Learn: BIO 309 Lab 1: Microscopy

Purpose of a compound microscope

Overcoming the limits of human vision.

Compound microscope definition

A two-lens system using an objective lens and an ocular lens.

Total magnification formula

(Power of the ocular) × (Power of the Objective)

Ocular lens function

Remagnifies the image formed by the objective lens.

Body tube function

Transmits the image from the objective lens to the ocular lens.

Objective lenses function

Primary lenses that magnify the specimen.

Stage function

Holds the microscope slide in position.

Condenser function

Focuses light through the specimen.

Diaphragm function

Controls the amount of light entering the condenser.

Illuminator function

Acts as the light source.

Four objective lenses and powers

Scanning (4x), Low power (10x), High power (40x), Oil Immersion (100x).

Oil immersion lens (100x) purpose

Increases light to the eye and prevents light refraction and loss.

Coarse focus rule for 100x lens

NEVER use the coarse focus knob with the oil immersion lens.

Initial magnification step

Start at 4x to find the correct field of vision.

Transitioning to 100x oil immersion

Make sure your sample is in great focus at 40x first.

Microscope lens cleaning rules

Only use lens paper and provided lens cleaner; never use paper towels.

What does 'compound' mean in a compound microscope?

It refers to a two-lens system.

What part controls light entering the condenser?

The diaphragm.

Additional step for maximum resolution at highest objective

Use immersion oil.

Definition of Biosafety

Use of safety precautions and practices to reduce exposure risk to infectious microorganisms and protect the environment and community.

Foundations of Biosafety

Based on principles of containment and risk assessment, incorporating microbiological practices, safety equipment, and facility safeguards.

The Four Biosafety Levels (BSLs)

BSL-1, BSL-2, BSL-3, and BSL-4.

Risk Groups (RGs) Determination

Determined by relative pathogenicity for healthy adult humans to help determine required containment and safety measures.

Relationship between BSL and Risk Group

BSL does not always match Risk Group; BSL is determined based on specific work and situations during risk assessment.

E. coli (non-pathogenic) Risk Group

Risk Group 1.

Ebola virus Risk Group

Risk Group 4.

Staphylococcus aureus Risk Group

Risk Group 2 (can cause mild skin infections).

Mycobacterium tuberculosis Risk Group

Risk Group 3 (causes tuberculosis).

HIV Risk Group and BSL

Risk Group 3 virus, but commonly handled under BSL-2 conditions.

Hepatitis B virus Risk Group

Risk Group 2.

Standard Microbiological Practices: Doors

Lab doors are locked when unoccupied; never prop open lab doors.

Handwashing requirements in BSL-2 lab

Wash hands often, especially after lab work, if gloves are compromised, or before leaving.

Prohibited activities in the lab

No eating, drinking, smoking, applying cosmetics, handling contact lenses, or storing food.

Sharps disposal rules

Disposed of in designated, hard-sided sharps containers placed close to the point of use.

Needle manipulation rule

Needles are never bent, sheared, broken, recapped, or otherwise manipulated before disposal.

Handling broken glassware

Never handled directly; use a broom and dustpan, tongs, or forceps.

Minimizing aerosols

Be conscientious of and work to minimize the production of aerosols and splashes during manipulations.

Work surface decontamination

Decontaminate surfaces after work completion or spills/splashes using appropriate disinfectant.

Pipetting rules

No mouth pipetting; use a mechanical pipetting device.

Animal and plant policy

Animals and plants not associated with the work are not permitted within the lab.

Biohazardous waste container capacity limit

Must not be overfilled; properly disposed of when 2/3 full.

When do Special Practices begin?

Begin at Biosafety Level 2 (BSL-2) and progressively increase; none required for BSL-1.

When is a Biological Safety Cabinet (BSC) required?

Used when there is potential for infectious aerosols or splashes.

Centrifuge containment requirements

Use small centrifuges in a BSC or use sealed rotors/safety cups loaded/unloaded inside a BSC.

Lab equipment decontamination

Decontaminated routinely, after spills, and before repair, maintenance, or removal.

Incident reporting in the lab

Incidents resulting in potential exposure must be immediately reported to the lab supervisor/PI.

Role of Personal Protective Equipment (PPE)

A barrier against biological hazards, but the least effective control measure when used alone.

Lab coat rules

Must be closed/buttoned when worn and never taken home to be laundered.

Glove selection preference

Nitrile gloves are recommended over latex in most situations and are more hypoallergenic.

Glove usage rules

Never reused, never worn outside of the lab, and changed frequently or when visibly contaminated.

Transporting materials outside the lab

Place in a secondary hard-sided shatterproof container with a tight-fitting labeled lid and disinfect exterior.

Required Laboratory Facilities for BSL-2

Self-closing/lockable doors, handwashing sink, eyewash station, and easily cleaned non-porous surfaces.