Microbiology Lab Fundamentals & Safety Guide

All microorganisms should be treated as

Potential pathogens

Purpose of lab safety

Prevent contamination and infection

Eating/drinking in lab

Not allowed

Touching face in lab

Not allowed

Why avoid touching face

Prevent transfer of microbes into body

Handwashing timing

Before and after lab

Bench cleaning timing

Before and after lab

Correct order after lab

Disinfect bench then wash hands

Lab coat requirement

Required to participate in lab

Closed-toe shoes

Required

Gloves and goggles

Required with chemicals/cultures

Why PPE is used

Protection from exposure to microbes/chemicals

Handling cultures

Treated as potential pathogens

Pipetting by mouth

Never allowed

Loops/needles after use

Must be sterilized

Contaminated tools placement

Never on bench

Spill cleanup step 1

Cover with paper towels

Spill cleanup step 2

Apply disinfectant

Spill cleanup step 3

Wait 15 minutes

Spill cleanup step 4

Dispose properly

Spill cleanup final step

Inform instructor

Biohazard waste

Autoclave container

Broken glass disposal

Glass container

Regular trash use for bio items

Never

1 meter equals how many mm

1000 millimeters

1 millimeter equals how many micrometers

1000 micrometers

1 micrometer equals how many nanometers

1000 nanometers

Bacteria size unit

Micrometers

Virus size unit

Nanometers

Scientific name format

Genus + species

Genus capitalization

Capitalized

Species capitalization

Lowercase

Scientific names formatting

Italicized or underlined

Genus alone

Acceptable

Species alone

Not meaningful

Limit of human eye resolution

~100 µm

Microscope purpose

View objects too small to see unaided

Total magnification formula

Ocular × Objective

4X objective total magnification

40X

10X objective total magnification

100X

40X objective total magnification

400X

100X objective total magnification

1000X

Magnification definition

Makes image larger

Resolution definition

Ability to distinguish two objects clearly

Key concept of magnification

Magnification ≠ resolution

Ocular lens function

Viewing (10X)

Objective lenses function

Provide magnification

Stage function

Holds slide

Coarse focus function

Large focus adjustments (low power)

Fine focus function

Precise focus

Condenser function

Focuses light on specimen

Iris diaphragm function

Controls light amount

First step when using microscope

Start at low power

Why start low power

Larger field of view

Coarse focus usage

Low power only

Fine focus usage

All lenses (required for high power)

Specimen position before zoom

Centered

As magnification increases field of view

Decreases

As magnification increases depth of field

Decreases

As magnification increases working distance

Decreases

Coarse focus allowed lenses

4X and 10X

Fine focus only lenses

40X and 100X

Parfocal definition

Remains in focus when changing lenses

Parcentric definition

Remains centered when changing lenses

Oil immersion lens

100X

Oil used with 40X

Never

Oil immersion purpose

Prevent light scattering

Oil immersion effect

Improves resolution

Why water is not used

Different refractive index

Wet mount contains

Live organisms

Wet mount advantage

Observe movement

Wet mount limitation

Less contrast/detail

Hanging drop purpose

Observe motility

Cells in hanging drop

Alive

Why stains not used

Kill cells

Motility definition

Directional movement

Brownian motion definition

Random vibration

True motility vs Brownian

Movement vs jiggling

Stained slide purpose

Increase visibility

Stained slides show

Shape and arrangement

Stained slides show motility

No

Reason stained slides show no motility

Cells are dead

Hanging drop best for

Motility

Stained slide best for

• Shape

• Arrangement

• Structure

Hanging drop cells

Alive

Stained slide cells

Dead

Cocci

Spherical cells

Bacilli

Rod-shaped cells

Spirilla

Spiral-shaped cells

Diplo

Pairs

Strepto

Chains

Staphylo

Clusters

Monotrichous

One flagellum

Amphitrichous

One at each end

Lophotrichous

Tuft of flagella

Peritrichous

All around cell

Normal microbiota definition

Microbes living on/in body

Role microbiota

Compete with pathogens

Benefit of microbiota

Protect the host