Microbiology Exam 1_Homework Questions

Differences between archaeal and bacterial characteristics.

Archaeal: Membranes can be monolayers or bilayer, cell envelope often contains S-layer, chromosome associated with histones, have cannulae and hami, membrane lipids contain isoprenic hydrocarbons Bacterial: Lipids with fatty acid chains attached to glycerol by ester bonds, cell envelopes with peptidoglycan, hollow flagella, flagellar rotation powered by proton motor force

Characteristics that would differentiate an archaellum from a bacterial flagellum.

Archaella are solid, while bacterial flagella are hollow, An archaellum is powered by ATP, while a bacterial flagellum is powered by the proton motive force.

If you found a microbe with an S-layer as the major component of its cell wall, how would you identify this microbe?

Archaeon

Characteristics of bacteria/archaeal vs. eukaryotic organisms.

Bacteria/archaeal: smaller, typically no cellular compartments, cell membrane is typically location of electron transport system, limited morphology Eukaryotes: larger, highly compartmentalized, cell membrane is NOT involved in electron transport system, morphologically diverse

Which microbial control method best describes how an autoclave sterilizes material?

By heat

Structures associated with archaeal cells

Cannulae, flagella, hami, pili

Could compose the cell walls of some fungi.

Cellulose, chitin, glucan

Match each of the following items that may influence the selection of an antimicrobial procedure with its correct description/rationale. Type of microbe

Certain microbes are highly resistant to killing methods (e.g. endospores).

Match each of the following items that may influence the selection of an antimicrobial procedure with its correct description/rationale. Composition of the item

Different materials respond differently to control measures. Some may even be destroyed by certain methods, preventing their use.

Match each of the following items that may influence the selection of an antimicrobial procedure with its correct description/rationale. Environmental conditions

Dirt, grease, and bodily fluids in/on an area can interfere with control methods, as can temperature, pH, and even humidity levels.

Assess the following control scenarios and classify them according to the most appropriate for each situation. - a school was closed after a high percentage of students suffered vomiting and diarrhea - A dad takes care of his daughter's injury after she falls from her bicycle and scrapes her knee - a microbiology is preparing nutrient broth tubes so she can batch culture E. coli - the janitor cleans the bathrooms at the mall

Disinfection - a school was closed after a high percentage of students suffered vomiting and diarrhea Antisepsis - A dad takes care of his daughter's injury after she falls from her bicycle and scrapes her knee Sterilization - a microbiology is preparing nutrient broth tubes so she can batch culture E. coli Sanitation - the janitor cleans the bathrooms at the mall

When a broth culture of Bacillus begins to run out of nutrients, the cells _________.

Form endospores

Statements regarding the cytoskeletal protein FtsZ?

FtsZ localization determines the site of cell wall growth by recruiting PBPs for peptidoglycan synthesis. FtsZ polymerizes to form the Z ring that determines the site of septum formation.

Some archaea have been observed to form tubelike structures with tiny grappling hooks at the ends. These tubelike structures are called _________.

Hami

Which microbial control method best describes the process of pasteurization?

Heat

Which best describes how heat controls microbes?

Heat denature proteins and nucleic acids

Which practices do you expect to see in a commercial establishment dedicated to body piercing?

Needles are factory-sterilized and used for only a single customer before disposal. The piercing environment is sanitized daily by wiping counters and furniture with a strong disinfectant.

Determine the statement that describes what is growing on the plate after membrane filtration.

Only microbes that were too large to fit through the filter are growing on the plate

The most notable differences are in the cell ______________ composition. Bacteria have well-defined cell walls, characterized as being either Gram-positive or Gram-negative, whereas archaea lack _____________________, most having instead an ________________ and some having no cell wall at all.

envelope; peptidoglycan; S-layer

Finally, if microbial populations are reduced just enough to meet public health standards, we call this process _____________________.

sanitization

If all of the microorganisms in a sample are killed by the biocide, including spores, we call this process __________________________.

sterilization

And further, those compounds that kill fungi are called ______________________.

fungicides

"cidal" and "static" definitions.

kills microbes= cidal keeps microbes from dividing = static

Assess statements and classify them according to whether they describe streak-plate, spread-plate, or a pour-plate protocol.

streak-plate: number of organisms diluted as each sector is inoculated spread-plate: After serial dilution, plates are inoculated with pipet and bent metal rod pour-plate protocol: after serial dilution, plates are inoculated by first mixing organisms into the liquid agar

While there are many similarities between bacteria and archaea, recognition of their differences resulted in them being sorted into entirely different ____________, rather than being characterized as "prokaryotes."

taxa

In those organisms that are motile, the structures of bacterial flagella and archaella differ significantly. Archaella are ________________ than bacterial flagella, they are not hollow, and are powered by _________________________.

thinner; ATP hydrolysis

Similar to bactericides, compounds that kill viruses are called ____________________.

viricides

Label the diagram to test your knowledge of temperature tolerance exhibited by various microorganisms.

1. Psychrophiles 2. Physcrotolerants 3. Mesophiles 4. Thermophiles 5. Hyperthermophiles

Rank the following from MOST biocidal to LEAST. sterilization, disinfection, antisepsis, sanitation

1. Sterilization 2. Disinfection 3. Sanitation 4. Antisepsis

Using the decimal reduction time (D-value) method, how many organisms would be left after one decimal reduction if you started with 1,000 bacteria?

100

Best description of how filtration works to control microbes.

A filter is a solid material containing small holes that only allows liquids to pass but restricts larger substances from passing to a sterile environment.

An archaeon in a nutrient-poor environment is most likely to use _________ for nutrient uptake.

ABC transport

Endocarditis occurs when bacteria infect the bloodstream and attach themselves to the inner lining of the heart or a defective heart valve. These bacteria are _________.

Sessile

Characteristic of a microbe that would allow it to be controlled by filtration.

Size of microbe

When comparing bacteria to eukaryotes, bacteria are ________.

Smaller and not compartmentalized

Why is it important to separate mixed communities of microbes into individual pure cultures of each different species?

So we can understand the biochemical characteristics of one species without confusing it with that of another contaminating species

Characteristics that apply to the cell envelopes found in eukaryotic cells.

Sterols (e.g. cholesterol) outer cell wall, sphingolipids

Archaea with a plasma membrane composed of a tetraether monolayer would most likely be found __________.

Temp of 90 degrees Celsius

Many foodborne pathogens are controlled by preservation processes that render the food unsuitable to support the growth of microbes. Match each food preservation technique with the environmental factor that is altered. Temperature Oxygen concentration pH Water activity

Temperature - freezing Oxygen concentration - vacuum packaging pH - pickling Water activity - dehydration

Describes eukaryotic cell cytoplasm?

The compartment within the cell membrane that contains various organelles and metabolic enzymes

High concentrations of sugar or salt are used to control food spoilage because most microorganisms only grow well in habitats with high water activity. (true/false)

True

If these agents are used on skin or tissues, the term ______________________ is used.

antiseptic

For example, those compounds that kill bacteria are called ________________________.

bactericides

However, if the agent does not kill bacteria, but merely prevents growth, it is termed __________________.

bacteriostatic

Significant differences are present in the cell membranes of bacteria and archaea; bacteria always have a phospholipid ________________, whereas the membranes of some archaea exist as a ________________, usually depending on their habitat and the need to maintain fluidity.

bilayer; monolayer

To control microorganisms, a ___________ must be evaluated for effectiveness.

biocide

However, if only those organisms likely to cause disease are killed, inhibited, or removed, this is termed _______________________.

disinfection

Drag the images to the label that correctly characterizes the bacterial growth response to atmospheric oxygen levels in thioglycolate broth.

(no image) 1. Obligate aerobe 2. Facultative anaerobe 3. Aerotolerant anaerobe 4. Strict anaerobe 5. Microaerophile

Label the anatomy of the mitochondrion.

(not exact image)

Identify the name of each organism to the level of disinfectant that is required for controlling it. Escherichia coli Mycobacterium tuberculosis Bacillus anthracis endospores Vibrio cholerae athlete's foot fungus Clostridium difficile (C-diff) endospores Methicillin resistant Staph. aureus (MRSA)

High level disinfectant: Bacillus anthracis endospores, Clostridium difficile (C-diff) endospores Intermediate level disinfectant: Mycobacterium tuberculosis Low level disinfectant: Escherichia coli, Vibrio cholerae, athlete's foot fungus, Methicillin resistant Staph. aureus (MRSA)

Match each of the following items that may influence the selection of an antimicrobial procedure with its correct description/rationale. Number of microorganisms

It takes longer to kill a large amount of microbes than a small amount.

Match each of the following items that may influence the selection of an antimicrobial procedure with its correct description/rationale. Risk for infection

Items that may come into direct contact with body tissues are more likely to cause serious infections if contaminated.

Nucleus

Location for DNA and RNA synthesis

Mitochondria

Location for most metabolic reactions in cellular respiration

Golgi apparatus

Location for protein modification prior to secretion or delivery to other cellular compartments

Endoplasmic reticulum

Location for protein synthesis and some protein modifications

Lysosomes

Location for storage of many types of degradative enzymes

Perioxosomes

Location for storage of protective compounds that break down lipids and detoxify certain chemicals

Chloroplast

Location for the cellular process of photosynthesis

Characteristics commonly found associated with eukaryotic cells that are NOT found in bacterial cells.

Presence of mitochondria and presence of nucleus

Characteristics describing pseudomurein vs. peptidoglycan.

Pseudomurein: L-amino acids in cross-links, contains N-acetyl talosaminuronic acid, beta(1-3) glyosidic bonds Peptidoglycan: D-amino acids in its cross-links, contains N-acetyl muramic acid, beta(1-4) glycosidic bonds

Microorganisms living within biofilms typically use molecular signals to communicate with each to regulate density-dependent growth; this is commonly referred to as _________.

Quorum sensing

What is the best form of microbial control you could use for a soft, plastic, surgical device that will melt at high temperatures?

Radiation

What is bound to the rough endoplasmic reticulum that makes it different from the smooth endoplasmic reticulum?

Ribosomes

In which organelle would you expect to find protein synthesis occurring?

Rough endoplasmic reticulum