DNA and the Central Dogma of Molecular Biology

Teaching about the Alphabet of our Identify

Source: http://www.unacknowledged.info/wp-content/uploads/2013/07/DNA.jpg

One of the most memorable professors that had a positive impact on me was Dr. June Faith Escara-Wilke. I can still vividly remember her American accent, although she is a Filipin, Tagalog was not her first language. Even before she taught in UPLB, she was already a professor of Molecular Biology in the US . One of the concerns of her students was that her American accent added difficulty in understanding the lesson; nevertheless, upon knowing our difficulty Dr. Wilke tried her best to speak in Filipino once in a while which was a great relief to us. In the 90’s, the field of molecular biology and biotechnology was still in its germinal stage in the Philippines. But despite the absence of sophisticated laboratory instruments, Dr. Wilke was able to inspire us to appreciate DNA. I must admit I’ve never heard about it in high school and so as the rest of my classmates, I suppose. We used to have a joke about taking Genetics as a major because it was really specializing in imagination. We imagine the DNA,RNA and protein. We view the chromosomes under the microscope but we imagine the processes that happens such as the transposons or the changing loci of the “jumping genes”. Dr. Wilke was a game changer - she actually one of the few professors who made use of popular magazines and even brought her own gadgets to our lecture class. When I was an undergrad, Molecular Biology was only a lecture class and there was no sophisticated biotechnology laboratory yet. Dr. Wilke brought samples of DNA, a hand-held UV light, protective glass, gloves, etc. The use of informative text such as the National Geographic and Time Magazine instead of textbook was not a common practice back then. But reading such material actually inspired me to read more classic papers. 

As an undergraduate Biology major, my very first encounter with the central dogma was during a lecture on replication (I think in my Biodiversity class). Imagine a lecturer who uses only chalk and occasional handwritten transparencies. It was really an effort to understand such an abstract concept. Back then, it would have been better if there was a brief historical background to help the students see the bigger picture. 

A brief history of DNA research leading to the PCR experiment can be downloaded from this link: https://classes.soe.ucsc.edu/bme215/Spring10/Reading%20Materials/Polymerase%20chain%20reaction.pdf

The Scientific American article featuring the story behind the conceptualization of the Polymerase Chain Reaction by Kary Mullis was one of those papers that not only the scientific mind would appreciate. But Dr. Wilke, the brilliance that she was, asked us to read such articles rather than a chapter of a textbook. I must admit that the PCR article was the turning point of my reading list. It instigated a much deeper appreciation of the classics. 

When it was my turn to present a paper in our undergraduate seminar, guess what my topic was. It was the use of PCR technology in genomic analysis of the Bacillus thuringensis ! My first serious job was still related to the bizarre world of DNA -  chromosome count analysis of wild rice. Eventually, I was fortunate to actually work in a molecular biology lab where we do PCR, isolate polymerase enzyme and do RAPDs. When I became a teacher, next to genetics and evolution, the central dogma would always share the lion’s share of my instructional time. My students would always find DNA studies difficult and challenging , nevertheless, I continue to promote it because it is definitely one of the pillars of the 21st century biology. They may not appreciate it now but I hope someday they would be grateful that sometime in their high school life they’ve heard about the DNA. 

A copy of the Scientific American article entitled "The Unusual Origin of the Polymerase Chain Reaction” can be downloaded from this link: 

http://www.ciens.ucv.ve:8080/generador/sites/labgeneticageneral/archivos/seminario%208-%20The%20Unusual%20Origin%20of%20PCR.pdf

It is an enjoyable article to read for someone who appreciates scientific creativity. 

Slide presentation to accompany Dr. Mullis’s Story can be accessed from:

https://www.biosearchtech.com/assets/KBM-Slides.pdf

Another classic paper that every biology teacher must read is the original paper of Watson and Crick that appeared in Nature Magazine way back 1953. A pdf copy can be accessed from this link: http://biology.mcgill.ca/watsoncrick_1953.pdf

In the current science curriculum, which is spiral in design, teaching about the DNA and the central dogma in general is a classic example how spiraling should be done. For Grade 7, DNA should be introduced more in visual such as a puzzle. In my own class, I asked them to cut patterns, put the patterns together so that they can draw out inferences how the purines and pyrimidines match or complement each other in terms of their molecular shapes. From their observations, they formulate inferences about the importance of specific base pairing. In Grade 8, they start doing math by applying Chargaff’s rules. They also start solving problems on N-base sequencing in simulations of the semi-conservative replication, predicting mRNA and amino acid sequences. For Grade 9, the central dogma of molecular biology is linked to genetic origin (mutations) of cancer and how spontaneous mutations can lead to evolution. Grade 9 students can actually now explain why certain genetic diseases are linked to abnormalities in protein function. Epigenetics is also introduced in Grade 9 which is discussed more deeply in Grade 10. Simulation of chromosome mapping is also fit for Grade 10. I would not recommend for the lower levels. The topic strand on molecular biology actually concludes with the discussion on genomic medicine. Grades 9 and 10 are appropriate level where students can isolate DNA using household chemicals like isopropyl alcohol and clarifying shampoo. Analysis of DNA fingerprints or genomic sequences can also be conducted in Grades 9 and 10 since they are capable already of understanding how classical genetics, molecular biology and evolution are interrelated with one another. With Grades 11 and 12, just thinking about it makes me excited. However, just thinking about it is stressful enough. What else should we teach them?

The video from the Science Symphony with the title "Greatest Show on Earth" is a wonderful introduction to a very challenging  and mysterious topic about the DNA. 

 https://www.youtube.com/watch?v=wxDOpAM2FrQ

For science teachers who want resources, Nature magazine website has a number of resources. 

http://www.nature.com/nature/dna50/

Many resources can also be downloaded for free from: www.hhmi.org, www.nih.gov., and www.learn.genetics.utah.edu. 

Two videos that I always used in my classes are easily downloaded from www.youtube. com

 The Central Dogma of Molecular Biology

animation video from the DNA Learning Center

Source: https://www.youtube.com/watch?v=9kOGOY7vthk

A more lengthy animation on the Central Dogma presenting replication, transcription and translation

Source: https://www.youtube.com/watch?v=J3HVVi2k2No

For further readings, I recommend two articles: 

DNA Strucutre: Alphabet Soup for the Cellular Soul 

by P. Shing Ho and Megan Carter

http://www.intechopen.com/books/dna-replication-current-advances/dna-structure-alphabet-soup-for-the-cellular-soul

The Central Dogma of Molecular Biology: A Retrospective after 50 years 

by Michel Morange

https://www.infona.pl/resource/bwmeta1.element.springer-bd9dc76a-1212-35c8-952a-3f07a93da1fc

Just a tip for those handling students. They appreciate cross analysis of documentary content and research article.