Microscope and Gram Staining Flashcards

A comprehensive set of flashcards covering important concepts related to microscopes, Gram staining, and hygiene practices.

Light Microscope

Used to visualize microorganisms (like bacteria).

Total Magnification

Eyepiece × objective lens.

Eyepiece (Ocular Lens)

Magnifies the image.

Objective Lens

Provides main magnification.

Revolving Nosepiece

Holds and switches objective lenses.

Stage

Holds the slide.

Condenser

Focuses light onto the specimen.

Iris Diaphragm

Controls the amount of light.

Coarse Focus

Big movement for focusing.

Fine Focus

Small precise adjustment for focusing.

Starting Lens

X10 objective is the first lens used.

Coarse Focus Usage

Only used on low power (X10).

Switching to X40 or X100

Use fine focus only.

Smear Location

Must be on top of the slide to focus.

Oil Immersion

Used for X100 magnification.

Purpose of Oil Immersion

Improves resolution.

Lens Out of Oil

You've gone too far and lost focus.

Carrying Microscope

Carry with two hands (arm + base).

Cleaning Lenses

Use lens paper ONLY.

Touching Lenses

Oil from fingers damages them.

Order of Gram Stain Reagents

1. Crystal violet 2. Iodine 3. Alcohol 4. Safranin.

Gram-positive Colour

Purple.

Gram-negative Colour

Pink/red.

Gram-positive Retention

Thick peptidoglycan traps the stain.

Gram-negative Staining

Stain washed out due to thin wall, safranin added.

Critical Step in Gram Staining

Decolourisation (alcohol step).

Smear

Thin layer of bacteria on slide.

Thin Smear Importance

So light can pass through.

Fixation

Stops biological activity and preserves cells.

Fixing Cells,

It preserves cells, not “glues” them to the slide.

Cooling Loop Importance

Hot loop kills cells and creates aerosols.

Purpose of 16-Streak Method

To isolate single colonies.

Avoiding Original Inoculum

Prevents overcrowding and promotes isolation.

One Colony Representation

Represents one original bacterial cell.

Moisten Swab Purpose

Helps pick up bacteria.

Labeling Plates Importance

To identify the sample source.

Hand Sampling

Compare before and after plates to test hand hygiene effectiveness.

No Touching After Washing

Avoid recontamination.

Glitterbug Simulation

Simulates bacteria on hands.

UV Light Use

To see missed areas during handwashing.

Poor Washing Result

Remaining glowing areas indicate poor washing.

WHO Technique Improvement

More bacteria removed after using this technique.