RNA splicing is a process where introns are removed from precursor messenger RNA (pre-mRNA) and exons are joined together to produce mature mRNA. It occurs in the nucleus and is essential for eukaryotes to produce proteins. The spliceosome, a large complex of RNA and proteins, facilitates two transesterification reactions that remove introns and ligate exons. RNA splicing generates protein diversity through alternative splicing and is important for cellular functions and disease processes.
Most bacteria are free-living organisms that grow by increasing
in mass and then divide by binary fission.
Growth and division are controlled by genes, the expression
of which must be regulated appropriately. Genes
whose activity is controlled in response to the needs of a
cell or organism are called regulated genes. All organisms
also have a large number of genes whose products
are essential to the normal functioning of a growing and
dividing cell, no matter what the conditions are. These
genes are always active in growing cells and are known as
constitutive genes or housekeeping genes; examples include
genes that code for the enzymes needed for protein
synthesis and glucose metabolism. Note that all genes are
regulated on some level. If normal cell function is impaired
for some reason, the expression of all genes, including
constitutive genes, is reduced by regulatory
mechanisms. Thus, the distinction between regulated
and constitutive genes is somewhat arbitrary.
Most bacteria are free-living organisms that grow by increasing
in mass and then divide by binary fission.
Growth and division are controlled by genes, the expression
of which must be regulated appropriately. Genes
whose activity is controlled in response to the needs of a
cell or organism are called regulated genes. All organisms
also have a large number of genes whose products
are essential to the normal functioning of a growing and
dividing cell, no matter what the conditions are. These
genes are always active in growing cells and are known as
constitutive genes or housekeeping genes; examples include
genes that code for the enzymes needed for protein
synthesis and glucose metabolism. Note that all genes are
regulated on some level. If normal cell function is impaired
for some reason, the expression of all genes, including
constitutive genes, is reduced by regulatory
mechanisms. Thus, the distinction between regulated
and constitutive genes is somewhat arbitrary.
Basics of Undergraduate/university fellows
Transcription is more complicated in eukaryotes than in prokaryotes because
eukaryotes possess three different classes of RNA polymerases and because of the
way in which transcripts are processed to their functional forms.
More proteins and transcription factors are involved in eukaryotic transcription.
CBCS 4TH SEM ,
CHARGING, STRUCTURE AND FUNCTION OF tRNA,
AMINOACYL RNA SYNTHETASE(ASR) PROOFREADING AND EDITING
https://www.youtube.com/watch?v=YzOVMWYLiCE
RNA splicing is a biological process where a newly synthesized pre-mRNA transcript is processed and transformed into mRNA. It involves the removing of non-coding regions of RNA (introns) and the joining of the coding regions (exons).
RNA splicing is a form of RNA processing in which a newly made precursor messenger RNA (mRNA) is transformed into a mature RNA by removing the non-coding sequences termed introns.
The process of RNA splicing involves the removal of non-coding sequences or introns and joining of the coding sequences or exons.
RNA splicing takes place during or immediately after transcription within the nucleus in the case of nucleus-encoded genes.
In eukaryotic cells, RNA splicing is crucial as it ensures that an immature RNA molecule is converted into a mature molecule that can then be translated into proteins. The post-transcriptional modification is not necessary for prokaryotic cells.
Basics of Undergraduate/university fellows
Transcription is more complicated in eukaryotes than in prokaryotes because
eukaryotes possess three different classes of RNA polymerases and because of the
way in which transcripts are processed to their functional forms.
More proteins and transcription factors are involved in eukaryotic transcription.
CBCS 4TH SEM ,
CHARGING, STRUCTURE AND FUNCTION OF tRNA,
AMINOACYL RNA SYNTHETASE(ASR) PROOFREADING AND EDITING
https://www.youtube.com/watch?v=YzOVMWYLiCE
RNA splicing is a biological process where a newly synthesized pre-mRNA transcript is processed and transformed into mRNA. It involves the removing of non-coding regions of RNA (introns) and the joining of the coding regions (exons).
RNA splicing is a form of RNA processing in which a newly made precursor messenger RNA (mRNA) is transformed into a mature RNA by removing the non-coding sequences termed introns.
The process of RNA splicing involves the removal of non-coding sequences or introns and joining of the coding sequences or exons.
RNA splicing takes place during or immediately after transcription within the nucleus in the case of nucleus-encoded genes.
In eukaryotic cells, RNA splicing is crucial as it ensures that an immature RNA molecule is converted into a mature molecule that can then be translated into proteins. The post-transcriptional modification is not necessary for prokaryotic cells.
• Define transcription• Define translation• What are the 3 steps.pdfarihantelehyb
• Define transcription
• Define translation
• What are the 3 steps of translation?
• Define the “genetic dogma”
• What is the function of Transfer RNA?
• What is the function of RNA polymerase?
• What is the function of DNA polymerase?
• Define “splicing of RNA”
• What is an exon?
• What component of the cell does the translation?
• What molecule in the cell does transcription?
• What are the functions of: operon, promotor?
• What is the difference between inducible operon and repressible operon?
Solution
• Define transcription
Transcription is the process of making an RNA copy of a gene sequence. This copy, called a
messenger RNA (mRNA) molecule, leaves the cell nucleus and enters the cytoplasm, where it
directs the synthesis of the protein, which it encodes. Here is a more complete definition of
transcription.
• Define translation
Translation is the process of translating the sequence of a messenger RNA (mRNA) molecule to
a sequence of amino acids during protein synthesis. The genetic code describes the relationship
between the sequence of base pairs in a gene and the corresponding amino acid sequence that it
encodes. In the cell cytoplasm, the ribosome reads the sequence of the mRNA in groups of three
bases to assemble the protein. Here is a more complete definition of translation:
• What are the 3 steps of translation?
Step # 1. Initiation:
Initiation of translation in E .coli involves the small ribosome subunit, a mRNA molecule, a
specific charge initiator tRNA, GTP, Mg++ and number of proteinaceous initiation factors (IFs).
These are initially part of the small subunit and are required to enhance binding affinity of the
various translational components (Table 8.1). Unlike ribosomal proteins, IFs are released from
the ribosome once initiation is completed.
Step # 2. Elongation:
Once both subunits of the ribosome are assembled with the mRNA, binding site for two charged
tRNA molecules are formed. These are designated as the ‘P’ or peptidyl and the ‘A’ or
aminoacyl sites. The charged initiator tRNA binds to the P site, provided that the AUG triplet of
mRNA is in the corresponding position of the small subunit. The increase of the growing
polypeptide chain by one amino acid is called elongation.
Step # 3. Termination:
Termination of protein synthesis is carried out by triplet codes (UAG, UAA, UGA; stop codons)
present at site A. These codons do not specify an amino acid, nor do they call for a tRNA in the
A site. These codons are called stop codons, termination codons or nonsense codons. The
finished polypeptide is still attached to the terminal tRNA at the P site, and the A site is empty.
• Define the “genetic dogma”
A theory in genetics and molecular biology subject to several exceptions that genetic information
is coded in self-replicating DNA and undergoes unidirectional transfer to messenger RNAs in
transcription which act as templates for protein synthesis in translation
• What is the function of Transfer RNA?
The tRNA molecule, or tr.
Post-transcriptional modification or co-transcriptional modification is a set of biological processes common to most eukaryotic cells by which an RNA primary transcript is chemically altered following transcription from a gene to produce a mature, functional RNA molecule
In my report on the cell cycle and its checkpoints, I delve into the phases of cell division and the regulatory mechanisms that ensure accurate replication. By examining these checkpoints, I uncover the essential processes that safeguard genomic integrity and maintain organismal function.
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
Read| The latest issue of The Challenger is here! We are thrilled to announce that our school paper has qualified for the NATIONAL SCHOOLS PRESS CONFERENCE (NSPC) 2024. Thank you for your unwavering support and trust. Dive into the stories that made us stand out!
Unit 8 - Information and Communication Technology (Paper I).pdfThiyagu K
This slides describes the basic concepts of ICT, basics of Email, Emerging Technology and Digital Initiatives in Education. This presentations aligns with the UGC Paper I syllabus.
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
For more information, visit-www.vavaclasses.com
Operation “Blue Star” is the only event in the history of Independent India where the state went into war with its own people. Even after about 40 years it is not clear if it was culmination of states anger over people of the region, a political game of power or start of dictatorial chapter in the democratic setup.
The people of Punjab felt alienated from main stream due to denial of their just demands during a long democratic struggle since independence. As it happen all over the word, it led to militant struggle with great loss of lives of military, police and civilian personnel. Killing of Indira Gandhi and massacre of innocent Sikhs in Delhi and other India cities was also associated with this movement.
The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
How to Make a Field invisible in Odoo 17Celine George
It is possible to hide or invisible some fields in odoo. Commonly using “invisible” attribute in the field definition to invisible the fields. This slide will show how to make a field invisible in odoo 17.
The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
Ethnobotany and Ethnopharmacology:
Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
Bio-prospecting tools for drug discovery,
Role of Ethnopharmacology in drug evaluation,
Reverse Pharmacology.
2. ‘RNA SPLICING:-
INTRODUCTION
RNA splicing is a form of RNA processing in
which a newly made precursor messenger RNA
(mRNA) is transformed into a mature RNA by
removing the non-coding sequences termed
introns.
The process of RNA splicing involves the
removal of non-coding sequences or introns and
joining of the coding sequences or exons.
3. RNA splicing takes place during or immediately after
transcription within the nucleus in the case of nucleus-
encoded genes.
In eukaryotic cells, RNA splicing is crucial as it
ensures that an immature RNA molecule is converted
into a mature molecule that can then be translated into
proteins.
The post-transcriptional modification is not
necessary for prokaryotic cells.
RNA splicing is a controlled process that is regulated
by various ribonucleoproteins
4. What are Introns
Introns are non-coding DNA sequences present
within a gene that are removed by the process of RNA
splicing during maturation of the RNA transcript.
The word ‘introns’ is used to denote both the DNA
sequences within the gene and the corresponding
sequence in RNA transcripts.
Introns are common in the protein-coding nuclear
genes of most jawed invertebrates other eukaryotic
organisms along with unicellular organisms like
bacteria.
Similarly, the mitochondrial genomes of jawed
vertebrates are almost entirely devoid of introns
whereas those in other eukaryotes have many introns.
5. During RNA splicing, the introns between the exons
are removed to connect two different exons that then
code for messenger RNA.
Introns are crucial because the variation in the
protein bio-product formed is greatly enhanced by
alternative splicing in which introns take part in
prominent roles.
Introns have a donor site (5′ end), a branch site
(near the 3′ end), and an acceptor site (3′ end) that are
required for splicing.
6. What are Exons
o Exons are protein-coding DNA sequences that contain
the necessary codons or genetic information essential
for protein synthesis.
o The word ‘exon’ represents the expressed region
present in the genome.
oThe exosome is the term used to indicate the entire
set of all exons present in the genome of the organisms.
o In genes coding for proteins, exons include both the
protein-coding sequence and the 5’ and 3’ untranslated
regions.
7. o Exons are found in all organisms ranging from jawed
vertebrates to yeasts, bacteria, and even viruses.
In the human genome, exons account for only 1% of the
total genome while the rest is occupied by intergenic
DNA and introns
o Exons are essential units in protein synthesis as they
carry regions composed of codons that code for various
proteins.
o Alternative splicing enables exons to be arranged in
different combinations, where different configuration
results in different proteins.
o A process similar to alternative splicing is exon
shuffling where exons or sister chromosomes are
exchanged during recombination.
8. SPLICEOSOME
A spliceosome is a large and complex molecule
formed of RNAs and proteins that regulate the process
of RNA splicing.
The spliceosome is composed of five small nuclear
RNAs (snRNA) and about 80 protein molecules.
The combination of RNAs with these proteins results in
the formation of an RNA-protein complex termed as
small nuclear ribonucleoproteins (snRNPs).
These are mostly confined within the nucleus where
they remain associated with the immature pre-RNA
transcripts.
9. These spliceosomes, in addition to working on RNA-
RNA interactions, are also involved in RNA-protein
interactions.
The spliceosome functions as an editor that selectively
cuts out unnecessary and incorrect materials (introns) to
produce a functional final-cut.
All spliceosomes are involved in both the removal of
introns and the ligation of remaining exons.
Another set of spliceosomes termed ‘minor
spliceosomes’ are also found in eukaryotic cells which
have less abundant RNAs and are involved in the splicing
of a rare class of pre-mRNA introns.
10. MECHANISM
1) The process of RNA splicing begins with the
binding of the ribonucleoproteins or spliceosomes
to the introns present on the splice site
2) The binding of the spliceosome results in a
biochemical process called transesterification
between RNA nucleotides.
3) During this reaction, the 3’OH group of a specific
nucleotide on the intron, which is defined during
spliceosome assembly, causes a nucleophilic attack
on the first nucleotide of the intron at the 5’ splice
site.
4) This causes the folding of the 5’ and 3’ ends,
resulting in a loop. Meanwhile, the adjacent exons
are also brought together.
11. 6) Finally, the looped intron is detached from the
sequence by the spliceosomes.
7) Now, a second transesterification reaction occurs
during the ligation of adjacent exon segments.
8) In this case, the 3’OH group of the released 5’ exon
then performs an electrophilic attack on the first
nucleotide present just behind the last nucleotide of the
intron at the 3’ splice site
9) This causes the binding of the two exon segments
along with the removal of the intron segment.
12. 10)Earlier, the intron released during splicing is
thought of as a junk unit.
11) Still, it has been recently observed that these
introns are involved in other processes related to
proteins after their removal.
12)Besides the spliceosomes, another group of
protein/ enzymes termed ‘ribozymes’ are also involved
in the control and regulation of the splicing process.
13. TYPES OF SPLICING
1.Self-splicing
Self-splicing is a type of RNA splicing which occurs in
some rare introns that are capable of promoting
phosphodiester bond cleavage and formation without
the help of other proteins or spliceosomes.
These introns are unique as they can mediate their
excision from precursor RNA and the subsequent
ligation of the flanking exons in a simple salt buffer.
This self-splicing reaction is facilitated by the tertiary
structure of the intron, which provides the ability to
recognize the splice sites of the precursor RNA and to
perform the cutting and ligation reactions in a very
precise manner.
14. There are three types of self-splicing introns that are
grouped as Group I, Group II, and Group III.
Group I and Group II introns perform the splicing process
in a mechanism similar to that by spliceosomes. These
suggest that these introns might be evolutionarily related to
the spliceosomes.
During self-splicing, the 5′ splice site is recognized by a
short sequence element in the intron called the internal
guide sequence.
Besides, other strongly conserved sequences of the introns
called P, Q, R, and S are needed to ‘catalyze’ the cutting and
ligation reactions.
Self-splicing follows a similar mechanism involving two
transesterification reactions resulting in the removal of
introns and ligation of exons.
15. 2.Alternative splicing- It is a splicing process resulting in
a varying composition of exons in the same RNA and
creating a range of unique proteins.
Alternative splicing of pre-mRNA is an essential
mechanism to enhance the complexity of gene
expression, and it also plays a vital role in cellular
differentiation and organism development.
Alternative splicing enables exons to be arranged in
different combinations where different configuration
results in different proteins
The process of alternative splicing might occur either by
skipping or extending some exons or by retaining
particular introns, resulting in different varieties of
mRNA formed.
16. Regulation of alternative splicing is a complex process
in which numerous components interact with each
other, including cis-acting elements and trans-acting
factors.
The process is further guided by the functional
coupling between transcription and splicing.
Additional molecular features, such as chromatin
structure, RNA structure, and alternative transcription
initiation or alternative transcription termination,
collaborate with these basic components to generate
the protein diversity due to alternative splicing.
17. Alternative splicing is also essential for other functions
like the identification of novel diagnostic and prognostic
biomarkers, as well as new strategies for therapy in
cancer patients.
Thus, alternative splicing has a role in almost every
aspect of protein function, including binding between
proteins and ligands, nucleic acids or membranes,
localization, and enzymatic properties.
18.
19. 3.tRNA splicing
• Like in mRNA, the genes in tRNA are also interrupted by
introns, but here the splicing mechanism is quite
different.
• Splicing in tRNA is catalyzed by three enzymes with
an intrinsic requirement for ATP hydrolysis.
• The process of tRNA splicing occurs in all three major
lines of descent, the Bacteria, the Archaea, and the
Eukarya, but the mechanism might differ in bacteria and
higher organisms.
• In bacteria, the introns in the tRNA are self-splicing.
20. • In Archaea and Eukarya, however, the tRNA splicing
reaction occurs in three steps where each step is
catalyzed by a distinct enzyme, each of which can
function interchangeably on all of the substrates.
In the first step, the pre-tRNA is cleaved at the two
splice sites by an endonuclease, resulting in two tRNA
half molecules and a linear intron with 5’-OH and 3’-
cyclic PO4 ends.
The cleavage is then followed by the ligation of the
two RNA half molecules in the presence of a tRNA ligase
enzyme.
Finally, the PO4 ends produced from splicing are
transferred to NAD in a process catalyzed by
nicotinamide adenine dinucleotide (NAD)-dependent
phosphotransferase.
21. RNA Splicing Application
There are various biological, medical applications
associated with pre-mature RNA splicing, some of which
are:
Pre-mRNA splicing is a fundamental process in
cellular metabolism that plays an essential role in
generating protein diversity.
The diversity is brought about by changes in the
number and sequence of exons and introns present in
the RNA sequence.
22. RNA splicing also helps in the regulation of gene and
protein content in the cell.
Splicing of RNA sequences assists the process of
evolution of new and improved proteins.
Various aberrant splicing isoforms act as markers for
cancer and as targets for cancer therapy.
Pre-mRNA splicing is a key to the pathology of
cancers where it regulates the three functional aspects
of cancer: proliferation, metastasis, and apoptosis.