Microbiology Lab: Microorganisms, Microscopy, and Staining Techniques

Vocabulary flashcards covering microbial classification, eukaryotic and prokaryotic characteristics, microscopy rules, and staining methods based on the lecture material.

Prokaryotes

Unicellular organisms lacking a membrane-bound nucleus or organelles, typically measuring $<1 - 5\,\mu\text{m}$, dividing by binary fission, and possessing a single loop of DNA, plasmids, small ribosomes, and a complex cell wall lacking a cytoskeleton.

Eukaryotes

Organisms with a clearly defined nucleus and membrane-bound organelles, measuring $10 - 100\,\mu\text{m}$, dividing by mitosis and meiosis, and possessing large ribosomes and a cytoskeleton of microtubules and actin filaments.

Archaea

Unicellular prokaryotic organisms that lack a true nucleus, membrane-bound organelles, endoplasmic reticulum, or chloroplasts, but possess cell walls.

Cyanobacteria

Blue-green photosynthetic unicellular bacteria that contain chlorophyll but lack a true nucleus and true organelles.

Green Algae

Eukaryotic organisms containing a nucleus, organelles, chloroplasts, and chlorophyll, where most species are unicellular and some form colonies.

Diatoms

Eukaryotic organisms possessing a nucleus, organelles, chloroplasts, a symmetrical shape, and a cell wall made of silica.

Protists

Unicellular eukaryotic organisms containing a nucleus while lacking a cell wall.

Amoebas

Protozoans within protists that have no definite shape, contain organelles, lack chloroplasts, and move using pseudopods.

Ciliates

Protozoans that move using cilia, lack chloroplasts, and possess two nuclei: a macronucleus for basic cell functions and a micronucleus for sexual reproduction.

Macronucleus

The nucleus in ciliates responsible for directing basic cell functions.

Micronucleus

The nucleus in ciliates responsible for sexual reproduction.

Euglenoids

Freshwater protozoans that move using flagella, possess chloroplasts, and feature an eyespot (stigma) that aids in locating light.

Stigma (Eyespot)

A red organelle component found in euglenoids that aids the cell in finding light.

Fungi

A kingdom in the eukaryotic domain including multicellular organisms (mushrooms, molds) and unicellular organisms (yeast) with cell walls composed of chitin that acquire food heterotrophically.

Immersion Oil

A substance used exclusively with the $100\times$ objective lens during microscopy that must be wiped off after use and should not remain on the lens for longer than $5\,\text{min}$.

Peptidoglycan

The major structural component of the bacterial cell wall that maintains cell shape, vital for growth, reproduction, nutrient acquisition, and movement.

Gram-Positive Bacteria

Bacteria possessing a thick layer of peptidoglycan that resist decolorization, retain crystal violet stain, and appear dark purple under the microscope.

Gram-Negative Bacteria

Bacteria possessing a thin layer of peptidoglycan and an outer layer of lipopolysaccharide (LPS), which decolorize easily due to high lipid content and stain pink.

Simple Stain

A staining procedure using a single dye (such as crystal violet, safranin, or methylene blue) to enhance visualization and differentiation of clear bacterial cells.

Gram Stain

A differential staining procedure utilizing crystal violet, iodine, Gram decolorizer, and safranin to differentiate Gram-positive (purple) from Gram-negative (red/pink) bacteria.

Heat Fixing

The laboratory step of passing an air-dried smear through a flame several times to kill and fix microorganisms onto the microscope slide.

Aseptic Technique

Laboratory procedures, including flaming inoculating loops until red-hot and flaming culture tube mouths, used to prevent contamination during cell culture transfers.