Formation of Nucleic Acids and their Backbones

Nucleic acids are naturally occurring chemical substances that make up the genetic material and act as the major information-carrying molecules in cells. Nucleic acids are abundant in all living things, where they produce, encode, and store information for every living cell in every life form on the planet. They then convey and express that information to the cell’s inner activities and, ultimately, to the future generation of each living thing, both inside and outside the nucleus. The nucleic acid sequence, which provides the ‘ladder-step’ ordering of nucleotides within the molecules of RNA and DNA, contains and conveys the encoded information. They are particularly crucial in controlling protein synthesis.

Formation of Nucleic Acids

There are two types of nucleic acids: DNA & RNA. The formation of both these nucleic acids is described below:

1. Formation of DNA

The sugar-phosphate backbone of DNA has a double-helix structure, with sugar and phosphate on the exterior of the helix. The nitrogenous bases are stacked in pairs in the interior, like steps on a stairway, and are connected by hydrogen bonds. The helix’s two strands go in opposite directions. This antiparallel orientation is crucial for DNA replication as well as many other nucleic acid interactions.

Base pairs

Only certain base pairings are permitted. This indicates that Adenine and Thymine pair up, and Guanine and Cytosine couple up. Because the DNA strands are complementary to each other, this is known as the base complementary rule. If one strand’s sequence is AATTGC, the complementary strand’s sequence is TTAACCGG.

DNA replication

Each strand of DNA is copied during replication, resulting in a daughter DNA double helix with one parental DNA strand and a freshly manufactured strand. It is possible that a mutation will arise at this time. A mutation is a change in the nitrogen base sequence. A mutation, for example, could alter the second T in the nucleotide AATTGGCC to a G. When this happens, the DNA is usually able to repair itself and restore the original base to the sequence. However, sometimes the repair fails, resulting in the production of new proteins.

DNA packaging

In live cells, DNA packaging is a vital process. A cell would be unable to accommodate the huge amount of DNA stored inside without it.

Backbone of DNA

The section of the DNA double helix that provides structural support to the molecule is known as the phosphate backbone. DNA is made up of two strands that are coiled together like a ladder. The backbone of each strand is made up of sugar (deoxyribose) and phosphate groups that alternate.

2. Formation of RNA

Synthesis I

RNA polymerases are enzymes that perform the synthesis of RNA. All three polymerases begin RNA synthesis at specified places on DNA and proceed down the molecule, sequentially connecting selected nucleotides until they reach the gene’s end and stop the growing RNA chain. The high-energy phosphate links found in the nucleotide precursors of RNA provide energy for RNA synthesis. The construction ingredient consists of a sugar, a base, and three phosphates, and each unit of the final RNA product is essentially a sugar, a base, and one phosphate.

Synthesis II

For each nucleotide integrated into RNA, two phosphates are cleaved and eliminated during synthesis. The phosphate bonds release energy, which is used to link the nucleotides. The sequence of nucleotides combined into a developing RNA chain is determined by the sequence of nucleotides in the DNA template: each adenine in DNA specifies uracil in RNA, each cytosine requires guanine, each guanine specifies cytosine, and each thymine specifies adenine in DNA. The information encoded in each gene is transcribed into RNA, which is then translated by the cytoplasm’s protein-synthesising machinery.

Transcription is the process of copying (transcription) a gene’s DNA sequence into an RNA molecule.

The main transcription enzyme is RNA polymerase.

When RNA polymerase connects to a promoter sequence near the start of a gene, transcription begins (directly or through helper proteins).

To build a new, complementary RNA molecule, RNA polymerase employs one of the DNA strands (the template strand) as a template.

Termination is the last step in the transcription process. Termination is determined by RNA sequences that signal the completion of the transcript.

Backbone of RNA

Instead of the deoxyribose found in DNA, an RNA molecule has a backbone consisting of alternating phosphate groups and the sugar ribose. Each sugar has one of four bases attached to it: adenine (A), uracil (U), cytosine (C), or guanine (G).

Conclusion

Nucleic acids are naturally occurring chemical substances that make up the genetic material and act as the major information-carrying molecules in cells. There are two types of nucleic acids, namely, DNA & RNA. The formation of both these nucleic acids has been described in this article.