microbiology test 1 review (9/17/26)

only the ones that are yellow/red

algae found in…

algae is known for

algae produces…

water

making their own food with sunlight (photosynthesis)

glucose and oxygen

fungi get their energy how? (different from algae)

they get nutrients by digesting them outside their body and absorbing them

are viruses prokaryotes or eukaryotes?

why?

none

made of no cells

methanogens?

located?

type of archaea that makes methane gas

in places with no oxygen (ex: swamps, sediments, animal intestines)

Robert Hooke?

van Leeuwenhoek?

Robert Hooke observed cells in cork and came up with the term cell

van Leeuwenhoek first observed living microorganisms

Needham?

Spallanzani?

Virchow?

Needham supported spontaneous generation after briefly heating broth and later observing that microoganisms appeared

Spallanzani: challenged spontaneous generation + observed no microbial growth after boiling broth longer and sealing it shut

Virchow supported biogenesis and stated that cells come from preexisting cells

Joseph Lister?

Robert Koch?

used a chemical antiseptic (phenol) to prevent surgical wound infections

linked specific microbes to specific diseases

What was Ehrlich’s “magic bullet”?

Ehrilich is known for developing? (hint: one of the first examples of a chemotherapeutic drug)

“magic bullet”: chemical that targets a pathogen without harming the host.

for developing a synthetic arsenic drug, Salvarsan, to treat syphilis

Name two examples of biotechnology that use recombinant DNA technology and two examples that do not.

Recombinant DNA examples: Human insulin production, Human growth hormone production

Biotechnology that doesn't use recombinant DNA: Yogurt production, Bread production

define resistance?

factors?

Resistance: ability of a microorganism to survive or continue growing despite something that is supposed to kill or stop it.

Resistance factors include skin and antimicrobial chemicals

1 micrometer (μm) is ___ nanometers (nm)?

1 micrometer (μm) = ___ millimeter (mm)?

1000

0.001

Phase-contrast

viewing the internal structure in living cells without staining

Differential interference contrast (DIC):

gives living cells a 3D like appearance + helps see surface details and internal structures

Fluorescence:

identifying specific cells/structures using fluorescent dyes + uses UV (short wavelength) light

Confocal

stained with fluorochrome dyes + short-wavelength light used to excite single plane of specimen + produces detailed 3D images

Two-photon:

2 photons of long-wavelength (red) light used to excite dyes + deeper into living tissues

Scanning acoustic:

examining structures using sound waves

color used for primary stain in gram stain?

cystal violet

Acid-fast stain:

stain for myobacterium and nocardia?

identifies bacteria with waxy mycolic acid in their peptidoglycan cell walls

stained endospores show as?

whats the stain name and what else does the schaeffer-fulton (aka endospore staining method) use?

Stained endospores show as green within red/pink cells

malachite green and heat

The glycocalyx

helps? (3)

is a sticky layer outside the bacterial cell wall

Helps bacteria attach to surfaces, helps prevent phagocytosis, and can help form biofilms

how do bacteria move?

Bacteria with flagella move by rotating their flagella.

Spirochetes move using axial filaments

functions of prokaryotic plasma membrane?

Controls what enters/leaves the cell

Produces energy (ATP)

Contains receptors and enzymes

Which agents can cause injury to the bacterial plasma membrane?

Alcohols

Detergents

Phenols

Some antibiotics

Certain disinfectants

Group translocation:

A substance is chemically changed while being transported into the cell

DNA locations in eukaryotes and prokaryotes?

nucleoid in prokaryotes

nucleus in eukaryotes

Metachromatic granules →

Polysaccharide granules →

Lipid inclusions →

Sulfur granules →

Metachromatic granules → phosphate storage

Polysaccharide granules → store carbon/energy

Lipid inclusions → store lipids/energy

Sulfur granules → store sulfur

how does the flagella move in prokaryotic vs eukaryotic

prokaryotic: rotate like a propeller

eukaryotic: move by bending/whipping

eukaryotic and/or prokaryotic: cilia & microvilli?

cilia vs microvilli?

eukaryotes have cilia and microvilli, prokaryotes dont

cilia = movement, microvilli = increase surface area, which increase absorption)

plasma membrane difference in prokaryotic vs eukaryotic?

Prokaryotic: generally lacks sterols, except organisms such as mycoplasmas (they get sterol from environment and dont have cell wall so need sterols in their cell membrane)

Eukaryotic: typically contains sterols such as cholesterol

eukaryotic ribosome and subunits?

prokaryotic ribosome and subunits?

80S with 60S large subunit and 40s small subunit

70S with 50S large and 30S small

6-1 Classify microbes into five groups on the basis of preferred temperature range

Psychrophile 0–20°C

Psychrotroph 0–35°C

Mesophile 20–45°C

Thermophile 45–80°C

Hyperthermophiles: 80* C+

nitrogen for…

sulfur for…

phosphorus for…

Nitrogen: Proteins and nucleic acids

Sulfur: proteins & certain amino acids (cysteine & methionine)

Phosphorus: DNA, RNA, ATP, phospholipids

aerotolerant anaerobe?

microaerophile?

Aerotolerant anaerobe: doesn't use O₂ but tolerates it

Microaerophile: needs low levels of O₂

growth pattern for

obligate aerobe?

obligate anaerobe?

facultative anaerobe?

aerotolerant anaerobe?

microaerophile?

obligate aerobe: only at top

obligate anaerobe: only at bottom

facultative anaerobe: everywhere but more on top

aerotolerant anaerobe: evenly throughout

microaerophile: right below the top

6-6 Identify ways in which aerobes avoid damage by toxic forms of oxygen. (hint: these are toxic molecules made from oxygen)

Aerobes protect themselves using enzymes such as:

Superoxide dismutase (Gets rid of superoxide (O₂⁻) & converts superoxide into hydrogen peroxide)

Catalase (Breaks down hydrogen peroxide (H₂O₂) into water + oxygen)

Peroxidase (breaks down hydrogen peroxide using another molecule into harmless products)

Differential media:

Enrichment media:

Differential media: allow you to distinguish microbes based on visible biochemical differences

Enrichment media: encourage growth of a particular desired organism

colony?

visible mass of microorganisms growing on a solid surface, usually originating from one cell or group of cells.

Can you think of any reason why a colony does not grow to an infinite size, or at least fill the confines of the Petri plate?

Nutrients become limited and waste products accumulate

6-12 Describe how pure cultures can be isolated by using the streak plate method.

Streak → spread bacteria out → individual cells → separate colonies → pure culture.

Binary fission:

One bacterial cell copies its DNA and divides into two cells.\

6-16 Explain four direct methods of measuring cell growth

Direct microscopic count

Viable plate count

Membrane filtration

Electronic cell counting

6-18 Explain three indirect methods of measuring cell growth.

Turbidity: more cells → cloudier culture

Metabolic activity: measures products of microbial metabolism

Dry weight: measures the mass of cells after drying

7-1 Define the following key terms related to microbial control: sterilization, disinfection, antisepsis, degerming, sanitization, biocide, germicide, and asepsis.

Sterilization: destroys/removes ALL microbial life, including endospores.

Disinfection: destroys pathogens on nonliving surfaces.

Antisepsis: destroys/inhibits microbes on living tissue.

Degerming: removes microbes from a limited area, usually by mechanical action (scrubbing).

Sanitization: reduces microbes to safe public-health levels.

Biocide: chemical that kills organisms.

Germicide: chemical that kills pathogens/microbes.

Asepsis: preventing contamination by unwanted microbes

7-2 Describe the patterns of microbial death caused by treatments with microbial control agents

Microbial death usually happens at a constant percentage, not a constant number

Describe the effects of microbial control agents on cellular structures.

Cell membrane → damaged → contents leak out → cell dies

Proteins → denatured → enzymes stop working

DNA/RNA → damaged → cell can't reproduce

Cell wall → damaged → cell can burst (lyse)

7-5 Describe how filtration, low temperatures, high pressure, desiccation, and osmotic pressure suppress microbial growth

Filtration → physically removes microbes from liquids or air.

Low temperatures → slow enzyme activity and metabolism, so microbes grow more slowly.

High pressure → damages cellular structures/proteins and inhibits microbial growth.

Desiccation → removes water needed for microbial metabolism and growth.

Osmotic pressure → high salt/sugar causes water to leave microbial cells, inhibiting growth.

7-6 Explain how radiation kills cells.

Radiation can split water molecules and produce hydroxyl radicals (•OH).

What is the connection between the killing effect of radiation and hydroxyl radical forms of oxygen?

These highly reactive molecules damage DNA and other cellular components, causing cell death.

7-8 Interpret the results of use-dilution tests and the disk-diffusion method.

Use-dilution test: Tests how effectively a disinfectant kills microorganisms on contaminated objects.

Disk-diffusion method: Measures how well a chemical inhibits microbial growth by observing a zone of inhibition around a disk.

Which is more likely to be used in a medical clinic laboratory, a use-dilution test or a disk-diffusion test?

Disk-diffusion test bc its commonly used to determine how effective an antimicrobial chemical/drug is by measuring the zone of inhibition

7-9 Identify the methods of action and preferred uses of chemical disinfectants.

Protein denaturation

Membrane disruption

DNA damage

Enzyme inhibition

Oxidation

Why is alcohol effective against some viruses and not others?

Alcohol is effective against viruses with a lipid envelope because it can disrupt the envelope.

➡ Enveloped virus = generally more susceptible (aka easily affected/harm)

➡ Non-enveloped virus = generally more resistant

halogens?

halogens include? what are they most commonly used as?

a group of chemicals used as antimicrobial agents/disinfectants

Halogens:

Iodine: Commonly used as an antiseptic on skin

Chlorine: Commonly used as a disinfectant for water and surfaces

7-11 Identify the appropriate uses for surface-active agents.

Surface-active agents, like soaps and detergents, reduce surface tension and help remove microorganisms from surfaces

7-12 List the advantages of glutaraldehyde over other chemical disinfectants.

Is a high-level disinfectant (Can kill a wide range of microorganisms)

Is effective against endospores with sufficient exposure

Can be used on medical equipment that cannot tolerate high temperatures

What chemical disinfectants can be considered sporicides?

Glutaraldehyde

Hydrogen peroxide at appropriate concentrations

Peracetic acid

What chemicals are used to sterilize?

Ethylene oxide

Glutaraldehyde (also considered a sporicide)

Hydrogen peroxide (also considered a sporicide at appropriate concentrations)

Peracetic acid (also considered a sporicide)

7-14 Explain how the type of microbe affects the control of microbial growth

Endospores → highly resistant

Mycobacteria → relatively resistant

Nonenveloped viruses → relatively resistant

Enveloped viruses → generally less resistant

autoclave is what temp, pressure, and minutes

121 C at 15 psi for 15 mins

membrane filters are physically trap what size microorganism?

microorganisms above the size 0.22 µm

physical methods of microbial control?

low temps like refrigeration, deep-freezing, and lyophilization (freeze dying)

ionizing radiation makes…

which can…

free radicals, which are highly reactive molecules/atoms w/ an unpaired electron

damage DNA, proteins, cell membranes

using heat sterilzation on plastic sleeves/balls can…

melt or deform

many heat-sensitive foods like steak (meat) can be microbial controlled by…

(i mean heat-sensitive as in heat needed for heat sterilization could damage food)

gamma rays (type of ionizating radiation)

test hint from professor:

soap is NOT a….

plasma is the…

main supercritical fluid and used for medical implants?

disinfectant

4th state of matter

carbon dioxide

supercritical fluid?

high pressure + high temp + has liquid-like and gas-ike properties

Pasteurization is the

Pasteruization is not a __ technique

heating a food/liquid for short time to kill/reduce harmful bacteria (wihtout changing food)

sterilization

Why can both Gram-positive and Gram-negative bacteria undergo plasmolysis (cytoplasm shrink) when placed in a hypertonic solution, despite having cell walls?

Gram-positive and Gram-negative cell walls do not prevent water loss in a hypertonic solution

generation time formula?

bacterial growth formula?

total time/generation time = n

final # of cells = starting number of cells x 2^{n (# of generations)}

bacteria load formula?

number of colonies x 1/dilution = bacteria/mL