BIOL 2905 Lecture Notes - Lecture 10: Safranin, Counterstain, Crystal Violet

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lemonturtle995

12 Dec 2016

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Based on the concept that if an individual cell is separated from other cells on a nutrient surface, it will form a colony. Colony a macroscopic cluster of cells appearing on a solid medium arising from the multiplication of a single cell. Requires the following: a medium with a firm surface, a petri dish. Loop dilution/poor plate technique : sample is inoculated serially into a series of cooled but still liquid agar tubes so as to dilute the number of cells in each successive tube in the series. In this technique some of the colonies develop deep in the medium itself and not just on the surface. Microbes can be identified through: microscopic appearance, characterization of cellular metabolism, determination of products given off during growth, presence of enzymes, and mechanisms for deriving energy, genetic and immunological characteristics. Cultures and specimens constitute a potential hazard. Stock cultures represe(cid:374)t a (cid:862)livi(cid:374)g (cid:272)atalog(cid:863) for stud(cid:455) a(cid:374)d e(cid:454)peri(cid:373)e(cid:374)tatio(cid:374)

Related Questions

In a quadrant streak, why do you intersect the previous lines and not the ends of the streak?

Select one:

a. More cell amount variability at ends, usually higher cell population

b. Keep streaks in the middle of the plate

c. Prevent cell death

d. To maintain a mixed culture

e. To count CFUs

How should you hold the inoculating loop?

Select one:

a. Maintain it at an angle at all times

b. In a test tube rack at all times

c. Like a pencil

d. Balanced on top of the tube

e. With dish gloves

Which of the following is used in the spread plate and not the streak plate method?

Select one:

a. Glass spreading rod

b. Flame loop

c. Agar plate

d. Bunsen burner/sterile utensil

e. Starting culture to sample

What would likely happen if the inoculum was not spread adequately over the agar surface?

Select one:

a. Contamination

b. Degradation

c. Sterilization

d. Uneven distribution

e. Cells will not grow

You have a mixed culture of unknown bacteria and want to identify one of the species by several subsequent experiments (needing multiple colonies of a pure culture). You do a quadrant streak and transfer to a sterile liquid medium. What next step makes the most sense?

Select one:

a. Perform a Gram stain

b. Note all colony morphology characteristics

c. Use the spread plate method or new streak plate on an isolated colony of the plate

d. Quantify the cells

e. Repeat using the other two methods of isolation

What would likely occur if the flame loop was not sterilized between streaks on the quadrant streak method?

Select one:

a. Bacteria will not stick to the loop

b. Virus will be introduced

c. Flame loop will be too hot

d. The sample will be contaminated

e. Subsequent streaks would have more colonies

Why is the glass rod in the spread plate method put in alcohol and ignited instead of sterilized like a flame loop?

Select one:

a. Glass oxidizes

b. Glass melts

c. Glass takes longer to cool

d. Glass burns

e. Glass is more sterile

Considering the cultures to be used for inoculating each medium in this exercise, how many microbial types should you expect to see in/on each medium?

Select one:

a. 3

b. 0

c. 1

d. Several

e. 2

Which of the following is common to minimize airborne contamination?

Select one:

a. Make someone else do the experiment

b. Perform the experiment in a windy room

c. Keep a microscope nearby

d. Breathing in sample

e. Hold open tubes at an angle

How can a hot sterile flame loop be cooled quickly to use in the next streak?

Select one:

a. Put in sterile portion of agar plate

b. Blow on it

c. Stick the loop in ice

d. Set the loop on the lab bench

e. Pour tap water on the loop

True or false: Most colonies can been seen without aid (naked eye), and most single cells cannot be seen without a microscope.

Select one:

True

False

An isolated, single colony forms after incubation of a:

Select one:

a. Virus (viral particle arrangement in some cases)

b. Single cell (cell arrangement in some cases)

c. Sterile agar plate

d. Sterile flame loop

e. Liquid mixed culture

These are commonly used for growing stock cultures that can be refrigerated for several weeks:

Select one:

a. Broth tubes

b. Cotton swabs

c. Gym socks

d. Agar slants

e. Petri dishes

Beginning at the base of the slant surface and gently moving the loop back and forth as you withdraw is called:

Select one:

a. Slant mixing

b. Fishtail inoculation

c. Zig-zag streaking

d. Squirrel inoculation

e. Quadrant streaking

If you are going to mix a broth culture prior to transfer, what is a safe way to do this without special equipment?

Select one:

a. Tap the tube with your fingers

b. Vortex it

c. Use a inoculating loop

d. Stick the tube in the outer cone

What is the primary purpose of the streak plate method?

Select one:

a. Quantify CFUs

b. Isolate an individual colony

c. Quantify the cell count of a mixed culture

d. Inoculate a culture on a plate

e. Confirm the identity of an unknown genus

Question 1

A microorganism's ability to use a harmful pesticide as a source of carbon and energy is an example of

Select one:

a. chemoautotrophy

b. nitrogen fixation

c. bioremediation

d. photoautotrophy

e. biosynthesis

Question 2

Autotrophs and heterotrophs differ in

Select one:

a. their ability to utilize CO2 as a sole carbon source.

b. their ability to incorporate CO2 into cells.

c. only a few enzymes.

d. their ability to synthesize precursor molecules.

e. their ability to utilize CO2 as a sole energy source.

Question 3

If the amino acid valine constituted approximately 4% of the total cell protein of a bacterium, how much valine should be added to a defined medium in order to grow 1 gram of this organism?

Select one:

a. 0.2 mg

b. 2 mg

c. 20 mg

d. 40 mg

e. 200 mg

Question 4

Transport of HPO₄ along with a proton (H⁺) is an example of

Select one:

a. antiport

b. uniport

c. facilitated diffusion

d. symport

e. group translocation

Question 5

The energy required for transport via ABC transporters is derived from

Select one:

a. a proton gradient

b. an electrical charge separation across the membrane

c. ATP hydrolysis

d. a symport mechanism

e. a high energy phosphate bond of PEP

Question 6

The spread plate method would clearly be preferred over the pour plate method when isolating colonies of

Select one:

a. anaerobic bacteria

b. thermophilic bacteria

c. bacteria from temperate lake zones

d. purple non-sulfur bacteria

e. agar-degrading bacteria

Question 7

Enrichment culture procedures for many microorganisms require intial growth in liquid media, followed by growth on solid media. The solid media is used to

Select one:

a. provide proper growth conditions.

b. isolate single colonies of the microbes.

c. get rid of competing microorganisms.

d. isolate strict aerobes.

e. enrich for specific nutrients.

Question 8

The optical density of light scattered by bacteria is a very useful tool for estimating population size. What can alter the bacteria's light-scattering properties?

Select one:

a. Cell volume depending on its growth stage

b. The condition of being absent of microorganisms.

c. The amount of light projected from the room.

d. The standard curve

e. Standard deviation from growth curve.

Question 9

What is true about a bacterial colony?

Select one:

a. It arises from an individual cell and represents an isolate strain.

b. Colonies, and CFU (colony forming units) on streak plates represent a diverse microbial culture.

c. In order to obtain a colony, on must perform cloning steps.

d. Axenic cultures to not represent CFUs or colonies.

e. Colonies require differential media in order to separate them from the population.

Question 10

What is a biofilm?

Select one:

a. All cells in a population achieve a steady state

b. A specialized, surface-attached, collaborative community of bacteria

c. A complex media made of the chemical building blocks that a cell needs

d. A type of anaerobic growth chamber.

e. A type of spore

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BIOL 2905 Lecture Notes - Lecture 10: Safranin, Counterstain, Crystal Violet

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