BSC 484 Lab midterm

Describe the procedures to contain a biohazard spill?

Spray the area with 10% bleach, lay paper towels on the spill and carefully clean with 70% ethanol

What is MSDS?

It shows what chemicals are dangerous, poisonous, etc. It stands for Material safety data sheet

Biohazard

Chemicals or anything that is extremely dangerous

Bio safety

Techniques used to stay protected against biohazards

Containment

Keeping anything in a safe environment

What risk group is Escherichia coli strain ER1647 in?

1

What risk group is Marburg virus in? Why?

4, because it produces untreatable diseases in humans

Describe 3 biosafety containment level 1 procedures

Protective gowns and glasses required

Wash hands before and after handling biohazard agents

No eating, drinking, or smoking

What volume of liquid (in units) can be transferred reasonably using a pipet-aid and an adjustable pipetter?

Pipet-aid: 1mL-50mL

Adjustable pipetter: 0.5uL-1000uL

What is the reason for adding antibiotics to the media (agar plates) after autoclaving?

Heat deactivates antibiotics. If it was added beforehand, the bacteria would not grow properly

Why do the LB agar plates contain antibiotics but the LB broth does not?

The bacteria in the agar plates has a resistance against the antibiotics, meaning the bacteria is able to grow without issue.

What is the purpose of flaming the neck/mouth of the tube in between inoculation steps?

To eliminate any stray bacteria on the mouth as well as release any air trapped inside the tube

Wha type of streaking method is used in lab?

Quadrant streaking

Why is it important to let the inoculation loop cool down prior to introduction into the bacterial culture?

It could damage/kill the bacterial culture and melt the agar.

What are the optima temperature and conditions for the growth of E.coli strain?

37 degrees Celsius

No humidity

No CO2

What is the name of the storage media used to store E.coli and how does that storage media help in preservation?

Glycerol (30%). It allows E.coli to freeze in certain conditions without damage by preventing ice-crystal formation

What is the purpose of the 20 minutes at 37 degrees Celsius incubation period after the Phage and Bacteria have been combined together?

It gives the bacteria enough time to replicate and start forming distinct traits to later recognize

What is the role of the SM Phage buffer?

It pulls water out of the concentration

What is the purpose of adding chloroform to the phage/SM buffer solution?

It kills the bacteria without killing the phage

What is DMSO? What is its role in freezing phage stocks?

Dimethyl Sulfoxide. It protects cells from freezing or frosting in any way.

Why were bacterial cells needed in this experiment?

The phage eats the bacteria to grow

What is the purpose for diluting the lambda bacteriophage?

If we were to plate it normally there would be too many cells to count

The media used to coat the 6 well plate

LURIA-BERTANI Agar

What is the purpose of the 20 minutes at incubation step after mixing the bacteria and the phage?

It allows the phage to fully absorb the bacteria

Why are plates incubated inverted?

So the moisture from the plate won’t drip into the media and contaminate it

Why do you add equal volumes of ER1647 and lambda bacteriophage for the assay?

The phage has been diluted prior to mixing with the bacteria. Therefore, there are more bacterial cells per phage in each dilution series mixture.

What is the difference between the dilution and the dilution factor?

Dilution=Volume/volume of (stock+SM)

Dilution factor=1/Dilution

If you add 10uL of lambda stock into 90uL of SM phage buffer, what dilution did you make?

1/10

If you add 10uL of lambda stock into 990uL of SM phage buffer, what dilution did you make?

1/100

If you add 50uL of lambda stock into 450uL of SM phage buffer, what dilution did you make?

1/10

If you add 50uL of lambda stock into 450uL of SM phage buffer, what is the dilution factor?

10