Lab Exam 1 Flashcards

Flashcards covering key concepts, definitions, techniques, and organism types from the provided Lab Exam 1 lecture notes.

What does each visible colony on a plate represent?

Growth from a single cell (or cluster of cells).

What medium is typically used for general bacterial growth?

TSA (Tryptic Soy Agar).

Why do we control incubation temperature and time?

To provide optimal growth conditions and avoid overgrowth.

What is the difference between a TSA slant and TSB broth?

TSA slant is a solid angled surface, while TSB is a liquid medium.

Name three aseptic technique tools.

Bunsen burner, loop, needle.

What is the purpose of a streak plate?

To isolate pure colonies.

How many quadrants do you typically streak in the streak plate method?

Four.

Why is the loop flamed between streaks during the streak plate method?

To reduce bacteria and ensure colony isolation.

Give examples of colony shapes.

Round, irregular (also filamentous, lobate).

What terms are used to describe colony height?

Convex, umbonate, flat, raised.

Describe a mucoid colony.

It has a slimy, sticky appearance.

What does 'filiform' growth on a slant mean?

A smooth, straight line of growth.

What does 'friable' growth look like?

It has a dry, crusty texture.

What does 'pellicle' mean in broth growth?

Growth forms a layer on the surface.

If broth growth is evenly cloudy, what term describes it?

Uniform fine turbidity.

What is the function of thioglycollate in media?

It removes oxygen except near the surface.

Which type of organism shows growth only at the top of thioglycollate media?

Obligate aerobe.

Which type of organism shows growth only at the bottom of thioglycollate media?

Obligate anaerobe.

Which type of organism shows growth throughout but is denser at the top of thioglycollate media?

Facultative anaerobe.

What test uses antibiotic disks to measure bacterial resistance?

Kirby-Bauer disk diffusion test.

How is resistance determined in the Kirby-Bauer test?

By measuring the zone of inhibition and comparing it to a chart.

What is a psychrophile?

A cold-loving organism.

Which group of organisms grows best at human body temperature (37°C)?

Mesophiles.

Which organisms thrive in hot environments?

Thermophiles.

What happens to cells in hypertonic solutions?

Water leaves the cell, leading to plasmolysis.

What organisms thrive in high salt environments?

Halophiles.

What technique ensures even distribution of diluted bacteria on plates?

Spread plate technique.

What is the formula for bacterial concentration?

Concentration = (Colonies 22 Dilution factor) / Volume plated.

If you count 150 colonies from a 10■■ dilution, plated at 0.1 mL, what’s the concentration?

1.5 22 10■ CFU/mL.

What are some general terms used to describe colony texture?

Moist, dry, mucoid.

How can colony characteristics like transparency and luster be described?

Opaque, translucent, shiny, dull.

Besides filiform and friable, what is another term for slant growth pattern?

Spreading edge.

What are some terms for growth patterns in broth, beyond pellicle and turbidity?

Sediment, flocculent.

Which type of organism grows just below the surface in thioglycollate media?

Microaerophile.