RNA editing is a post-transcriptional process that makes discrete changes to RNA sequences. There are three main types of RNA editing: cytosine to uracil deamination, adenine to inosine deamination, and guide RNA-mediated insertion/deletion of uridine bases. Cytidine deamination is site-specific and involves enzymes like cytidine deaminase. Adenine deamination occurs in RNA secondary structures and involves enzymes like ADAR. Guide RNA editing involves hybridization of RNA to guide RNA, cleavage by an endonuclease, addition of uridine by TuTase, and ligation. RNA editing increases protein diversity and is essential for organelle development in eukaryotes.
Dna supercoiling and role of topoisomerasesYashwanth B S
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Gene regulation in eukaryotes in a nutshell covering all the important stages of gene regulation in eukaryotes at transcriptional level, translation level and post-translational level.
Nutrient – a substance (element or compound) that promotes growth and health in living things
Oxygen, carbon, hydrogen and nitrogen are needed in large quantities – these are known as macronutrients
Trace elements such as magnesium, sulphur and phosphorous are called micronutrients
This is a power point presentation on The Oxygen Carbon Dioxide cycle which will give you too much of Information on The cycle and please like , share , download and love my power point p
Dna supercoiling and role of topoisomerasesYashwanth B S
supercoiling is one of the important process to condenses the huge amount of DNA to fit inside the histone and its also plays a role during the replication ,transcription etc..,these activities is carried out by an enzyme called topoisomerases.
Gene regulation in eukaryotes in a nutshell covering all the important stages of gene regulation in eukaryotes at transcriptional level, translation level and post-translational level.
Nutrient – a substance (element or compound) that promotes growth and health in living things
Oxygen, carbon, hydrogen and nitrogen are needed in large quantities – these are known as macronutrients
Trace elements such as magnesium, sulphur and phosphorous are called micronutrients
This is a power point presentation on The Oxygen Carbon Dioxide cycle which will give you too much of Information on The cycle and please like , share , download and love my power point p
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is a conserved biological response to double-stranded RNA that mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes. This natural mechanism for sequence-specific gene silencing promises to revolutionize experimental biology and may have important practical applications in functional genomics, therapeutic intervention, agriculture and other areas.
RNA Editing
Discovery of RNA Editing in Trypanosome Mitochondria
real functional genes
RNA EDITING IN KINETOPLAST OF TRYPANOSOMES.
Guide RNA (gRNA)
Guide RNAs Direct Editing in Trypanosomes
Editing is catalyzed by a multiprotein complex
Other Systems with RNA Editing
RNA EDITING
RNA editing, like RNA splicing, can change the sequence of the RNA after it has
been transcribed. Instead of stretches of the mRNA being reassorted, during
editing, individual bases are either inserted, deleted or changed. That is the
coding information in the RNA is altered.
There are two mechanisms that mediate editing:
1. Site specific deamination of adenines or cytosines
2. Guide RNA directed uridine insertion or deletion
1. Site specific deamination of adenines
➢ The mammalian apolipoprotein B gene has several exons among which
one is CAA codon that is targeted for editing.
➢ It is the C within the code that gets deaminated. The deamination is
performed by the enzyme cytidine deaminase, that converts C to U. the
deamination occurs in a tissue-specific manner: messages are edited in
intestinal cells but not in liver cells.
➢ The CAA codon, which is translated as glutamine in the unedited message
in the liver, is thus converted to UAA- a stop codon in the intestine. The
result is full length protein is formed in the liver but a truncated
polypeptide is made in the intestine.
➢ The longer form of apolipoprotein, in the liver is involved in the transport
of endogenously synthesized cholesterol and triglycerides. The shorter
form, in the intestine transports dietary lipids to various tissues.
Fig: Site specific deamination.
Site specific deamination of cytosines
➢ This reaction is performed by the enzyme ADAR (adenosine deaminase
acting on RNA) to generate inosine from adenine.
➢ Inosine can base pair with cytosine, and thus this change can readily alter
the sequence of the protein encoded by the mRNA.
➢ An ion channel expressed in mammalian brains is the target of this type
of editing. A single edit in its mRNA elicits a single amino acid change in the protein, which in turn alters the Ca2+ permeability of the channel. In
the absence of this editing, brain development is seriously impaired.
2. Guide RNA directed uridine insertion
or deletion
➢ In this case, multiple Us are inserted into specific regions of mRNA after
transcription. The addition of Us to the message changes codons and
reading frames, completely altering the meaning of the message.
➢ In a specific region of the mRNA of the trypanosome coxII gene, four Us
are inserted between adjacent sites at three sites.
➢ Us are inserted in to the message by so called guide RNAs (gRNAs). Each
gRNAs are divided in to three regions:
1. The anchor at the 5’ end. It directs the gRNA to the region of the
mRNA it will edit.
2. The region that determines exactly where the Us will be inserted
within the edited sequence.
3. Poly- U stretch at the 3’ end. ➢ A stretch of gRNA complementary to the region in the message to be
edited contains additional As. The As are at positions in the gRNA opposite
where Us will be inserted in to the mRNA.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
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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.
This is a presentation by Dada Robert in a Your Skill Boost masterclass organised by the Excellence Foundation for South Sudan (EFSS) on Saturday, the 25th and Sunday, the 26th of May 2024.
He discussed the concept of quality improvement, emphasizing its applicability to various aspects of life, including personal, project, and program improvements. He defined quality as doing the right thing at the right time in the right way to achieve the best possible results and discussed the concept of the "gap" between what we know and what we do, and how this gap represents the areas we need to improve. He explained the scientific approach to quality improvement, which involves systematic performance analysis, testing and learning, and implementing change ideas. He also highlighted the importance of client focus and a team approach to quality improvement.
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!
2. Introduction
RNA editing is a molecular process through which some cells
can make discrete changes to specific nucleotide sequences
within a RNA molecule after it has been generated
by RNA polymerase.
Defination: any type of change in RNA trancript sequence
without RNA splicing called RNA editing.
In pre-RNA having three types of modification occur to
become a mature RNA
1) Capping at 5 end and polyadenylation at 3 end
2) RNA editing
3) RNA splicing
3.
4. This is done to obtain large diversity in proteins by using
small no of genes.
Editing is done by insertion , modification or deletion of
one or more bases.
Editing was firstly discovered in mitochondria of
Trypnosomes.
5. Types of RNA Editing
1) Site specific deamination of cytosine and adenine
2) guide RNA mediated site specific insertion and
deletion of uridine base
6. Site specific deamination of cytosine and adenine
Cytidine deamination is tissue or site specific.
Like Cytidine deaminase occur in intestine carry out
deamination of cytosine in mRNA of ApoB100 genes to produce
apoB48
7.
8. Mechanism of cytosine deamination to uracil
A Cytidine deaminase activity involved in Apobec protein
Another protein ACF (apobec complimentation factor) is
also required
Apobec + ACF complex called as editisome
Both recognizes the sequences flanking the C to edited.
9.
10. deamination of adenine to Inosine
A to I modification usually occurs in sec. structure
regions of RNA.
Set of protein required for deamination of adenosine
called ADAR or dsRNA dependant deaminase
11. This ionise can be base pair with either A,T,G or C
Inosine detect as guanine during translation.
Eg. Different types of glut receptars for insuline
13. guide RNA mediated site specific insertion and
deletion of uridine base
guide RNA : it is a part of degraded introns.
It is a small fraction of RNA sequence just come out of the
splicing of RNA.
This small part of rna act as guide RNA
Guide RNA guide the process of RNA editing in eukaryotes
that’s why called as guide RNA.
14. Mechanism of gRNA mediated RNA editing
Steps :
1) hybridization of RNA with gRNA
2) cleavage of RNA with endonuclease
3) activity of TuTase and addition of uridine base
4) ligation of nick using ligase
15.
16. Significance of RNA editing
It is essential in regulating gene expression of organism
RNA editing mutant was reported with strong defects in
organelle development
It is a mechanism to increases the number different
proteins available without the need to increase the no of
genes in the genome
