General Microbiology Test 2 (Chapters 4, 5, & 6)

Grow at 0-20C with optimal of 15C

Psychrophiles

Grow at 15-45Cwith optimal of 38C

Mesophiles

Grow at 40-80C with optimal of 60C

Thermophiles

Grow at 65-121C with optimal of 90C

Hypothermophiles

The growth rate is roughly doubled for every ___ degrees celcius?

10C

What is Heat-Shock Response?

When a microorganism experiences a rapid change in temperature and activates batches of stress response genes.

Barophiles or Piezophiles are organisms adapted to grow in _______?

Very High Pressure (up to 1,000atm(110 MPa, or 15,000 psi))

Define: Barotolerant

Organisms that grow well over the range of 1-50 MPa, but their growth rate falls off thereafter

Water activity (aw) is measured by _____?

how much water is available for use.

What is typically measured as the ratio of the solution's vapor pressure relative to that of pure water?

Water activity

Most bacteria require water activity levels __?

> 0.91

Fungi can tolerate water activity levels ____?

> 0.86

Define: Osmolarity

The measure of the number of solute molecules in a solution and is inversely related to aw.

Define: Aquaporins

Membrane-channel proteins that allow water to traverse the membrane much faster than by diffusion.

What do Aquaporins allow?

Help protect the cell from osmotic stress

In addition to moving water, microbes have at least two mechanisms to minimize osmotic stress which are?

Compatible solutes and mechanosensitive channels

Define: Compatible solutes

In hypertonic media, bacteria protect their internal water by synthesizing or importing compatible solutes (e.g., proline or K+)

Define: Mechanosensitive channels

In hypotonic media, pressure-sensitive or mechanosensitive channels can be used to leak solutes out of the cell.

Halophiles require?

High salt concentrations (From 2 to 4 M NaCl (10%-20% NaCl))

Seawater is _____% NaCl?

-3.5%

To achieve a low internal concentration of Na+, halophilic

microbes use special ___ _____ to _____ _____ and replace it with other cations, such as K+

-Ion pumps

-excrete sodium

Define: Sterilization

killing of all living organisms

Define: Disinfection

killing or removal of pathogens from inanimate objects

Define: Antisepsis

killing or removal of pathogens from the surface of living tissues

Define: Sanitation

reducing the microbial population to safe levels

Define: Eutrophication

The sudden infusion of large quantities of a formerly limiting nutrient

Eutrophication can lead to a "Bloom" of _____?

of microbes, which can threaten the existence of competing species

List in order of harshness: Disinfection, Sanitation, Sterilization, Antisepsis

Sterilization, Disinfection, Antisepsis, and Sanitation

Decimal reduction time (D-value) is the ______?

length of time it takes an agent or a condition to kill 90% of the population.

Moist heat is _____effective than dry heat

More

Killing spores and thermophiles usually requires a combination of _____ _____ and _____.

-high pressure

-temperature

Temp and pressure of a Steam autoclave?

121oC at 15 psi for 20 minutes

Two types of Pasteurization?

-LTLT (low temperature/long time)

63oC for 30 minutes

-HTST (high temperature/short time)

72oC for 15 seconds

Pasteurization kills _______ _____the causative agent of Q fever.

Coxiella burnetii

the 5 Physical Agents That Kill Microbes?

-High temperature

-Pasteurization

-Cold

-Filtration

-Irradiation

Micropore filters with pore sizes of _____ can remove microbial cells, but not viruses, from solutions.

0.2 mm

Samples from 1 ml to several liters can be drawn through a membrane filter by _____ or can be forced through it using a ____?

-vacuum

-syringe

T or F: Air can also be sterilized by filtration?

TRUE

Laminar flow biological safety cabinets force air through HEPA filters, which remove > 99.9% of airborne particulate material _____ in size or larger.

0.3 μm

Irradiation is the used of _____?

-Ultraviolet light

-Gamma rays, electron beams, and X-rays

Ultraviolet light pros and cons?

-Has poor penetrating power

-Used only for surface sterilization

-less harmful

Gamma rays, electron beams, and X-rays pros and cons?

-Have high penetrating power

-Used to irradiate foods and other heat-sensitive items

A number of factors influence the efficacy of a given chemical agent, including:

-The presence of organic matter

-The kinds of organisms present

-Corrosiveness

-Stability, odor, and surface tension

Commercial Disinfectants and Antiseptics include?

Ethanol

Iodine (Wescodyne and Betadine)

Chlorine

Ethylene oxide (a gas sterilant)

These damage proteins, lipids, and/or DNA?

Disinfectants and Antiseptics

The hygiene hypothesis is?

since we're being exposed to less pathogens, we are having more auto-immune diseases

Phenolic

Alcohols

Aldehydes

T/F: Bacteria Can Develop Resistance to Disinfectants?

True

What are the ways bacteria can develop resistance to disinfectants?

-Altering the fatty acid synthesis protein normally targeted by triclosan

-Producing membrane-spanning, multidrug efflux pumps

-Forming multispecies biofilms, which offer collaborative protection

What are chemical compounds synthesized by one microbe that kill or inhibit the growth of other microbial species?

Antibiotics

Penicillin is a(n)?

Antibiotic

How does Penicillin work?

Penicillin mimics part of the bacterial cell wall and Prevents cell wall formation and is bactericidal

What do antibiotics target?

-Protein synthesis

-DNA replication

-Cell membranes

What is the use of one microbe to control the growth of another?

Biocontrol

What contains certain microbes that, when ingested, aim to restore balance to intestinal flora?

Probiotics

ex. Lactobacillus and Bifidobacterium

What aims to treat infectious diseases with a virus targeted to the pathogen?

Phage therapy

A possible alternative to antibiotics in the face of rising antibiotic resistance is ____ ____?

Phage Therapy

A ____ is a noncellular particle that must infect a host cell, where it reproduces that it typically subverts the cell's machinery and directs it to produce viral particles.

Virus

The virus particle, or _____, consists of a single nucleic acid (DNA or RNA) contained within a protective protein capsid

Virion

In oceans viruses are really important for ?

Global chemical cycling

In more complex viruses, the protective protein may be called a ?

Head coat

A virion by itself_____?

Does nothing

What is a virus that infects bacteria?

Bacteriophage

What forms a plaque of lysed cells on a lawn of bacteria?

Bacteriophage

An example of a human virus is the _____ virus?

measles

An example of a plant virus is the _______ _______ virus.

Tobacco mosaic virus (TMV)

A virus that integrates its genome into the DNA of a bacterial genome is called a ?

Prophage

Within a human cell, an integrated viral genome is called a?

Provirus

A permanently integrated provirus transmitted via the germ line is called an?

Endogenous virus

We now know that a virus may interconvert among three very different forms:

1.

2.

3.

?

1. Virion, or virus particle

2. Intracellular replication complex

3. Viral genome integrated within host DNA

Define: Virion, or virus particle

An inert particle that does not carry out any metabolism or energy conversion

Define: Intracellular replication complex

Within a host cell, the viral gene products direct the cell's enzymes to assemble progeny virions at "virus factories" called replication complexes.

T/F: Viral genome integrated within host DNA - This may be a permanent condition?

True

Acute viruses (which rapidly kill their hosts) act as _____?

predators or parasites to limit host population density and they also recycle nutrients from their host bodies

Virus-associated mortality may ______ the genetic diversity of host species?

increase

Persistent viruses remain in hosts, where they may ______?

evolve traits that confer positive benefits in a virus-host mutualism.

Marine viruses infect most ____, releasing their minerals in the upper water, where they are available for other phototrophs?

phytoplankton

On a global scale, viruses play an important role in the ____ ____?

carbon balance

Each species of virus infects a particular group of host species, known as its _____ ____?

host range

Which is more common, Chronic viral infections or acute disease?

Chronic viral infections

In contrast to our vast arsenal of antibiotics (effective against bacteria), the number of antiviral drugs remains ____?

Small

West Nile virus is transmitted by mosquitoes infect,______?

many species of birds and mammals.

Chronic infections last ______?

A long time

Acute infections last ____?

A short time

HIV infects _____?

Only humans

Most of our antiviral drugs are all for ____?

Herpes

HIV

Influenza

________

The structure of a virion is to ____?

keeps the viral genome intact, and it enables infection of the appropriate host cell.

The capsid does what?

packages the viral genome and delivers it into the host cell.

T/F: Different viruses make different capsid forms?

True

______ are with 20 identical triangular faces and are super efficient

and have a structure that exhibits rotational symmetry

polyhedral

In some ________ viruses, the capsid is enclosed in an envelope, formed from the cell membrane

icosahedral

The envelope contains _____ ____, which are encoded by the virus.

glycoprotein spikes

between the envelope and capsid, ____ _____ may be found

tegument proteins

Characteristics of Filamentous viruses?

-The capsid consists of a long tube of protein, with the genome coiled inside.

-Vary in length, depending on genome size

-Include bacteriophages as well as animal viruses

-very easy to form (don't need enzymes)

Filamentous viruses show_____symmetry

helical

The pattern of _____ ____ forms a helical tube around the genome, which usually winds helically within the tube.

Capsid Monomers

Tailed Viruses have complex ____ _____?

multipart structures

T4 bacteriophages is also referred to as?

Lunar Lander Model