The Central Dogma: DNA –> RNA –> Protein

The central dogma is foundational to our understanding of biology. It might need a little updating, perhaps a fresh suit. But it is still the foundation. Just know that there is a version 2.0 to this story.

The Central Dogma of Molecular Biology

The central dogma states that DNA is transcribed into RNAs; messenger RNAs (mRNAs) are translated into proteins.

The central dogma of molecular biology can be compared to E = mc2 in physics. It is that foundational. It is how it works in the cells in yours and my body, as well as fluffy (your favorite pet) and even in microorganisms. The caveat, however, is that in biology, there are always exceptions. Kinda like French! Oui!

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Figure 1. The central dogma shown above is the foundational concept of molecular biology. DNA is where the genetic information is stored. DNA is transcribed into messenger RNA (mRNA), which then can be translated into proteins. Proteins can be likened to little factories or little workers that carry out an array of biological processes. (Photo: Khan Academy)

DNA

Think of DNA as alphabet letters. Genes are made of strings of DNAs; just like words are made up of a string of letters. Then, chromosomes are made of a series of genes; just like sentences are made of a series of words. Eventually, a few chromosomes constitute a genome; just like sentences make a paragraph. Your genome is like your fingerprint, unique to you and you alone. Since heritable DNA information is passed down from parents to children, your genome bears similarities to your parents.

RNA

Biologists used to think that RNAs are merely a product of DNA transcription, something that is, really, not much of use. But alas. Biologists should have known better. There are always exceptions; the “junk” we throw out seem to always make us eat our words. Early on, biologists already observed that DNAs are used as templates to be transcribed into messenger RNAs (mRNAs). Now, we have amassed much, much more evidence for its various roles in gene regulation, beyond the role of a messenger.

Protein

Proteins are the soldiers, the executors, the ones that do the work, as coded by RNAs (which came from DNAs, remember?). Proteins, like soldiers, like executors, like worker bees–are quite replaceable. Once their jobs are completed, they “retire.” Proteins are constantly being degraded, i.e. chewed up, and being replenished by new ones and carry on.

DNA, RNA and Proteins

So there it is. The central dogma that dictates the entire biological world. Am I right? Well, not so quick. It is biology after all. Nuances, nuances, nuances. Keep searching for them!

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