[ Swords clanging ] - Glorinna: What do swords have to do with bacteria?
Well, bacteria fight each other with little swords.
Which we know because scientists saw it under a microscope using GFP,
and it turns out doing this kind of research requires the use of a pipette!
♫ Intro Music ♫
- Justine: In a recent paper, scientists were trying to study
a type of gut bacteria that only grows in the absence of oxygen.
But to see these little swords, they're called type 6 secretion systems,
they needed to use a fluorescent protein, like GFP.
But the problem is that GFP doesn't light up if there is no oxygen around.
The scientists discovered that they could grow the bacteria in
a little bit of oxygen that wasn't too much for the bacteria,
but was just enough for GFP to light up.
This was the first time that scientists could see the type 6 secretion system,
and other cellular processes in these bacteria, which means we can study them better.
- Glorianna: To do this experiment, they used pipettes!
They needed to grow the bacteria in liquid media, which they needed to precisely measure.
Pipettes are a very handy tool for measuring precise amounts of liquid.
♫ Music ♫
A pipette is a laboratory tool used to transport small amounts of measured liquid accurately.
- Glorianna: The pipette is like a turkey baster,
it sucks up the liquid and squirts it back out again. It's just more accurate.
- Justine: Now you're making me hungry for turkey!
- Glorianna: Oops!
Micropipettes are for measuring amounts less than one ml.
Pipettes are for measuring 1 to 25 ml of liquid,
and for liquid amounts greater than 25 ml you should use a graduated cylinder.
- Justine: When using these measurements scientists refer to milliliters as ml (mils).
- Glorinna: Who calls it milliliters?!!
♫ Music ♫
- Justine: Before you start, make sure you choose an appropriately sized measuring device.
For example, if I needed to measure 8 ml,
I would choose a 10 ml pipette to do the job, not 25 ml.
Because smaller pipettes measure more accurately.
But, obviously, you should choose a pipette that's big enough to hold your desired volume.
- Glorianna: There are little lines on the side of
the pipette that act like a ruler to help you measure the liquid.
Always measure the liquid amount from the bottom of the meniscus.
- Justine: What is a meniscus? - Glorianna: The meniscus is
this water line right here.
- Justine: When you are measuring the amount of liquid you are taking in,
you should start measuring from the smaller numbers closer to the bottom of the pipette.
When you are trying to release the liquid from the top, you'll have measurements going downward...
to help you see how much you are moving.
Pipettes come in different sizes, but the measurements will always be in ml.
- Before we explain how to use a pipette properly, let's show you how not to use a pipette.
There are two things you should never do when using a pipette.
First, when you measure the liquid in your pipette, never tilt it to the side.
Otherwise, the liquid will run into the machine, and cause it to malfunction.
You know, like this.
Second, never fill up the pipette up all the way,
or the liquid will get into the device and keep it from working properly.
This pipette is really easy to use. Simply press the up arrow to take in the liquid,
and press the down arrow to release the liquid.
This pipette is like a turkey baster.
First, squeeze the bowl.
Then press the knob to take in the liquid,
and then press the knob, on the side, to release it.
This pipette has a roller on the side, that you use your thumb to control.
Moving the roller downwards takes in the liquid, and moving it up releases it.
♫ Chimes ♫
- Justine: Once you're finished using the pipette, release all the liquid from the device
and then place it in this container, so it can be cleaned.
Now, you know how to use a pipette!
- Maybe you can conduct your own experiment using GFP, to attract bacteria.
- Comment down below how you're going to use your pipette.