This document discusses RNA transcription and processing in eukaryotes. It describes how RNA polymerase II binds transcription factors at promoter regions to initiate transcription. The primary transcript undergoes 5' capping, 3' polyadenylation, and RNA splicing in the nucleus. 5' capping involves adding a 7-methylguanosine cap. Polyadenylation cleaves the pre-mRNA and adds a poly-A tail. Splicing removes introns and joins exons using a spliceosome complex containing small nuclear RNAs and proteins. The fully processed mRNA is then exported from the nucleus for translation.
RNA polymerase is an enzyme that produces RNA in cells. It was discovered in 1960 and is essential for all organisms. In prokaryotes, a single RNA polymerase synthesizes different RNA types, while eukaryotic RNA polymerase is a multi-subunit enzyme. RNA polymerase I synthesizes rRNA for ribosomes, polymerase II synthesizes pre-mRNA and most snRNA/miRNA, and polymerase III synthesizes tRNA and other small RNAs. The transcription process involves initiation, elongation, and termination stages.
Scientists have recently explored the amazing discovery that many cells produce thousands of much smaller RNA molecules, micro RNAs. Instance, more than 500 different micro RNAs have been found in human cells alone.
Micro RNA plays an important role in post-transcriptional gene regulation, such as RISC, and can cause interference and shut down gene activity.
Micro RNA is a form of ribonucleic acid and does not contain genetic information.
Protein synthesis involves three main steps - initiation, elongation, and termination. Initiation requires various factors to recruit the small ribosomal subunit to mRNA and load it with initiator tRNA. Elongation repeatedly adds amino acids to the growing polypeptide chain through tRNA selection and peptide bond formation. Termination occurs when a stop codon is reached in the mRNA, signaling the release of the complete polypeptide chain catalyzed by release factors. The ribosome is a complex macromolecule composed of RNA and proteins that serves as the site of protein synthesis, with three key sites that facilitate the process through molecular recognition and catalytic functions.
regulation of gene expression in eukaryotes is a complex mechanism involved many factors. out of many levels of regulations, chromosomal and transcription level of regulation are discussed in this slides.
Anjali Krishnan from the Department of Botany discusses polyadenylation. Polyadenylation is the addition of a poly(A) tail to messenger RNA. This is part of processing eukaryotic mRNA before translation. The poly(A) tail is important for nuclear export, translation, and stability of mRNA. It is also involved in degrading mRNA when shortened to a certain length. While polyadenylation degrades prokaryotic RNA, it can also store eukaryotic mRNA for later activation.
RNA is synthesized from DNA in a process called transcription. There are both similarities and differences between prokaryotic and eukaryotic transcription. In prokaryotes, transcription occurs in the cytoplasm, is carried out by a single type of RNA polymerase, and mRNA is transcribed directly from DNA. In eukaryotes, transcription occurs in the nucleus, utilizes three types of RNA polymerases, and produces hnRNA which is processed into mRNA. The key stages of transcription, initiation, elongation, and termination, occur through different mechanisms in prokaryotes and eukaryotes.
transcription activators, repressors, & control RNA splicing, procesing and e...ranjithahb ranjithahbhb
RNA processing involves several steps to convert primary transcripts into mature mRNA in eukaryotic cells. These include 5' capping, 3' cleavage and polyadenylation, and RNA splicing. RNA splicing involves two transesterification reactions that remove introns and join exons. Alternative splicing allows a single gene to produce multiple protein variants. Eukaryotic gene expression is regulated by transcriptional activators and repressors that bind cis-regulatory elements like promoters and enhancers. Activators recruit transcriptional machinery while repressors inhibit transcription. Chromatin structure also influences transcription with acetylation associated with active genes.
The document summarizes the process of DNA replication in prokaryotic cells like E. coli. It describes the three main stages: initiation at the Ori C origin site involving DnaA and DnaB proteins, elongation where the leading strand is synthesized continuously and the lagging strand requires RNA primers, and termination when the replication forks meet specific termination sites and DnaB is released. DNA replication allows faithful copying of the parental DNA to produce two identical progeny DNA molecules.
RNA polymerase is an enzyme that produces RNA in cells. It was discovered in 1960 and is essential for all organisms. In prokaryotes, a single RNA polymerase synthesizes different RNA types, while eukaryotic RNA polymerase is a multi-subunit enzyme. RNA polymerase I synthesizes rRNA for ribosomes, polymerase II synthesizes pre-mRNA and most snRNA/miRNA, and polymerase III synthesizes tRNA and other small RNAs. The transcription process involves initiation, elongation, and termination stages.
Scientists have recently explored the amazing discovery that many cells produce thousands of much smaller RNA molecules, micro RNAs. Instance, more than 500 different micro RNAs have been found in human cells alone.
Micro RNA plays an important role in post-transcriptional gene regulation, such as RISC, and can cause interference and shut down gene activity.
Micro RNA is a form of ribonucleic acid and does not contain genetic information.
Protein synthesis involves three main steps - initiation, elongation, and termination. Initiation requires various factors to recruit the small ribosomal subunit to mRNA and load it with initiator tRNA. Elongation repeatedly adds amino acids to the growing polypeptide chain through tRNA selection and peptide bond formation. Termination occurs when a stop codon is reached in the mRNA, signaling the release of the complete polypeptide chain catalyzed by release factors. The ribosome is a complex macromolecule composed of RNA and proteins that serves as the site of protein synthesis, with three key sites that facilitate the process through molecular recognition and catalytic functions.
regulation of gene expression in eukaryotes is a complex mechanism involved many factors. out of many levels of regulations, chromosomal and transcription level of regulation are discussed in this slides.
Anjali Krishnan from the Department of Botany discusses polyadenylation. Polyadenylation is the addition of a poly(A) tail to messenger RNA. This is part of processing eukaryotic mRNA before translation. The poly(A) tail is important for nuclear export, translation, and stability of mRNA. It is also involved in degrading mRNA when shortened to a certain length. While polyadenylation degrades prokaryotic RNA, it can also store eukaryotic mRNA for later activation.
RNA is synthesized from DNA in a process called transcription. There are both similarities and differences between prokaryotic and eukaryotic transcription. In prokaryotes, transcription occurs in the cytoplasm, is carried out by a single type of RNA polymerase, and mRNA is transcribed directly from DNA. In eukaryotes, transcription occurs in the nucleus, utilizes three types of RNA polymerases, and produces hnRNA which is processed into mRNA. The key stages of transcription, initiation, elongation, and termination, occur through different mechanisms in prokaryotes and eukaryotes.
transcription activators, repressors, & control RNA splicing, procesing and e...ranjithahb ranjithahbhb
RNA processing involves several steps to convert primary transcripts into mature mRNA in eukaryotic cells. These include 5' capping, 3' cleavage and polyadenylation, and RNA splicing. RNA splicing involves two transesterification reactions that remove introns and join exons. Alternative splicing allows a single gene to produce multiple protein variants. Eukaryotic gene expression is regulated by transcriptional activators and repressors that bind cis-regulatory elements like promoters and enhancers. Activators recruit transcriptional machinery while repressors inhibit transcription. Chromatin structure also influences transcription with acetylation associated with active genes.
The document summarizes the process of DNA replication in prokaryotic cells like E. coli. It describes the three main stages: initiation at the Ori C origin site involving DnaA and DnaB proteins, elongation where the leading strand is synthesized continuously and the lagging strand requires RNA primers, and termination when the replication forks meet specific termination sites and DnaB is released. DNA replication allows faithful copying of the parental DNA to produce two identical progeny DNA molecules.
DNA Replication In Eukaryotes (Bsc.Zoology)DebaPrakash2
This Slide Is explanation of Mechanism of DNA Replication In Eukaryotes.
As we know we all have DNA as the genetic material and So we should know how this DNA getting Duplicated so that it'll pass to daughter cells.
This document discusses gene regulation in prokaryotes. It begins by introducing the concept of gene regulation and how only a fraction of genes are expressed at any given time. It then discusses several key examples of gene regulation in prokaryotes, including the lac, trp, and arabinose operons. The lac operon regulates lactose metabolism in E. coli in response to glucose and lactose availability. The trp operon regulates tryptophan synthesis using both repression and attenuation. The arabinose operon regulates arabinose metabolism using both positive and negative regulation by the AraC protein. The document also briefly discusses the SOS response, stringent response, and gene regulation in bacteriophage lambda.
PROKARYOTIC DNA REPLICATION PRESENTATIONTahmina Anam
Prokaryotic DNA replication occurs through a semiconservative process involving three main steps: initiation, elongation, and termination. Initiation begins with unwinding of the DNA at the origin of replication by helicase. Elongation then takes place as DNA polymerase adds nucleotides to form new strands, with leading strand synthesis occurring continuously and lagging strand in fragments. Termination occurs when the replication forks from opposite directions meet and are halted by tus-ter complexes, separating the duplicated chromosomes.
RNA polymerases are enzymes that transcribe DNA into RNA. In prokaryotes, a single RNA polymerase synthesizes RNA, while eukaryotes contain three RNA polymerases that synthesize different RNA molecules. RNA polymerases are large complex protein machines made of multiple subunits that work together to unwind DNA, add nucleotides, and proofread the newly synthesized RNA. The transcription process involves initiation, elongation, and termination stages that are regulated by various transcription factors.
This document discusses gene silencing, which is the suppression or interruption of gene expression at the transcriptional or translational level. It regulates gene expression and prevents certain genes from being expressed. There are several types of gene silencing, including transcriptional silencing through genomic imprinting, paramutation, and transposon silencing. Post-transcriptional gene silencing occurs through RNA interference pathways using small interfering RNA, microRNA, Dicer, and RISC complex. Research methods for gene silencing include antisense oligonucleotides, ribozymes, siRNA, and microRNA. Gene silencing has applications in biotechnology and medicine, with advantages such as being cost effective and having high specificity, though it also has disadvantages like potential toxicity.
The document summarizes the ara operon, which regulates genes involved in the metabolism of arabinose sugar. It consists of 3 key components: structural genes that encode enzymes for arabinose catabolism, an operator site that binds a repressor protein, and a promoter that enables transcription. Specifically, the ara operon contains 3 structural genes - araB, araA, araD - that code for enzymes converting arabinose into an intermediate. It is regulated by the araC gene product, which can act as both a repressor and activator depending on arabinose and glucose levels. When arabinose is low and glucose high, the araC repressor binds the operator sites, forming a DNA loop that
Eukaryotic translation is the process by which messenger RNA is translated into proteins. It involves three main phases: initiation, elongation, and termination. Initiation requires several eukaryotic initiation factors to form a pre-initiation complex and recruit the small ribosomal subunit to the 5' end of mRNA. Elongation then adds amino acids to the growing polypeptide chain via three elongation factors. Termination occurs when release factors recognize a stop codon and allow dissociation of the ribosome and release of the completed protein. The process is more complex in eukaryotes compared to prokaryotes due to the larger ribosome size and additional initiation factors required.
Translation is the process by which the genetic code in mRNA is used to direct the synthesis of proteins. It involves three main steps - initiation, elongation, and termination. Initiation requires the small and large ribosomal subunits to assemble around an mRNA molecule along with initiator tRNA and other initiation factors. Elongation then adds amino acids one by one to the growing polypeptide chain according to the mRNA codons. Termination occurs when a stop codon is reached, causing the ribosome to dissociate and release the complete protein.
DNA and RNA Structure
Central Dogma of Life
Protein Engineering (Brief)
Introduction to microRNA (miRNA)
History of miRNA
Biogenesis of miRNA
Conservation of miRNA
Impact of miRNA
miRNA Therapy
Conclusion
The document summarizes the process of translation (protein synthesis) from messenger RNA to protein. It describes how mRNA travels from the nucleus to the ribosome in the cytoplasm. The ribosome reads the mRNA codons and uses transfer RNA to add amino acids in the proper sequence specified by the mRNA to produce a protein. Key aspects covered include the genetic code, structure and role of transfer RNA and ribosomes, and the three main stages of translation - initiation, elongation, and termination.
Split genes contain both coding (exon) and non-coding (intron) regions. During mRNA splicing, introns are removed from pre-mRNA and exons are joined together to form mature mRNA. This process is catalyzed by the spliceosome, a complex of five small nuclear RNAs and numerous proteins. The spliceosome facilitates two transesterification reactions which remove the intron and ligate the exons, allowing gene sequences to code for multiple proteins through alternative splicing. Splicing increases gene and protein diversity in the cell.
Bacteria regulate gene expression through operons, which are groups of functionally related genes that are controlled together. Operons can be regulated positively or negatively in response to environmental conditions. The lac operon in E. coli controls the transport and metabolism of lactose and consists of structural genes regulated by a promoter, terminator, and repressor. The lac operon is negatively regulated - the lac repressor normally binds the operator to prevent transcription, but is released when bound by the inducer allolactose, allowing expression. Transcription is also controlled by the availability of glucose and regulated by the catabolite activator protein CAP.
All eukaryotes have at least three different RNA polymerase (Pol I, II,and III; and plants have a Pol IV & a Pol V). In addition, whereas bacteria require only one additional initiation factor (σ), several initiation factors are required for efficient and promoter-specific initiation in eukaryotes. These are called the general transcription factors (GTFs)
Translation in prokaryotes and eukaryotesANUSHIKA2
In this Assignment (Translation) following topics are :
Introduction
Component of Translation
Translation in prokaryotes and eukaryotes
Regulation of translation
Post-translational modification
References
Gene expression is the process by which DNA directs the production of proteins. It involves two main stages: transcription and translation. In transcription, the DNA sequence of a gene is transcribed into mRNA with the help of RNA polymerase. In eukaryotes, the pre-mRNA undergoes processing including 5' capping, splicing, and 3' polyadenylation to produce mature mRNA. Translation then uses the mRNA to produce a polypeptide with the help of ribosomes and tRNA. It involves initiation, elongation through the sequential addition of amino acids, and termination when a stop codon is reached.
This pdf encodes a variety of information regarding Molecular biology and its basic concepts like Translation and Protein synthesis. Various factorial details are provided by proper diagrams. This will help students of B.Sc. especially.
Transcription in eukariotes by kk sahuKAUSHAL SAHU
INTRODUCTION
A STRUCTURAL GENE
EUKARYOTIC RNAPs
MACHANISM OF TRANSCRIPTION IN EUKARYOTES:
- INITIATION
-ELONGATION
-TERMINATION
RNA SPLISING
DIFFERENT BETWEEN PROKARYOTIC & EUKARYOTIC TRANSCRIPTION
BIBLIOGRAPHY
RNA Polymerase
Introduction
Purification
History
PRODUCTS OF RNAP
Messenger RNA
Non-coding RNA or "RNA genes
Transfer RNA
Ribosomal RNA
Micro RNA
Catalytic RNA (Ribozyme)
prokaryotic and eukaryotic
Transcription by RNA Polymerase
TYPES OF RNA POLYMERASE
Type I
Type II
Type III
Prokaryotic Transcription Unit
EXPRESSION OF A PROKARYOTIC GENE
Prokaryotic Polycistronic Message Codes for Several Different Proteins
Eukaryotic Transcription Unit
ENHANCERS AND SILENCERS
RESULT OF THE TRANSCRIPTION CYCLE
RNAP III TRANSCRIBES HUMAN MICRORNAS
RNAP I–specific subunits promotepolymerase clustering to enhance the rRNA genetranscription cycle
RNAP II–TFIIB STRUCTURE ANDMECHANISM OF TRANSCRIPTION INITIATION
FIVE CHECKPOINTS MAINTAINING THE FIDELITY OFTRANSCRIPTION BY RNAP IN STRUCTURAL ANDENERGETIC DETAILS
Gene expression in eukaryotes is controlled at multiple levels, including chromatin structure, transcription, RNA processing, and translation. Chromatin structure determines if genes are transcriptionally active or inactive. Transcription is regulated by the interaction of promoters, transcription factors, and enhancers. RNA processing controls splicing and transport of mRNA. Finally, translation and post-translational modifications further regulate gene expression. Overall, eukaryotic gene expression is tightly controlled through complex mechanisms at the chromatin, transcription, RNA, translation, and protein levels.
This document summarizes eukaryotic transcription by RNA polymerases. It discusses the three types of RNA polymerases (I, II, and III) found in eukaryotic cells, what genes each polymerase transcribes, and the basic stages and mechanisms of transcription (initiation, elongation, termination). It also describes the promoters, processing, and other regulatory elements involved in eukaryotic transcription.
RNA synthesis, processing and modification.pptxArifulkarim4
The presentation discusses RNA synthesis, processing, and modification, explaining that RNA is synthesized from DNA through transcription by RNA polymerase. It describes the post-transcriptional modification of primary transcripts, including splicing of introns from mRNA, addition of a 5' cap and 3' poly-A tail, and modification of tRNA. The presentation also covers regulatory sequences that control transcription and the role of reverse transcription in retroviruses like HIV.
DNA Replication In Eukaryotes (Bsc.Zoology)DebaPrakash2
This Slide Is explanation of Mechanism of DNA Replication In Eukaryotes.
As we know we all have DNA as the genetic material and So we should know how this DNA getting Duplicated so that it'll pass to daughter cells.
This document discusses gene regulation in prokaryotes. It begins by introducing the concept of gene regulation and how only a fraction of genes are expressed at any given time. It then discusses several key examples of gene regulation in prokaryotes, including the lac, trp, and arabinose operons. The lac operon regulates lactose metabolism in E. coli in response to glucose and lactose availability. The trp operon regulates tryptophan synthesis using both repression and attenuation. The arabinose operon regulates arabinose metabolism using both positive and negative regulation by the AraC protein. The document also briefly discusses the SOS response, stringent response, and gene regulation in bacteriophage lambda.
PROKARYOTIC DNA REPLICATION PRESENTATIONTahmina Anam
Prokaryotic DNA replication occurs through a semiconservative process involving three main steps: initiation, elongation, and termination. Initiation begins with unwinding of the DNA at the origin of replication by helicase. Elongation then takes place as DNA polymerase adds nucleotides to form new strands, with leading strand synthesis occurring continuously and lagging strand in fragments. Termination occurs when the replication forks from opposite directions meet and are halted by tus-ter complexes, separating the duplicated chromosomes.
RNA polymerases are enzymes that transcribe DNA into RNA. In prokaryotes, a single RNA polymerase synthesizes RNA, while eukaryotes contain three RNA polymerases that synthesize different RNA molecules. RNA polymerases are large complex protein machines made of multiple subunits that work together to unwind DNA, add nucleotides, and proofread the newly synthesized RNA. The transcription process involves initiation, elongation, and termination stages that are regulated by various transcription factors.
This document discusses gene silencing, which is the suppression or interruption of gene expression at the transcriptional or translational level. It regulates gene expression and prevents certain genes from being expressed. There are several types of gene silencing, including transcriptional silencing through genomic imprinting, paramutation, and transposon silencing. Post-transcriptional gene silencing occurs through RNA interference pathways using small interfering RNA, microRNA, Dicer, and RISC complex. Research methods for gene silencing include antisense oligonucleotides, ribozymes, siRNA, and microRNA. Gene silencing has applications in biotechnology and medicine, with advantages such as being cost effective and having high specificity, though it also has disadvantages like potential toxicity.
The document summarizes the ara operon, which regulates genes involved in the metabolism of arabinose sugar. It consists of 3 key components: structural genes that encode enzymes for arabinose catabolism, an operator site that binds a repressor protein, and a promoter that enables transcription. Specifically, the ara operon contains 3 structural genes - araB, araA, araD - that code for enzymes converting arabinose into an intermediate. It is regulated by the araC gene product, which can act as both a repressor and activator depending on arabinose and glucose levels. When arabinose is low and glucose high, the araC repressor binds the operator sites, forming a DNA loop that
Eukaryotic translation is the process by which messenger RNA is translated into proteins. It involves three main phases: initiation, elongation, and termination. Initiation requires several eukaryotic initiation factors to form a pre-initiation complex and recruit the small ribosomal subunit to the 5' end of mRNA. Elongation then adds amino acids to the growing polypeptide chain via three elongation factors. Termination occurs when release factors recognize a stop codon and allow dissociation of the ribosome and release of the completed protein. The process is more complex in eukaryotes compared to prokaryotes due to the larger ribosome size and additional initiation factors required.
Translation is the process by which the genetic code in mRNA is used to direct the synthesis of proteins. It involves three main steps - initiation, elongation, and termination. Initiation requires the small and large ribosomal subunits to assemble around an mRNA molecule along with initiator tRNA and other initiation factors. Elongation then adds amino acids one by one to the growing polypeptide chain according to the mRNA codons. Termination occurs when a stop codon is reached, causing the ribosome to dissociate and release the complete protein.
DNA and RNA Structure
Central Dogma of Life
Protein Engineering (Brief)
Introduction to microRNA (miRNA)
History of miRNA
Biogenesis of miRNA
Conservation of miRNA
Impact of miRNA
miRNA Therapy
Conclusion
The document summarizes the process of translation (protein synthesis) from messenger RNA to protein. It describes how mRNA travels from the nucleus to the ribosome in the cytoplasm. The ribosome reads the mRNA codons and uses transfer RNA to add amino acids in the proper sequence specified by the mRNA to produce a protein. Key aspects covered include the genetic code, structure and role of transfer RNA and ribosomes, and the three main stages of translation - initiation, elongation, and termination.
Split genes contain both coding (exon) and non-coding (intron) regions. During mRNA splicing, introns are removed from pre-mRNA and exons are joined together to form mature mRNA. This process is catalyzed by the spliceosome, a complex of five small nuclear RNAs and numerous proteins. The spliceosome facilitates two transesterification reactions which remove the intron and ligate the exons, allowing gene sequences to code for multiple proteins through alternative splicing. Splicing increases gene and protein diversity in the cell.
Bacteria regulate gene expression through operons, which are groups of functionally related genes that are controlled together. Operons can be regulated positively or negatively in response to environmental conditions. The lac operon in E. coli controls the transport and metabolism of lactose and consists of structural genes regulated by a promoter, terminator, and repressor. The lac operon is negatively regulated - the lac repressor normally binds the operator to prevent transcription, but is released when bound by the inducer allolactose, allowing expression. Transcription is also controlled by the availability of glucose and regulated by the catabolite activator protein CAP.
All eukaryotes have at least three different RNA polymerase (Pol I, II,and III; and plants have a Pol IV & a Pol V). In addition, whereas bacteria require only one additional initiation factor (σ), several initiation factors are required for efficient and promoter-specific initiation in eukaryotes. These are called the general transcription factors (GTFs)
Translation in prokaryotes and eukaryotesANUSHIKA2
In this Assignment (Translation) following topics are :
Introduction
Component of Translation
Translation in prokaryotes and eukaryotes
Regulation of translation
Post-translational modification
References
Gene expression is the process by which DNA directs the production of proteins. It involves two main stages: transcription and translation. In transcription, the DNA sequence of a gene is transcribed into mRNA with the help of RNA polymerase. In eukaryotes, the pre-mRNA undergoes processing including 5' capping, splicing, and 3' polyadenylation to produce mature mRNA. Translation then uses the mRNA to produce a polypeptide with the help of ribosomes and tRNA. It involves initiation, elongation through the sequential addition of amino acids, and termination when a stop codon is reached.
This pdf encodes a variety of information regarding Molecular biology and its basic concepts like Translation and Protein synthesis. Various factorial details are provided by proper diagrams. This will help students of B.Sc. especially.
Transcription in eukariotes by kk sahuKAUSHAL SAHU
INTRODUCTION
A STRUCTURAL GENE
EUKARYOTIC RNAPs
MACHANISM OF TRANSCRIPTION IN EUKARYOTES:
- INITIATION
-ELONGATION
-TERMINATION
RNA SPLISING
DIFFERENT BETWEEN PROKARYOTIC & EUKARYOTIC TRANSCRIPTION
BIBLIOGRAPHY
RNA Polymerase
Introduction
Purification
History
PRODUCTS OF RNAP
Messenger RNA
Non-coding RNA or "RNA genes
Transfer RNA
Ribosomal RNA
Micro RNA
Catalytic RNA (Ribozyme)
prokaryotic and eukaryotic
Transcription by RNA Polymerase
TYPES OF RNA POLYMERASE
Type I
Type II
Type III
Prokaryotic Transcription Unit
EXPRESSION OF A PROKARYOTIC GENE
Prokaryotic Polycistronic Message Codes for Several Different Proteins
Eukaryotic Transcription Unit
ENHANCERS AND SILENCERS
RESULT OF THE TRANSCRIPTION CYCLE
RNAP III TRANSCRIBES HUMAN MICRORNAS
RNAP I–specific subunits promotepolymerase clustering to enhance the rRNA genetranscription cycle
RNAP II–TFIIB STRUCTURE ANDMECHANISM OF TRANSCRIPTION INITIATION
FIVE CHECKPOINTS MAINTAINING THE FIDELITY OFTRANSCRIPTION BY RNAP IN STRUCTURAL ANDENERGETIC DETAILS
Gene expression in eukaryotes is controlled at multiple levels, including chromatin structure, transcription, RNA processing, and translation. Chromatin structure determines if genes are transcriptionally active or inactive. Transcription is regulated by the interaction of promoters, transcription factors, and enhancers. RNA processing controls splicing and transport of mRNA. Finally, translation and post-translational modifications further regulate gene expression. Overall, eukaryotic gene expression is tightly controlled through complex mechanisms at the chromatin, transcription, RNA, translation, and protein levels.
This document summarizes eukaryotic transcription by RNA polymerases. It discusses the three types of RNA polymerases (I, II, and III) found in eukaryotic cells, what genes each polymerase transcribes, and the basic stages and mechanisms of transcription (initiation, elongation, termination). It also describes the promoters, processing, and other regulatory elements involved in eukaryotic transcription.
RNA synthesis, processing and modification.pptxArifulkarim4
The presentation discusses RNA synthesis, processing, and modification, explaining that RNA is synthesized from DNA through transcription by RNA polymerase. It describes the post-transcriptional modification of primary transcripts, including splicing of introns from mRNA, addition of a 5' cap and 3' poly-A tail, and modification of tRNA. The presentation also covers regulatory sequences that control transcription and the role of reverse transcription in retroviruses like HIV.
Translation is the process by which proteins are synthesized using the genetic code carried by mRNA. It involves three main steps - initiation, elongation, and termination. In initiation, the small ribosomal subunit binds to the 5' end of mRNA and scans until the start codon. In elongation, tRNAs bring amino acids to the ribosome according to mRNA codons and link them together via peptide bonds. Termination occurs when a stop codon is reached, releasing the full protein. Eukaryotes have more complex translation than prokaryotes due to nuclear/cytoplasmic separation and mRNA processing such as splicing.
The document summarizes eukaryotic transcription and its regulation. It discusses the core promoter elements, pre-initiation complex formation, the three phases of transcription (initiation, elongation, termination), and the role of RNA polymerase and general transcription factors. It also describes mRNA processing events like capping, splicing, and polyadenylation. Finally, it discusses mechanisms of transcriptional regulation including cis-regulatory elements like promoters and enhancers, the role of chromatin structure, and common DNA-binding domains in transcription factors.
Transcription is the process of creating messenger RNA (mRNA) from DNA. In eukaryotes, RNA polymerase binds to promoter regions and transcribes DNA into pre-mRNA, which undergoes processing including capping, polyadenylation, and splicing to remove introns. The mature mRNA is exported from the nucleus to the cytoplasm for protein synthesis. Prokaryotic transcription involves RNA polymerase binding to promoter regions and transcribing DNA into mRNA. Transcription is regulated by factors that influence RNA polymerase binding and activity.
The document provides information about the process of transcription. It defines transcription as the first step of gene expression where an RNA molecule is formed from DNA. It describes the key steps and components of transcription in both prokaryotes and eukaryotes. These include initiation, elongation, and termination of transcription, as well as the enzymes like RNA polymerase that are involved. The summary highlights that transcription involves copying genetic information from DNA to RNA, and differs between single-celled and multi-cellular organisms in its regulation and RNA polymerases used.
Messenger RNA carries genetic code from DNA and is translated by the ribosome into proteins. This involves transfer RNA molecules that associate amino acids with their codons. Translation begins with initiation factors recruiting the small ribosomal subunit to the start codon. Elongation then occurs through peptide bond formation catalyzed by the ribosome and translocation of transfer RNAs. Termination occurs when a stop codon is reached. Translation is highly conserved and essential for protein synthesis in all organisms.
DNA- Transcription and Tranlation, RNA, Ribosomes and membrane proteins.pptxLaibaSaher
Detailed presentation on the topic of DNA, transcription and translation, RNA, Ribosomes and Membrane proteins. Along with their structure and functions. Detailed Diagram and complete description of the processes. Along with references and Gifs that makes the presentation look more creative.
Post-transcriptional modifications process the primary transcript RNA in eukaryotic cells through 5' capping, polyadenylation at the 3' end, and splicing of introns. This processing protects the RNA from degradation, aids in export from the nucleus to the cytoplasm, and allows only protein-coding exons to be translated, increasing protein synthesis efficiency. Alternative splicing also expands the proteome by producing multiple mRNA variants from a single primary transcript.
This document provides an overview of transcription in prokaryotes and eukaryotes. It describes that transcription is the first step of gene expression where RNA is synthesized from a DNA template. In prokaryotes, transcription occurs in the cytoplasm and is carried out by RNA polymerase, while in eukaryotes it occurs in the nucleus and requires transcription factors. The process involves initiation, elongation, and termination stages. In prokaryotes, RNA polymerase binds directly to promoter sequences, while in eukaryotes transcription factors are needed to recruit RNA polymerase. The document compares the key differences between prokaryotic and eukaryotic transcription.
How cells read the genome from DNA to protein NotesYi Fan Chen
The document summarizes the process of transcription and translation in cells. It describes:
1) Transcription of DNA to RNA which is catalyzed by RNA polymerase and involves the formation of RNA through the addition of ribonucleotides.
2) Processing of eukaryotic pre-mRNA which involves capping, splicing, and polyadenylation to form mature mRNA.
3) Translation of mRNA to protein which occurs on ribosomes and involves tRNAs carrying amino acids that are linked together through peptide bond formation catalyzed by the ribosome. Accuracy is ensured by induced fit binding and kinetic proofreading.
1. There are four main classes of RNA: ribosomal RNA, messenger RNA, transfer RNA, and small nuclear RNA.
2. Transcription involves three stages - initiation, elongation, and termination. It uses DNA as a template to produce RNA.
3. Eukaryotic transcription requires RNA polymerase and other transcription factors to initiate transcription from a promoter region on DNA. The transcription process includes initiation, elongation, and termination.
Post-transcriptional modifications help process primary transcripts into mRNA in eukaryotes. This involves 5' capping, addition of a poly-A tail, and splicing of introns. 5' capping adds a guanine cap to protect the 5' end from degradation. Poly-A polymerase adds around 200 adenine bases to the 3' end. Splicing removes introns and ligates exons by the spliceosome, producing mature mRNA that can be translated into protein. Alternative splicing allows different mRNA and protein isoforms from a single gene.
This document provides information about translation, the process by which the nucleotide sequence of mRNA is converted into the amino acid sequence of a protein. It describes the key components and steps of translation, including the roles of the ribosome, tRNA, mRNA, and various initiation, elongation and termination factors. Translation is universal but can vary slightly between cytoplasmic and mitochondrial genetic codes. The document also discusses regulation of translation and clinical implications.
Post-transcriptional modifications help process primary transcripts into mRNA in three main ways: 1) 5' capping protects the transcript and aids export from the nucleus, 2) Polyadenylation aids stability and transport, and 3) Splicing removes introns and ligates exons to form mature mRNA. In eukaryotes, this occurs in the nucleus and is essential for efficient translation. It can also result in alternative splicing to increase protein diversity from a single gene.
Transcription is the synthesis of RNA from a DNA template. In prokaryotes, DNA-dependent RNA polymerase binds to promoter sequences on DNA and synthesizes RNA in the 5' to 3' direction using complementary bases. The primary transcript may undergo processing like capping, polyadenylation, splicing, and editing to produce mature mRNA. Eukaryotic transcription involves multiple RNA polymerases and regulatory proteins. RNA classes include mRNA, rRNA, tRNA, and non-coding RNAs which have important cellular functions.
Post-transcriptional modifications are a set of processes that alter RNA transcripts following transcription to produce mature functional RNAs. These include adding a 5' cap, polyadenylating the 3' end with a poly-A tail, and splicing out introns. The cap protects the RNA from degradation and aids in nuclear export and translation. Polyadenylation and splicing make the RNA more stable and translatable. Splicing involves snRNPs that recognize splice sites and catalyze intron removal through transesterification reactions. Alternative splicing allows single genes to encode multiple proteins.
RNA is synthesized from DNA in a process called transcription. There are three main stages: initiation, elongation, and termination. In initiation, RNA polymerase binds to promoter sequences and unwinds the DNA helix. In elongation, RNA polymerase reads the template strand and adds complementary RNA nucleotides. Termination occurs when termination signals are reached. Prokaryotes and eukaryotes differ in their RNA polymerases and transcription control. Eukaryotic pre-RNA undergoes processing including 5' capping, 3' polyadenylation, splicing, and editing to produce mature mRNA.
The document provides information about protein synthesis and processing. It begins with an overview of the topics to be covered, including ribosome formation, initiation and elongation factors, termination, the genetic code, tRNA aminoacylation, aminoacyl-tRNA synthetases, translational proofreading, inhibitors, and post-translational modifications. It then discusses the machinery of protein synthesis, including transcription, the genetic code, RNA, tRNA identity, aminoacyl-tRNA synthetases, aminoacylation of tRNA, and the ribosome. The mechanisms of initiation, elongation, and termination are explained in detail.
Lecture.10 Gene Therapy for Neurological Disorders: IntroductionDrQuratulAin5
This document appears to be a lecture presentation on gene therapy for neurological disorders given by Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D. It includes an introduction to the topic, mentions that it is the 10th lecture in the series, and provides contact information for Qurat-ul-Ain. The document also includes slides on topics like what a brain tumor is, the different types of brain tumors, glioblastoma, and the genes involved in different types of glioblastoma. It concludes by thanking the audience.
Lecture.9 Gene Therapy: An IntroductionDrQuratulAin5
Qurat-ul-Ain, who holds a B. Pharm, M. Phil, and Ph.D., teaches the 9th lecture on basic processes of molecular biology and introduction to molecular medicine and gene therapy. She is a visiting assistant professor at the Department of Physical Therapy, Faculty of Health & Medical Sciences at Hamdard University in Karachi, Pakistan and an assistant professor at the Department of Pharmaceutical Chemistry, Faculty of Pharmacy at Hamdard University in Karachi, Pakistan. The document provides her contact information.
This document appears to be a series of lecture slides presented by Qurat-ul-Ain on basic processes of molecular biology. The slides cover topics including cell-based DNA cloning, nucleic acid hybridization assays, PCR, DNA sequencing, in vitro mutagenesis, physical mapping, and thank attendees. The lectures were presented in six parts and focused on fundamental molecular biology techniques.
This document discusses the process of translation and protein synthesis. It covers topics like the genetic codon, tRNA, amino acid activation, and the roles of the ribosome. It also discusses inhibitors of protein and RNA synthesis that can act on prokaryotes, both prokaryotes and eukaryotes, or just eukaryotes. Finally, it briefly touches on protein folding, molecular chaperones, protein quality control, and triggering sister chromatid separation. The document is authored by Qurat-ul-Ain, who has a Ph.D. in molecular biology and genetics.
This document discusses DNA recombination, including homologous genetic recombination, site-specific recombination, and DNA transposition. It describes processes like DNA synapsis, Holliday junction formation, gene conversion, and the roles of proteins like RecA. It also discusses different types of DNA transposons and how they can mobilize genetic material through cut-and-paste or copy-and-paste mechanisms using transposase enzymes. Retrotransposons are described as resembling retroviruses in producing an RNA intermediate that is reverse transcribed into DNA for integration into new genomic sites.
This document discusses DNA recombination, including homologous genetic recombination, site-specific recombination, and DNA transposition. It describes the key processes involved in homologous recombination, including DNA breaks, synapsis formation facilitated by RecA and single-strand binding proteins, branch migration, Holliday junction formation, and resolution. It also discusses gene conversion and how cells prevent promiscuous recombination between poorly matched sequences. Site-specific recombination and different classes of transposons are also summarized.
1) The document discusses various mechanisms of DNA repair, including mismatch repair, base excision repair, nucleotide excision repair, direct repair, and error-prone translesion synthesis.
2) Mismatch repair involves methyl-directed repair of mismatched base pairs using MutS and MutL complexes in both prokaryotes and eukaryotes.
3) Base excision repair removes damaged or inappropriate bases using DNA glycosylases and follows with endonuclease cleavage, DNA synthesis, and ligation.
4) Nucleotide excision repair removes oligonucleotides containing damaged bases by dual incisions around the lesion, followed by filling in and ligation.
The document discusses DNA replication in prokaryotes and eukaryotes. In prokaryotes, replication begins with initiation at the origin of replication (oriC) mediated by DnaA and other proteins. Bidirectional replication forks are established with the help of helicases and DNA polymerases. Elongation involves continuous synthesis of leading and discontinuous synthesis of lagging strands in Okazaki fragments. Termination occurs when the replication forks from opposite directions converge. In eukaryotes, replication is regulated by cyclin-dependent kinases and occurs at multiple origins of replication with similar initiation and elongation processes as prokaryotes.
Lecture 3.part.1Denaturation,Renaturation of DNA Replication of DNA DrQuratulAin5
The document discusses denaturation and renaturation of DNA and replication of DNA. It provides details on how DNA can be denatured using heat, chemicals, or proteins. Renaturation requires energy and slow cooling to allow base pairs to rebuild. DNA replication is semiconservative, with each strand serving as a template to produce a new complementary strand. Meselson and Stahl's experiment demonstrated that replication is semiconservative through detection of bands at different densities on centrifugation.
The document discusses the benefits of exercise for mental health. Regular physical activity can help reduce anxiety and depression and improve mood and cognitive function. Exercise causes chemical changes in the brain that may help protect against mental illness and improve symptoms.
Lecture 1 part.1 Structure and Function of Nucleic AcidDrQuratulAin5
This presentation is the part of Molecular Biology and Genetic course that would describe you about structure and function of nucleic acid and there types
This document provides an overview of wound healing, its functions, stages, mechanisms, factors affecting it, and complications.
A wound is a break in the integrity of the skin or tissues, which may be associated with disruption of the structure and function.
Healing is the body’s response to injury in an attempt to restore normal structure and functions.
Healing can occur in two ways: Regeneration and Repair
There are 4 phases of wound healing: hemostasis, inflammation, proliferation, and remodeling. This document also describes the mechanism of wound healing. Factors that affect healing include infection, uncontrolled diabetes, poor nutrition, age, anemia, the presence of foreign bodies, etc.
Complications of wound healing like infection, hyperpigmentation of scar, contractures, and keloid formation.
Philippine Edukasyong Pantahanan at Pangkabuhayan (EPP) CurriculumMJDuyan
(𝐓𝐋𝐄 𝟏𝟎𝟎) (𝐋𝐞𝐬𝐬𝐨𝐧 𝟏)-𝐏𝐫𝐞𝐥𝐢𝐦𝐬
𝐃𝐢𝐬𝐜𝐮𝐬𝐬 𝐭𝐡𝐞 𝐄𝐏𝐏 𝐂𝐮𝐫𝐫𝐢𝐜𝐮𝐥𝐮𝐦 𝐢𝐧 𝐭𝐡𝐞 𝐏𝐡𝐢𝐥𝐢𝐩𝐩𝐢𝐧𝐞𝐬:
- Understand the goals and objectives of the Edukasyong Pantahanan at Pangkabuhayan (EPP) curriculum, recognizing its importance in fostering practical life skills and values among students. Students will also be able to identify the key components and subjects covered, such as agriculture, home economics, industrial arts, and information and communication technology.
𝐄𝐱𝐩𝐥𝐚𝐢𝐧 𝐭𝐡𝐞 𝐍𝐚𝐭𝐮𝐫𝐞 𝐚𝐧𝐝 𝐒𝐜𝐨𝐩𝐞 𝐨𝐟 𝐚𝐧 𝐄𝐧𝐭𝐫𝐞𝐩𝐫𝐞𝐧𝐞𝐮𝐫:
-Define entrepreneurship, distinguishing it from general business activities by emphasizing its focus on innovation, risk-taking, and value creation. Students will describe the characteristics and traits of successful entrepreneurs, including their roles and responsibilities, and discuss the broader economic and social impacts of entrepreneurial activities on both local and global scales.
How to Setup Warehouse & Location in Odoo 17 InventoryCeline George
In this slide, we'll explore how to set up warehouses and locations in Odoo 17 Inventory. This will help us manage our stock effectively, track inventory levels, and streamline warehouse operations.
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
"Learn about all the ways Walmart supports nonprofit organizations.
You will hear from Liz Willett, the Head of Nonprofits, and hear about what Walmart is doing to help nonprofits, including Walmart Business and Spark Good. Walmart Business+ is a new offer for nonprofits that offers discounts and also streamlines nonprofits order and expense tracking, saving time and money.
The webinar may also give some examples on how nonprofits can best leverage Walmart Business+.
The event will cover the following::
Walmart Business + (https://business.walmart.com/plus) is a new shopping experience for nonprofits, schools, and local business customers that connects an exclusive online shopping experience to stores. Benefits include free delivery and shipping, a 'Spend Analytics” feature, special discounts, deals and tax-exempt shopping.
Special TechSoup offer for a free 180 days membership, and up to $150 in discounts on eligible orders.
Spark Good (walmart.com/sparkgood) is a charitable platform that enables nonprofits to receive donations directly from customers and associates.
Answers about how you can do more with Walmart!"
LAND USE LAND COVER AND NDVI OF MIRZAPUR DISTRICT, UPRAHUL
This Dissertation explores the particular circumstances of Mirzapur, a region located in the
core of India. Mirzapur, with its varied terrains and abundant biodiversity, offers an optimal
environment for investigating the changes in vegetation cover dynamics. Our study utilizes
advanced technologies such as GIS (Geographic Information Systems) and Remote sensing to
analyze the transformations that have taken place over the course of a decade.
The complex relationship between human activities and the environment has been the focus
of extensive research and worry. As the global community grapples with swift urbanization,
population expansion, and economic progress, the effects on natural ecosystems are becoming
more evident. A crucial element of this impact is the alteration of vegetation cover, which plays a
significant role in maintaining the ecological equilibrium of our planet.Land serves as the foundation for all human activities and provides the necessary materials for
these activities. As the most crucial natural resource, its utilization by humans results in different
'Land uses,' which are determined by both human activities and the physical characteristics of the
land.
The utilization of land is impacted by human needs and environmental factors. In countries
like India, rapid population growth and the emphasis on extensive resource exploitation can lead
to significant land degradation, adversely affecting the region's land cover.
Therefore, human intervention has significantly influenced land use patterns over many
centuries, evolving its structure over time and space. In the present era, these changes have
accelerated due to factors such as agriculture and urbanization. Information regarding land use and
cover is essential for various planning and management tasks related to the Earth's surface,
providing crucial environmental data for scientific, resource management, policy purposes, and
diverse human activities.
Accurate understanding of land use and cover is imperative for the development planning
of any area. Consequently, a wide range of professionals, including earth system scientists, land
and water managers, and urban planners, are interested in obtaining data on land use and cover
changes, conversion trends, and other related patterns. The spatial dimensions of land use and
cover support policymakers and scientists in making well-informed decisions, as alterations in
these patterns indicate shifts in economic and social conditions. Monitoring such changes with the
help of Advanced technologies like Remote Sensing and Geographic Information Systems is
crucial for coordinated efforts across different administrative levels. Advanced technologies like
Remote Sensing and Geographic Information Systems
9
Changes in vegetation cover refer to variations in the distribution, composition, and overall
structure of plant communities across different temporal and spatial scales. These changes can
occur natural.
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
1. MOLECULAR BIOLOGY & GENETICS
Basic Processes of Molecular Biology
DNA Transcription
6th Lecture
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D.,
Visiting Assistant Professor
Department of Physical Therapy, Faculty of Health& Medical Sciences,
Hamdard University, Karachi, Pakistan
Assistant Professor
Department of Pharmaceutical Chemistry, Faculty of Pharmacy, Hamdard
University, Karachi, Pakistan.
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
2. RNA Transcription
• RNA polymerase binds to the bacterial DNA in spe region known as promoter
• The polymerase, using its σ factor recognizes this DNA seq by making specific
contacts with the portions of the bases that are exposed on the outside of the helix
• After RNA polymerase binds tightly to the promoter DNA in this way, it opens up
the double he;lix to expose short stretches of nt on each strand
• Instead of DNA helicase, here the nick does not require the hydrolysis of ATP,
both DNA and polymerase structurally changes themselves in a more energetically
favor state.
• One DNA act as a template for the incoming ribonucleotides, joined by RNA
polymerase
• After few additions of nt on newly RNA, polymerase works without its sigma
factor and goes in to more structurally stable state.
•50 nt/ sec is added by bacterial RNA polymerase, and it continues until it
recognized the terminator seq
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
3. • RNA polymerase I transcribed 5.8 S, 18S, and 28S rRNA genes
• RNA polymerase II transcribed all protein-coding genes,plus snoRNA
genes and some snRNA genes
• RNA polymerase III transcribed tRNA genes, 5S rRNA genes, some
snRNA genes and genes for other small RNAs
RNA polymerases in Eukaryotic cells
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
4. In Eukaryotes: RNA polymerase II
• RNA polymerase II along another
transcription factors are required for the
correct position at the promoter side on
the DNA strand.
• The transcription factors helps in pulling
apart the DNA strand to allow
transcription to begin and release RNA
polymerase from the promoter into
elongation mode
• The general transcription factors are
called as TFII, TFIIA, TFIIB (transcription
factor for polymerase II)
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
5. Initiation of the RNA transcription by RNA polymerase II
• All the transcription factors assembled on the
promoter region which is recognized by the RNA
ployII
• First TFIID binds to short stretch of DNA helix,
composed of T and A or TATA box and to TATA
binding protein (TBP)
• TATA box is localized 25nt upstream from the
transcription start
• It is not the only seq at which initiation starts but
RNA polymerase II prefers this seq much better
• For transcription initiation complex, TFIID
creates a big loop in the DNA strand so that all
the factors can join and assembled at the
promoter region for the protein assembly steps.
6. • TFIIH has a kinase activity as well as a helicase
property
• The termination of RNA is carried out TFIIH
which adds phosphate groups to the tail of the
RNA polymerase known as CTD or C-terminal
domain
• RNA polymerase then disengage form the
initiation complex
• Undergo many structural conformations and
binds tightly with the DNA , binds to many other
proteins and start the synthesis of RNA for a
longer distances
• PO4rlylation important in that sense that it
signals to the RNA processing units as it comes
from the polymerase
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
7. RNA processing (Post transcriptional modification)
The basic features of transcription are the same in
prokaryotic and eukaryotic cells, but eukaryotic genes and
their mRNA molecules are more complex than those of
bacteria. Eukaryotic mRNA molecules undergo
posttranscriptional modifications, which apparently protect
eukaryotic mRNA molecules from degradation and to give
them longer lifetimes than bacterial mRNA.
A DNA sequence containing both exons (coding regions)
and introns (noncoding regions) is transcribed by RNA
polymerase to make the primary transcript, or mRNA
precursor. As it is synthesized, the pre-mRNA is capped
by the addition of a modified base to its 5' end (5'
capping) and a poly-A tail (100 to 250 nucleotides long)
is added to the 3' end. Introns are later removed from the
mRNA precursor. Exons are spliced together to produce a
continuous protein-coding sequence. Finally, mature
mRNA is transported through the nuclear envelope and
into the cytosol to be translated.
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
9. The pre-mRNA molecule undergoes three main
modifications. These modifications are 5' capping, 3'
polyadenylation, and RNA splicing, which occur in the cell
nucleus before the RNA is translated.
5' Processing
Capping of the pre-mRNA involves the addition of 7-
methylguanosine (m7G) to the 5' end. To achieve this, the
terminal 5' phosphate requires removal, which is done with
the aid of a phosphatase enzyme. The enzyme guanosyl
transferase then catalyses the reaction, which produces the
diphosphate 5' end. The diphosphate 5' prime end then
attacks the α phosphorus atom of a GTP molecule in order to
add the guanine residue in a 5'5' triphosphate link. The
enzyme S-adenosyl methionine then methylates the guanine
ring at the N-7 position. This type of cap, with just the (m7G)
in position is called a cap 0 structure. The ribose of the
adjacent nucleotide may also be methylated to give a cap 1.
Methylation of nucleotides downstream of the RNA molecule
produce cap 2, cap 3 structures and so on. In these cases
the methyl groups are added to the 2' OH groups of the
ribose sugar. The cap protects the 5' end of the primary RNA
transcript from attack by ribonucleases that have specificity
to the 3'5' phosphodiester bonds.
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
10. 3' Processing
Cleavage and Polyadenylation
The pre-mRNA processing at the 3' end of the RNA molecule involves
cleavage of its 3' end and then the addition of about 200 adenine residues to
form a poly(A) tail. The cleavage and adenylation reactions occur if a
polyadenylation signal sequence (5'- AAUAAA-3') is located near the 3' end of
the pre-mRNA molecule, which is followed by another sequence, which is
usually (5'-CA-3'). The second signal is the site of cleavage. A GU-rich
sequence is also usually present further downstream on the pre-mRNA
molecule. After the synthesis of the sequence elements, two multisubunit
proteins called cleavage and polyadenylation specificity factor (CPSF) and
cleavage stimulation factor (CStF) are transferred from RNA Polymerase II to
the RNA molecule. The two factors bind to the sequence elements. A protein
complex forms that contains additional cleavage factors and the enzyme
Polyadenylate Polymerase (PAP). This complex cleaves the RNA between the
polyadenylation sequence and the GU-rich sequence at the cleavage site
marked by the (5'-CA-3') sequences. Poly(A) polymerase then adds about 200
adenine units to the new 3' end of the RNA molecule using ATP as a precursor.
As the poly(A) tails is synthesised, it binds multiple copies of poly(A) binding
protein, which protects the 3'end from ribonuclease digestion.[3]
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
11. Splicing
RNA splicing is the process by which introns, regions of RNA that do
not code for protein, are removed from the pre-mRNA and the
remaining exons connected to re-form a single continuous molecule.
Although most RNA splicing occurs after the complete synthesis and
end-capping of the pre-mRNA, transcripts with many exons can be
spliced co-transcriptionally.[4] The splicing reaction is catalyzed by a
large protein complex called the spliceosome assembled from proteins
and small nuclear RNA molecules that recognize splice sites in the pre-
mRNA sequence. Many pre-mRNAs, including those encoding
antibodies, can be spliced in multiple ways to produce different mature
mRNAs that encode different protein sequences. This process is
known as alternative splicing, and allows production of a large variety
of proteins from a limited amount of DNA.
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
12. RNA Capping
• The 5’ end of the new RNA molecule is modified by the addition of a
cap contains a modified Guanine nucleotide
• The capping reaction is catalyzed by
1- Phosphatase which removes a PO4 from 5’ end of the RNA
2- a guanyl transferase that adds GMP in a reversal linkage 5’-5’
instead to 5’-3’
3- Methyl transferase that adds a methyl group to the guanosine
• These enzyme binds the PO4rylated RNA as soon as it synthesized
from the polymerase and will modify 5’ end of the RNA
• The 5’ methyl cap signals the 5’ end of eukaryotic mRNAs- this is to
distinguish the RNA from the other types of RNA mols in the cells
• For eg RNA polymerase I and II produce uncapped RNAs during
transcription, because they lack tails
• In nucleus the cap binds a protein complex called CBC (cap-binding
complex), that helps RNA to processed and export out in the cytosol
properly
• 5’ methyl cap is very important in translation of mRNAs in the
cytosol
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
16. Removal of Introns from the newly synthesized Pre- mRNA
• Eukaryotes genes were found in many
coding sequence known as expressed or
axon and intervening sequences or introns
• However both are transcribed in to RNA
• During RNA Splicing these introns are
removed from the RNA and only axons are
joined back
• After 5’ and 3’ end have been processed,
and only those mols. of Pre-RNA goes in to
splicing who r destined to become mRNA
• One splicing removes only one intron
• In this two sequential phosphoryltransfer
reaction or transesterfications join the exons
while removing the introns as a “lariat”
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
17. RNA Splicing Maschinery
• It consists of 5 additional RNA
mols. + > 50 proteins + requires
many ATP mols/ splicing
• This event should be highly
accurate, any mistake in splicing
could harm or kill the cells
• Importance of introns= To
produce new types of proteins +
helps in genetic recombination to
combine the axons of different
genes + with the same genes
• emergence of Protein domains
• Due to mRNA splicing many
different types of mRNA and
proteins are produce
• RNA splicing also helps cells to
change the nature of its gene
expression
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
18. • Introns can be 10 nt to 100,000 nt long
• Picking the correct place for their removal
is not easy
• This is done at 3 positions
1- 5’ splice site
2- 3’ splice site
3- Branch point at the middle of the intron
(excised lariat)
• These all positions have similar
consensus nt sequences which mark
splicing positions
• Still difficult to remove all
Splicing positions on Introns
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
19. Spliceosome
• RNA molecules are involved instead of
proteins for splicing
• Short RNA mols (200 nt) and named U1,
U2, U4, U5, U6
• They all form a complex called as snRNAs
(small nuclear RNAs)
• snRNAs work with 7 protein subunits,
snRNP (small nuclear ribonulceo protein)
• snRNAs + snRNPs forms the core of
spliceosome
• The recognition b/w 5’ and 3’ splice
junction, branch point take place b/w Pre-
mRNA substrate and consensus RNA nt
sequences
• RNA-RNA rearrangement occur in which
U1 is replaced by U6 at 5’ and so on
• This permits the checking and rechecking
of RNA seq before the chemical reaction is
allowed to proceed.
• This enhance accuracy
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
21. Complex RNA-RNA Rearrangements
• ATP is required for the assembly of the spliceosome
• RNA helicase are used to break up the RNA-RNA
interaction and need ATP
• Total 50 proteins for each splicing event
• ATP-requiring RNA-RNA rearrangements occur within
themselves and b/w the snRNPs and the Pre-mRNA
• Active site on Pre-mRNA is created after the
rearrangements
• Catalytic site:
1- It is made of RNA mols
2- U1 and U2 forms a 3 dimensional structure in
spliceosome that juxtaposes the 5’ end splice site of Pre-
mRNA
3- This site is also attched with the branch point
4- Causes the 1st Esterfication reaction
5- This brings 5’ and 3’ splice junctions close and requires
U5 snRNA for the 2nd esterfication
6- At the end the product is released but snRNPs remian
attached. Same procedure starts again
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
23. Proper splice sites in Pre-mRNA
• Soon after the transcription and the 5’ cap formation
several functions of spliceosome acts on the
PO4rylated tail of the RNA polymerase
1- Pre-mRNA coming from RNA polymerase keeps
the track of intron and exons
• The 5’ snRNP with only one 3’splice site
•This helps to prevent wrong exon skipping
2- Exon definition hypothesis
• RNA synthesis proceeds with SR proteins act like a
component of spliceosome
• They mark 3’ and 5’ splice site starting from 5’ end
of RNA
• This involves U1 snRNA, mark the exon boundary
and U2AF, help to specify other
• These complexes on nascent RNA prevents cryptic
sites
• Splicing is done while RNA is still synthesizing from
RNA polymerase, this means that splicing can be
done along transcription or after the transcription
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
24. snRNPs splice a small fraction of Intron sequences
• A small set of snRNPs that direct spliceosome
recognizes only specific set of DNA sequences, AT-AC
spliceosome
• However same RNA-RNA rearrangements are present
Another variation of splicing mechanism exits called as
trans-splicing
• In this exons from two separate RNA transcripts are
spliced together to form a mature mRNAmols.
• Trypanosomes produce all their mRNA in this way,
however few nematode mRNA are produce by
transplicing
1- one exon is spliced in to 5’ end of many different RNA
transcripts produce by the cell
2- This way all RNA have same 5’ but diff 3’ ends
3- trans-splicing uses snRNP, SLRNP
• Importance is that may be same 5’ site enhances the
translation of mRNA
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
26. RNA splicing and Plasticity
• When a mutation occurs in a nucleotide seq critical for
splicing of a particular intron, it did not splice that intron
• The exon will be skipped
• New pattern of splicing comes inaction and creates a
cryptic junctions and picks out the best pattern of splice
junctions
• If the present one got mutated it will seek out a new
one having best pattern
• This flexibility in the process of RNA splicing suggest
that mutations and changes in pattern are important in
evolution of genes and organisms
• Plasticity also refers that the cell can easily regulate
the pattern of RNA splicing
• Alternative splicing give rise to many different types of
proteins belong to the same gene. They are
constitutive in the cells.
• Some times their expressions are regulated by the
cells
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
27. RNA-Processing Enzymes Generate the 3’ end of Eucaryotic mRNAs
• RNA polymerase continues its movement along gene,
the spliceosome on the RNA and cut the intron and
axon boundaries
• The long C-terminal tail of the RNA polymerase make
sure that all the components for the splicing should be
present on the RNA
• It also initiates the 3’ end of the mRNA for the
processing
• Processing starts after getting signals from DNA to
transcribe in to RNA as the RNA polymerase II moves
through them
• They are also recognized by the presence of RNA
binding protein and processing enzymes
• CstF (Cleavage stimulation factor) and CPSF
(cleavage and polyadenylation specificity factor) travel
with the RNApolymerase II and transferred to 3’ end
processing seq on an RNA mol emerges from the
enzyme
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
29. RNA-Processing Enzymes Generate the 3’ end of Eucaryotic mRNAs
• Subunits of CPSF are associated with
transcription factor TFIID
• During transcription initiation these subunits
moves on to RNA polymerase tail
• Once RNA mols comes from the polymerase
it will accompanied by the binding proteins to
form 3’endof mRNA. 1st RNA cleaved by this
• Next the enzyme called poly-A polymerase
adds, one time 200 nt A nt to the 3’end to
create a cut
• 5’ and 3’ end has been formed by ATP mol
• RNA Polymerase A does not require a RNA
template, hence not coded in the genome
• Poly A site is synthesized by addition of
Adenines on 3’ end
• Poly-A tail on mRNA now enters in the
cytosol and help to direct the synthesis of
proteins on ribosome
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
30. RNA-Processing Enzymes Generate the 3’ end of Eucaryotic mRNAs
• After 3’ end of eukaryotes pre-mRNA mol have
been cleaved the RNA polymerase II while keep
transcribing
• Soon after polymerase looses its grip on RNA
template and termination a occurs
• Piece of RNA downstream of the cleavage site
is then degraded in the cell nucleus
• Two theories for RNA polymerase processivity
loss
1- transfer of 3’ end processing factors from RNA
polymerase to RNA causes a conformational
changes in the polymerase
2- Lack of 5’ cap of the RNA that arises form
polymerase might signals to eh enzyme to
terminate transcription
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
31. Transport of Eukaryote mRNA from the Nucleus
• The introns, broken RNA and cryptic sites are
dangerous to the cells
• That’s why mRNA is trnasferred to the cytosol for
translation
• Transport is done via nuclear pore complex for
complete processed mRNA
• Appropriate sets of proteins should be bound on
mRNA to be transported to the cytosol
• Nuclear Pore Complex
1- They are aqueous channels in the nuclear
membranes that directly connect nucleoplasm and
cytosol
2- Small mols < 50,000 daltons can diffuse freely
through them
3- Macromols signals cells for import and
exportpolymerase or mRNA respectively
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
33. Nuclear Pore Complex
1- They are aqueous channels in the nuclear
membranes that directly connect nucleoplasm
and cytosol
2- Small mols < 50,000 daltons can diffuse freely
through them
3- Macromols signals cells for import and
exportpolymerase or mRNA respectively
4- Only useful RNA exported out via pores
5- hnRNPs (heterogenous nuclear ribonuclear
proteins, 30 of them in humans)
are present in abundant on the pre-mRNA
6- Some are useful in removing hairpin helices
from the RNA
7- Some pack RNA in long introns seq found in
genes of complex organism
Transport of Eukaryote mRNA from the Nucleus
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
34. Transport of Eukaryote mRNA from the Nucleus
8- Besides histones, hnRNP proteins are most
abundantin the cell nucleus
9- These proteins help to distinguished b/w
mature and unprocessed mRNA
10- Hoever hnRNP are reoved from the exon seq
proir binding of spliceosome components
11- They are destroyed later
12- mRNA with its 5’ end first enters in to the
cytosol with structural trnasitions
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
35. Noncoding RNAs synthesis: rRNA
• Few % of dry cell weight is RNA
•The most abundant RNA in the cell is rRNA ie
80%
• 3-5 % mRNA
• RNA polymerase I (structually similar to II)
produces rRNA
• RNA polymerase I have no C-terminal ie why
they are neither capped or polyadenylated
• Ribosome are final gene products and a growing
cell must synthesize approx. 10 million copies of
each type of rRNA in each cell generation to
construct its 10 million ribosomes
• This is done by the presence of enough rRNA
genes for rRNAs.
• Ecoli need 7 copies of its rRNA genes copies per
haploid genome, on 5 chromosomes
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
36. Noncoding RNAs synthesis: rRNA
Eukaryotic rRNAs
• 4 types of rRNAs, one on each copy of ribosome
• 3 of four are 18S, 5.8S and 28S
• They are synthesized from a chemically modified
and cleaved process generating single large
precursor rRNA
• 5.8S is synthesized from a separate cluster of
genes by a different polymerase
• RNA polymerase III does not require chemical
modification and transcribed separately
• Many chemical modifications occur in the 13,000-
nucleotide-long precursor r RNA before the rRNA
are cleaved out of it and assembled into ribosomes
• Chemical modifications includes 100 methylations
of the 2’OH positions on nt sugars and 100
isomerizations of uridine nt to pseudouridine
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
37. Noncoding RNAs synthesis: rRNA
Modifications:
• It is made at specific position in the prescursor rRNA
• These positions are specified by several hundred “guide
RNAs” which locate themselves via bp to the precursor
rRNA thereby move RNA-modifying enzyme to the
appropriate position
• Other guide RNAs promote cleavage of the precursor
rRNAs in to the mature rRNAs probably by causing
conformational changes in the precurosor rRNA
• They all belong to theRNA class of small nucleolar RNAs
(snoRNAs)
• Many snoRNA are encoded in the introns of other genes
specially those encoding ribosomal proteins
• They are therefore synthesized by RNA polymerase II and
processed from excised intron sequences
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
39. Nucleolus: A Ribosomal-Producing Factory
• Nucleolus is the rRNA processing site and their
assemblky into ribosome
• It is large aggregate of macromolecules, including
the rRNA genes themselves, precursor RNAs,
mature rRNAs, rRNA processing enzymes,
snoRNPs, ribosomal protein subunits and partly
assembled ribosomes
• It is the site where other RNAs are produced and
other RNA-protein complexex are assembled
• An eg: The U6 snRNA is chemically modified by
snoRNAs in the nucleolous before its final assembly
there into the U6 snRNP
• Telomerase and signal recognition particle are
said to be synthesized in nucleolus
• tRNA are also processed in here
• Nucleolus size changes with the type of cells
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
42. The Nucleus
• Contains GEMS (Gemini of coiled bodies) and
speckles (interchromatin granule clusters)
• These structures are highly dynamic bc of tight
association of RNA-protein
• GEMS and speckles are paired in the nucleus
•This is the site where snRNAs and snoRNAs
undergo their final modifications and assemble with
proteins
• RNA and proteins for snRNPs synthesis are partly
assembled in cytoplasm but are transported in to the
nucleus for final modification
• They are the Cajal/GEMS site where snRNPs are
recycled and their RNAs are “reset” after
rearrangements that occur during splicing of pre-
mRNA
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
43. The Nucleus
• Interchromatin granule clusters have been proposed
to be stock piles of fully mature snRNPs that are ready
to be used in splicing of pre-mRNA
• GEMS contain SMN (survival motor neurons)
proteins. Mutations in GEMS gene encoding for this
protein can cause the spinal muscular atrophy
• In this disease subtle defects in snRNPs assembly
and subsequent splicing of pre-mRNA takes place
• RNA splicing take place at various location in
chromosome bc splicing is co-transcriptional
• At Interphase when chromosomes occupy discrete
territories in the nucleus, then transcription and pre-
mRNA splicing takes place
• Chromosomes at interphase and can be located via
gene expression
For e.g. Presence of transcriptionally silent regions of
interphase chromosomes are often associated with
nuclear envelop where the conc. of heterochromatin
components is believed to be esp. high
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com
45. The Nucleus
• But when the same region become
transcriptionally active, they relocate towards the
interior of the nucleus, which is richer in the
components required for mRNA synthesis
• Mammalian cells express 15,000 genes so
transcription and RNA splicing must take place
at several thousands sites in the nucleus
• Nucleus is seems to be very dynamic and
divided in to subdomains, with snRNPs,
snoRNPs and other nuclear components moving
between them according to the need of the cell
Qurat-ul-Ain, B. Pharm., M. Phil., Ph.D., qurat.fophu@yahoo.com