What’s Bigger – DNA or Gene?
What’s Bigger – DNA or Gene? What do you think?
DNA is bigger than a gene. A gene is just only a section of a DNA molecule.
A DNA molecule is a polynucleotide that has about 7 billion base pairs in a single human diploid cell.
Whereas, a gene is only a section of that DNA molecule that can have a few hundred DNA bases to more than 2 million base pairs only.
DNA molecule is so long that it can have coding or non-coding DNA sequence. Whereas, genes always consist of coding DNA sequences only.
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.
DNA is a huge molecule, a polymer of nucleotide. And in a single human chromosome, there consists of a coiled DNA molecule that is about 2 inches long.
A gene is only a short piece or stretch of DNA that control the hereditary information of organisms.
Offspring resemble their parents because genes are passed from parents onto their children and in this way, information can be transferred from one generation to the next.
Each DNA nucleotide is independent of each other, but the DNA polynucleotide can work together as a unit when present in a particular gene thus able to express a particular genetic trait.
That’s why we don’t say DNA expression. We call it Gene expression. Because a single DNA nucleotide cannot express itself directly to bring on a genetic trait but, a gene can express itself because it contains various DNA nucleotides working together as a unit.
It’s like, a single DNA molecule is a huge-long city, and a gene is a community of that city.
It’s also like, a DNA city can have various Gene communities. Each gene community can work in expressing a piece of particular genetic information or so.
A DNA molecule is a polymer of millions of nucleotides attached together one after another in a long chain to form genes, then wraps around the nucleosomes, then forms the chromatin, then the chromatid, and at last forms the chromosomes.
Genes are those chunks of DNA that contains the information of how, when, and why to code for proteins. It has the information to stop or start DNA replication, transcription, and further the translation process.
Genes are the chunks of DNA that pass from the parents to offspring. Genes are just like the processor and motherboard of the genetic information.
This diagram shows how a very long DNA strand is coiled and then supercoiled to form a very small size in order to fit in a portion inside the chromosome.
(Image: Thomas Splettstoesser (www.scistyle.com) / CC BY-SA)
Size Info: DNA & Gene
Size of DNA
There are a total of 3 billion base pairs in each human cell’s uncoiled DNA which is about 2 metres long.
All the DNA in all your cells put together would be about twice the diameter of the Solar System. That’s how long all of the cells uncoiled DNA is if added together.
DNA is so compressible that a DNA helix with a diameter of 2nm (2 x 10-9 m) can be supercoiled to become a chromatid of 700nm (700 x 10-9 m) diameter or so.
A chromosome consists of two chromatids attached together. A chromosome can contain hundreds to thousands of genes.
Size of Gene
In humans, genes vary in size from a few hundred DNA bases to more than 2 million bases.
The Human Genome Project estimated that humans have between 20,000 and 25,000 genes inside every cell of the body.
Every person has two copies of each gene, one inherited from each parent during sexual reproduction.
A gene is a unit of DNA polynucleotides, that contain coding DNA. The other non-coding DNA nucleotide (not part of genes) helps the coding DNA in gene expression and are removed from the genes, like introns.
Reasons why Genes are smaller than DNA
1. A gene is simply a section of various nucleotides of the long DNA molecule that is present in each chromosome. DNA simply cannot take part in gene expression, it has to work in a unit where each and every nucleotide of the DNA has its own job which together helps in gene expression.
2. In each cell, it is the 2.2 metres long DNA double helix molecule that coils and supercoils to form genes. Each such gene contributes to each specific genetic function in the body.
3. Replication and Transcription of the DNA simply cannot occur without the influence of other factors. All of these factors are present in a gene. These factors are part of DNA polynucleotides that regulate, control, stops, processes, and promote the Gene expression. If it is a non-coding DNA factor then it is removed from the gene later.
4. DNA is the chemical unit of genetic inheritance that makes various genes at the various locations of the DNA strand. And many of such genes together constitute the structure of a chromosome. A gene is basically the physical and functional unit of heredity that stores a particular genetic trait.
5. A gene is a part of a long polynucleotide sequence of the DNA that codes for various proteins that can express a particular genetic trait in the living body. But, DNA is that long molecule that includes its contribution to various genes at its various nucleotide sequence at the same time.
6. DNA is the chemical unit of hereditary, Gene is the functional unit of hereditary, and Chromosome as a whole is the carrier of hereditary information from generation to generation. This means that DNA supercoils itself to create both genes and chromosomes.
7. DNA is your body’s internal, hard-coded, genetic storehouse that makes you. Genes are just DNA sequences. DNA is very long as just 1% of your DNA sequence is genes.
8. DNA is so long that it can contain both coding and non-coding regions. The coding regions are known as genes and contain the information necessary for a cell to make proteins. And, the non-coding regions help in controlling the way how the gene works, and functions during gene expression.
Are genes more complex than DNA?
Genes are actually DNA. But, a complex part of DNA showing a variety of functions and mechanisms.
Yes, of course, genes are more complex than the DNA. It’s because genes contain various DNA nucleotides that code for various proteins, regulate, control, repress, and support gene expression.
DNA molecule is simply a polynucleotide chain but when that chain forms a gene, it shows various regions of coding DNA, non-coding DNA, gene-expression regulation factors, proteins, associated enzymes, etc. all working as a unit. That’s why the gene is more complex than the simple DNA double helix strand.
It is important to note that gees cannot contain non-coding DNA sequences, and if it does then, non-coding sequences gets removed from the final transcript during the production of proteins).
A part of DNA- genes are made up of A, T, G, and C nucleotides of DNA. The nucleotides of the opposite strand bind with hydrogen bonds and the adjacent nucleotide bind with phosphodiester bonds.
The gene structure is not just simply DNA, it is more complex than that. In general, the gene structure consists of core elements, regulatory elements, and maintenance elements that make it complex both in its working and structure.
Exons are core elements that contain the coding DNA parts of the gene and take part in protein formation. Introns are intervening non-coding DNA parts of the gene.
Regulatory elements are located on the extreme ends of a gene that controls the gene expression.
There are Promotes that are non-coding DNA sequences in the gene that facilitates binding sites for enzymes and transcriptional factors to work.
It is the presence of all of these factors that makes genes more complex. In fact, DNA polynucleotides give the ability to regulate, promote, provide structural support to the gene, thus making it more complex.
