MCB 3020L Lecture Notes - Aureus, Subculture, Petri Dish

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byzantiumjackal692

25 Feb 2014

School

University of Florida

Department

Microbiology and Cell Science

Course

MCB 3020L

Professor

ashgar

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Document Summary

Isolation of colonies from a mixed culture (streak-plate technique) The purpose of this experiment is to learn how to isolate a culture by streaking. Being able to isolate a single organism is an extremely important aspect to working in a microbiology lab. In order to examine a specific organism on a petri dish, that organism must be isolated from the many other types of organisms that may be present. To do so, the aseptic technique, as well as properly streaking a petri dish must be employed. The goal of this experiment is to isolate an e. coli organism by transferring it from one petri dish to another. Incubate the petri dish inverted for 24 to 48 hours at 37 degrees c. An isolated sample of e. coli (right) and s. aureus (left) were the result of proper aseptic and streak-plating techniques.

Related Questions

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

sapphireguinea-pig180

Class 6: Viruses (and Cells, continued)

Making connections: viruses and microbes Match the cell biology concept (on page 1) with an important application of that concept (on page 2). Then answer the follow-up questions at the bottom of page 2.

Cell Biology concepts
1. Bacteria that cannot construct new cell wall material become fragile and break down.
2. During influenza infection, the viral enzyme neuraminidase is required to release new viruses from the host cell in which they were made. Once released, the new viruses can infect many additional cells.
3. Thermus aquaticus is a bacterium found in hot springs and can live at temperatures up to ~80Â°C (175Â°F). It has adapted so that its enzymes are most functional at the elevated temperatures, compared with many organismsâ enzymes that function best ~37Â°C (98Â°F).
4. Until the isolation and investigation of retroviruses, scientists thought that RNA could be copied from DNA, but DNA could not be copied from RNA. Research on this class of viruses led to an update to this âCentral Dogmaâ of biology.
5. Some bacteria have adapted, so that the enzymes involved in making cell wall materials have a slightly different shape and can no longer be bound by certain drugs.
6. Rhizobia are bacteria that colonize the roots of certain plants (legumes, including beans and peas). The host plant benefits from the prokaryotesâ ability to âfixâ nitrogen, converting N2 from the atmosphere into a form that is usable by the plant.
7. Many species of bacteria contain the enzyme cellulase. More than 10 billion such bacteria and other symbiotic microbes may be found in a single milliliter of material from inside the digestive system of ruminant mammals.
8. Fungi, including those that cause athleteâs foot, use ergosterol to maintain healthy membranes. Animal cells do not make ergosterol, they use a similar lipid â cholesterol.
9. During retrovirus infection, a DNA copy is made of the virusâs RNA genome. A cut is made in the host cellâs DNA and the DNA copy of the viral genome is pasted into the host chromosome by a viral enzyme called integrase.
10. Prokaryotic cells contain smaller ribosomes (â70Sâ ribosomes) than eukaryotic cells (â80Sâ ribosomes). Both types of ribosomes synthesize proteins, but the macromolecules they use to do it are somewhat different.

2
Applications
_______ Oseltamivir, also called Tamiflu, binds and inhibits the viral protein neuraminidase.
_______ Clotrimazole is a drug that is used to treat certain infections. It interferes with synthesis of ergosterol, a lipid involved in phospholipid membranes.
_______ Penicillin is a drug that interferes with synthesis of peptidoglycans (these are biological molecules that are part protein and part carbohydrate) that are present in certain cell walls.
_______ HIV is often treated with several drugs that inhibit different parts of the viral replicative cycle. Raltegravir is an example of a drug that interferes with the integration of viral genes into the host cellâs chromosome.
_______ Cows, like other vertebrates, lack the ability to breakdown cellulose. Yet they are able to live on a diet of grass and other vegetation high in cellulose.
_______ Enzymes isolated from extremophiles have been very useful in laboratory research. For example, Taq polymerase facilitates PCR, a revolutionary technique for production of DNAs of particular sequences, which requires cycling reactions through high temperatures.
_______ Plants and animals require nitrogen to make biological macromolecules, however theyâre unable to convert atmospheric nitrogen (N2) into a biologically useful form.
_______ Azithromycin is a drug that binds to 70S ribosomes and blocks synthesis of any new proteins.
_______ Methicillin-Resistant Staphylococcus aureus (MRSA) can cause life-threatening infections of the skin and bloodstream. One of the reasons MRSA infections are so serious is that they are resistant to treatment by many antibiotics, including methicillin and penicillin.
_______ The enzyme reverse transcriptase, isolated from retroviruses, is an important tool in molecular biology research. Scientists interested in learning what genes are turned on in particular cells use it to make DNA copies of RNAs they are studying (The DNA copies are useful because they are more stable).

When you have completed the matching activity, answer these follow-up questions:
â¢ What types of infections can be treated with the following drugs?
o Penicillin
o Clotrimazole
o Azithromycin
o Tamiflu
o Raltegravir
â¢ Why are these drugs (above) safe for you to take? That is, why donât they kill your cells?
â¢ Cancer cells are your own human cells that have become deregulated so that they divide and pile up in an uncontrolled way. Many chemotherapy drugs treat cancer by interfering with cell division and other cell processes.
o Why are there so many more side effects for individuals undergoing chemotherapy than for individuals taking antibiotics?

MCB 3020L Lecture Notes - Aureus, Subculture, Petri Dish

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