Biological Importance of DNA and RNA

DNA & RNA are the two genetic molecules present inside the living cells. Both are equally important in a living body.

The things that DNA can do, can’t be done by RNA. And, the jobs than RNA can do, is unique to only RNA.

RNA (Ribonucleic acid) and DNA (Deoxyribonucleic acid) are both nucleic acids involved in gene expression and genetic mechanisms.

RNA is related to DNA in a number of ways. Both are genetic materials, nucleic acids, help in gene expression, somewhat similar in structure, and they both are dependent on each other.

RNA is single-stranded while DNA is double-stranded. And, do you know that DNA is more stable than RNA and, RNA is derived from DNA.

Let’s talk about the biological importance of both DNA & RNA separately.

Biological Importance of DNA

1. DNA is the genetic information storehouse

With the exception of viruses, DNA is the nucleic acids that are present in each and every cell of the body that can store the genetic information.

DNA contains the instructions needed for an organism to develop, survive, and reproduce.

In prokaryotes, DNA remains naked and it lies in protoplasm. But in eukaryotes, genetic DNA is highly packed and stored only inside the nucleus of the cell.

2. DNA is important in terms of heredity

Heredity simply means the transferring of physical or mental characteristics genetically from one generation to another.

DNA is the chemical unit of heredity. This means that the structure of the DNA in offspring can store the genetic information from both of the parents.

During the cell division, DNA and its genetic information get packed/compressed in the form of chromosomes and get passed to the next generation.

3. DNA makes genes

The basis of DNA packaging lies in the fact that DNA makes genes and genes make chromosomes. That’s how the genetic information gets passed from one generation to another.

A gene is just only a section of a DNA molecule. A gene is so small than the DNA that for example, in humans 2 metres of DNA can have about 20,000 to 25,000 genes present altogether.

A gene is simply a section of various nucleotides of the long DNA molecule that is present in each chromosome.

4. DNA supercoils to form chromosome

The main relationship between DNA, genes, and chromosomes is that genes are made up of segments of coiled DNA, and chromosomes are long supercoiled chains of DNA that are composed of various genes.

DNA has the ability to coil and supercoil. It’s a way of the packaging itself to fit inside the nucleus of the cell.

And while DNA packaging, DNA makes genes and genes subsequently make chromosomes.

That’s why it’s said that DNA super coils to form chromosome.

5. DNA and proteins relationship is vital for living organisms

DNA stores the genetic information in an encrypted form whereas, mRNA decrypts the same information and makes it easy to encode proteins.

In simple words, the DNA has the information to encode proteins but, DNA cannot be converted into protein directly because there are no enzymes available to translate DNA directly into protein.

So, DNA creates mRNA, and mRNA encodes proteins.

So, proteins, when formed, are utilized by the cells to show/express the genetic characteristics in the living body.

6. DNA is very stable

The structure of the DNA is very stable because of the presence of strong covalent bonds between pentose sugar, and hydrogen bonds between nucleotides of the two strands.

The hydrogen bonds are strengthened and protected from solvent hydration by the hydrophobic stacking of the bases. Thus, giving the double-strand huge stability.

And moreover, the deoxy pentose sugar in the backbone of each DNA strand does not have a hydroxyl group (OH) on the 2′ position. This also makes it even more stable as compared to RNA.

7. DNA can have a variety of shapes and lengths

There are different shapes, lengths, and sizes of DNA, all are double-stranded. These are A-DNA, B-DNA,and Z-DNA.

The double helix of A-DNA and B-DNA are right-handed in nature. Z-DNA is a left-handed with the double-stranded helix winded to the left in a zig-zag manner.

Dehydration of Z-DNA drives it into the A-DNA form, and this form protects the DNA under conditions such as the extreme desiccation of bacteria.

B-DNA is the normally available form of DNA. It follows the Watson & Crick model of DNA structure.

Z-DNA is one of the many possible double helical structures of DNA. It is formed in those cells where processive enzymes such as polymerases and helicases generate insufficiently-wound DNA in their wake.

8. DNA has major and minor grooves

The major and minor grooves occur due to the antiparallel arrangement of the two backbone strands of DNA.

Antiparallel means one strand of DNA is 3′ to 5′ direction and the other stand is 5′ to 3′ direction.

In reality, these grooves are actually present and can be seen when visualized under an electron microscope.

These grooves are important because it provides binding sites for the various DNA proteins and enzymes that are involved in replication and transcription.

9. Conformations of DNA

DNA conformation means any of the spatial arrangements that the atoms in the DNA molecule may adopt especially by rotating around the individual bonds.

The conformations can change the shape of the helix and its length sometimes.

These spatial arrangements are actually relatively mild changes in conditions or can coexist in a single, continuous double helix.

DNA conformations can play a vital role in various cellular processes and gene expression rates/mechanisms by involving interactions with various DNA-binding enzymes and proteins.

10. DNA can supercoil

The DNA that is present in the human cell is about 2 meters long. Such long DNA needs to fit inside the cell’s nucleus which is just 6-micron across.

Here, the role of DNA packaging comes into place. The DNA gets supercoiled from its open double-helix structure, and it becomes smaller, compresses in size just in order to fit the nucleus of the cell.

Histone gives structural support to the DNA to wrap around its octamer (8 histone proteins) thus leading to DNA supercoiling in order to fit it inside the cell’s nucleus.

11. DNA’s coding and non-coding strand

The presence of DNA’s coding and non-coding strand is every important.

The double helix structure arranges DNA in such a way that it has a template (non-coding) strand and the non-template (coding) strand.

The non-template (coding) strand acts to facilitate proper transcription of mRNA from the DNA.

For protein synthesis, messenger RNA must be made from one strand of DNA called the template strand. The other strand, called the coding strand, matches the messenger RNA in sequence except for its use of uracil in place of thymine.

These are the two different strands of the double helix that are joined together by hydrogen bonds.

12. DNA fingerprinting

It is a technique of DNA profiling utilized in determining the DNA nucleotide sequences which are specific to each individual.

This means that almost every person has his/her unique nucleotide sequence.

This technique involves identifying differences in some specific regions in the DNA sequence called as repetitive DNA because, in these sequences, a small stretch of DNA is repeated many times.

This is useful in solving paternity and maternity disputes, in determining population and genetic diversities, in the detection of crimes, etc.

13. DNA can replicate

During cell division, DNA first replicates itself and passes to the next generation following the process of mitosis or meiosis.

This is an important step for getting the same copy of the DNA in the newly formed cells.

DNA can be replicated because both strands contain a complete set of information and both of the strands can act as templates for the generation of a daughter DNA double helix that is identical to the parent.

14. DNA can transcript

Transcription simply means the flow of genetic information from DNA to mRNA. This is possible because the DNA can transcript.

During transcription, DNA has to be converted into mRNA (messenger RNA) strand.

This mRNA will act as some kind of intermediate between DNA and formation of proteins.

Thus, mRNA will only act as a messenger between DNA and protein formation. This mRNA stores the information on how to code for proteins.

15. DNA undergoes slow mutation

Over a lifetime, our DNA can undergo changes or mutations in the sequence of bases: A, C, G, and T. This results in changes in the proteins that are made during gene expressions.

Mutations can occur during DNA replication if errors are made and not corrected in time.

Physical and chemical factors like UV rays, exposure to alkylating agents such as Ethylmethane sulfonate and N-methyl-N-nitrosourea can also result in mutation.

It is interesting to note that, the DNA proofreading and repair mechanisms save the DNA from being mutated, if somehow mutation has occurred.

This is one big advantage of DNA that mutation occurs slowly as the DNA molecule is very stable. And also the DNA proofreading and repair mechanisms are always in an active mode to protect it.

This is good for evolution as evolution supports slow changes.

16. Long-term storage of information

Yes, DNA is the long-term storage of information. Till today, DNA is carrying the genetic information from generation after generation, as it was passed by our ancestors.

In molecular evolution, if you see, you will find that DNA is present in all living organisms. The molecular sequence is same as well, in all organisms in the majority of the cases.

This shows how we have evolved from simple living organisms to the present day complex ones.

It’s the inheritance and variation of the DNA that we presently have is derived from our ancestors.

In simple words, the DNA we presently have is a replicated and variated version of the DNA that our ancestors have transferred to their next generations.

17. DNA codes for all of the cell proteins

The sequence of bases in a DNA molecule can determine the order of amino acids in a protein molecule.

But, we have already learned that DNA cannot produce proteins so, it will create mRNA first which will then create the proteins.

Groups of three bases called triplets represent different amino acids. This is the basis of the genetic code which is encrypted in DNA and passed to mRNA.

A sequence of bases (genetic information) on DNA that codes for a protein is called a gene.

18. DNA is the life of every cell

All living things have DNA within their cells. It contains the instructions to construct other components of the cell, such as proteins and RNA molecules.

In fact, nearly every cell in a multicellular organism possesses the full set of DNA required for that organism.

The DNA and the genetic information that is stored in it will determine actually how the cell will function, develop, divide, and grow.

19. DNA is required for reproduction

DNA (part of the genome) is self-replicating and it passes to the next generation during reproduction, either sexually or asexually.

During, sexual reproduction the DNA first replicates itself and passes to the next generation via. gametogenesis following the process of meiosis.

In the case of asexual reproduction, the DNA passes to the next generation via. spores, or budding, or binary fission following the process of the mitosis.

20. DNA is required for regular cell division

Again the topic of DNA replication comes into place.

During reproduction, DNA plays a vital role in transferring parental characters to the offspring.

Cell division is the mechanism by which DNA is passed from one generation of cells to the next and ultimately, from parent organisms to their offspring.

This also involves the process of formation of gametes which unites to form offsprings.

Although eukaryotes and prokaryotes both engage in cell division, they do so in different ways.

Biological Importance of RNA

1. RNA encodes proteins

We know that genetic information is stored in DNA. That genetic information is first transcribed from DNA to mRNA.

mRNA contains the RNA version of the DNA that can encode proteins via. the process of translation.

There are both Non-coding RNAs (ncRNAs) and Coding RNAs (cRNAs). Only the cRNAs can be translated to encode proteins.

2. mRNA contains the protein blueprint

The master blueprint is DNA, which contains all of the information to build the new protein (house).

The working copy of the DNA’s master blueprint is called messenger RNA (mRNA), which is copied from the DNA.

The flow of genetic information from mRNA to the amino acid sequence of polypeptide forms the proteins. This is also known as Translation.

The mRNA that was formed from DNA is very short-lived so, it has to be converted to some form. So in order to do so, mRNA attracts ribosomes.

The role of the ribosomes here is just to decode the message stored in the mRNA and transfer it to tRNA (transfer RNA). That tRNA transfers amino acids to a newly forming protein.

3. tRNA binds the specific amino acid

During the time of translation (protein synthesis) from mRNA to proteins, the tRNA reads the mRNA based on a particular sequence of three nucleotides (codons) and then creates the amino acids respectively.

Each codon consists of three nucleotides, usually corresponding to a single amino acid.

For example, the codon CAG represents the amino acid glutamine.

4. rRNA forms ribosomes that acts as catalyst

We all know that ribosomes act as catalysts during the translation process. It helps to connect mRNA with tRNA and then leads to the creation of proteins.

But, how are the ribosomes made? rRNA is transcribed from ribosomal DNA (rDNA) and then bound to ribosomal proteins to form small and large ribosome subunits. The small and large subunits together create the ribosome.

This is how rRNA (ribosomal RNA) associates with a set of proteins to form ribosomes which acts as catalyst.

5. RNAs help in gene regulation

Gene regulation is simply the ability to control the expression of a gene or not. It is a very important aspect of genetic science.

The types of RNA molecules that control gene regulation are messenger RNAs (mRNAs), small RNAs such as microRNAs, and lastly, antisense RNAs.

RNA controls gene regulation by controlling transcription, translation, modifying the protein structures, binding to mRNA targets to block it, etc.

6. RNA is genetic carrier in viruses

RNA viruses (retroviruses) have genomes composed of RNA that encodes a number of proteins. They are also able to self-replicate RNA.

So, RNA (not DNA) is very much important for non-living viruses as it is their storehouse of genetic information.

RNA of these viruses first synthesizes DNA in the presence of Reverse Transcriptase enzyme. DNA then transfers information to RNA and the translation occurs.

So, that’s why it’s said that RNA viruses have genomes composed of RNA that encodes a number of proteins.

7. snRNA helps in processing pre-messenger RNA

snRNA helps in RNA splicing of the premature messenger RNA.

The mRNA first formed from DNA transcript is premature messenger RNA.

The premature messenger RNA contains coding RNA sequences (exons) and non-coding sequences (introns).

snRNA helps in removing the introns and joining the exons. The pre-mRNA then, it becomes mature messenger RNA (mRNA).

This is a very important step in gene expression.

8. RNA helps to provide immunity

The RNA molecules that take part in the immunity of our body are mostly non-coding in nature.

These RNAs are highly reactive and are strictly involved in the body’s responses to infections.

Just like the RNA molecule called nc886. In humans, this RNA molecule helps to fight against deadly viruses.

9. rRNA forms ribosomes

Ribosomes are protein-synthesizing machines. Each mRNA molecule is simultaneously translated by many ribosomes.

rRNA is formed from the rDNA section of a gene. That rRNA joins with various ribosomal proteins to form ribosomes.

Each ribosome has 2 different sub-units. Each subunit is made up of its own specific rRNA molecules.

10. RNA is less stable

RNA is more resistant to damage from UV light than DNA. RNA’s mutation rate is relatively higher.

It’s all due to the less stability of RNA. RNA is single stranded, which is a disadvantage to its stability as compared to that of DNA.

And also, the presence of (OH) hydroxyl group on the 2′ position of Pentose sugar makes RNA less stable than DNA as it becomes more susceptible to hydrolysis.

11. RNA helps study genetic codes

The relationship between the sequence of amino acids in a protein polypeptide chain and the nucleotide sequence of mRNA is called Genetic code. A genetic code consists of 64 codons.

The three-nucleotide sequence (codons) of mRNA is determined and read by the tRNA that creates the amino acids respectively. A protein is a huge polypeptide chain of amino acids.

This indicates how each sequence of mRNA is very crucial in understanding what protein is going to be encoded from the mRNA by tRNA.

12. RNA can move out of the nucleus of the cell

RNA forms in the nucleolus, and then move to specialized regions of the cytoplasm depending on the type of RNA formed.

Famous examples of such RNA includes ribosomal RNA (rRNA), small cytoplasmic RNA (scRNA), etc.

Just take the example of ribosomes that conrtains rRNA. Ribosomes can be found outside the cell nucleus.

Ribosomes remain floating in the cytoplasm and also remain attached to the rough Endoplasmic reticulum.

Ribosomes can catalyze the translation of mRNA to proteins outside the nucleus.

13. RNA interference (RNAi) can find and turn off specific genes

RNA interference (RNAi) is a biological process/pathway that controls or pauses the gene expression by the use of various RNA molecules.

As the name suggests, it’s just the interfering job of the RNA molecule.

RNA molecules like microRNA (miRNA) and small interfering RNA (siRNA) can actively take part in the RNA interference process.

They can inhibit the gene expression or translation, by neutralizing targeted mRNA molecules, changing the mRNA target sites, changing the molecular shapes, etc.

14. RNA is a unique polymer

RNA can serve as a unique polymeric material to build variety of nanostructures including nanoparticles, polygons, arrays, bundles, membrane, and microsponges that have potential applications in biomedical and material sciences.

Like DNA, RNA can bind with great specificity to either DNA or another RNA through complementary base pairing.

It can also bind specific proteins or small molecules, and, remarkably RNA can also catalyze biochemical reactions like joining amino acids to make proteins.

15. RNA is the intermediate between transcription and translation

The DNA although has the power but directly cannot bring the genetic traits in the living body.

So, DNA has to depend on the formation of RNA as an intermediate, and this RNA will form the structure of the proteins.

The primary reason why RNA is so important to life on earth because it acts as an intermediate for transcribing the information stored in DNA leading to the formation of proteins.

16. RNA is temporary

Unlike DNA, RNA does not permanently store genetic information in cells.

RNA strands are continually made, broken down and reused. DNA can make temporary copies of the information as RNA.

If the RNA copies are damaged or more are needed, the cell makes more copies from the DNA.

Also during the gene expression, you will find that the mRNA that is formed from DNA is very short-lived. That mRNA gets soon translated into proteins and get broken down.

17. RNA can renaturate very quickly

Renaturation of RNA simply means the reconstruction/restoration of a protein or nucleic acid (such as DNA/RNA) to their original form, especially after denaturation.

RNA being less stable is more reactive. This helps in increasing the chances of renaturation of RNA even after it is denaturated.

But, the molecules need to be present there in order for renaturation to take place.

If RNA is totally destroyed along with the complete breakdown of each bond and atoms in each molecule, then it’s very rare that it can renature.

18. RNA is more versatile than DNA

Versatility is the ability to adapt to many different functions or activities.

Due to the versatile nature, the RNA molecule is involved in many other essential cellular functions like cell signaling, transcription, translation, etc.

The versatility of RNA derives from its unique ability to use direct readout via. base-pairing for sequence-specific targeting (or templating) in combination with its capacity to form elaborate three-dimensional structures.

Such structures can perform catalysis or serve as protein recognition surfaces as well.

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