Central dogma

Central Dogma was immediately explained by Kirk and Watson after immediately giving the double
helix structure of dna. Central Dogma was one of the most important breakthroughs in the history of
molecular biology. Central dogma explains how the information from the dna is converted into useful
form of proteins that is useful for the body. Central Dogma explains the following steps of how the
DNA which is the genetic material is converted into mrna and at the end protein. The Central Dogma.
This states that once "information" has passed into protein it cannot get out again. In more detail,
the transfer of information from nucleic acid to nucleic acid, or from nucleic acid to protein may be
possible, but transfer from protein to protein, or from protein to nucleic acid is impossible.
Information here means the precise determination of sequence, either of bases in the nucleic acid or
of amino acid residues in the protein. The central dogma involves the following steps of replication,
Transcription, translation. This has helped in changing medical industries ,therapeutics and many
other biotech reserves. These are the three classes In which the DNA is converted into able of the
three classes of information transfer.

Transcription

Transcription is one of the process in the central dogma. This is an important process in which the
genetic material dna is converted into a form of information which Can be used by the cells.
Transcription is the process of copying a segment of DNA into RNA. Some segments of DNA are
transcribed into RNA molecules that can encode proteins, called messenger RNA (mRNA). Other
segments of DNA are transcribed into RNA molecules called non-coding RNAs (ncRNAs).

Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as
a complementary language. During transcription, a DNA sequence is read by an RNA polymerase,
which produces a complementary, antiparallel RNA strand called a primary transcript.

In virology, the term transcription is used when referring to mRNA synthesis from a viral RNA
molecule. The genome of many RNA viruses is composed of negative-sense RNA which acts as a
template for positive sense viral messenger RNA - a necessary step in the synthesis of viral proteins
needed for viral replication. This process is catalyzed by a viral RNA dependent RNA polymeraseA
DNA transcription unit encoding for a protein may contain both a coding sequence, which will be
translated into the protein, and regulatory sequences, which direct and regulate the synthesis of that
protein. The regulatory sequence before (upstream from) the coding sequence is called the five
prime untranslated regions (5'UTR); the sequence after (downstream from) the coding sequence is
called the three prime untranslated regions (3'UTR). This Transduction occurs only at specific sites,
while the promoters on the Terminator are present. In case of eukaryotes, the RNA polymerase 2
And in case of bacteria, or prokaryotes. Rna polymerase are used for this process. In this process the
unprocessed or immature for precursor mrna is produced. Did this mrna or hnrna another small
sequence of nucleotide is produced, called as mirna. The unprocessed mrna goes under processing
like capping ,splicing and tailing. And the mi rna that is produced helps in the post graduation process
of mrna

What is miRNA?

MIRNa is different from MRNa, so it is not to be confused with both of them.

Micro ribonucleic acid (microRNA, miRNA, µRNA) are small, single-stranded, non-coding
RNA molecules containing 21–23 nucleotides. Found in plants, animals, and even some viruses,
miRNAs are involved in RNA silencing and post-transcriptional regulation of gene expression.[2]
[3]
miRNAs base-pair to complementary sequences in messenger RNA (mRNA) molecules,
[4]
then silence said mRNA molecules by one or more of the following processes:

 Cleaving the mRNA strand into two pieces.

 Destabilizing the mRNA by shortening its poly(A) tail.

 Reducing translation of the mRNA into proteins.

In cells of humans and other animals, miRNAs primarily act by destabilizing the mRNA

miRNAs resemble the small interfering RNAs (siRNAs) of the RNA interference (RNAi) pathway,
except miRNAs derive from regions of RNA transcripts that fold back on themselves to form short
hairpins, whereas siRNAs derive from longer regions of double-stranded RNA.[2] The human
genome may encode over 1900 miRNAs, However, only about 500 human miRNAs represent bona
fide miRNAs in the manually curated miRNA gene database MirGeneDB

miRNAs are abundant in many mammalian cell types.[11][12] They appear to target about 60% of the
genes of humans and other mammals.[13][14] Many miRNAs are evolutionarily conserved, which
implies that they have important biological functions.[15][1] For example, 90 families of miRNAs have
been conserved since at least the common ancestor of mammals and fish, and most of these
conserved miRNAs have important functions, as shown by studies in which genes for one or more
members of a family have been knocked out in mice.

When and how the miRNA was discovered?

The first miRNA was discovered in the early 1990s. Research revealed different sets of miRNAs
expressed in different cell types and tissues and multiple roles for miRNAs in plant and animal
development and in many other biological processes and multiple roles for miRNAs in plant and
animal development and in many other biological processes. The first miRNA was discovered in 1993
by a group led by Victor Ambros and including Lee and Feinbaum. However, additional insight into its
mode of action required simultaneously published work by Gary Ruvkun's team, including Wightman
and Ha.[19][37] These groups published back-to-back papers on the lin-4 gene, which was known to
control the timing of C. elegans larval development by repressing the lin-14 geneThe first miRNA was
discovered in 1993 by a group led by Victor Ambros and including Lee and Feinbaum. However,
additional insight into its mode of action required simultaneously published work by Gary Ruvkun's
team, including Wightman and Ha.[19][37] These groups published back-to-back papers on the lin-
4 gene, which was known to control the timing of C. elegans larval development by repressing
the lin-14 gene. The let-7 RNA was found to be conserved in many species, leading to the suggestion
that let-7 RNA and additional "small temporal RNAs" might regulate the timing of development in
diverse animals, including humans. The let-7 RNA was found to be conserved in many species,
leading to the suggestion that let-7 RNA and additional "small temporal RNAs" might regulate the
timing of development in diverse animals, including humans

How miRNA revolutionise human growth?

The first human disease associated with deregulation of miRNAs was chronic lymphocytic leukemia.
In this disorder, the miRNAs have a dual role working as both tumor suppressors and oncogenes. In
the context of human growth, miRNAs influence the activity of growth hormones and insulin-like
growth factors (IGFs), which are vital for longitudinal growth and overall body development. By fine-
tuning the expression of genes involved in these pathways, miRNAs help ensure proper growth and
development throughout different life stages3.

As we know that miRNA is the one that controls the mRNA that is transcripted , we can use this to
our advantage by making it silence the mRNA that is affects the metabolic pathway in a negative way.

As it’s function in humans has been recently found it’s efficient uses in human growth can’t be done
for now

Were does the miRNA actually target?

Plant miRNAs usually have near-perfect pairing with their mRNA targets, which induces gene
repression through cleavage of the target transcripts. Plant miRNAs usually have near-perfect pairing
with their mRNA targets, which induces gene repression through cleavage of the target transcripts,
Plant miRNAs usually have near-perfect pairing with their mRNA targets, which induces gene
repression through cleavage of the target transcripts. Aa the miRNA that is given can have many
target sites in different kind of mRNA or the same miRNA is only specific for just one kind of mRNA.
Estimates of the average number of unique messenger RNAs that are targets for repression by a
typical miRNA vary, depending on the estimation method, but multiple approaches show that
mammalian miRNAs can have many unique targets. For example, an analysis of the miRNAs highly
conserved in vertebrates shows that each has, on average, roughly 400 conserved targets. Other
experiments show that a single miRNA species may repress the production of hundreds of proteins,
but that this repression often is relatively mild which is much less than the 2.5 folds

Formation of miRNA in the process of transcription

miRNA genes are usually transcribed by RNA polymerase II (Pol II). The polymerase often binds to a
promoter found near the DNA sequence, encoding what will become the hairpin loop of the pre-
miRNA. The resulting transcript is capped with a specially modified nucleotide at the 5'
end, polyadenylated with multiple adenosines (a poly(A) tail), and spliced. Animal miRNAs are
initially transcribed as part of one arm of an ~80 nucleotide RNA stem-loop that in turn forms part of
a several hundred nucleotide-long miRNA precursor termed a pri-miRNA. When a stem-loop
precursor is found in the 3' UTR, a transcript may serve as a pri-miRNA and a mRNA. RNA polymerase
III (Pol III) transcribes some miRNAs, especially those with upstream Alu sequences, transfer
RNAs (tRNAs), and mammalian wide interspersed repeat (MWIR) promoter units.

Nuclear processing
A single pri-miRNA may contain from one to six miRNA precursors. These hairpin loop structures are
composed of about 70 nucleotides each. Each hairpin is flanked by sequences necessary for efficient
processing.

The double-stranded RNA (dsRNA) structure of the hairpins in a pri-miRNA is recognized by a nuclear
protein known as DiGeorge Syndrome Critical Region 8 (DGCR8 or "Pasha" in invertebrates), named
for its association with DiGeorge Syndrome. DGCR8 associates with the enzyme Drosha, a protein
that cuts RNA, to form the Microprocessor complex. A single pri-miRNA may contain from one to six
miRNA precursors. These hairpin loop structures are composed of about 70 nucleotides each. Each
hairpin is flanked by sequences necessary for efficient processing.

The double-stranded RNA (dsRNA) structure of the hairpins in a pri-miRNA is recognized by a nuclear
protein known as DiGeorge Syndrome Critical Region 8 (DGCR8 or "Pasha" in invertebrates), named
for its association with DiGeorge Syndrome. DGCR8 associates with the enzyme Drosha, a protein
that cuts RNA, to form the Microprocessor complex.

Nomenclature of the miRNA

The prefix "miR" is followed by a dash and a number, the latter often indicating order of naming. For
example, miR-124 was named and likely discovered prior to miR-456. A capitalized "miR-" refers to
the mature form of the miRNA, while the uncapitalized "mir-" refers to the pre-miRNA and the pri-
miRNA. he genes encoding miRNAs are also named using the same three-letter prefix according to
the conventions of the organism gene nomenclature. For examples, the official miRNAs gene names
in some organisms are "mir-1 in C. elegans and Drosophila, Mir1 in Rattus norvegicus and MIR25 in
human.

miRNAs with nearly identical sequences except for one or two nucleotides are annotated with an
additional lower case letter. For example, miR-124a is closely related to miR-124b. For example:

hsa-miR-181a: aacauucaACgcugucggugAgu

hsa-miR-181b: aacauucaUUgcugucggugGgu

Pre-miRNAs, pri-miRNAs and genes that lead to 100% identical mature miRNAs but that are located
at different places in the genome are indicated with an additional dash-number suffix. For example,
the pre-miRNAs hsa-mir-194-1 and hsa-mir-194-2 lead to an identical mature miRNA (hsa-miR-194)
but are from genes located in different genome regions.

Therapeutics

The major revolution that occurred due to MIRNA is a therapeutics that can be done and cure many
diseases.

 Cancer Treatment: miRNAs can act as tumor suppressors or oncogenes. By targeting specific
miRNAs, researchers can inhibit cancer cell growth, induce apoptosis (programmed cell death), and
prevent metastasis1. For example, miRNA-based therapies are being explored for breast cancer
treatment1.

 Biomarkers: miRNAs can serve as biomarkers for early disease detection and prognosis. Changes in
miRNA levels can indicate the presence of diseases like cancer, cardiovascular disorders, and
diabetes4.
 Drug Resistance: miRNAs can modulate drug resistance in cancer cells. By targeting miRNAs
involved in drug resistance pathways, it's possible to enhance the effectiveness of existing
chemotherapy drugs1.

 Gene Regulation: miRNAs can regulate gene expression post-transcriptionally, making them useful
for correcting gene dysregulation in genetic disorders.

 Delivery Methods: Advances in nanotechnology have improved the delivery of miRNA-based

These are the some of the uses that can be currently done with the help of mirror. Soon the research
on mi rna will improve on the uses of mi rna will be found on viable and efficient way for human
growth