Lab Notes Flashcards: Microscopy, Surfaces, Media, Gram Staining, and Epidemic Simulation (Labs 1.1–6.1)

A comprehensive set of Q&A flashcards covering microscope basics, bacterial morphology, colony morphology, selective/differential media, Gram staining, antibiotic susceptibility, and epidemic modeling from Labs 1.1–6.1.

Who invented the microscope and in what year?

Hans & Zacharias Jansen, 1590.

Who coined the term ‘cell’ and when?

Robert Hooke in 1667.

Who first observed live bacteria?

Antonie van Leeuwenhoek in 1675.

What are the main parts of a light microscope mentioned in the notes?

Base and Arm (support), Stage (with clips and knobs), Light Source with condenser and iris diaphragm, Nosepiece with objectives, Ocular lens, Coarse and Fine focus knobs.

What are the four objective magnifications used on the standard microscope?

4X (scanning), 10X (low), 40X (high dry), 100X (oil immersion).

What is the standard ocular magnification?

10X.

How is total magnification calculated?

Total magnification = ocular magnification × objective magnification.

What is the total magnification for 4X, 10X, 40X, and 100X objectives?

4X → 40X, 10X → 100X, 40X → 400X, 100X → 1000X.

What does resolution mean in microscopy?

The ability to distinguish between two points as separate.

What size range is typically considered microscopic (not visible to the naked eye)?

Less than 0.1 mm.

What are two-handed handling rules for carrying a microscope?

Carry with the arm and base supported by two hands.

What should you do before and after using a microscope?

Clean the lenses and surfaces before and after use.

Which objective should you start with when using a microscope?

4X scanning objective.

When should you use fine focus adjustment?

Only at 40X and 100X objectives.

When is oil immersion used?

With the 100X objective only.

How should you store the microscope after use?

On low power with the stage lowered.

What are the four basic bacterial shapes mentioned?

Cocci (spheres), Bacilli (rods), Vibrio (curved rod), Spirillum (spiral).

What are the bacterial arrangements listed?

Strepto- (chains), Staphylo- (clusters), Diplo- (pairs), Tetrads (groups of 4), Sarcina (cube-like packets).

Why is microscopy important in healthcare?

For diagnosis, identification of pathogens, studying microbes, and monitoring antibiotic resistance.

What does the Latin root Vibrio mean?

To vibrate or sway.

What does Cocci mean in Latin roots?

Spherical berries.

What does Strepto mean?

Twisted chain.

What does Bacillus mean?

Little rod.

What does Staphylo mean?

Bunch of grapes.

Name the three domains of life.

Bacteria, Archaea, Eukarya.

What characterizes prokaryotes vs eukaryotes?

Prokaryotes have no nucleus or organelles; Eukaryotes have a true nucleus and membrane-bound organelles.

What is oil immersion used for and why?

Used with the 100X objective to increase resolution and reduce light scatter.

What four features describe colony morphology? (Size, Form, Margin, Elevation)

Size (punctiform to large), Form (circular, irregular, rhizoid, filamentous, lobate), Margin (entire, undulate, filamentous, curled), Elevation (flat, raised, convex, pulvinate, umbonate).

What are common post-staining colony arrangements observed after staining?

Cocci in chains (Strepto), clusters (Staphylo), Bacilli in single cells or chains, Spirilli.

What are the three general categories of media and their purposes?

General Purpose (nutrient agar), Selective (promotes some while inhibiting others), Differential (distinguishes species by color/changes).

What does MSA select for and how is Staphylococcus aureus distinguished on it?

MSA is selective for Staphylococcus; mannitol fermentation causes yellow color (S. aureus ferments mannitol).

What does MAC select for and how is lactose fermentation indicated?

MAC is selective for Gram-negative bacteria; lactose fermentation yields pink color.

What is aseptic technique and why is it important?

Techniques to prevent contamination of cultures and the environment.

Which surfaces showed the most diverse microbial colonies in the surface study?

Shoe showed the most diverse colonies.

What is the purpose of incubating plates upside down?

To prevent condensation from dripping onto the culture and causing contamination.

What is Kirby-Bauer testing used for?

To assess bacterial resistance or susceptibility to antibiotics by measuring zones of inhibition.

What does MIC stand for in antibiotic testing?

Minimum Inhibitory Concentration.

In Kirby-Bauer data, what does a larger zone of inhibition indicate?

Greater sensitivity of the organism to that antibiotic.

Which antibiotic showed the largest inhibition zone for E. coli in the data example?

Ciprofloxacin (40 mm).

Which antibiotics were ineffective against E. coli and B. cereus in the data example?

Penicillin (0 mm) for both organisms.

What is Gram staining used for in ID, and what colors correspond to Gram+ and Gram−?

Used to differentiate bacteria; Gram+ appear purple, Gram− appear pink/red.

What is the basic sequence of Gram staining steps?

Crystal violet (primary) → Gram’s iodine (mordant) → decolorizer (ethanol) → Safranin (counterstain).

Which cell wall features cause Gram+ to retain crystal violet?

Thick peptidoglycan layer and teichoic acids retain crystal violet.

Which cell wall features cause Gram− to lose crystal violet and take up safranin?

Thin peptidoglycan layer with an outer membrane containing LPS; crystal violet is washed out, safranin stains pink.

What is LPS and why is it significant?

Lipopolysaccharide, an endotoxin; harmful when bacteria die.

What causes Gram variability and which organisms are known for it?

Old cultures or certain species stain inconsistently; Mycoplasma lacks a cell wall so Gram stain may not work.

Why is Gram staining important in healthcare?

Guides antibiotic selection because Gram+ and Gram− have different cell wall structures.

What is epidemiology?

The study of occurrence, distribution, transmission, and reservoirs of disease.

Define morbidity, incidence, and prevalence.

Morbidity: diseased condition; Incidence: number of new cases in a time period; Prevalence: total number of cases (new + existing).

What are reservoirs in epidemiology?

Human, animal (zoonoses), and environmental (soil, water) reservoirs.

What is the difference between direct and indirect transmission?

Direct: contact, droplets, skin-to-skin; Indirect: fomites (surfaces, objects).

What are the types of carriers?

Passive (transmit without being infected), Active (infected and spreading), Asymptomatic (no symptoms but can spread).

Describe the six links in the chain of infection.

Agent → Reservoir → Portal of Exit → Transmission → Portal of Entry → Susceptible Host.

What does incidence measure in an outbreak?

The rate of new cases developing over a specific period.

What does prevalence measure in an outbreak?

The total number of existing cases at a given time.

What are key prevention strategies for reducing direct transmission?

Handwashing, surface disinfection, masks, gloves, avoiding contact.

What is an endemic, epidemic, and pandemic?

Endemic: baseline level in an area; Epidemic: sudden local rise; Pandemic: worldwide spread.