Micro Lab exam

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1

Final/Total Magnification

Total magnification of the object is calculated by multiplying the magnification of the ocular (usually 10X) by the magnification of the objective lens.

2

Oil immersion

Has the highest magnification (97 X to 100 X) most important lens in micro

3

steps of aseptic techinque

  1. sterilize loops by holding the wire in the flame till it is red hot
  2. while holding sterile loop and bacterial culture, remove cap
  3. briefly pass mouth of tube through flame 3 times before inserting loop for inoculum
  4. get loop full of culture
  5. heat mouth of tube and replace cap
4

Aseptic Technique

used to exclude contaminates

5

Broth

provide large numbers of bacteria in a small space, are easily transported

6

Agar Slant

Test tubes containing solid culture media that are solidified at an angle, provide solid growth surface.

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Deeps

When agar solidifies at the bottom of test tube, often used when bacteria requires less O2

8

Steps to prepare slides for staining

  1. Apply primary stain(crystal violet)
  2. Apply mordant (grams iodine)
  3. Apply decolorizing agent ( Ethanol or ethanol acetone)
  4. Apply secondary stainer/ Counterstain ( Safranin)
9

Defined Media

Medium whose exact composition is known

10

Complex Media

The exact chemical composition varies slightly from batch to batch

11

Why some cells stain positive and some negative in gram staining

Gram + has a thick peptidoglycan wall that gets stained purple from the crystal violet, Gram - has a thin peptidoglycan wall that does not retain stain and is counter stained pink by safranin .

12

Endospores

  • Resting structure formed inside some bacteria
  • Formed when essential nutrients or water are not available
  • Do not metabolize, resistant to heat, various chemicals, and many harsh environmental conditions
  • Use Schaeffer- Fulton endospore stain
13

Capsule

  • An outer, viscous covering on some bacteria composed of a polysaccharide or polypeptide
  • Simple stains will not adhere and are clear, = Negative
14

Flagella

  • Used for cellular locomotion
  • can only be stained after being coated with mordant which increases diameter
  • 2 types Peritrichous ( all around bacteria) , and Polar ( at one or both ends of cell)
15

Selective media

Contains chemicals that prevent the growth of unwanted bacteria without inhibiting growth of desired organism

16

Enrichment Media

Contains chemicals that enhance the growth of desired bacteria. Other bacteria will grow but growth of desired bacteria will increase

17

Differential Media

A solid culture medium that makes it easier to distinguish colonies of the desired organism

18

Streak plate

Method of isolating a culture by spreading microorganisms over the surface of a solid culture medium

19

Spread plate

A plate count method in which inoculum is spread over the surface of a solid culture medium

20

Pour plate

A method of inoculating a solid nutrient medium by mixing bacteria in the melted medium and pouring the medium into a Petri dish to solidify

21

Simple Microscope

Consists of the biconvex lenses, essentially magnifying glasses

22

Brightfield compound microscope

Shows objects in a bright field, is used most often

23

Ocular Lens

eye piece, remagnifies the image formed by the objective lens

24

Body tube

Transmits image from objective lens to the ocular lens

25

Objective lens

Primary lens that magnified the specimen

26

Mechanical stage

Holds microscope slide

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Condenser

focuses light through specimen

28

Diaphragm

controls amount of light entering the condenser

29

Illuminator

light source

30

Fine focusing knob

used for focusing specimen between the objective lens and the specimen

31

Light intensity

Adjusts current to lamp

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Focal point

Where the image is formed when light converges at one point

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Spherical Aberration

light passes through once region of the lens that has a different focal part of the lens. multiple focal points

34

Chromatic Aberration

lens may give each wave length of light a different focal point

35

nutrient broth

Commonly used liquid complex medium, when agar is added it becomes solid = nutrient broth

36

lAgar

An extract from marine red algae, only few microbes can degrade it

37

Steam sterilization/autoclaving

Uses steam to sterilize, material placed in autoclave and heated to 121oC at 15 pounds of pressure for 15 min

38

Petri plate

Contain solid medium, provide larger surface area for examination of colonies

39

Inoculation

Microbes introduced into a culture medium to initiate growth

40

Turbid

Cloudy as a result of bacterial growth

41

Colony

Population of cells that arise from a single bacterial cell

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Colony forming unit

A group of microbes of some colony attached to each other

43

Heat fix

Pass through bunsen burner flam several times or place on s 60oC slide warmer for 10 min may not kill all bacteria

44

Chemically fix

cover smear w/ 95% methanol for 1 min

45

Chromophore

Ion that is colored

46

Basic stain

Positive ion

47

Acidic stain

Negative ion

48

Simple stain

Procedure that uses only one stain

49

Direct stain

Simple stain that stains the bacteria

50

Negative stain

Simple stain that stains the background but not the bacteria

51

Virulence

disease causing ability

52

Motile

Ability to move from one position to another

53

Fermentation tube

used to detect acid and gas production from carbs

54

MRVP test

Used to distinguish organisms that produce large amounts of acid from glucose or other organisms that produce neutral production acetone

55

Structural stains

Can be used to identify and study the structure of bacteria