So, we've covered a basic look into genetics as a whole last week. But now, we will dive a little deep into the chemistry behind the molecules that started it all: nucleic acids.
DNA and RNA are quite interesting macromolecules. Macromolecules are essentially large molecular structures composed of monomers. Carbohydrates, lipids, proteins, and nucleic acids are the four macromolecules required by animals, including humans. Three (all but nucleic acids) are required to be consumed in moderation to ensure a healthy lifestyle. Nucleic acids, however, are passed down.
These nucleic acids have three major building blocks, called monomers, associated with them. These three monomers include sugar, nitrogenous bases, and a phosphate group. Let´s go one by one to discuss them.
SUGAR & PENTOSE
SUGAR! We all love it. Nucleic acids contain two different types of sugar, specifically pentose: ribose and deoxyribose. Deoxyribose is found in DNA while ribose is found in RNA. The difference between ribose and deoxyribose? The latter lacks an additional oxygen atom, hence the name. Otherwise, the formula and molecular composition are quite similar, making them structural analogs. Both are essential in the formation of a backbone for the nucleic acids. The pentose binds with both the phosphate (creating a pentose-phosphate backbone) and the nitrogenous bases. They aid in the creation of 5´ (5 prime) and 3´ ends for the nucleic acid. This will be explained further later.
NITROGENOUS BASES
A, T, C, G, & U. These five letters have dominated the world of genetics. Adenine, thymine, cytosine, guanine, and uracil. Each is their own nitrogenous base, an essential monomer of their nucleic acid. Adenine and guanine are purines, while cytosine, thymine, and uracil are pyrimidines.
Adenine and guanine are not only examples of purines, but they are also essential for understanding nucleic acids. Purines are identified by both their six-membered and five-membered nitrogen-containing rings bounded together with pyrimidines. Adenine and guanine are remarkably similar in their chemical formulas. The major difference is that guanine contains an oxygen atom while adenine does not. Adenine binds with thymine in DNA and uracil in RNA. Guanine binds with cytosine.
Cytosine, thymine, and uracil are pyrimidines. Cytosine binds with guanine, while thymine and uracil bind with adenine in their respective nucleic acid. Pyrimidines are identifiable by their six-membered nitrogen-containing ring. Thymine and uracil are quite similar in their chemical formula other than the addition of 1 carbon and 2 hydrogen atoms in thymine.
These five letters are transcripted and translated in order to catalyze protein synthesis in the ribosome (next week´s lesson!).
PHOSPHATE GROUPS
The phosphate group is bound to ribose or deoxyribose in its respective nucleic acid. It provides structural support for the macromolecule. ATP is a precursor to nucleic acids and phosphates aid in that creation. Phosphate is an anion made of 1 phosphorus atom for every four oxygen atoms.
In conclusion, DNA and RNA are essential macromolecules for survival! Next week, we will discuss protein synthesis.
“Adenine - an Overview | ScienceDirect Topics.”ScienceDirect, www.sciencedirect.com/topics/neuroscience/adenine. Accessed 6 July 2020.
Amoeba Sisters. “DNA vs RNA (Updated).”YouTube, uploaded by Amoeba Sisters, 30 Aug. 2019, www.youtube.com/watch?v=JQByjprj_mA.
“Guanine - an Overview | ScienceDirect Topics.”ScienceDirect, www.sciencedirect.com/topics/neuroscience/guanine. Accessed 6 July 2020.
“Phosphate Backbone.”Genome.Gov, NIH, www.genome.gov/genetics-glossary/Phosphate-Backbone. Accessed 6 July 2020.
“Purines vs Pyrimidines | Understanding Nitrogenous Bases of RNA and DNA.”YouTube, uploaded by 2 Minute Classroom, 17 Sept. 2019, www.youtube.com/watch?v=Xjja9w0Z8tA.
Written by Tyler Vazquez
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