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What is 98% of the genome? Uncover the true face of non-coding DNA!
In our genome, only about 1-2% of the DNA codes for proteins, which means the remaining 98-99% is non-coding DNA (ncDNA). These seemingly redundant DNA may actually have unexplored functions, which has aroused widespread concern in the scientific community. What exactly is non-coding DNA? Why does it make up such a large proportion of the genome?
Non-coding DNA is not just "junk DNA". In contrast, many non-coding regions are indeed involved in gene regulation and other biological functions. For example, non-coding RNA molecules such as transfer RNA (tRNA), small nuclear RNA (snRNA), microRNA (miRNA) and long non-coding RNA (lncRNA) are derived from this DNA sequence. In addition, non-coding DNA also contains gene regulatory elements, horizontal extension sequences and other structural and functional regions.
For example, regulatory sequences and promoters in mammalian genomes are non-coding DNA, and the impact of these sequences on gene expression cannot be ignored.
Types of non-coding DNA and their functions
Non-coding DNA can be subdivided into several types, the most important of which include non-coding genes, promoters, regulatory elements, introns and other structural regions. The number of non-coding genes is larger in eukaryotes than in prokaryotes, and the functions of these genes in cells have not yet been fully understood. Scientists have now identified at least 60,000 to 130,000 non-coding genes, but the exact number is still being discussed.
Non-coding genes
Non-coding genes usually discuss those genes that are not translated into proteins. They can be transcribed into various RNA molecules, which play regulatory or structural functions in cells. These genes account for at least 6% of the non-coding parts of the human body.
Promoters and regulatory elements
A promoter is a DNA sequence upstream of a gene, which is the starting point for transcription, while regulatory elements control the transcription process of nearby genes. These regulatory elements play an integral role in gene expression and exert a powerful influence despite their short length.
The presence of regulatory sequences has a critical impact on turning genes on and off, which is why it is so important to further explore the functions of these sequences.
Intron
Introns are part of the RNA transcription process but are removed by splicing in mature RNA. The length and number of introns vary between species but play important regulatory roles in eukaryotes.
Repeat sequences and transposons
Much wild genetic information originates from transposons and repetitive sequences, such as retrotransposons, which account for a large proportion of the genome. Such structures may be important drivers of genome growth and evolution.
The unsolved mysteries of non-coding DNA
It is worth noting that many scientists have reservations about a portion of non-coding DNA, especially the portion labeled as "junk DNA," believing that these DNA sequences may have undiscovered functions. This is one of the reasons why the scientific community continues to explore non-coding DNA.
As some scientists have said, various non-coding DNA components may form complex regulatory networks that affect gene expression and cell function.
Future research directions
With the continuous development of genomics technology, future research will explore the functions of non-coding DNA in more depth. In particular, studies that correlate genomic screens with dominant phenotypes will further reveal the potential role of non-coding DNA. These studies are not only related to understanding basic issues in biology, but may also affect early diagnosis and treatment of diseases.
For a 98% non-coding DNA that is so closely related to our human genome, are there still more unknown functions and potentials waiting for us to discover?
