As we have discussed in our previous text, the human body is a cooperative effort of trillions of cells. Each cell type displays specific functions necessary to sustain life. Within the nucleus of each of our cells, there is a full copy of our genetic code* that dictates the structure and action of each cell. This genetic information is contained in a structure known as DeoxyriboNucleic Acid (DNA)[1]. It is a sequence of nucleotides (A, T, G, and C), organized in groups of three, forming a stable triplet code [2]. This is a common feature of all life on earth, suggesting that every species shares some common ancestry.
Fully stretched out, the human genome, containing 3.1 billion letters, would extend approximately 1.8 meters in length (5 feet)! [3]. Therefore, it needs to be extremely well organized and packed into each cell. This makes the information contained in DNA secure but difficult to access. To increase accessibility, cells copy small “transcripts” of gene sequences from the DNA. These genetic copies are known as Ribonucleic acid (RNA) [4], a sequence of ribonucleotides (A, U, G, and C – where the T in DNA is substituted with U) that serves to rapidly accelerate protein production. The main difference between RNA and DNA is the structure.
RNA is only slightly different due to an added hydroxide (OH-) group on its backbone. This structure makes RNA much more unstable, so it degrades quickly and is rapidly cleared from the cell once the protein is produced. For this reason, RNA must be stored at very low temperatures for pharmaceutical applications.
To create the wide variety of structures and machinery that allow cells to live, the triplet DNA code is transcribed into a messenger RNA (mRNA) sequence that is then translated into 21 amino acids [2]. Each string of amino acids forms a unique structure known as protein. Proteins are the major functional units and carry out cellular processes. Every action a cell takes relies on the versatility of proteins provided by the boundless number of arrangements of the 21 amino acids.
The information flows from DNA (stable information storage) to RNA (quick information transfer) to protein (function and form). This mechanism ensures that cells regulate which proteins are produced and when – which is the central foundation for all life processes [5].
*Genetic Code - The code formed by DNA or RNA and contained within the cells of living beings. The code is transcribed from DNA to RNA, and then the information in RNA is translated into protein depending on the sequence of codons, which are groups of three nucleotides that define the amino acid (in proteins) to which the RNA corresponds to.
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Written by: Adrian
Edited by: María and Natasha
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References:
Dahm, R. Friedrich Miescher and the discovery of DNA. Dev. Biol. 278, 274–88 (2005). https://pubmed.ncbi.nlm.nih.gov/15680349/
Yanofsky, C. Establishing the triplet nature of the genetic code. Cell 128, 815–8 (2007). https://pubmed.ncbi.nlm.nih.gov/17350564/
International Human Genome Sequencing Consortium. Finishing the euchromatic sequence of the human genome. Nature 431, 931–45 (2004). https://www.nature.com/articles/nature03001
Rich, A. & Davies, D. R. A new two stranded helical structure: Polyadenylic acid and polyuridylic acid. J. Am. Chem. Soc. 78, 3548–3549 (1956). https://pubs.acs.org/doi/abs/10.1021/ja01595a086
Crick, F. Central dogma of molecular biology. Nature 227, 561–3 (1970). https://www.nature.com/articles/227561a0
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