Which of the following is not a factor in considering a good microscope?

TYPES OF MICROSCOPE BASED ON SOURCE

This type of microscope utilizes visible light; uses light waves and mirrors

A subtype of light microscope which has short focal length and only has 1 lens that magnifies up to 300x

A subtype of light microscope which has 2 sets of lenses which can magnify up to 1000x

This type of microscope uses electron beams as energy source. It has higher magnification and resolving power than its counterpart. 

It is used for viewing objects smaller than 0.2 mm in diameter. 

In a vacuum

MICROSCOPES UNDER LIGHT MICROSCOPE

MICROSCOPES UNDER LIGHT MICROSCOPE

Objects under study are darker. The microscopic field is brightly lit. 

For gross morphology, e.g. Bacillus anthracis and its cerebrospinal fluid

MICROSCOPES UNDER LIGHT MICROSCOPE

Objects under study are luminous. The microscopic field is dark. 

For specimens that are invisible in the ordinary light, those that cannot be stained by standard methods, and those that are distorted by staining. 

MICROSCOPES UNDER LIGHT MICROSCOPE

The principle behind this is based on variations in the refractive indices (measure of bending or refracting of a beam of light on entering a denser medium) 

In using this microscope, it is not necessary to fix or stain cells. 

There is detailed examination of the internal structure of the specimen. 

For instance, unstained epithelial cells are observed under this microscope.

MICROSCOPES UNDER LIGHT MICROSCOPE

The principle for this is based on variations in the refractive indices.

Advantage: No diffraction halo associated with phase contrast

Disadvantage: The three-dimensional appearance may not represent reality.

>No diffraction, a little bit distorted but better view of the specimen.

MICROSCOPES UNDER LIGHT MICROSCOPE

This makes use of fluorochromes. 

This microscope visualizes specimens that fluoresce (glow/shine), used for the detection of immunological reactions

Fluorescence Microscope: Direct vs Indirect Immunofluorescence

MICROSCOPES UNDER LIGHT MICROSCOPE

This microscope is useful for thick specimens like biofilms. Used to visualize structures.

 MICROSCOPES UNDER LIGHT MICROSCOPE

This microscope is used for examining living cells within intact tissues. 

However, it is currently limited to advanced clinical and research laboratories. 

MICROSCOPES UNDER ELECTRON MICROSCOPE

MICROSCOPES UNDER ELECTRON MICROSCOPE

Observing the ultrastructure in thin section of the cells

This microscope can project images in a much higher resolution up to the atomic level of thinner objects.

It is used to EXAMINE VIRUSES. Viruses caught in thin sections.

MICROSCOPES UNDER ELECTRON MICROSCOPE

Observing the surface features of viruses and cells.

This microscope REVEALS A 3-D IMAGE.

In examining microorganisms, it is advantageous to use living specimens when you are looking for motility and cellular processes.

Which is more difficult to prepare in examining microorganisms, living microorganisms or dead microorganisms?

It is advantageous for examining living microorganisms that their cells have similar refractive index in that of water

When observing microorganisms, stained specimens are already dead

ADVANTAGES AND DISADVANTAGES IN STAINED PREPARATIONS OF DEAD SPECIMENS

WHAT ARE THE 3 BASIC STEPS IN STAINING?

PROCESS OF STAINING

Smear Preparation:

PROCESS OF STAINING

_____________

Its purpose is to kill the cells and make the cells sticky. This increases the apparent diameter of the cells. 

Type of Fixation by sliding the slide through the flame/direct flame or steam 2 to 3 times.

Type of Fixation which uses alcohols when the sample is "heat-sensitive". For instance, a milk sample is heat sensitive, so we use this type instead. 

PROCESS OF STAINING

The application of biological dyes.

These are organic compounds carrying chromophoric ions and makes cell's internal and external structures more visible with increased contrast with the background. 

Ex: Flood slide with stain; rinse and dry

3 Types of Stain

STAINING PROCEDURES: TYPES/MODES OF STAINING

STAINING PROCEDURES: TYPES/MODES OF STAINING

Uses only one dye

STAINING PROCEDURES: TYPES/MODES OF STAINING

SIMLE STAINING

Cells are stained using basic dyes which are positively charged. Cells are the same color as the dye. For instance, methylene blue for Saccharomyces cerevisiae. When you attach positive dye to negative; ATTRACTION

STAINING PROCEDURES: TYPES/MODES OF STAINING

SIMPLE STAINING

Cells are colorless or luminous. Acid fuchsin, eosin, rose bengal, india ink, nitrosin.

When you attach negative to negative dye; REPULSION

STAINING PROCEDURES: TYPES/MODES OF STAINING

Two or more dyes or reagents are used

DIFFERENTIAL STAINING: Gram Positive vs Gram Negative

STAINING PROCEDURES: TYPES/MODES OF STAINING

Type of Differential Staining where there is gram positive and gram negative depending on the cell wall

STAINING PROCEDURES: TYPES/MODES OF STAINING

Type of Differential staining wherein it is used for the diagnosis of tuberculosis. Diagnosis of mycobacterium tuberculosis responsible for tuberculosis.

STAINING PROCEDURES: TYPES/MODES OF STAINING

Two or more dyes and/or reagents are used. It differs with differential staining in its use of emphasizing a particular structure.

Examples are capsule staining, endospore staining, flagella staining (color or number of flagella/mode of motility)< and storage granule staining (metachromatic granules of Corynebacterium diphtheriae

Storage Granule Staining is for selected bacteria only since it is used as storage of energy when no energy is available. However, it is NOT PRESENT IN ALL ORGANISMS, JUST SOME.