S-STEM Scholar Claudia Millanes's Blog

On 4/7, I was shown how to make media. Media is to nourish the bacteria. They live in it and eat it as well. The ingredients that were used to make media was:  Tryptone, 1.25 grams Yeast extract, 1.25 grams Dextrose (Glucose), .25g  Water, 250ml  A flask was place on a stirring hot plate and it was turn to a medium speed and 100 ml of water was added. Add the ingredients one at a time. Lastly, add the remaining water, the 150 ml, which makes it a total of 250 ml of water. I was just shown how to make media, so I didn't do anything with it once it was made.  Also,  I did a gram stain on D. Radiodurans. A gram stain is when you want to know whether a bacteria is gram-positive or gram-negative. Gram- positive bacteria have a thick layer of peptidoglycan in its cell wall, so its able to retain the crystal violet, making it look purple. After staining D. Radiodurans, it was found to be gram positive. 

On 3/30, I was shown how to use micropipette correctly and their correct measurements. The reason for the micropipette is to transfer small amounts of liquid (< 1ml). The scale on the micropipette are in microliters, so 1000 ul = 1 ml. Also, when using two different volumes with micropipette, the largest volume is always added first and then the smallest volume. There are four pipettes I was shown: P20, P100, P200 and P1000.  Each one has a low volume and a high volume. In the picture, the red one is the P20;  the limits are 2 ul to 20 ul. The colorless one is P100: the limits are 20 ul to 100 ul The P200, which is the yellow: the limits are 50 ul to 200 ul Lastly, the P1000 is the blue one: the limits are 200 ul and 1000ul.