At the molecular level, all life has basically the same building blocks—DNA and RNA. Although DNA and RNA are made of nucleotides, there are some differences between DNA and RNA. Thus, the main difference between DNA and RNA is that DNA is double-stranded and RNA is single-stranded. DNA is responsible for transmitting genetic information, while RNA transmits the genetic code that is required for protein formation.
What is DNA?
Deoxyribonucleic acid or DNA is a molecule made up of two polynucleotide chains. This coil forms a complex double helix that contains the genetic instructions for growth, function, development and reproduction of all living organisms. The two strands of double-stranded DNA store the same biological information, which is repeated when the two strands are separated.
What is RNA?
The full form of RNA Ribonucleic acid is a type of polymeric molecule. It helps in various biological roles such as coding, decoding, regulation and expression of genes. In cellular organisms, messenger RNA (mRNA) helps to deliver genetic information that directs the synthesis of specific proteins.
comparison of the helix and base structure of RNA and DNA
DNA Vs RNA comparison
| Comparison | DNA | RNA |
|---|---|---|
| Name | Deoxyribonucleic Acid | Ribonucleic Acid |
| Function | DNA copies and stores genetic information. It is the blueprint for all the genetic information contained in an organism. | RNA converts the genetic information contained in DNA into a format used to make proteins, and then carries it to ribosomal protein factories. |
| Structure | DNA consists of two strands, arranged in a double helix. These strands are made up of subunits called nucleotides. Each nucleotide consists of a phosphate, a 5-carbon sugar molecule, and a nitrogenous base. | RNA consists of only one strand, but like DNA, is made up of nucleotides. RNA strands are shorter than DNA strands. RNA sometimes forms a secondary double helix structure, but only intermittently. |
| Length | DNA is a much longer polymer than RNA. For example, a chromosome is a single, long DNA molecule that is several centimeters in length when it is cleaved. | RNA molecules are variable in length, but are much smaller than long DNA polymers. A large RNA molecule can be only a few thousand base pairs long. |
| Sugar | The sugar in DNA is deoxyribose, which has one less hydroxyl group than the ribose of RNA. | Without the hydroxyl modifications of deoxyribose, RNA consists of ribose sugar molecules. |
| Base Pairs | Adenine and thymine pairs (A-T) Cytosine and guanine pairs (C-G) | Adenine and Uracil pairs (A-U) Cytosine and Guanine pairs (C-G) |
| Bases | The bases in DNA are Adenine (‘A’), Thymine (‘T’), Guanine (‘G’) and Cytosine (‘C’). | RNA shares Adenine (‘A’), Guanine (‘G’) and Cytosine (‘C’) with DNA, but contains Uracil (‘U’) rather than Thymine. |
| Location | DNA is found in the nucleus, with small amounts of DNA also in the mitochondria. | RNA is made in the nucleolus, and then moves to specific regions of the cytoplasm depending on the type of RNA formed. |
| Reactivity | Because of its deoxyribose sugar, which contains a less oxygenated hydroxyl group, DNA is a more stable molecule than RNA, which is useful for a molecule whose function is to protect genetic information. | RNA, which contains the ribose sugar, is more reactive than DNA and is not stable in alkaline conditions. The large helical groove of RNA means that it is more easily subject to attack by enzymes. |
| Ultraviolet (UV) Sensitivity | DNA is susceptible to damage from ultraviolet light. | RNA is more resistant to damage from UV light than DNA. |
DNA
DNA was first established by Friedrich Miescher in 1869. In February 1953, Watson and Crick completed their model, which is now accepted as the first correct model of the DNA double-helix. DNA is a long polymer chain made up of repeating units called nucleotides. Each of these nucleotides is represented by a letter. It is a nucleic acid.
Deoxyribonucleic acid (DNA) contains the genetic instructions for the growth and function of living things. DNA in a cell stores information for a long time. Information is organized into sequences of DNA fragments called genes.
Three different types of DNA are shown below:
- A-DNA: This is a right-handed double helix similar to the B-DNA form.
- B-DNA: This is the most common DNA conformation and is a right-handed helix.
- Z-DNA is a left-handed DNA where the double helix winds to the left in a zig-zag pattern.
RNA
In 1868, Friedrich Miescher discovered nucleic acids. He named the material ‘nuclein’ because it is found in the nucleus. Leslie Orgel is the father of RNA. He was an alchemist and established a one-world theory of the origin of life.
RNA is present in all living cells. It is an important biological macromolecule primarily involved in the synthesis of proteins, carrying messenger instructions from DNA, which itself contains the genetic instructions necessary for the development and maintenance of life.
Three different types of RNA are shown below:
- Messenger RNA (mRNA), mRNA is transcribed from DNA and contains the genetic blueprint for making proteins. Prokaryotic mRNA does not need to be processed and can immediately proceed to synthesize proteins.
- Transfer RNA (tRNA), tRNAs are RNA molecules that translate mRNA into proteins. They have a clover structure consisting of a 3′ acceptor site, a 5′ terminal phosphate, a D arm, a T arm and an anticodon arm. The primary function of tRNA is to transport amino acids to their 3′ acceptor sites in the ribosome complex with the help of aminoacyl-tRNA synthetase.
- Ribosomal RNA (rRNA), rRNA makes up ribosomes, which are essential in protein synthesis. A ribosome consists of a large and a small ribosomal subunit. In prokaryotes, the small 30S and large 50S ribosomal subunits make up the 70S ribosome.
