermentation media

Answer 18

It contains sugars that can be fermented, has a pH indicator, it’s in a Durham tube.

Question 19

Describe transport media

Answer 19

Used to maintain/preserved specimens before clinical analysis. It’s used to sustain delicate species.

Question 20

What procedures can be utilized to obtain a pure culture?

Answer 20

Aseptic technique

Question 21

Define CFU

Answer 21

Colony forming units

Question 22

How can microbes be identified?

Answer 22

Appearance, biochemical tests.

Question 23

Briefly describe the differences in maintenance and disposal of cultures in a medical laboratory verse a research laboratory

Answer 23

Most medical laboratories have a strict rule about promptly and properly disposing cultures and specimens because they can pose a potential threat or hazard. Teaching and research laboratories still need a proper way to dispose of cultures and specimens however they do not do it so quick Willy. They actually maintain a line of stock cultures that represent living catalogs for study and experimentation.

Question 24

List the four major laboratory safety designations. What type of protection and microbes are associated with each level?

Answer 24

Biosafety level – 1– non infectious bacteria.
Biosafety level – two – mild disease, difficult to contract, genetically modified organisms, lab coat gloves and eye protection necessary!
Biosafety level – three – serious or potentially lethal disease after inhalation, biosafety cabinet to prevent airborne transmission.
Biosafety level – four – high risk of aerosol transmission, severe to fatal disease. Sealed, negative pressure, exhaust air is filtered twice

Question 25

What are the average sizes of viruses, bacteria, protozoan and algae?

Answer 25

Bacteria- 200 nm
Protozoa & algae- 3-4 mm
Viruses- 20-800 nm

Question 26

What is the difference between resolution and magnification? What allows for greater resolution.

Answer 26

Magnification will amplify the image. Resolution is the capacity to distinguish to adjacent points. An oils immersion lens will allow for greater resolution.

Question 27

Defined re-fraction

Answer 27

The bending of light as it passes from one medium to another with a different index of reflection

Question 28

What is refractive index and how does it relate to contrast?

Answer 28

Reflective and DAX refers to the degree of bending that light undergoes as it passes from one medium such as water or glass to another medium such as bacteria cells. The higher the difference and reflective indexes – the more bending of light – the sharper the contrast that is registered by the microscope and the eye.

Question 29

What is total magnification?

Answer 29

The objective lens times the ocular lens.

For example The total magnification of a specimen that’s being viewed through an ocular lens with a 10 X magnification and a objective lens with a 100 X magnification would be 1000

Question 30

What is the purpose of oil immersion

Answer 30

To increase resolution. The oil immersion lens will capture light that would otherwise be lost to scatter and reducing scatter increases resolution

Question 31

No the parts of a light microscope

Answer 31

Ocular is the eyepiece the body holds up the eyepiece the nose piece is what attaches to the objective lenses the mechanical stage is what will hold the slide the arm is the back of the microscope the aperture Diaphragm controls how much light is let in. The babies will hold the field diaphragm lever which is how the light shines through the course focus adjustment knob is on the outside and the fine focus adjustment knob is on the inside both of those are on the side of the arm the stage adjustment knobs are going to be on the side of the stage attached.

Question 32

List the types of microscope he and what light they utilize

Answer 32

Visible light microscope – brightfield, dark field, phase – contrast, differential interference.

Ultra violet rays microscope – fluorescent, confocal.

Electron beam microscopic – transmission electron microscope, scanning electron microscope.

Question 33

What is the difference between Lightfield and dark field microscope he? What accounts for this difference?

Answer 33

The difference is that the dark field microscope contains a stop which is applied to the condenser. The stop blocks all light from entering the objective lens except peripheral light is reflected off the side of the specimen itself.

Question 34

Compare and contrast phase contrast microscopy differential interference contrast microscopy Which allows for a more detailed picture?

Answer 34

They both use light intensities to pass through the object in sept always the difference is that the D I C has additional refinements including two prisms that I had contrasting colors the image so the DIC microscope produces a much better image.

Question 35

Describe fluorescent microscopy

Answer 35

The fluorescent microscope especially modified with an ultraviolet radiation source and a filter that protects the viewers eye from injury. The name of this microscope originates from the use of certain dies and minerals that show fluorescence. For an image to be formed the specimen must be coded with a source of fluorescent fluorescence microscopic he has its most useful applications in diagnosing infections caused by specific bacteria protozoans and viruses

Question 36

Describe TEM and SEM

Answer 36

TEM is transmission electron microscope ups and they are the method of choice for viewing the detailed structure of cells and viruses. Because electrons cannot penetrate thick preparations the specimen is sectioned into extremely thin slices. The slices are stained or coated with metals that will increase contrast.

S EN is the scanning electron microscope and it provide some of the most dramatic and realistic images this is instrument is designed to show an extremely detailed three dimensional view of all kinds of objects that object is created with metal coated special specimen with electrons while scanning back-and-forth over it

Question 37

Why must a specimen be prepared?

Answer 37

Safety, appropriate dye used to allow best view

Question 38

Define smear

Answer 38

Spreading a thin film made from a liquid suspension of cells on a slide and air drying it

Question 39

How is a microbe fixed to a slide?

Answer 39

Putting the slide face up through the flame three or four times that will simultaneously kill the specimen and secures it to the side

Question 40

What is the difference between a basic and acidic die? Which one is in anion? Cation? Which one is used for positive staining? Negative staining?

Answer 40

Cation is basic and they have positive charge so they are used for negatively charged cell parts

Anion is acidic and they have a negative charge so they will attract positively charged cell parts

Question 41

What is the difference between a simple stain and a differential stain?

Answer 41

Simple stains require only a single guy and an un-complicated procedure. Differential stains used to differently colored dyes caught a primary die and the counterstain to distinguish between cell types or parts.

Question 42

What is a mordant?

Answer 42

The mordant in the Gram stain is iodine.

Question 43

Explain the process of grand staining. What color are gram-positive organisms? What color are Graham negative organisms?

Answer 43

Prepare heat fix slide.
Drop a few drops of crystal violet stain on to the fixed slide.
Drop a few drops of iodine and let stand for 20 seconds. This will fix the crystal violet to the the peptidoglycan if the molecule is gram positive
Drop decolonizer onto slide
Drop contrast dye onto slide (counterstain)
View under microscope

Gram positive will be purple
Gram negative will be pink

Question 44

What is acid fast? What are two genera of acid-fast bacteria? Explain acid-fast protocol. What color are acid-fast bacteria? Non-acid fast bacteria?

Answer 44

Acid-fast bacteria is pink. Non-acid-fast bacteria is blue. This stain is used to detect myco-bacterium tuberculosis in specimens. These bacterial cell walls hold fast to the dye (carbon fuchsia) even when washed with an acid or alcohol containing substance

Question 45

Describe endospore stain.

Answer 45

It is similar to the acid-fast stain because a guy is forced by heat into resistant bodies called spores. The stain is designed to distinguish between spores in the cells that they come from. Endospores will show up red and vegetative cells will show up blue

Question 46

Discuss capsule staining

Answer 46

It is often negatively staying with India ink or it may be demonstrated by special positive things. The background of the stain is maroon while there are light pink cocci with another circle inside the cocci

Question 47

What are the five I’s of culturing microbes? Describe each.

Answer 47

Inoculation, incubation, isolation, inspection, identification.

Inoculation is when the sample is placed into a container of sterile medium containing appropriate nutrients to sustain growth.

Incubation is when an incubator is used to create the proper growth temperature and other conditions.

Isolation is when microbes may take the form of separate colonies on solid media or turbidity in broths.

Inspection is when the colonies or broth cultures are observed macroscopically for growth characteristics color, texture, size, that could be useful in analyzing the specimen contents.

Identification is the major purpose of the five I’s. Information used an identification can include relevant data already taken during initial inspection and additional test that further describe and differentiate the microbes.