pGLO Lab

        In the pGLO lab, we added plasmids to E. coli bacteria containing araC, GFP, and ampicillin resistance genes. After heat shocking the bacteria, we plated them onto luria broth with ampicillin nd arabinose and waited for the colonies to grow.
        Though my group's bacteria failed to receive the plasmid successfully due to possible errors in adding the plasmid and heat shocking, we recorded data from a more successful group to analyze.

Our failed plates (note no GFP in bacteria seen under black light)

Another group's successful plates
(from left to right: -pGLO with LB,
+pGLO with LB and amp,
+pGLO with LB, amp, and arabinose)

Plate	Number of Colonies	Color of colonies under room light	Color of colonies under UV light
- pGLO LB	1 large colony with incoherent boundaries	Murky gray	Yellowish gray
+ pGLO LB/amp	9 large colonies	Murky gray	Yellowish gray
+ pGLO LB/amp/ara	7 colonies	Murky gray	Bright green

        There were likely about 10,000,000 bacteria in each 100 uL E. coli sample plated, assuming about 100,000,000 in each milliliter. This estimate takes into account the millions of bacteria that exist everywhere and gives a reasonable number without a reference, though an equally large number is possible as well.

        Out of these, a very small number of bacteria (i.e. around 1,000,000) successfully received the plasmid. These transformed bacteria had the pGLO gene as well as ampicillin resistance, allowing them to be isolated in the luria broth, as the ampicillin killed off the rest of the bacteria. In addition, arabinose acted like a trigger to activate the GFP intron in the pGLO plasmid, allowing the bacteria to produce GFP when the sugar was present. Where arabinose was absent, (as in the +pGLO LB/amp plate) the gene was not expressed; in the plate with the trigger sugar, the gene was expressed, and the bacteria glowed.

        This kind of genetic engineering is very useful and can be applied in a variety of places. GFP is used in many areas, including as a cell marker, in which it is added to plasmids of interest to gauge how many bacteria have successfully taken in the plasmid; as a transcription reporter, in order to monitor the expression under a certain promoter; and in FACS (fluorescence-activated cell sorting), to separate different cells based on their fluorescent signals. Furthermore, genetic engineering involving the enzyme Cas9 in CRISPR editing can be done in order to modify the genome of different organisms, including humans, with low costs and equipment. This can been done to change the inheritance of traits or characteristics of embryos, and is currently being studied.

Gel Electrophoresis Lab

        Though there are natural alternatives, artificial food colors can be preferable to both consumers and manufacturers. They are much easier to mass-produce and obtain, and also include a wider range of bright colors (or colors that make food seem fresher) that can seem more appealing to consumers. Though I usually tend to avoid foods and snacks with dyes, I have seen sodas that contain different dyes, as well as chips (e.g. Doritos) that contain dyes like Yellow 5 and Yellow 6. Additionally, one large source of artificially dyed foods is dog food: manufacturers tend to add artificial food colors like Yellow 5, Blue 2, Red 40, and Yellow 6. This is likely to create a more “nutritious” appearance that may sway consumers.

        In our DNA electrophoresis lab, we ran dyes found in various common candies. We used the Red 40, Yellow 5, Yellow 6, and Blue 1 reference dyes to compare our dyes to. Observing the molecular structures of other dyes, we can see that they have similar structures to the four reference dyes we used, with analogous substituents (e.g. phenyl, hydroxyl, carbonyl); these similar structures would lead to them to migrate similarly in gel electrophoresis. For example, carminic acid is similar to Yellow 6, betanin acid bears resemblance to Yellow 5, fast green FCF is like Blue 1, and citrus red 2 resembles Red 40.

        Our dyes ran mostly as expected, with the orange dye being Yellow 6, and the other dyes turning out to be their corresponding reference dyes. However, our green dye separated into 2 different bands when we ran the gel electrophoresis. This green was actually a mixture of a blue and a red dye (Blue 1 and Red 40), since green dyes are likely harder to produce.

Final gel results (4 test dyes on left, 4 reference dyes on right)

        The colored dye solutions we used also migrated different distances, and this effect was contributed to by multiple factors. First of all, the larger molecules are less flexible and will be hindered more by the gel’s channels. Also, the molecule concentrations would make a difference: a dye with a higher concentration might advance slower than another dye with a lower concentration.

Gel electrophoresis setup

        The movement of the dyes through the gel is facilitated by their negative charge and the voltage of the electricity. Their charge makes them attracted toward the anode, and smaller molecules can advance further, because they are less obstructed by imperfections and twists in the gel. DNA molecules, which are commonly used in gel electrophoresis, would also separate like the dyes we used. DNA of a lower dalton size would advance the furthest, while the largest molecules would advance much slower and thus traverse less distance.

New Year Goals

        This semester I will strive to improve upon last semester's performance in several specific ways. In order to attain more understanding in biology, I will study and investigate more into each unit. I will make connections to different aspects of biology and find in-depth information about each one, enhancing my understanding about the specific subject and its place in the world of biology.
        Additionally, I will improve my expository writing in English, which will entail forming stronger and better substantiated points and theses, as well as creating a conclusion that better wraps up the essay. This will allow me to better express my opinion and evidence in future letters or pieces of writing.
        In order to gauge my progress, I will reflect (perhaps sometimes physically) on my accomplishments toward my goal in each unit or subject: in Biology, this would involve connecting the topic to other concepts, while in English I would keep track of each facet I expressed successfully or included after each essay or other practice opportunity.