All of us involved with planning of the winter term of the Elder Collegium are pleased with the fine array of courses now underway, and the good registration for these courses, which perhaps is not surprising. We have a number of new courses underway, and I hope to present short photo reviews of each. Here is the first, entitled “DNA Basics”, taught by Mary Caroline Henry on Tuesday afternoons at VOC. She has taught biology at a girls’ school in Cairo and basic biology at a women’s college in Tehran. Later she taught neurobiology at Carleton College and animal physiology and neuroscience at St. Olaf.
DNA stands for “desoxyribonucleic acid”, and is the marvellous group of chemicals which make up the bulk of chromosomes, the controllers of inheritance in all of biology, whether plants, animals, humans, or even bacteria. Moving from top to bottom, we first see Mary Caroline explaining how the two purines, adenine and guanine, and the two pyrimidines, cytosine and thymidine, are combined with ribose phosphate and linked into long, two-stranded chains, or helixes.
In the next photo Pai Yang is learning how to extract DNA from (believe it or not) strawberries. Strawberries are a rich source of DNA because, unlike humans, who have 46 chromosomes in each cell, the larger varieties of strawberries may have up to 70. Pai is squashing some strawberries in a plastic bag in order to expose the cells more easily to fluids, which come next.
Next Mary Caroline is adding some simple substances available in a supermarket, such as table salt and detergent, to the mashed strawberries, to release DNA from the cells. Richard Von Korff gives it his close attention.
The last photo shows that after the mix is filtered and extracted with isopropyl alcohol, a cloudy material rises above the red residue. This cloudy material is the extracted DNA, which can now be analyzed in a bewildering variety of ways to detect such things as parentage, susceptibility to diseases, connection with certain crimes, origin of epidemics, susceptibility of bacteria to antibiotics, and many other applications.
Let us know of other topics of interest to you, and we’ll do our best to address them. Ed