Earth’s Artificial Moon

So what is RNA?

There are two types of "nucleic acids": deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). RNA converts genetic information from DNA to proteins and is located in every cell. DNA is first copied onto a strand of messenger RNA (mRNA) during a process called transcription. Then, the code on the mRNA is "read" and used to create a protein during a process called translation. Translation is broken down into three stages: Initiation, Elongation and Termination. 1. In Initiation the ribosome, mRNA and first transfer RNA (tRNA) all link together. 2. Next, in Elongation, amino acids are transferred to the ribosome by tRNA and are added to the growing protein. 3. Finally, in Termination, a stop codon is reached, and the complex separates and releases the newly formed protein. A codon is a sequence of three nucleotides in mRNA that codes for one amino acid, therefore a stop codon is a codon that signals the end of the translation process of the protein. These two processes are effectively summed up by the central dogma of molecular biology:

DNA → RNA → Protein.

In the 1950s, the Miller-Urey experiment, which experimented on a mixture of water and simple chemicals with electric pulses (mimicking the impact of lightning), proved that amino acids are easy to make. (In case you’re wondering, amino acids are the very building blocks of proteins.) However, other molecules of life are actually harder to synthesise than we imagined, the central reason being the incredible versatility of RNA. Not only can it act like an enzyme, but RNA can also store and transmit information. The catalytic activity of the RNA component in the ribosome synthesises all protein in all organisms. This is what scientists say suggests that RNA dominated an early stage in the evolution of life. So how did the first RNA and DNA molecules form? When I was researching I found that a man named Nicholas Hud, a Georgia tech chemist, and his team say that they have discovered that “the molecule ethidium can assist short polymers of nucleic acids, known as oligonucleotides, in forming longer polymers. Ethidium can also select the structure of the base pairs that hold together two strands of DNA." As it grew, the two ends of the growing polymer often reacted with each other as opposed to forming longer chains. This faced the team with quite a challenge known as strand cyclization. Fortunately, Hud and his research team discovered that if they could use a molecule to secure in between two base pairs of DNA, called an intercalator, they could bring short pieces of DNA and RNA together. This way, they could create much longer molecules. The team’s conclusion from the problem they faced was that "if you have the intercalator present, you can get polymers”, but “with no intercalator, it doesn't work”. Apparently “it's that simple.

Midwife molecules are believed to be the molecular "midwives" that help “give birth” to RNA. This team tested how much influence a midwife molecule had on creating the Watson-Crick base pairs that make up the structure of DNA. To clarify, the essential rule of the Watson-Crick base pairing system is that Adenine binds to Thymine and Cytosine binds to Guanine, forming base-pairs through hydrogen bonding. Their findings were that the matching base pair was dependent on the midwife present during the reaction and that Ethidium was the most helpful for synthesising polymers with the specific Watson-Crick base pairs of DNA.

Hud’s conclusion was that “the midwife molecules we used had a direct effect on the kind of base pairs that formed.” "We're not saying that ethidium was the original midwife, but we've shown that the principle of a small molecule working as a midwife is sound." So in conclusion of Hud’s conclusion, although it is not absolutely 100% scientists have found how life on Earth was created.

Sources

● How Did Life Begin? | NSF - National Science

Foundation. 2022. How Did Life Begin? | NSF -

National Science Foundation. [ONLINE]

Available at: nsf.gov/discoveries/dis ● c_summ.jsp?cntn_id=117380&org=NSF. [Accessed 10 February 2022]. ● Nature. 2022. How Did Life Begin?. [ONLINE]

Available at: nature.com/articles/d41586-01805098-w. [Accessed 10 February 2022]. ● Pressbooks. 2022. 5.7 Protein Synthesis –

Human Biology. [ONLINE] Available at: humanbiology.pressbooks.tru.ca/chapter/5-6protein-synthesis/. [Accessed 10 February 2022]. ● Molecular ‘Midwives’ Helped Give Birth to RNA | News | Astrobiology . 2022. Molecular

‘Midwives’ Helped Give Birth to RNA | News |

Astrobiology . [ONLINE] Available at: astrobiology.nasa.gov/news/molecularmidwives-helped-give-birth-to-rna/. [Accessed 10 February 2022]publications.