Introduction
What RNA Splicing???
Discovery
Types
Alternative Splicing
Mechanism
Regulatory element And protein
Splicing repression
Splicing activation
Significance
Diseases
Conclusion
Refrences
Alternative splicing is a deviation from the conventional splicing as it removes introns in a different manner. It has a lot of significance in the development of diseases like cancers and in plants adapting to various stress conditions.
1. Gene regulation in prokaryotes and eukaryotes involves control at the levels of transcription and translation.
2. In prokaryotes, genes are often organized into operons and regulated through inducible and repressible operons controlled by regulatory proteins binding to operator and promoter sites. The lac and trp operons are examples of inducible and repressible operons, respectively.
3. In eukaryotes, gene expression is controlled through chromatin structure, transcriptional initiation, transcript processing and modification, transport, stability, and small RNA-mediated pathways. This allows for complex tissue-specific and developmental control of gene expression.
Riboswitches are RNA elements found in the 5' untranslated region of mRNA that can bind to specific metabolites and undergo a conformational change to regulate gene expression. They are classified based on the ligand they bind and their secondary structure. Examples include TPP, lysine, glycine, FMN, purine, and cobalamin riboswitches. A riboswitch has two domains - an aptamer domain that binds the ligand and an expression platform domain that can adopt two structures to control transcription or translation. Binding of a metabolite can induce formation of a terminator stem loop to terminate transcription, mask the ribosome binding site to inhibit translation initiation, or trigger self-cleavage of the mRNA.
RNA splicing is the process by which introns, or non-coding sequences, are removed from pre-messenger RNA (pre-mRNA) to produce mature mRNA that can be translated into protein. Most genes contain introns that are removed by a spliceosome, a complex of RNA and proteins, leaving just the coding exons to form mRNA. Alternative splicing allows one gene to encode multiple proteins by selecting different combinations of exons. Errors in splicing can cause diseases if they result in truncated or abnormal proteins.
The document summarizes the processing of transfer RNA (tRNA) in organisms. TRNA undergoes extensive processing where nucleotides are removed from both the 5' and 3' ends by endonucleases and exonucleases to generate mature tRNA that is 80-90 nucleotides long. A key step is the addition of the 3' terminal CCA sequence by tRNA nucleotidyl transferase. The mature tRNA also contains various modified bases introduced by enzymatic modifications. Introns are also excised from precursor tRNA to form mature functional tRNA for protein synthesis.
This document summarizes post-transcriptional modifications in eukaryotes. It discusses how eukaryotic mRNA undergoes processing, including capping, splicing to remove introns, and polyadenylation. Splicing requires snRNPs and the spliceosome to recognize splice sites. Alternative splicing allows one gene to code for multiple proteins. tRNA and rRNA also undergo processing as they mature, including modification of bases and removal of sequences. Final mature mRNA, tRNA, and rRNA are then ready for translation.
Translation is the process by which proteins are synthesized from messenger RNA (mRNA) in eukaryotes, which are organisms with membrane-bound nuclei. Translation involves mRNA being decoded on ribosomes into a polypeptide chain. It occurs through three main steps - initiation, elongation, and termination. Initiation involves the small ribosomal subunit binding to the 5' end of mRNA and scanning for the start codon. Elongation is the sequential addition of amino acids specified by the mRNA codons. Termination occurs when a stop codon is reached and release factors cause the ribosome to dissociate and release the completed protein.
Alternative splicing is a deviation from the conventional splicing as it removes introns in a different manner. It has a lot of significance in the development of diseases like cancers and in plants adapting to various stress conditions.
1. Gene regulation in prokaryotes and eukaryotes involves control at the levels of transcription and translation.
2. In prokaryotes, genes are often organized into operons and regulated through inducible and repressible operons controlled by regulatory proteins binding to operator and promoter sites. The lac and trp operons are examples of inducible and repressible operons, respectively.
3. In eukaryotes, gene expression is controlled through chromatin structure, transcriptional initiation, transcript processing and modification, transport, stability, and small RNA-mediated pathways. This allows for complex tissue-specific and developmental control of gene expression.
Riboswitches are RNA elements found in the 5' untranslated region of mRNA that can bind to specific metabolites and undergo a conformational change to regulate gene expression. They are classified based on the ligand they bind and their secondary structure. Examples include TPP, lysine, glycine, FMN, purine, and cobalamin riboswitches. A riboswitch has two domains - an aptamer domain that binds the ligand and an expression platform domain that can adopt two structures to control transcription or translation. Binding of a metabolite can induce formation of a terminator stem loop to terminate transcription, mask the ribosome binding site to inhibit translation initiation, or trigger self-cleavage of the mRNA.
RNA splicing is the process by which introns, or non-coding sequences, are removed from pre-messenger RNA (pre-mRNA) to produce mature mRNA that can be translated into protein. Most genes contain introns that are removed by a spliceosome, a complex of RNA and proteins, leaving just the coding exons to form mRNA. Alternative splicing allows one gene to encode multiple proteins by selecting different combinations of exons. Errors in splicing can cause diseases if they result in truncated or abnormal proteins.
The document summarizes the processing of transfer RNA (tRNA) in organisms. TRNA undergoes extensive processing where nucleotides are removed from both the 5' and 3' ends by endonucleases and exonucleases to generate mature tRNA that is 80-90 nucleotides long. A key step is the addition of the 3' terminal CCA sequence by tRNA nucleotidyl transferase. The mature tRNA also contains various modified bases introduced by enzymatic modifications. Introns are also excised from precursor tRNA to form mature functional tRNA for protein synthesis.
This document summarizes post-transcriptional modifications in eukaryotes. It discusses how eukaryotic mRNA undergoes processing, including capping, splicing to remove introns, and polyadenylation. Splicing requires snRNPs and the spliceosome to recognize splice sites. Alternative splicing allows one gene to code for multiple proteins. tRNA and rRNA also undergo processing as they mature, including modification of bases and removal of sequences. Final mature mRNA, tRNA, and rRNA are then ready for translation.
Translation is the process by which proteins are synthesized from messenger RNA (mRNA) in eukaryotes, which are organisms with membrane-bound nuclei. Translation involves mRNA being decoded on ribosomes into a polypeptide chain. It occurs through three main steps - initiation, elongation, and termination. Initiation involves the small ribosomal subunit binding to the 5' end of mRNA and scanning for the start codon. Elongation is the sequential addition of amino acids specified by the mRNA codons. Termination occurs when a stop codon is reached and release factors cause the ribosome to dissociate and release the completed protein.
Regulation of gene expression in eukaryotesAnna Purna
Presence of nucleus and complexity of eukaryotic organism demands a well controlled gene regulation in eukaryotic cell. Tissue specific gene expression is essential as they are multicellular organisms in which different cells perform different functions. This PPT deals with various control points for the gene regulation and expression within a cell.
This document discusses transposable elements (TEs), which are segments of DNA that can change positions within the genome. It classifies TEs into two classes based on their mechanism of transposition. Class 1 elements use a "cut and paste" mechanism involving transposase, while Class 2 retrotransposons use reverse transcriptase in a "copy and paste" mechanism. Examples of TEs discussed include Ac-Ds elements in maize, P elements in Drosophila, and LINEs and SINEs in humans. The effects of TE insertion include gene mutation, changes in gene regulation, gene duplication, deletion, and chromosome rearrangements. Applications of TEs include their use as cloning vectors and providing raw material for evolution
1. Chromatin remodeling is the process by which chromatin structure is dynamically modified to allow access of DNA for processes like transcription.
2. There are two main types of chromatin remodeling - covalent histone modification and ATP-dependent chromatin remodeling complexes.
3. ATP-dependent complexes use energy from ATP hydrolysis to move, eject, or restructure nucleosomes, allowing access to DNA.
4. Examples of chromatin remodeling complexes include SWI/SNF, ISWI, CHD, and INO80 families, which have different activities like nucleosome sliding or histone variant exchange.
Gene expression in eukaryotes is regulated through multiple mechanisms at the transcriptional and post-transcriptional levels. These mechanisms allow for adaptation, tissue specificity, and development. Regulation occurs through chromatin remodeling, enhancers/repressors, locus control regions, gene amplification, rearrangement, and alternative RNA processing. Key differences between prokaryotic and eukaryotic gene expression include larger eukaryotic genomes, different cell types, lack of operons, chromatin structure, and uncoupled transcription/translation.
Post translational modification of proteincoolsid13
The document discusses various types of post-translational modifications (PTMs) of proteins. It describes how PTMs are necessary for normal protein functioning by affecting stability, activity, localization, and signaling. It provides examples of common PTMs like phosphorylation, glycosylation, acetylation, lipidation, disulfide bonding, and ubiquitination. It also discusses protein folding, subunit aggregation, and protein splicing - key processes in protein maturation that occur after translation. PTMs are an important mechanism for regulating protein structure and function after synthesis.
Transposable elements are mobile DNA sequences found in genomes of all organisms. Barbara McClintock discovered transposable elements called Ac and Ds in maize that cause color patterns in corn kernels. Her discovery showed that genes can move within genomes. Experiments with Drosophila revealed another transposable element called P elements that cause hybrid dysgenesis. Transposable elements can provide genetic variation and flexibility that influences evolution.
Reverse transcription of RNA, which refers to the conversion of the RNA template into its complimentary DNA strand (cDNA) is an essential step in the analysis of gene transcripts.
cDNA can be sequenced, cloned and applied to estimate the copy number of specific genes in order to characterize and to validate gene expression.
DNA methylation is an epigenetic mechanism that involves the addition of a methyl group to cytosine residues in DNA. It is catalyzed by DNA methyltransferase enzymes and plays a key role in gene expression and cellular differentiation. Aberrant DNA methylation, including both hypermethylation and hypomethylation, has been associated with cancer development by disrupting gene expression. Detection of DNA methylation patterns can provide insights into cancer biology and may have applications as a diagnostic tool.
Reeta yadav. roll no. 02. transposable element in eukaryotes.Manisha Jangra
This document discusses transposable elements in eukaryotes. It begins by introducing transposable elements as DNA sequences that can move within genomes. It then covers the discovery of early transposable elements like Ac and Ds in maize. It describes different types of transposable elements like retrotransposons, including viral retrotransposons like Ty1 in yeast and non-viral retrotransposons like LINEs and SINEs in humans. The document concludes by discussing the significance of transposable elements in genome evolution and genetic variation.
The document provides an overview of the history and techniques of transcriptome analysis. It discusses how RNA was separated from DNA with the formulation of the central dogma in 1958. Key developments include the discoveries of messenger RNA, transfer RNA, and ribosomal RNA in the 1960s. The document outlines techniques such as serial analysis of gene expression (SAGE) and RNA sequencing (RNA-seq) that allow comprehensive analysis of gene expression patterns. It provides details on the basic steps and advantages of SAGE and describes how next generation sequencing revolutionized transcriptome analysis through massive parallel sequencing.
Gene silencing is the regulation of gene expression in a cell to prevent the expression of a certain gene. Gene silencing can occur during either transcription or translation and is often used in research.
Chromatin remodeling involves modifying chromatin structure through two main classes of protein complexes: covalent histone-modifying complexes and ATP-dependent chromatin remodeling complexes. Covalent histone-modifying complexes catalyze addition or removal of elements like acetyl groups on histone tails, loosening or tightening DNA binding. ATP-dependent complexes use energy from ATP hydrolysis to move, eject, or restructure nucleosomes, exposing DNA for transcription. Chromatin remodeling plays a central role in gene expression regulation by providing dynamic access to the packaged genome.
Co and post translationational modification of proteinsSukirti Vedula
This document discusses co-translational and post-translational modifications of proteins. It begins with an introduction to protein modification and defines co-translational and post-translational modifications. It then covers various co-translational modifications including regulation of translation, protein folding, and enzymes that catalyze protein folding. Post-translational modifications discussed include protein cleavage, glycosylation, addition of GPI anchors, ubiquitination, and phosphorylation. The document provides examples and details for many of the modification processes.
This document discusses different types of chaperone proteins. It begins by explaining that chaperones assist other proteins in folding correctly by interacting with unfolded or misfolded proteins. The main types discussed are molecular chaperones like Hsp70 and Hsp90, and chaperonins. Hsp70 binds to hydrophobic regions of unfolded proteins to prevent aggregation, while Hsp90 helps activate client proteins. Chaperonins form folding chambers and there are two groups - group 1 found in prokaryotes and organelles, and group 2 in eukaryotes and archaea. Specific examples of chaperone homologs in different organisms are also provided.
This document summarizes the process of nuclear export of messenger RNA (mRNA). It begins with an introduction describing how mRNA must be exported from the nucleus to the cytoplasm to be translated into protein. It then discusses the importance of nuclear export and describes the nuclear pore complex that facilitates transport. The document outlines the roles of Ran GTPase and transport receptors in nuclear export. It provides details on the adaptor-receptor system and multistep process of mRNA export, including recruitment of export factors, translocation through the nuclear pore, and release into the cytoplasm. The summary concludes with sections on regulation and quality control of mRNA export.
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.
Protein-DNA interactions can be either specific or non-specific. Specific interactions involve transcription factors that regulate gene expression by binding to DNA motifs through domains like helix-loop-helix, leucine zipper, or zinc finger motifs. Non-specific interactions involve histones that help structure DNA into nucleosomes within chromatin and can be chemically modified through methylation, demethylation, acetylation, and phosphorylation.
This document discusses various classes of transcriptional regulatory elements. It begins by introducing transcriptional regulation and the basic transcriptional machinery. It then discusses the different elements that make up promoters, including the core promoter and proximal promoter elements. It also covers distal regulatory elements such as enhancers, silencers, insulators, and locus control regions. Enhancers can activate transcription from far away and silencers can repress it. Insulators protect genes from neighboring influences. Locus control regions coordinate expression of entire gene clusters.
Regulation of eukaryotic gene expressionMd Murad Khan
The document discusses various mechanisms of regulating gene expression in eukaryotes. It explains that regulation can occur at multiple levels, including DNA, transcription, mRNA processing, and protein synthesis. Key points include: (1) Regulation allows adaptation and cellular differentiation; (2) In eukaryotes, transcription and translation are separated, allowing more complex regulation; (3) Regulation mechanisms include controlling chromatin structure, transcription initiation, mRNA splicing/stability, and protein modifications. Environmental factors like heat and hormones can also induce gene expression changes through transcription factors.
Retrotransposons are genetic elements that copy and paste themselves throughout the genome using an RNA intermediate and reverse transcription. There are two main types: LTR retrotransposons, which mimic retroviruses through reverse transcription of an RNA copy into DNA; and non-LTR retrotransposons like LINEs and SINEs. LINEs (Long Interspersed Nuclear Elements) are autonomous retrotransposons over 6kb with endonuclease and reverse transcriptase proteins. SINEs (Short Interspersed Nuclear Elements) are shorter than 300bp and non-autonomous, relying on LINEs to reverse transcribe themselves.
1. Operon refers to a cluster of structural genes regulated by a common operator and involved in the same metabolic pathway. Examples include the lac and tryptophan operons.
2. Signal transduction is the process by which extracellular signals are converted into intracellular responses, involving the steps of reception, transduction, and response.
3. Cloning involves making identical copies of a gene, which can be the original or a mutated version, using DNA ligase and restriction endonucleases.
This document summarizes various processes involved in RNA processing in eukaryotes. It discusses 5' capping and polyadenylation of pre-mRNA, as well as splicing of introns and exons. Splicing involves two transesterification reactions catalyzed by a spliceosome complex containing U1, U2, U4, U5 and U6 small nuclear ribonucleoproteins (snRNPs). Alternative splicing and RNA editing are also described, where editing can involve base modification or insertion/deletion of nucleotides guided by small RNAs.
Regulation of gene expression in eukaryotesAnna Purna
Presence of nucleus and complexity of eukaryotic organism demands a well controlled gene regulation in eukaryotic cell. Tissue specific gene expression is essential as they are multicellular organisms in which different cells perform different functions. This PPT deals with various control points for the gene regulation and expression within a cell.
This document discusses transposable elements (TEs), which are segments of DNA that can change positions within the genome. It classifies TEs into two classes based on their mechanism of transposition. Class 1 elements use a "cut and paste" mechanism involving transposase, while Class 2 retrotransposons use reverse transcriptase in a "copy and paste" mechanism. Examples of TEs discussed include Ac-Ds elements in maize, P elements in Drosophila, and LINEs and SINEs in humans. The effects of TE insertion include gene mutation, changes in gene regulation, gene duplication, deletion, and chromosome rearrangements. Applications of TEs include their use as cloning vectors and providing raw material for evolution
1. Chromatin remodeling is the process by which chromatin structure is dynamically modified to allow access of DNA for processes like transcription.
2. There are two main types of chromatin remodeling - covalent histone modification and ATP-dependent chromatin remodeling complexes.
3. ATP-dependent complexes use energy from ATP hydrolysis to move, eject, or restructure nucleosomes, allowing access to DNA.
4. Examples of chromatin remodeling complexes include SWI/SNF, ISWI, CHD, and INO80 families, which have different activities like nucleosome sliding or histone variant exchange.
Gene expression in eukaryotes is regulated through multiple mechanisms at the transcriptional and post-transcriptional levels. These mechanisms allow for adaptation, tissue specificity, and development. Regulation occurs through chromatin remodeling, enhancers/repressors, locus control regions, gene amplification, rearrangement, and alternative RNA processing. Key differences between prokaryotic and eukaryotic gene expression include larger eukaryotic genomes, different cell types, lack of operons, chromatin structure, and uncoupled transcription/translation.
Post translational modification of proteincoolsid13
The document discusses various types of post-translational modifications (PTMs) of proteins. It describes how PTMs are necessary for normal protein functioning by affecting stability, activity, localization, and signaling. It provides examples of common PTMs like phosphorylation, glycosylation, acetylation, lipidation, disulfide bonding, and ubiquitination. It also discusses protein folding, subunit aggregation, and protein splicing - key processes in protein maturation that occur after translation. PTMs are an important mechanism for regulating protein structure and function after synthesis.
Transposable elements are mobile DNA sequences found in genomes of all organisms. Barbara McClintock discovered transposable elements called Ac and Ds in maize that cause color patterns in corn kernels. Her discovery showed that genes can move within genomes. Experiments with Drosophila revealed another transposable element called P elements that cause hybrid dysgenesis. Transposable elements can provide genetic variation and flexibility that influences evolution.
Reverse transcription of RNA, which refers to the conversion of the RNA template into its complimentary DNA strand (cDNA) is an essential step in the analysis of gene transcripts.
cDNA can be sequenced, cloned and applied to estimate the copy number of specific genes in order to characterize and to validate gene expression.
DNA methylation is an epigenetic mechanism that involves the addition of a methyl group to cytosine residues in DNA. It is catalyzed by DNA methyltransferase enzymes and plays a key role in gene expression and cellular differentiation. Aberrant DNA methylation, including both hypermethylation and hypomethylation, has been associated with cancer development by disrupting gene expression. Detection of DNA methylation patterns can provide insights into cancer biology and may have applications as a diagnostic tool.
Reeta yadav. roll no. 02. transposable element in eukaryotes.Manisha Jangra
This document discusses transposable elements in eukaryotes. It begins by introducing transposable elements as DNA sequences that can move within genomes. It then covers the discovery of early transposable elements like Ac and Ds in maize. It describes different types of transposable elements like retrotransposons, including viral retrotransposons like Ty1 in yeast and non-viral retrotransposons like LINEs and SINEs in humans. The document concludes by discussing the significance of transposable elements in genome evolution and genetic variation.
The document provides an overview of the history and techniques of transcriptome analysis. It discusses how RNA was separated from DNA with the formulation of the central dogma in 1958. Key developments include the discoveries of messenger RNA, transfer RNA, and ribosomal RNA in the 1960s. The document outlines techniques such as serial analysis of gene expression (SAGE) and RNA sequencing (RNA-seq) that allow comprehensive analysis of gene expression patterns. It provides details on the basic steps and advantages of SAGE and describes how next generation sequencing revolutionized transcriptome analysis through massive parallel sequencing.
Gene silencing is the regulation of gene expression in a cell to prevent the expression of a certain gene. Gene silencing can occur during either transcription or translation and is often used in research.
Chromatin remodeling involves modifying chromatin structure through two main classes of protein complexes: covalent histone-modifying complexes and ATP-dependent chromatin remodeling complexes. Covalent histone-modifying complexes catalyze addition or removal of elements like acetyl groups on histone tails, loosening or tightening DNA binding. ATP-dependent complexes use energy from ATP hydrolysis to move, eject, or restructure nucleosomes, exposing DNA for transcription. Chromatin remodeling plays a central role in gene expression regulation by providing dynamic access to the packaged genome.
Co and post translationational modification of proteinsSukirti Vedula
This document discusses co-translational and post-translational modifications of proteins. It begins with an introduction to protein modification and defines co-translational and post-translational modifications. It then covers various co-translational modifications including regulation of translation, protein folding, and enzymes that catalyze protein folding. Post-translational modifications discussed include protein cleavage, glycosylation, addition of GPI anchors, ubiquitination, and phosphorylation. The document provides examples and details for many of the modification processes.
This document discusses different types of chaperone proteins. It begins by explaining that chaperones assist other proteins in folding correctly by interacting with unfolded or misfolded proteins. The main types discussed are molecular chaperones like Hsp70 and Hsp90, and chaperonins. Hsp70 binds to hydrophobic regions of unfolded proteins to prevent aggregation, while Hsp90 helps activate client proteins. Chaperonins form folding chambers and there are two groups - group 1 found in prokaryotes and organelles, and group 2 in eukaryotes and archaea. Specific examples of chaperone homologs in different organisms are also provided.
This document summarizes the process of nuclear export of messenger RNA (mRNA). It begins with an introduction describing how mRNA must be exported from the nucleus to the cytoplasm to be translated into protein. It then discusses the importance of nuclear export and describes the nuclear pore complex that facilitates transport. The document outlines the roles of Ran GTPase and transport receptors in nuclear export. It provides details on the adaptor-receptor system and multistep process of mRNA export, including recruitment of export factors, translocation through the nuclear pore, and release into the cytoplasm. The summary concludes with sections on regulation and quality control of mRNA export.
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.
Protein-DNA interactions can be either specific or non-specific. Specific interactions involve transcription factors that regulate gene expression by binding to DNA motifs through domains like helix-loop-helix, leucine zipper, or zinc finger motifs. Non-specific interactions involve histones that help structure DNA into nucleosomes within chromatin and can be chemically modified through methylation, demethylation, acetylation, and phosphorylation.
This document discusses various classes of transcriptional regulatory elements. It begins by introducing transcriptional regulation and the basic transcriptional machinery. It then discusses the different elements that make up promoters, including the core promoter and proximal promoter elements. It also covers distal regulatory elements such as enhancers, silencers, insulators, and locus control regions. Enhancers can activate transcription from far away and silencers can repress it. Insulators protect genes from neighboring influences. Locus control regions coordinate expression of entire gene clusters.
Regulation of eukaryotic gene expressionMd Murad Khan
The document discusses various mechanisms of regulating gene expression in eukaryotes. It explains that regulation can occur at multiple levels, including DNA, transcription, mRNA processing, and protein synthesis. Key points include: (1) Regulation allows adaptation and cellular differentiation; (2) In eukaryotes, transcription and translation are separated, allowing more complex regulation; (3) Regulation mechanisms include controlling chromatin structure, transcription initiation, mRNA splicing/stability, and protein modifications. Environmental factors like heat and hormones can also induce gene expression changes through transcription factors.
Retrotransposons are genetic elements that copy and paste themselves throughout the genome using an RNA intermediate and reverse transcription. There are two main types: LTR retrotransposons, which mimic retroviruses through reverse transcription of an RNA copy into DNA; and non-LTR retrotransposons like LINEs and SINEs. LINEs (Long Interspersed Nuclear Elements) are autonomous retrotransposons over 6kb with endonuclease and reverse transcriptase proteins. SINEs (Short Interspersed Nuclear Elements) are shorter than 300bp and non-autonomous, relying on LINEs to reverse transcribe themselves.
1. Operon refers to a cluster of structural genes regulated by a common operator and involved in the same metabolic pathway. Examples include the lac and tryptophan operons.
2. Signal transduction is the process by which extracellular signals are converted into intracellular responses, involving the steps of reception, transduction, and response.
3. Cloning involves making identical copies of a gene, which can be the original or a mutated version, using DNA ligase and restriction endonucleases.
This document summarizes various processes involved in RNA processing in eukaryotes. It discusses 5' capping and polyadenylation of pre-mRNA, as well as splicing of introns and exons. Splicing involves two transesterification reactions catalyzed by a spliceosome complex containing U1, U2, U4, U5 and U6 small nuclear ribonucleoproteins (snRNPs). Alternative splicing and RNA editing are also described, where editing can involve base modification or insertion/deletion of nucleotides guided by small RNAs.
The hereditary material of organisms is DNA, which contains genetic information in the form of a specific nucleotide sequence. This DNA is organized into chromosomes that make up an organism's genome. Gene expression involves transcription of DNA into RNA, which may undergo processing before being translated into proteins. The proteins then fold and are transported within the cell. Regulation of gene expression controls when and how much of gene products are made to allow cells to adapt. Gene expression can be measured to provide insight into cellular processes.
The document discusses several key concepts in molecular biology including DNA, RNA, transcription, translation, and protein synthesis. It explains that DNA is transcribed into RNA which is then translated into proteins. It describes the central dogma of molecular biology and provides more details on processes like transcription, splicing, and translation. It also discusses topics like alternative splicing, RNA editing, and RNA interference.
1. What is post transcriptional Modification of RNA
2. How is Post Transcriptional Modification of RNA different in Prokaryotes and Eukaryotes
3. What are the Various Types of Post Transcriptional Modification of RNA
4. What is the Mechanism of 5' Capping of RNA
5. What is the Mechanism of 3' Polyadenylation of RNA
6. What is the Function of 5' Capping of RNA
7. What is Function of 3' Polyadenylation of RNA
8. What is Splicing ?
9. What is the Mechanism of Splicing ?
10. What is Spliceosomes ?
11. What is Sn RNA or Small Nuclear RNA ?
12. What is SnRNP Complex or SNURPs ?
13. Beta Thalessemia because of faulty Splicing ?
14. What is Methylation post transcriptional modification ?
15. What is Alternative Splicing?
16. What is Selective Splicing ?
17. What is Alternative polyadenylation ?
18. What is Alternative 5' donor Splicing ?
19. What is Alternative 3' Donor Splicing ?
20. What is the role of Alternative Splicing ?
21. What is RNA Editing ?
22. How is RNA Editing an Exception to Central Dogma ?
23. Example of Apolipoprotein B Gene for RNA Editing
24. Other Examples of RNA Editing
RNA splicing is a process in which introns are removed from pre-mRNA transcripts and exons are joined together to produce mature mRNA. There are three main types of splicing pathways: spliceosomal splicing, self-splicing, and tRNA splicing. Spliceosomal splicing involves the spliceosome complex and is the most common in eukaryotes. Self-splicing occurs without proteins through ribozyme activity. tRNA splicing uses ribonucleases and ligases. Alternative splicing allows different mRNA isoforms to be produced from the same pre-mRNA. Splicing errors can cause genetic diseases by disrupting protein sequences.
The document discusses various aspects of genome organization, including:
1. Chromatin assembly begins with the incorporation of histone proteins to form nucleosomes, which are then folded and organized into higher order structures within the nucleus.
2. Genes can be split, overlapping, or pseudogenes. Split genes contain introns that are spliced out, while overlapping genes share nucleotide sequences. Pseudogenes are non-functional copies of genes.
3. Gene families consist of genes related by common ancestry that may be clustered or dispersed throughout the genome. Members can vary in sequence but often retain similar functions.
Gene silencing is a process that down regulates gene expression without altering the DNA sequence. It can occur at the transcriptional or post-transcriptional level. Common methods of gene silencing include RNA interference technologies like siRNA, shRNA, and miRNA, which induce degradation of mRNA transcripts. Gene silencing is used for both basic research and applications like crop improvement, as it allows precise down regulation of gene expression.
Gene silencing is a process that downregulates gene expression without altering the DNA sequence. It can occur at the transcriptional or post-transcriptional level through various methods like RNA interference, DNA methylation, and histone modifications. Gene silencing is important for normal development and cellular differentiation, but can also contribute to diseases if aberrantly silencing critical genes. It is currently being explored as a tool for crop improvement, drug discovery, and antiviral therapies.
ONLY THE LAST QUESTION IS THE POINT OF POST. THE OTHER PAGES ARE B.pdfamzonknr
ONLY THE LAST QUESTION IS THE POINT OF POST. THE OTHER PAGES ARE
BACKGROUND CONTEXT Lab: Differential Expression Differential gene expression provides
the ability for a cell or organism to respond to a constantly changing external environment. The
specific constellation of proteins required for optimal function and growth varies with cellular
age and environmental context. Thus, protein production is carefully regulated by multiple
mechanisms that modulate both transcriptional and translational pathways. Control of
transcription initiation by RNA polymerase is a predominant mechanism for regulating
expression of specific proteins, presumably because it provides maximal conservation of energy
for the cell. We can often observe the consequence of differential transcription due to the
presence or absence of particular proteins or the growth in particular environments. Control can
also occur at translation; the mRNA is synthesized, but only in certain circumstances is it
translated. Control can also occur at the level of protein function; the protein is inactive, or
activity is not observed due to the lack of the substrate. In this lab we will observe differential
expression of two different genes encoded on plasmids. We will analyze transcriptional activity,
translational activity, and protein function. Plasmids are extra-chromosomal DNA. Bacteria often
have plasmids and will replicate the plasmid and pass it to daughter cells (vertical transmission)
and to neighboring cells (horizontal). Plasmids are a mechanism of gene diversity. In order to
stably retain the plasmid, there needs to be some type of metabolic reason for the bacteria to
maintain the plasmid. In other words, the plasmid confers an advantage. Plasmids contain: 1. Ori:
the plasmid may present is low or high copy number. 2. Lab generated plasmids typically also
contain a selectable marker (antibiotic resistance), 3. Additional gene for ease of visual screening
4. Multiple cloning site
pUC19 is one of a series of plasmid cloning vectors created by Joachim Messing and co-workers.
The designation "pUC" is derived from the classical "p" prefix (denoting "plasmid") and the
abbreviation for the University of California, where early work on the plasmid series had been
conducted. It is a circular double stranded DNA and has 2686 base pairs. pUC19 is one of the
most widely used vector molecules as the recombinants, or the cells into which foreign DNA has
been introduced, can be easily distinguished from the non-recombinants based on color
differences of colonies on growth media. pUC18 is similar to pUC19, but the MCS region is
reversed. - pUC 19 has an origin of replication and is maintained at a high copy number. -
pUC19 encodes for an ampicillin resistance gene (amopR), via a -lactamase enzyme that
functions by degrading ampicillin and reducing its toxicity to the host. - It has an N-terminal
fragment of -galactosidase (lacZ) gene of E. coli which allows for visual screening of
recombinant.
ONLY THE LAST QUESTION IS THE POINT OF POST. THE OTHER PAGES ARE BAC.pdfamzonknr
ONLY THE LAST QUESTION IS THE POINT OF POST. THE OTHER PAGES ARE
BACKGROUND CONTEXT Lab: Differential Expression Differential gene expression provides
the ability for a cell or organism to respond to a constantly changing external environment. The
specific constellation of proteins required for optimal function and growth varies with cellular
age and environmental context. Thus, protein production is carefully regulated by multiple
mechanisms that modulate both transcriptional and translational pathways. Control of
transcription initiation by RNA polymerase is a predominant mechanism for regulating
expression of specific proteins, presumably because it provides maximal conservation of energy
for the cell. We can often observe the consequence of differential transcription due to the
presence or absence of particular proteins or the growth in particular environments. Control can
also occur at translation; the mRNA is synthesized, but only in certain circumstances is it
translated. Control can also occur at the level of protein function; the protein is inactive, or
activity is not observed due to the lack of the substrate. In this lab we will observe differential
expression of two different genes encoded on plasmids. We will analyze transcriptional activity,
translational activity, and protein function. Plasmids are extra-chromosomal DNA. Bacteria often
have plasmids and will replicate the plasmid and pass it to daughter cells (vertical transmission)
and to neighboring cells (horizontal). Plasmids are a mechanism of gene diversity. In order to
stably retain the plasmid, there needs to be some type of metabolic reason for the bacteria to
maintain the plasmid. In other words, the plasmid confers an advantage. Plasmids contain: 1. Ori:
the plasmid may present is low or high copy number. 2. Lab generated plasmids typically also
contain a selectable marker (antibiotic resistance), 3. Additional gene for ease of visual screening
4. Multiple cloning site
pUC19 is one of a series of plasmid cloning vectors created by Joachim Messing and co-workers.
The designation "pUC" is derived from the classical "p" prefix (denoting "plasmid") and the
abbreviation for the University of California, where early work on the plasmid series had been
conducted. It is a circular double stranded DNA and has 2686 base pairs. pUC19 is one of the
most widely used vector molecules as the recombinants, or the cells into which foreign DNA has
been introduced, can be easily distinguished from the non-recombinants based on color
differences of colonies on growth media. pUC18 is similar to pUC19, but the MCS region is
reversed. - pUC 19 has an origin of replication and is maintained at a high copy number. -
pUC19 encodes for an ampicillin resistance gene (amopR), via a -lactamase enzyme that
functions by degrading ampicillin and reducing its toxicity to the host. - It has an N-terminal
fragment of -galactosidase (lacZ) gene of E. coli which allows for visual screening of
recombinant.
The document summarizes post-transcriptional modifications of RNA in eukaryotes. It describes how the primary transcript (hnRNA) undergoes processing to form mature mRNA through the addition of a 5' cap and 3' poly-A tail and splicing of introns. The 5' cap and 3' poly-A tail protect the mRNA from degradation. Splicing involves removing introns and joining exons, facilitated by interactions with small nuclear ribonucleoproteins and other proteins to form the spliceosome complex. This results in mRNA containing only the coding exons that can then be translated into protein.
Hello everyone, I am Dr. Ujwalkumar Trivedi, Head of Biotechnology Department at Marwadi University Rajkot. I teach Molecular Biology to the students of M.Sc. Microbiology and Biotechnology.
The current presentation describes various co-transcriptional and post-transcriptional RNA modifications in eukaryotic cells. The following processes are described in detail:
1. 5' mRNA Capping
2. Splicing
3. Alternative Splicing
4. 3' Polyadenylation
5. RNA Editing
Enjoy Reading.
This document provides an overview of gene silencing. It begins with definitions of gene silencing and discusses how it differs from gene knockout. The document then covers the short history of gene silencing research from the 1990s onwards. It describes different methods of gene silencing including transcriptional gene silencing and post-transcriptional gene silencing. Specific gene silencing techniques like RNA interference are explained in more detail. The document also includes a case study on gene silencing in petunias and discusses applications of RNAi.
Gene:its nature expression and regulationroshanchristo
This document provides an overview of gene expression. It discusses that gene expression involves the process by which a gene's information is converted into the structures and functions of a cell through production of a protein or RNA molecule. It describes the eukaryotic cell structure, with genes containing exons and introns. The stages of protein synthesis - transcription, RNA processing, and translation - are explained. Key differences between prokaryotes and eukaryotes in these processes are highlighted.
Gene expression is the process by which information from a gene is used to produce a functional gene product like a protein or RNA. This process allows cells to control their structure and functions and gives rise to phenotypes. Gene expression can be measured by quantifying gene products like mRNA or proteins to understand processes like viral infection or drug resistance. It is regulated through mechanisms that control transcription, RNA processing, translation, and protein modifications.
Please describe in detaila. How to create and to use a transpo.pdf4babies2010
Please answer the discussion questions and TYPE you answers. MINICASE ARE YOU
REALLY BUYING AMERICAN? Consider the follawing scenario of a typical\" American fam
work, stopping for gas at the Shell station. At the grocery ily: The Osbornes, Jesse and Ann, live
in the suburbs of store, she fills her cart with a variety of items, including Chicago Jesse is a
manager at Trader Joe\'s specialty grocery Ragu spaghetti sauce, Hellmann\'s mayonnaise,
Carnation store chain. Ann is an edvertising executive for Leo Burnett Instant Breakfast drink, a
case of Arrowhead water, CoffeeMate nondairy coffee creamer, Chicken-of the-Sea Ann listens
to the new Adam Lambert CD on her Alpine car stereo in her Jeep Cherakes while driving homa
from canned tuna, Lipton tea, a hall-dozen cans of Slim-Fast. Dannon yogurt, and several
packages of Stouffer\'s Lean dinners and some Hot Packats. For a treat. Groupe Danone of
France produces Dannon yogurt she picks up some Ben & Jerry\'s ice cream, Toll House cook-
es, and a Butterfinger candy bar. She also grabs several cans af Alpo for thair dog, Sassy, and a
box of Friskies and a bag of Tidy Cat cat litter for their cat, Lily. She goes down the toilet- ries
aisle for some Dove soap, Q-tips cotton swabs, Vaseline Samsung smartphones are made by
South Korea\'s lip gloss, and Jergen\'s moisturizing lotion. Before fhng,Samsung- she calls Jesse
on her Samsung smartphone to see whetherBertelsmann AG of Germany owns 53 percent of
there is anything else he needs. Ho asks her to pick up some PowerBars for him to take to the
gym during his lunchtime the remaining 47 percent. workouts next week. She also stops at the
bookstore andSociete Bic of France produces Bic pens picks up the new John Grisham book
published by Random House, signing the credit card slip with her Bic pen. Chicken-of the Sea
tuna is made by Chicken of the Sea International, which is besed in Thailand. Japan\'s Kao owns
Jergen\'s. Penquin Random House, and Pearson plc of the UK owns ·Japan\'s Bridgestone
Corporation owns Firestone. BP of the United Kingdom owns BP gas stations. After leaving his
office, Jesse stops at the BP gas station to fili his gas tank and checks the air pressure in his
Firestone tires. He heads to the liquor store for a cese of Miller Genuine thSpiderman movies
Sony Pictures Tolovision distrib- Draft beer and a bottle of Wild Turkey bourbon. He walks next
door to the sporting goods store to pick up someSABMiller plc of the United Kingdom produces
Miller Columbia Pictures, owned by Sony of Japan, released utes Breaking Bad. Wilson
racquetballs for his workouts next week. boer, Ann\'s favorite TV show, Breaking Bad, is just
startinDavide Campari of Italy awns the Wild Turkay brand. comes in the door, so she pours
hersalf a glass af Amer Group of Finland owns Wilsan Sporting Goods. and turns on their Philips
high-. Baringer Winery of Napa, California, is owned by definition talevision while Jasse
prepares dinner loads the latest Spiderman inst.
This document summarizes pre-RNA trans-splicing as a gene therapy technique. It involves joining exons from two different primary RNA transcripts end to end through the spliceosome. This emerging technique can be used to repair mutated mRNA by providing an externally designed pre-trans-splicing molecule containing the corrected coding sequence. The technique has been studied for diseases like cystic fibrosis and hemophilia in animal models, showing significant repair. One application is for Duchenne muscular dystrophy, where trans-splicing could replace the mutated dystrophin exon. While still in pre-clinical research, pre-RNA trans-splicing offers targeted repair of mutated genes with potential advantages over other gene therapy approaches.
Introduction
History
Tumor suppressor gene- pRB
- RB gene
- Role of RB in regulation of cell cycle
- Tumor associated with RB gene mutation
Tumor suppressor gene- p53
- What is p53 gene?
- Function of p53 gene
- How it regulates cell cycle
- What happen if p53 gene inactivated
- Cancer associated with p53 mutation
- Conclusion
- References
Introduction
Definition
History
Two hit hypothesis
Functions
Mutation in tumor suppressor genes
What is mutation
Inherited mutation of TSGs
Acquired mutation of TSGs
What is Oncogenes?
TSGs and Oncogenes : Brakes and accelerators
Stop and go signal
Examples of TSGs:
RB-The retinoblastoma gene
P53 protein
TSGs &cell suicide
Conclusion
References
This document discusses tumor suppressor genes. It begins by defining a tumor suppressor gene as a gene that protects cells from cancer progression by normally functioning to inhibit cell division or promote cell death. It describes the "two-hit hypothesis" whereby both copies of a tumor suppressor gene must be mutated for full cancer development. Examples are given of important tumor suppressor genes like retinoblastoma protein (pRb) and p53, which are commonly mutated in many cancer types.
This document summarizes two important tumor suppressor genes - PRB and P53. It provides background on tumor suppressor genes, noting that they function through loss of function to regulate cell cycle and suppress uncontrolled cell proliferation. For PRB, it describes its role in retinoblastoma cancer and cell cycle regulation. For P53, it discusses its role as the "guardian of the genome" in DNA repair and apoptosis, as well as its structure and functions in halting the cell cycle when damage is detected.
Introduction
Protein synthesis
Synthesis of secretory proteins on membrane-bound ribosomes
Processing of newly synthesized proteins in the ER
Synthesis of integral membrane protein on membrane bound ribosomes
Maintenance of membrane asymmetry
Conclusion
Reference
Introduction
Definition
Factors required for Translation
Formation of aminoacyl t-RNA
1)Activation of amino acid
2) Transfer of amino acid to t-RNA
Translation involves following steps:-
1)Initiation
2)Elongation
3)Termination
Conclusion
Reference
Introduction
Definition
History
central dogma
Major components
mRNA,tRNA,rRNA
Energy source
Amino acids
Protien factor
Enzymes
Inorganic ions
Step involves in translation:
Aminoacylation of tRNA
Initiation
Elongation
termination
Importance of translation
Conclusion
Reference
Introduction
Protein modifications
Folding
Chaperon mediated
Enzymatic
Cleavage
Addition of functional groups
Chemical groups
Hydrophobic groups
Proteolysis
Conclusion
Reference
INTRODUCTION
HISTORY
WHAT IS TRANSCRIPTION
PROKARYOTIC TRANSCRIPTION
STEPS OF TRANSCRIPTION
HOW TRANSCRIPTION OCCURS
PROCESS OF TRANSCRIPTION
Initiation
Elongation
Termination
CONCLUSION
REFRENCES
Enzyme Kinetics and thermodynamic analysisKAUSHAL SAHU
Introduction
Kinetics and thermodynamicSG
Thermodynamic in enzymatic reactions
balanced equations in chemical reactions
changes in free energy determine the direction & equilibrium state of chemical reactions
the rates of reactions
Factors effecting enzymatic activity
(i) Enzyme concentration.
(ii) Substrate concentration.
(iii)Temperature
(iv) pH.
(v) Activators.
(vi)Inhibitors
Michaelis-menten equation
CONCLUSIONS
REFERENECES
Recepter mediated endocytosis by kk ashuKAUSHAL SAHU
INTRODUCTION
DEFINITION OF RECEPTOR MEDIATED ENDOCYTOSIS
WHAT TYPE OF LIGANDS ENTER BY RME?
FORMATION OF CLATHRIN-COATED VESICLES
TRISKELIONS
ROLE OF DYNAMIN IN THE FORMATION OF CLATHRIN-COATED VESICLES
ROLE OF PHOSPHOLIPIDS IN THE FORMATION OF COATED VESICLES
ENDOCYTIC PATHWAY
LDLs AND CHOLESTROL METABOLISM
CONCLUSION
REFERENCES
The delivery of newly synthesized protein to their proper cellular destination, usually referred to as protein targeting or sorting.
The mode of protein transport depends chiefly on the location in the cell cytoplasm of the polysomes involved in protein synthesis.
There are two modes of protein sorting:-
1) Co - translational Transportation.
2) Post - translational Transportation.
Prokaryotic translation machinery by kk KAUSHAL SAHU
Introduction
Definition
Factors required for Translation
Formation of aminoacyl t-RNA
1)Activation of amino acid
2) Transfer of amino acid to t-RNA
Translation involves following steps:-
1)Initiation
2)Elongation
3)Termination
Conclusion
Reference
Sexuality - Issues, Attitude and Behaviour - Applied Social Psychology - Psyc...PsychoTech Services
A proprietary approach developed by bringing together the best of learning theories from Psychology, design principles from the world of visualization, and pedagogical methods from over a decade of training experience, that enables you to: Learn better, faster!
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
Authoring a personal GPT for your research and practice: How we created the Q...Leonel Morgado
Thematic analysis in qualitative research is a time-consuming and systematic task, typically done using teams. Team members must ground their activities on common understandings of the major concepts underlying the thematic analysis, and define criteria for its development. However, conceptual misunderstandings, equivocations, and lack of adherence to criteria are challenges to the quality and speed of this process. Given the distributed and uncertain nature of this process, we wondered if the tasks in thematic analysis could be supported by readily available artificial intelligence chatbots. Our early efforts point to potential benefits: not just saving time in the coding process but better adherence to criteria and grounding, by increasing triangulation between humans and artificial intelligence. This tutorial will provide a description and demonstration of the process we followed, as two academic researchers, to develop a custom ChatGPT to assist with qualitative coding in the thematic data analysis process of immersive learning accounts in a survey of the academic literature: QUAL-E Immersive Learning Thematic Analysis Helper. In the hands-on time, participants will try out QUAL-E and develop their ideas for their own qualitative coding ChatGPT. Participants that have the paid ChatGPT Plus subscription can create a draft of their assistants. The organizers will provide course materials and slide deck that participants will be able to utilize to continue development of their custom GPT. The paid subscription to ChatGPT Plus is not required to participate in this workshop, just for trying out personal GPTs during it.
The binding of cosmological structures by massless topological defectsSérgio Sacani
Assuming spherical symmetry and weak field, it is shown that if one solves the Poisson equation or the Einstein field
equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
field capable of driving flat rotation (i.e. Keplerian circular orbits at a constant speed for all radii) of test masses on a thin
spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
concentrically a number of such topological defects can establish a flat stellar or galactic rotation curve, and can also deflect
light in the same manner as an equipotential (isothermal) sphere. Thus, the need for dark matter or modified gravity theory is
mitigated, at least in part.
The cost of acquiring information by natural selectionCarl Bergstrom
This is a short talk that I gave at the Banff International Research Station workshop on Modeling and Theory in Population Biology. The idea is to try to understand how the burden of natural selection relates to the amount of information that selection puts into the genome.
It's based on the first part of this research paper:
The cost of information acquisition by natural selection
Ryan Seamus McGee, Olivia Kosterlitz, Artem Kaznatcheev, Benjamin Kerr, Carl T. Bergstrom
bioRxiv 2022.07.02.498577; doi: https://doi.org/10.1101/2022.07.02.498577
Mending Clothing to Support Sustainable Fashion_CIMaR 2024.pdfSelcen Ozturkcan
Ozturkcan, S., Berndt, A., & Angelakis, A. (2024). Mending clothing to support sustainable fashion. Presented at the 31st Annual Conference by the Consortium for International Marketing Research (CIMaR), 10-13 Jun 2024, University of Gävle, Sweden.
Evidence of Jet Activity from the Secondary Black Hole in the OJ 287 Binary S...Sérgio Sacani
Wereport the study of a huge optical intraday flare on 2021 November 12 at 2 a.m. UT in the blazar OJ287. In the binary black hole model, it is associated with an impact of the secondary black hole on the accretion disk of the primary. Our multifrequency observing campaign was set up to search for such a signature of the impact based on a prediction made 8 yr earlier. The first I-band results of the flare have already been reported by Kishore et al. (2024). Here we combine these data with our monitoring in the R-band. There is a big change in the R–I spectral index by 1.0 ±0.1 between the normal background and the flare, suggesting a new component of radiation. The polarization variation during the rise of the flare suggests the same. The limits on the source size place it most reasonably in the jet of the secondary BH. We then ask why we have not seen this phenomenon before. We show that OJ287 was never before observed with sufficient sensitivity on the night when the flare should have happened according to the binary model. We also study the probability that this flare is just an oversized example of intraday variability using the Krakow data set of intense monitoring between 2015 and 2023. We find that the occurrence of a flare of this size and rapidity is unlikely. In machine-readable Tables 1 and 2, we give the full orbit-linked historical light curve of OJ287 as well as the dense monitoring sample of Krakow.
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...Sérgio Sacani
Context. The observation of several L-band emission sources in the S cluster has led to a rich discussion of their nature. However, a definitive answer to the classification of the dusty objects requires an explanation for the detection of compact Doppler-shifted Brγ emission. The ionized hydrogen in combination with the observation of mid-infrared L-band continuum emission suggests that most of these sources are embedded in a dusty envelope. These embedded sources are part of the S-cluster, and their relationship to the S-stars is still under debate. To date, the question of the origin of these two populations has been vague, although all explanations favor migration processes for the individual cluster members. Aims. This work revisits the S-cluster and its dusty members orbiting the supermassive black hole SgrA* on bound Keplerian orbits from a kinematic perspective. The aim is to explore the Keplerian parameters for patterns that might imply a nonrandom distribution of the sample. Additionally, various analytical aspects are considered to address the nature of the dusty sources. Methods. Based on the photometric analysis, we estimated the individual H−K and K−L colors for the source sample and compared the results to known cluster members. The classification revealed a noticeable contrast between the S-stars and the dusty sources. To fit the flux-density distribution, we utilized the radiative transfer code HYPERION and implemented a young stellar object Class I model. We obtained the position angle from the Keplerian fit results; additionally, we analyzed the distribution of the inclinations and the longitudes of the ascending node. Results. The colors of the dusty sources suggest a stellar nature consistent with the spectral energy distribution in the near and midinfrared domains. Furthermore, the evaporation timescales of dusty and gaseous clumps in the vicinity of SgrA* are much shorter ( 2yr) than the epochs covered by the observations (≈15yr). In addition to the strong evidence for the stellar classification of the D-sources, we also find a clear disk-like pattern following the arrangements of S-stars proposed in the literature. Furthermore, we find a global intrinsic inclination for all dusty sources of 60 ± 20◦, implying a common formation process. Conclusions. The pattern of the dusty sources manifested in the distribution of the position angles, inclinations, and longitudes of the ascending node strongly suggests two different scenarios: the main-sequence stars and the dusty stellar S-cluster sources share a common formation history or migrated with a similar formation channel in the vicinity of SgrA*. Alternatively, the gravitational influence of SgrA* in combination with a massive perturber, such as a putative intermediate mass black hole in the IRS 13 cluster, forces the dusty objects and S-stars to follow a particular orbital arrangement. Key words. stars: black holes– stars: formation– Galaxy: center– galaxies: star formation
Candidate young stellar objects in the S-cluster: Kinematic analysis of a sub...
Alternative splicing by kk sahu
1. Pacific Networks Pacific NetworksAlternative Splicing
ALTERNATIVE SPLICING
By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )
2. Pacific Networks Pacific Networks
Synopsis
Alternative Splicing
Introduction
What RNA Splicing???
Discovery
Types
Alternative Splicing
Mechanism
Regulatory element And protein
Splicing repression
Splicing activation
Significance
Diseases
Conclusion
Refrences
3. Pacific Networks Pacific Networks
Introduction-
Alternative Splicing
Alternative splicing (or differential splicing) is a
process by which the exons of the RNA produced by
transcription of a gene a primary gene transcript or
pre-mRNA are reconnected in multiple ways during
RNA splicing.
The resulting different mRNAs may be translated into
different protein isoforms; thus, a single gene may
code for multiple proteins.
5. Pacific Networks Pacific NetworksAlternative Splicing
Genetic information is transferred from genes to the proteins
they encode via a “messenger” RNA intermediate
DNA GENE
messenger RNA
(mRNA)
protein
transcription
translation
6. Pacific Networks Pacific NetworksAlternative Splicing
Most genes have their protein-coding information
interrupted by non-coding sequences called “introns”.
The coding sequences are then called “exons”
DNA GE NE
intron
exon 1 exon 2
transcription
precursor-mRNA
(pre-mRNA)
intron
7. Pacific Networks Pacific NetworksAlternative Splicing
The intron is also present in the RNA copy of
the gene and must be removed by a process
called “RNA splicing”
protein
translation
mRNA
RNA splicing
pre-mRNA
intron
8. Pacific Networks Pacific NetworksAlternative Splicing
Discovery
Alternative splicing was first observed in 1977. Adenoviruses
produce two different primary transcripts, one early in the life
cycle and one later, after DNA replication. Researchers found
that the primary RNA transcript produced by adenovirus type 2
in the late phase was spliced in different ways, resulting in
mRNAs encoding different viral proteins.
In 1981, the first example of alternative splicing in a
transcript from a normal, endogenous gene was characterized.
The gene encoding the thyroid hormone calcitonin was
found to be alternatively spliced in mammalian cells. Examples
of alternative splicing in immunoglobin gene transcripts in
mammals were also observed in the early 1980s.
Since then, alternative splicing has been found to be
ubiquitous in eukaryotes.
10. Pacific Networks Pacific NetworksAlternative splicing
Alternative Splicing
5’ UTR 3’ UTRCoding Sequence
mRNA 1 mRNA 2
Isoform 1 Isoform 2
Transcription
Translation
Folding
AS region
11. Pacific Networks Pacific NetworksAlternative Splicing
Alternative splicing
mechanisms
General splicing mechanism•When the pre-mRNA has been transcribed from the DNA.The
exons to be retained in the mRNA are determined during the
splicing process. The regulation and selection of splice sites are
done by trans-acting splicing activator and splicing repressor
proteins.
•The typical eukaryotic nuclear intron has consensus sequences
defining important regions. Each intron has GU at its 5' end. Near
the 3' end there is a branch site. The nucleotide at the branch
point is always an A; the consensus around this sequence varies
somewhat.
•The branch site is followed by a series of pyrimidines, or
polypyrimidine tract, then by AG at 3' end.
•Splicing of mRNA is performed by an RNA and protein complex
known as the spliceosome, containing snRNPs designated U1, U2,
U4, U5, and.
•U1 binds to 5' GU and U2 binds to branch site (A) with the
assistance of the U2AF protein factors. The complex at this stage
is known as the spliceosome A complex. Formation of the A
complex is usually the key step in determining the ends of the
intron to be spliced out, and defining the ends of the exon to be
retained.
12. Pacific Networks Pacific NetworksAlternative Splicing
Regulatory elements and proteins
Splicing repression
15. Pacific Networks Pacific NetworksAlternative Splicing
Alternative acceptor sites:
Drosophila Transformer
•Pre-mRNAs of the Transformer (Tra) gene of
Drosophila melanogaster undergo alternative
splicing via the alternative acceptor site mode.
•The gene Tra encodes a protein that is
expressed only in females. The primary transcript
of this gene contains an intron with two possible
acceptor sites. In males, the upstream acceptor
site is used.
•This causes a longer version of exon 2 to be
included in the processed transcript, including an
early stop codon. The resulting mRNA encodes a
truncated protein product that is inactive.
Females produce the master sex determination
protein Sex lethal (Sxl).
16. Pacific Networks Pacific NetworksAlternative Splicing
Exon definition: Fas recepto
Alternative splicing of the Fas receptor pre-mRNAMultiple
isoforms of the Fas receptor protein are produced by alternative
splicing.
An mRNA including exon 6 encodes the membrane-bound form
of the Fas receptor, which promotes apoptosis, or programmed
cell death. Increased expression of Fas receptor in skin cells
chronically exposed to the sun, and absence of expression in
skin cancer cells, suggests that this mechanism may be
important in elimination of pre-cancerous cells in humans.
If exon 6 is skipped, the resulting mRNA encodes a soluble Fas
protein that does not promote apoptosis. The inclusion or
skipping of the exon depends on two antagonistic proteins, TIA-
1 and polypyrimidine tract-binding protein (PTB).
•Binding of TIA-1 protein to an intronic splicing enhancer site
stabilizes binding of the U1 snRNP. The resulting 5' donor site
complex assists in binding of the splicing factor U2AF to the 3'
splice site upstream of the exon, through a mechanism that is
not yet known Exon 6 contains a pyrimidine-rich exonic splicing
silencer, ure6, where PTB can bind. If PTB binds, it inhibits the
effect of the 5' donor complex on the binding of U2AF to the
acceptor site, resulting in exon skipping .
18. Pacific Networks Pacific NetworksAlternative Splicing
Significance
•Alternative splicing is one of several exceptions to the original idea that one DNA
sequence codes for one polypeptide .
• It might be more correct now to say "One gene – many polypeptides.” External
information is needed in order to decide which polypeptide is produced, given a DNA
sequence and pre-mRNA..
• It has been proposed that for eukaryotes alternative splicing was a very important step
towards higher efficiency, because information can be stored much more economically.
•It also provides evolutionary flexibility.
•A single point mutation may cause a given exon to be occasionally excluded or included
from a transcript during splicing, allowing production of a new protein isoform without
loss of the original protein
• Research based on the Human Genome Project and other genome sequencing has
shown that humans have only about 30% more genes than the roundworm
Caenorhabditis elegans, and only about twice as many as the fly Drosophila melanogaster.
•This finding led to speculation that the perceived greater complexity of humans, or
vertebrates generally, might be due to higher rates of alternative splicing in humans than
are found in invertebrates.
•However, a study on samples of 100,000 ESTs each from human, mouse, rat, cow, fly (D.
melanogaster), worm (C. elegans), and the plant Arabidopsis thaliana found no large
differences in frequency of alternatively spliced genes among humans and any of the
other animals tested.
19. Pacific Networks Pacific NetworksAlternative Splicing
Alternative splicing and disease
Changes in the RNA processing machinery may lead to mis-splicing of multiple
transcripts, while single-nucleotide alterations in splice sites or cis-acting splicing
regulatory sites may lead to differences in splicing of a single gene, and thus in the
mRNA produced from a mutant gene's transcripts. A probabilistic analysis indicates that
over 60% of human disease-causing mutations affect splicing rather than directly
affecting coding sequences.
Abnormally spliced mRNAs are also found in a high proportion of cancerous cells. Until
recently, it was unclear whether such aberrant patterns of splicing played a role in
causing cancerous growth, or were merely a consequence of cellular abnormalities
associated with cancer.
It has been shown that there is actually a reduction of alternative splicing in
cancerous cells compared to normal ones, and the types of splicing differ; for instance,
cancerous cells show higher levels of intron retention than normal cells, but lower levels
of exon skipping. Some of the differences in splicing in cancerous cells may result from
changes in phosphorylation of trans-acting splicing factors.
One study found that a relatively small percentage of alternative splicing variants were
significantly higher in frequency in tumor cells than normal cells, suggesting that there
is a limited set of genes which, when mis-spliced, contribute to tumor development
One example of a specific splicing variant associated with cancers is in one of the
human DNMT genes. Recent provocative studies point to a key function of chromatin
structure and histone modifications in alternative splicing regulation
21. Pacific Networks Pacific NetworksAlternative Splicing
References
Cell and molecular biology by Gerald Karp
Molecular biology of the gene by J.d. Watson
Gene VIII by Benjamine Lewine
Internet source
www.alternativesplicingwiki.com
www.sparknotes.com
www.googleimages.com