Tests
Tests
[Megan pouring a bucket of purple liquid on the presents at the base of a Christmas tree.]
[Megan pouring a bucket of pink liquid on the presents at the base of a Christmas tree.]
[Megan looking at the soaked presents.]
Megan: All my presents appear to be Gram-negative. Cueball: I wish you hadn't opened the home bio lab kit first.
The first present Megan opened contained a home biology lab kit, including the equipment needed to perform a Gram stain. Gram staining is a technique used in microbiology to separate bacteria into two broad categories based on the structure of their cell walls. The sample is treated with two different dyes: first a purple dye, then secondly a pink one. When subsequently examined under a microscope, "Gram-positive" bacteria retain the purple color of the first dye, whereas "Gram-negative" bacteria do not, allowing the second pink stain to show. All Megan's presents have been stained pink, and are presumably therefore Gram-negative.
In the process, she has damaged the other presents, hence Cueball's wish that she had opened another present first.
The title text refers to two bacteria commonly used as controls to confirm that the technique has been correctly performed: Staphylococcus aureus (Gram-positive) and Escherichia coli (Gram-negative). Neither are bacteria you want to be coming into contact with in any substantial quantities [ citation needed ] , hence the need to stop accepting presents from " That Guy ".
[Megan pouring a bucket of purple liquid on the presents at the base of a Christmas tree.]
[Megan pouring a bucket of pink liquid on the presents at the base of a Christmas tree.]
[Megan looking at the soaked presents.]
Megan: All my presents appear to be Gram-negative. Cueball: I wish you hadn't opened the home bio lab kit first.