micro unit 2 exam – Flashcards

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question
What substances can damage the plasma membrane?
answer

alcohol

detergent

polymyxin antibiotics

question
Why is the plasma membrane a good target for antibiotics?
answer
  • disrupts the transport of substances across the membrane
  • leakage causes cell death
  • disrupts the electronic transport chain which produces ATP
question

How do salty foods prevent the growth of bacteria?

 

answer
Hypertonic environments, the cell shrinks and water moves out.
question
What antibiotic/substances can damage Gram-positive cells?
answer
  • penicillin
  • lysozyme
  • detergents
question

What antibiotic/substances can damage Gram-negative cells?

 

answer
  • streptomycin
  • chloramphenicol
  •  tetracycline
question
Which microscope can see internal structures of a cell and needs ultrathin sections so electrons can pass through the specimen?
answer
Transmission Electron Microscope
question
What microscope enhances diffraction of the light that passes through a live specimen to see the internal structures of cells with out stain?
answer
Phase-contrast microscope
question
What microscope is used to stuy surface features of a specimen?
answer
Scanning electron Microscope
question
What microscope uses visible light to see a specimen against a bright background and uses stains to create contrast?
answer
compound light microscope
question
What microscope uses UV light, flourescent stains and antibodies to ake a specimen glow, and allows rapid detection of pathogens in tissues?
answer
Fluorescence microscope
question
What microscope has a special condenser that blocks most light to see the outline of a live specimen with out staining?
answer
Darkfield microscope
question
What is the ability of lenses to distinguish two points?
answer
refraction
question

What is the composition and function of the plasma membrane for a prokaryote?

Eucaryote?

answer

Prokaryote- composition: made of phospholipids and proteins

function: permeability, makes ATP, Transportation

Eukaryote- composition: Phospholipid bilayer, sterols

Funtion: transportation 

question

What is the comopsition and function of the cell wall of a prokaryote?

eukayote?

 

answer

Prokaryote- composition: peptidoglycan

Function: protection

 

Eukaryote- no cell walls

question

What is the funtion and composition of ribosomes in a eukaryote?

prokaryote?

answer

Both: function: protein synthesis

composition: protein

question

What is the composition and function of chromosomes in a prokaryote?

eukaryote?

answer

Prokaryote- composition: nucleic acids (DNA) 1 chromosome 

Function: storage of information

 

Eukaryote- composition: 46 DNA

function: storage of information

 

question
In what ways do eukaryotes and prokaryotes preform cell division?
answer

Prokaryotes: binary fission

 

Eukaryotes: meiosis and mitosis

question

What is the optimum temp for Mesophiles? psychrophiles? psychrotrophs? Thermophiles? hyperthermophiles?

 

answer

in order:

37 C

13 C

23 C

62 C

93 C

question
What is the danger zone for bacteria where some may produce toxins?
answer
15 C - 51 C
question
What do microbes need to make organic molecules ot form their cell structures? What are these organic molecules?
answer

Carbon

 

Carbohydrates, proteins, lipids, nucleic acids

question
What element do microbes need as a source of energy?
answer
carbon
question
What element do microbes need to make proteins and nucleic acids besides carbon?
answer
nitrogen
question
How do microbes aquire nitrogen?
answer

protein sources (food)

 

 

Nitrogen fixing bacteria can get nitrogen from the atmosphere

question
What important role does sulfur play in microbial growth?
answer
its needed to make some amino acids and vitamins
question
What element do microbes need to make nucleic acids and the bilayer of plasma membranes.
answer
phosphorus
question
What element(s) do microbes need to make cofactors of enzymes?
answer
trace elements, mineral elements
question
What are organic growth factors? Give an example of some.
answer

essential organic compounds from the environment

 

eg. vitamins, amino acids, and bases of DNA and RNA

question
What pH do bacteria like?
answer
neutral, 6.5 - 7.5
question

What pH do fungi like?

 

answer
acidic 5-6
question

Nutrients prepared to grow microbes

eg. nutrient agar

answer
Culture Medium
question
Contains no living microbes
answer
sterile
question
microbe introduced into a culture medium to initate growth
answer
inoculum
question
microbes growing in/on a culture medium
answer
culture
question
contains only one species or strain
answer
pure culture
question
a visible mass of microbial cells that arose from a single cell, spore, or a group of attached cells
answer
colony
question

what does preserbing bacterial cultures for a long term do to bacteria? How long does this last?

 

answer

totaly stops metabolism

 

years

question
What does preserving bacterial cultures for a short term do to bacteria? How long does this last?
answer

slows down metabolism

 

3-4 months

question
name and define 2 long term ways to preserve bacterial cultures and the temperature they are stored at
answer

Deep-freezing - in liquid nitrogen -50 to -95 C

 

Lyophilization- freeze drying; dehydrate in a vacuume then freeze  -54 to -72 C

question
Name 2 methods of obtaining a pure culture
answer

pour plate method

streak plate method

question

Which culture media has a chemical composition that varies slightly per batch and is routinely used to grow many kinds of bacteria?

eg. nutrient agar

answer
Complex media
question
which culture media are we using where the exact chemical composition is known?
answer
chemically defined media
question

Which culture media suppresses the growth of uneanted microbes and encourages he growth of the desired microbe?

eg. Sabourand agar

answer
selective media
question
Which culture media makes it easier to distinguish colonies of desired microbes?
answer
differential media
question
which culture media encourages the growth of the desired microbe?
answer
enrichment media
question
What is the time for a cell to divide and its population to double called?
answer
generation time
question
Which phase of the bacterial growth curve is intense cellular activity and no cell division?
answer
lag phase
question
Which phase of the bacterial growth curve used to determine generation time, is most effective to treat infections, and is under optimum conditions?
answer
log phase
question
Which phase of the bacterial growth curve is slower growth and has new cells and dying cells?
answer
stationary phase
question
which phase of the bacterial growth curve shows a logarithmic decline where dying cells exceed new cells formed?
answer
Death phase
question
Name the 4 phases of the bacterial growth curve.
answer

lag phase

log phase

stationary phase

death phase

question
Name the 4 direct methods of measuring microbial growth.
answer

plate count

most probable number (mpn)

direct microscope count

filtration

question
Which method of measuring microbial growth is a common method for estimating the number of bacteria in a sample, uses colony forming units (CFU), and assumes that each bacterial cell grows in a single colony?
answer
Plate count
question
What are the advantages and disadvantages of a plate count in measuring microbial growth?
answer

A: counts only the number of living viable cells

 

D: -need a lot of materials to preform serial dilutions of a sample

-requires time for incubation

question
Which method of measuring microbial growth is a statistical estimation of a bacterial count and is used when microbes wont grow on solid media or will only grow in liquid differential media.
answer
Most Probale Number (MPN)
question
which method in measuring microbial growth uses a special slide that can hold a measured volume of bacterial suspension?
answer
direct microscope count
question
What are the advantages and disadvantages of the direct microscope count method in measuring microbial growth?
answer

A: a fast way of counting the number of cells

D: -requires a high concenration of cells in a sample

-does not work if the baceria are motile

-counts living and dead cells

question
which method in measuring microbial gowth is where bacteria are sieved out onto the surface of a membrane filter then transferred to a culture medium and the CFUs are counted?
answer
Filtration method
question
Which method in measuring microbial growth is a useful method when the bacterial count is low?
answer
Filtration method
question
Name the 3 indirect methods of measuring microbial growth.
answer

turbidity

metabolic activity

dry weight

question
Which method for measuring microbial growth measures the level of cloudiness and uses an instrument that measures he amount of light that passes through a suspension of cells? What is that instrument called?
answer

Turbidity

 

spectrophotometer

question
Which method in measuring microbial growth measures he amount of metaolic profucts such as acid, gas, and enzyme production?
answer
Metabolic Activity method
question
Which method in measuring microbial growth is used for filamentous organisms, like fungi and algae, that can be grown, dried, and weighed?
answer
Dry weight method
question
What is the structure in a bacteria that is small, circular, self replicating DNA that may contain a few genes?
answer
plasmid
question
What type of media is a Mannitol salt agar?
answer
selective and differential
question
what type of medium is a blood agar?
answer
differential
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