RNA vs. DNA

In cell biology, Ribonucleic acid (RNA) and Deoxyribonucleic acid (DNA) are considered the most important molecules. They are in charge of storing and reading genetic information that supports life.

RNA and DNA are linear polymers. They’re made up of bases, phosphates, and sugars. However, there are key differences between the two molecules. These dissimilarities enable RNA and DNA to work together while fulfilling their all-important roles.

Both DNA and RNA play important roles in biological functions. 

There is a wide range of RNA functions — from the translation of genetic information to gene activity regulation for development, cellular differentiation, and changing environments.

DNA’s biological roles are vital for inheritance, protein-coding, and the provision of instruction for life and its many processes.

Ribonucleic acid (RNA) and Deoxyribonucleic acid (DNA) are important molecules in the body. They are in charge of storing and reading genetic information that supports life.

Both RNA and DNA are made up of building blocks called bases (which connect into base pairs), phosphates, and sugars. However, they're not exactly the same, and those differences are what make them a great team in human cells.

Still, both DNA and RNA play important roles in our bodies.

How Is RNA Different from DNA?

RNA translates the instructions in our genes and controls when and how genes are used for development, cellular differentiation, and changing environments.

On the other hand, DNA passes down important information to the next generation, makes proteins, and directs various life processes in human cells. It stores genetic information.

Both DNA and RNA depend on hydrogen bonds between complementary bases to keep their structures intact. These bonds are like the links on a chain in the DNA double helix, holding the two strands together.Additionally, the backbone of DNA and RNA is held together by phosphodiester bonds. These bonds help keep the molecules structurally stable, making sure they don't fall apart.

The Differences Between RNA and DNA

We compare RNA vs. DNA. We look at their key differences in terms of function, location, structure, sugar deoxyribose content, bases, stability, and sensitivity to ultraviolet light.

Ribonucleic Acid (RNA)		Deoxyribonucleic Acid (DNA)
	Function
RNA is responsible for the conversion of genetic information found inside DNA to a format used for the synthesis of protein. It is then moved to ribosomal protein factories.		A DNA strand is responsible for replicating and storing genetic information. DNA is considered the blueprint for all of the genetic information found inside an organism.
	Location
RNA is found in the ribosome, nucleus, and cytoplasm		A DNA strand is found in the nucleus, with small amounts in the mitochondria
	Structure
Single-stranded molecule A-helix with shorter nucleotide chains		Double-stranded molecule B-helix with long-chain nucleotides
	Sugar Content
Ribose		Deoxyribose
	Bases or base pairs
Adenine (A), Cytosine (C), Guanine (G), and Uracil (U)		Adenine (A), Cytosine (C), Guanine (G), and Thymine (T)
	Stability
Unstable in alkaline conditions		More stable than RNA
	Sensitivity to Ultraviolet (UV) Light
Relatively resistant to UV damage compared to DNA		Vulnerable to UV damage

What is DNA?

DNA are double-stranded molecules that contain the instructions needed by living things to develop, grow, and reproduce. They store genetic information or instructions. These instructions are found in every cell and are passed down from generation to generation.

DNA is the nucleic acid in cells that provides the original blueprint for protein synthesis. It contains phosphates, deoxyribose sugar, and a unique sequence of the following nitrogenous bases (which combine to be a base pair): 

• Adenine (A) 
• Guanine (G) 
• Cytosine (C)
• Thymine (T)

A DNA strand is composed of nucleotides containing a phosphate group, a nitrogenous group, and a sugar group. The order of the nitrogenous bases Adenine (A), Guanine (G), Cytosine (C), and Thymine (T) is very important in determining your genetic code.

The human genome is composed of approximately three billion DNA base pairs.

The base pairing is as follows: Adenine and Thymine, Guanine and Cytosine.

DNA molecules appear as a spiral with two long strands. They are so long that they cannot fit inside the cell. To be able to do so, they are tightly coiled and connected at each base pair, producing chromosomes.

Each chromosome has one DNA molecule. Humans have 23 pairs of chromosomes present inside the cell’s nucleus.

Aside from storing genetic information as one of its primary functions, DNA also plays a part in:

• Cellular metabolism
• DNA Fingerprinting
• Gene Therapy
• Mutation
• Replication process

The Types of DNA

• A-DNA – This is present at 75% humidity, at higher salt or ionic concentrations, or in a state of dehydration. A-DNA has the broadest helical diameter compared to other DNA forms. It is a right-handed double-helical structure that is similar to the B-DNA form. 
• B-DNA – This is present at 9.25% humidity and low ionic or salt concentrations. Like A-DNA, B-DNA is also a right-handed double helix. It is the most common DNA conformation.
• Z-DNA – This is found in environments with very high salt concentrations. Z-DNA is a left-handed double helix that winds to the left side in a jigsaw pattern. It is thought to play a role in the regulation of genes.

What is RNA?

RNA is considered an important nucleotide found in all living cells, with long chains of nucleic acids. It’s a single-stranded molecule that acts as a “messenger,” forwarding instructions from DNA to control the production of protein.

It plays a direct role in the synthesis of proteins. 

RNA molecules contain phosphates and sugar ribose. Just like DNA, it also has nitrogenous bases: Adenine (A), Guanine (G), Cytosine (C), and Uracil (U). Take note that in DNA, Uracil (U) is replaced by Thymine (T).

RNA plays three roles in the production of protein: as a messenger, for transfer, and in ribosome production. These roles are reflected in the different types of RNA. RNA come in single strands.

Types of RNA

Not all of the genes in cells are expressed into Ribonucleic acid; only some of them are. The types of RNA are as follows:

• tRNA – Also known as “transfer” RNA, tRNA carries the amino acids to the ribosomes. It is a free-roaming molecule that is found in the cell’s cytoplasm.
• mRNA – Also known as “messenger” RNA, the mRNA encodes a polypeptide’s amino acid sequences. It is found in the cell’s nucleus.
• rRNA – Also known as “ribosomal” RNA, rRNA is responsible for ribosome protein production. Ribosomes are organelles where ribosomal proteins are made.
• snRNA – Also known as “small nuclear” RNA, snRNA forms the proteins and complexes used to process RNA in eukaryotic cells.

Aside from these four, other types of RNA continue to revolutionize molecular biology as we know it. These include siRNA (small interfering RNA) and miRNA (microRNA).

What Is Transcription in RNA?

Transcription is a fundamental process in the cells. It can be similar to making a copy of important instructions.

Imagine having a recipe book (your DNA) with all the instructions for your body's functions. When your cell needs to follow an instruction, it doesn't bring the whole book. Instead, it makes a photocopy of just that one instruction.

Transcription is like photocopying those specific set of instructions.

Inside your cell, there's a special unit called RNA polymerase that reads the instructions from the DNA and makes a copy of it. It looks like translating the instructions from one language (DNA) to another (RNA).

This copy, which is the RNA, is a messenger that goes to the cell, where it's used as a guide to make the proteins needed for your body to work correctly.

What Is Complementary Base Pairing?

Complementary base pairing describes how DNA and RNA form pairs by binding to each other.

In DNA, there are four nitrogenous bases: adenine (A), thymine (T), cytosine (C), and guanine (G). In RNA, thymine (T) is replaced by uracil (U). These bases pair together in a highly specific manner:

1. Adenine (A) pairs with Thymine (T) in DNA or Uracil (U) in RNA, forming an A-T (or A-U) base pair.
2. Cytosine (C) pairs with Guanine (G), forming a C-G base pair.

The complementary base pairing is essential for the processes of DNA replication and transcription.

During DNA replication, the two strands of the DNA double helix separate, and each strand serves as a template for the synthesis of a new complementary strand. The specific base pairing ensures that the new strand's sequence is identical to the original strand.

In transcription, a similar base pairing occurs when RNA is synthesized based on a DNA template.

Complementary base pairing helps keep the fidelity of genetic information transfer, ensuring that the genetic code is accurately preserved during DNA replication and transcription processes.

In a way, it helps prevent errors in genetic information.

Commonly Asked Questions on DNA and RNA

What are RNA and DNA composed of?

RNA and DNA are nearly identical nucleotide polymers. They have the same three base pairs, except for Thymine (T) and Uracil (U). Thymine is found in DNA, while Uracil substitutes Thymine in RNA.

Where are RNA and DNA found?

RNA is found in the following sites: nucleus, cytoplasm, and ribosomes. Meanwhile, DNA is located in the mitochondria and nucleus of the cell. 

How does RNA and DNA propagate?

While DNA is able to self-replicate, RNA cannot. RNA is synthesized into DNA as needed.

Which is the better genetic material?

Between the nucleic acids, DNA is more stable because its deoxyribose sugar has one less oxygen-containing hydroxyl group. On the other hand, RNA has ribose sugar and is more reactive compared to DNA. Thus, DNA is considered a better genetic material than RNA.

Are there similarities between RNA and DNA?

Yes. RNA and DNA have three similar nitrogenous bases: Cytosine (C), Adenine (A), and Guanine. They also have phosphate backbones where the bases are attached.