Exercise 1: Lab Intro and Two-Tube Transfer

Before lab starts, what do you use to clean the benches?

70% EtOH

After lab ends, what do you use to clean the benches?

bleach wipes

You only need to wash hands after lab is finished, T or F?

false, you need to wash your hands before and after lab

Labeling the petri dish is done on the lid, the portion where the medium is, T or F?

false, the medium is not on the lid, its the bottom portion. Labeling is always done on the bottom of the plate where the medium is

What goes on the plate when labeling?

-seat #

-date

-organism that you are inoculating

When storing a petri dish, the medium side should be down on the table, T or F?

false; petri dishes should always be stored inverted

Why do petri dishes need to be stored inverted?

b/c of condensation forming on the lid; condensation may fall on the plate and ruin inoculation

Most petri dishes are incubated at what temp?

37 degrees C

What type of organism may not go in the 37C incubator?

yeast

What are the three different types of media?

-general purpose

-selective

-differential

What are the most common preparations of media?

-broth

-agar slant

-agar deep tube

-agar plate

When handling test tubes, there is no specific way to hold the tube, T or F?

false; never pick up the tube by the cap

When handling test tubes, caps should never go on the benchtop, T or F?

true

Which hand do you use to remove caps?

dominant hand

What hand do you hold the test tube with?

non dominant hand

An inoculating loop is used for:

transffering culture

Inoculating loops do not need to be sterilized when working with the same culture, T or F?

false; they must be sterilized before and after each transfer/inoculation, even when working with the same organism

What device/tool is used for sterilization of the loop and test tubes?

micro incinerator

What much of the loop needs to be glowing red for sterilization?

3/4

asepsis means:

without infection

Why is aseptic technique needed in the lab?

-limits the presence/spread of potentially organism

-limiting exposure to yourself and others

-reducing contamination

How many steps are there in a two tube transfer? What are they?

7

-sterilize loop

-uncap loop

-sterilize tubes

-transfer culture to fresh medium

-sterilize tubes

-recap tubes

-sterilize loop

During a two tube transfer, if the media you are working with are broth cultures, what do you need to do? Why?

re-suspend; to homogenize mixed cultures/tends to sediment (bacteria fall to the bottom of tube)