Sunday, February 28, 2021 Smile of the Day: DNA
On this Day:
In 1953, Francis Crick and James Watson announced that they discovered the chemical structure of the DNA-molecule (double-helix polymer).
Deoxyribonucleic acid (DNA) is a molecule composed of two polynucleotide chains that coil around each other to form a double helix carrying genetic instructions for the development, functioning, growth and reproduction of all known organisms and many viruses. DNA and ribonucleic acid (RNA) are nucleic acids. Alongside proteins, lipids and complex carbohydrates (polysaccharides), nucleic acids are one of the four major types of macromolecules that are essential for all known forms of life.
In May 1952, Raymond Gosling, a graduate student working under the supervision of Rosalind Franklin, took an X-ray diffraction image, labeled as “Photo 51”, at high hydration levels of DNA. This photo was given to Watson and Crick by Maurice Wilkins and was critical to their obtaining the correct structure of DNA. Franklin told Crick and Watson that the backbones had to be on the outside. Before then, Linus Pauling, and Watson and Crick, had erroneous models with the chains inside and the bases pointing outwards. Her identification of the space group for DNA crystals revealed to Crick that the two DNA strands are antiparallel.
In February 1953, Linus Pauling and Robert Corey proposed a model for nucleic acids containing three intertwined chains, with the phosphates near the axis, and the bases on the outside. Watson and Crick completed their model, which is now accepted as the first correct model of the double-helix of DNA. On 28 February 1953 Crick interrupted patrons’ lunchtime at The Eagle pub in Cambridge to announce that he and Watson had “discovered the secret of life”.
In the 25 April 1953 issue of the journal Nature, were published a series of five articles giving the Watson and Crick double-helix structure DNA, and evidence supporting it. The structure was reported in a letter titled “MOLECULAR STRUCTURE OF NUCLEIC ACIDS A Structure for Deoxyribose Nucleic Acid”, in which they said, “It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism for the genetic material.” Followed by a letter from Franklin and Gosling, which was the first publication of their own X-ray diffraction data, and of their original analysis method. Then followed a letter by Wilkins, and two of his colleagues, which contained an analysis of in vivo B-DNA X-ray patterns, and supported the presence in vivo of the Watson and Crick structure.
In 1962, after Franklin’s death, Watson, Crick, and Wilkins jointly received the Nobel Prize in Physiology or Medicine. Nobel Prizes are awarded only to living recipients. A debate continues about who should receive credit for the discovery.
In an influential presentation in 1957, Crick laid out the central dogma of molecular biology, which foretold the relationship between DNA, RNA, and proteins, and articulated the “adaptor hypothesis”. Final confirmation of the replication mechanism that was implied by the double-helical structure followed in 1958 through the Meselson–Stahl experiment. Further work by Crick and co-workers showed that the genetic code was based on non-overlapping triplets of bases, called codons, allowing Har Gobind Khorana, Robert W. Holley, and Marshall Warren Nirenberg to decipher the genetic code. These findings represent the birth of molecular biology.
First, a Story:
When DNA is getting dressed for a night out on the town, what cosmetic does it put on? Genetic makeup of course!
Second, a Song:
“Grenade” is a song by American singer and songwriter Bruno Mars from his debut studio album, Doo-Wops & Hooligans (2010). The pop ballad was written and produced by the Smeezingtons (Mars, Phillip Lawrence, Ari Levine) with additional songwriting by Brody Brown, Claude Kelly, and Andrew Wyatt. The song was developed from an unreleased track with similar lyrical themes played by record producer Benny Blanco to Mars. “Grenade” was completely rearranged and re‑recorded two days before the album’s release. The lyrics carry a message of unrequited love and how Mars’ heart was broken, despite his best efforts to show her his love. Elektra Records released the song as the second promotional single and as the second official single, to contemporary hit and rhythmic contemporary stations in the United States in October 2010.
“Grenade” was well received by critics, praising the vocals and emotional lyrics of the song and also considered it as one of the stand-out tracks on Doo-Wops & Hooligans. The single reached number one in fifteen different countries, giving Mars his third number one single on the Billboard Hot 100, and topping the Canadian Hot 100 for three non-consecutive weeks. “Grenade” was certified diamond by the Recording Industry Association of America (RIAA) and seven Australian Recording Industry Association (ARIA), as well as six times by Music Canada (MC). Worldwide, it was the second best selling digital single of 2011 with 10.2 million copies. (per Wikipedia).
Mr. Parr is a musician as well as a teacher, so integrating music with science just seemed like a natural progression to him. He says:
“One of the most important benefits of using music in my classroom is music’s ability to aid in the retention and recall of information. In my classroom, a musically rich environment generates student involvement, increases learning, promotes memorization of concepts, and encourages creativity, which provides for a positive learning experience. Simply stated, my songs promote learning, practice, and recall. I am currently a 6th grade science teacher at Franklin Avenue Middle School (FAMS) in Franklin Lakes” (per https://www.teacherspayteachers.com/Store/Parrmr).
Here Mr. Parr takes “Grenade” and sets it to his own lyrics to explain how DNA works. It discusses that DNA and the genetic code determines how someone or something looks. The chorus talks about the pairings of Adenine and Thymine; Guanine and Cytosine and the other verses discuss the differences between DNA and RNA and how cells make protein. The song is presented as a slideshow with the lyrics of each verse printed in each slide along with a visual graphic of the concept in that verse. It is a fun resource for students learning about DNA and genetics and combines the visual and auditory senses for increased learning and retention (from https://schoollibrarymediamaterials.wordpress.com/2013/07/31/dna-song-by-mr-parr-youtube-video/).
Here is Mr. Parr in his mashup performing the DNA song. I hope you enjoy this!
Thought for the Day:
“Genes are like the story, and DNA is the language that the story is written in.” – Sam Kean
Have a great day!
Dave & Colleen
© 2021 David J. Bilinsky and Colleen E. Bilinsky
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