Observing Microorganisms Through a Microscope (chapter 3)
Microorganisms are measure in
LM = > or Micrometers um (10-6 m) is equal to 0.000001m.
EM = < or Nanometers um (10-9 m)
A virus measures 100 nm in length. What is its length in um?
- lm=106 mm
- lm= 10 9mm
- lm= 1012 m
- lm= 10-6m
- micro meter
- nano meter
- pico meter
A microorganism measures 5 um in length. Its length in mm would be
Simple microscope consists of
A compound microscope has
Simple staining is necessary to improve contrast in which microscope?
compound light microscope
The most common microscope used in microbiology is
The compound light Microscope
The total magnification of an object is calculated:
Multiplying the Ocular magnification X Objective magnification by the magnification of the ocular lens.
10x x 40x = Total magnification 400x
The compound light microscope uses
The maximum resolution, or resolving power
(ability to distinguish between two points)
Compound light microscope is 0.2 um,maximum magnification is 2000x.
Specimens are stained to increase the difference between
The refractive indexes of the specimen and the medium
Immersion oil is used with the 100x objective lens of the compound light microscope to ______.
Reduce light loss between the slide and lens
Brightfield illumination is used for
Used for stained smears
Which microscope produces an image of a light cell against a dark background; internal structures are presence of extremely small organisms.
Which of the following types of microscopy is most useful for viewing the internal structures of unstained specimens? It brings direct and reflection.
Phase Contrast Microscope
Which microscope provides a colored,three-dimensional image of the object being observed.
Differential Interference Contrast Microscope
Which microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light?Allows organisms to be identified base on antigens,even if the organisms are inside a cell.
Which microscope is used a computer to process the images,two-dimensional three- dimensional images of cells can produced.
Which microscope is based on the Interpretation of sound waves through a specimen. It is used to study living cells attached to surfaces such as cancer cells,artery plaque,and biofilms.
Scanning Acoustic Microscopy
A student is observing an object that displays the internal detail on virus at great magnification. Which type of microscope is used for this image?
Transmission Electron Microscopy
A microscopist is studying the surface pores on a bacterial specimen.
Which microscope provides the best three-dimensional surface structure image?
Scanned -Probe Microscopy
What is the 3 lenses system in a 10 pound LM?
- Ocolar lenses
- Condenser lenses
- Objective lenses
2 Types of electron microscopes?
- Scanning- SEM
Electron Microscopes use?
A beam of electrons instead of light.
Preparing means coloring a microorganism with a dye to make some structures more visible.
Fixing uses heat or alcohol to kill and attach microorganism to a slide.
A smear is a thin film of material used for microscopic examination.
Bacteria are negatively charged, and the colored positive ion of a basic dye will stain bacterial cells.
The colored negative ion of an acidic dye will stain the background of a bacterial smear;a negative stain is produced.
Preparing Smears for Staining
What are 2 types of staining?
- Simple Stain
- Simple stain is an aqueous or alcohol solution of a single basic dye.
- It is used to make cellular shapes arrangements visible.
- A mordant may be used to improve bonding between the stain and the specimen.
- Such as the Gram stain and acid-fast stain,differentiate bacteria according to their reactions to the stains.
- The Gram stain procedure uses a purple stain (crystal violet),iodine as a mordant,an alcohol decolorizer, and a red counterstain.
- Gram-positive bacteria retain the purple stain after the decolorization step;gram-negative bacteria do not and thus appear pink from the counterstain.
- Acid-fast microbes,such as members of the genera Mycobacterium and Nocardia,retain carbolfuchsin after acid-alcohol decolorization and appear blue.
What are the 2 types of differential stains?
- Gram Stain ( positive,negative)
- Acid Fast Stain
Gram Positive Cell Wall is ?
Thicker than gram negative
What are 3 types of dyes ?
- Methylene (Blue)
- Crystal (Violet)
- Safrarin (Bright Red)
Gram Stain and Acid Fast Stain is used for ?
Special Structone Stain is used for?
What color is Gram postive?
What color is Gram negative?
Gram postive - purple
Gram negative- red
Gram postive is kill by?
Gram negative is?
- Penicillin and detergents
- Resistant to antibiotics
What two Acids do not respond to gram stain?
Mycobacterium: mycolic acid
Nocardia: mycolic acid
What is mordants used for?
To hold stain or coat the specimen to enlarge. (EX: Iodine)
What are the 3 characteristics of simple stain?
- Cell arrangement
View details of specimen with dye.
Negative staining is used to make microbial capsules visible.
The endospore stain and flagella stain are special stains that color only certain parts of bacteria.
What are the 3 stains of special structural stain?
What does endospores produce?
Acid-Fast Stain Binds?
Strong only to bacteria that have waxy material in their cell walls.
You are performing a Gram stain on gram positive bacteria and you stop after the addition of the first dye. What is the appearance of the bacteria at this point?
You are performing a Gram stain on gram negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point?
You are performing a Gram stain on gram negative bacteria and you stop after the descolorizer. What is the appearance of the bacteria at this point?
You are performing a Gram stain on gram positive bacteria and you stop after the addition of the counterstain. What is the appearance of the bacteria at this point?
Which type of stain is useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection?
Which step in the Gram stain is the critical step in differentiating gram positive cells from gram negative cell?
Which of the following steps of the Gram stain are in correct order?
a) Crystal Violet
c) Alcohol acetone
You find colorless areas in cell in a gram stained smear. What should you apply next?
an endospore stain
Which microscope is used to see intracellular detail in a living cell?
The courterstain used in the Gram stain is a basic dye