RNA Transcription - an overview (2022)

Human Genetic Diversity : Mutation and Polymorphism

Robert L. Nussbaum MD, FACP, FACMG, in Thompson & Thompson Genetics in Medicine, 2016

Mutations Affecting RNA Transcription, Processing, and Translation

The normal mechanism by which initial RNA transcripts are made and then converted into mature mRNAs (or final versions of noncoding RNAs) requires a series of modifications, including transcription factor binding, 5′ capping, polyadenylation, and splicing (seeChapter 3). All of these steps in RNA maturation depend on specific sequences within the RNA. In the case of splicing, two general classes of splicing mutations have been described. For introns to be excised from unprocessed RNA and the exons spliced together to form a mature RNA requires particular nucleotide sequences located at or near the exon-intron (5′ donor site) or the intron-exon (3′ acceptor site) junctions. Mutations that affect these required bases at either the splice donor or acceptor site interfere with (and in some cases abolish) normal RNA splicing at that site. A second class of splicing mutations involves base substitutions that do not affect the donor or acceptor site sequences themselves but instead create alternative donor or acceptor sites that compete with the normal sites during RNA processing. Thus at least a proportion of the mature mRNA or noncoding RNA in such cases may contain improperly spliced intron sequences. Examples of both types of mutation are presented inChapter 11.

For protein-coding genes, even if the mRNA is made and is stable, point mutations in the 5′ and 3′-untranslated regions can also contribute to disease by changing mRNA stability or translation efficiency, thereby reducing the amount of protein product that is made.

Human T-Cell Leukemia Viruses: General Features

M. Yoshida, in Encyclopedia of Virology (Third Edition), 2008

Transcription and splicing

RNA transcription from the 5′ LTR to 3′ LTR generates the viral genomic RNA, and this step represents a potential regulatory stage of the viral replication cycle. HTLV genomic RNA serves as an mRNA for Gag and Pol proteins, but has to be spliced to express other viral proteins: into a 4.2kbp (singly spliced) env mRNA for Env expression, and into a 2.1kbp (doubly spliced) mRNA for the regulatory proteins, Tax and Rex (Figure 1). Various alternative splicing events also take place to express alternative proteins.

Genomic transcription depends on cellular factors that respond to 21bp enhancers in the HTLV LTR, but initial transcriptional activity is weak. The low levels of viral transcripts are fully spliced into Tax/Rex mRNA. The Tax thus produced trans-activates transcription further enhancing viral transcription to produce more Tax/Rex mRNA. This trans-activation is mediated by Tax binding to a transcriptional factor, cAMP-responsive element binding protein (CREB) that responds to the 21 bp enhancers in the LTR. To express the virion proteins, Gag, Pol, and Env, the accumulated Rex protein specifically suppresses splicing of the viral RNA, and thus upregulates expression of unspliced genomic RNA and singly spliced env mRNA. In return, this Rex regulation reduces the level of spliced Tax/Rex mRNA, resulting in a lower level of Tax and ultimately reducing viral transcription. The combination of Tax and Rex functions exerts a feedback control on viral expression, making viral expression transient and resulting in the escape of infected cells from host immune surveillance. This feedback mechanism is unique to HTLV among oncogenic retroviruses and explains why HTLV is so repressed in expression and replication.

HTLV replication has also been reported to be regulated by small proteins such as p12(I), p10(I), p11(V), that are expressed by alternative splicing of the pX sequence. The regulatory mechanisms are not well understood but seem to be important for in vivo viral replication.

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(Video) Transcription and mRNA processing | Biomolecules | MCAT | Khan Academy

Molecular Diagnostics : Basic Principles And Techniques

Richard A. McPherson MD, MSc, in Henry's Clinical Diagnosis and Management by Laboratory Methods, 2022

Transcription Of DNA To RNA

Sections of DNA that specify amino acid sequences of proteins are calledgenes. One gene contains the amino acid sequence code for one protein as well as the DNA sequences necessary for the regulation of the production of that protein. Within the 6 billion nucleotides of the human genome, there are about 20,000 to 25,000 protein-coding genes. Although these coding sequences are of paramount importance to the cell and to the function of the organism as a whole, they actually make up less than 2% of the nucleotides. The vast majority of the human genome is composed of noncoding DNA regions referred to in the past asjunk DNA. While much of the function of noncoding DNA remains unknown, diverse roles of biological importance have been identified, such as regulation of gene expression, origins of replication, and coding of RNA (see later section on Gene Regulation Mediated by Small RNA andCech & Steitz, 2014).

Protein synthesis begins with the activation of the appropriate gene. A copy of the gene is made from DNA in the form of RNA. Because the RNA copy carries the code from the DNA in the cell nucleus to the cytoplasm where amino acid synthesis takes place, this type of RNA is calledmessenger RNA (mRNA). mRNA is synthesized from only one strand (coding strand) of the DNA gene; the complementary DNA (cDNA) strand is not used. This is accomplished by a process calledtranscription. DNA promoter sequences present near the start of the gene to be transcribed promote the ability of RNA polymerases and associated proteins to recognize the nucleotide at which mRNA synthesis initiation begins. Synthesis of mRNA proceeds in much the same fashion as DNA replication, with the ssDNA sequence dictating the mRNA sequence using the same rules of base pair complementarity (uracil base pairs with adenine). When the end of the gene is reached, mRNA synthesis is terminated. Some genes are always expressed, while others are only active in certain physiologic situations. The rate of transcription also varies in different cells (see later section on Transcriptional Control).

RNA-Binding Domains in Proteins

D. SenGupta, in Brenner's Encyclopedia of Genetics (Second Edition), 2013

Introduction

Following transcription, RNA is subjected to various processing and modification events. In eukaryotic cells, it is critical that RNA is transported to a specific cellular compartment. For example, in developing embryos, some messenger RNAs (mRNAs) localize to a specific region of the embryo and thus determine its body plan. In addition, the translation of some mRNAs is regulated in a temporal as well as a spatial manner during development. These critical cellular events require specific interactions between RNA and protein. Several recurring RNA-binding sequence motifs have been identified in some of these important proteins. These protein sequence motifs probably appeared early in evolution and have become widespread because of their versatile RNA-binding properties. We have now begun to understand how these RNA-binding protein domains recognize their specific target RNA(s).

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Molecular Biology and Genetic Engineering

A. Wesley Burks MD, in Middleton's Allergy: Principles and Practice, 2020

(Video) Transcription (DNA to mRNA)

Transcriptional Control

To transcribe a gene, RNA polymerase binds to the promoter region, a specific sequence of nucleotides on the gene that informs the RNA polymerase where to begin transcribing. Other protein-binding nucleotide sequences on DNA regulate transcription by affecting the binding of RNA polymerase to the promoter. The interaction of proteins to the regulatory sequence either inhibits transcription by interfering with RNA polymerase binding to the promoter region or stimulates it by facilitating polymerase binding to the promoter.

To initiate transcription, assembly of a set of proteins, the transcriptional factors, on the promoter is required for the stabilization of binding of RNA polymerase to the promoter. The assembly begins some 25 nucleotides upstream from the transcription start site, where a transcription factor (basal factor) composed of several subunits binds to a short TATA sequence (Fig. 10.4). Other transcriptional factors (coactivators) link the basal transcriptional factors with the regulatory proteins, the activators. This completes the formation of a full transcription complex that is able to engage RNA polymerase. The transcription complex then phosphorylates the bound RNA polymerase, disengaging it from the complex so that it is free to start transcription. Any factor that reduces the availability of a particular transcriptional factor, or blocks its assembly into the transcription complex, is likely to inhibit transcription.

Regulatory proteins bind to the edges of base pairs exposed in the major grooves of DNA. Most of these regulatory proteins contain structural motifs, such as zinc finger or leucine zipper. The regulatory proteins are composed of two distinct domains, the DNA-binding domain and the regulatory domain. The DNA-binding domain physically attaches the protein to DNA at a specific site, using one of the structural motifs. The regulatory domain interacts with other regulatory proteins. These two domains of regulatory proteins provide them with an advantage, allowing a regulatory protein to bind to a specific DNA sequence on one site of a chromosome and to exert its regulatory effect over a promoter at another site. The distant sites to which regulatory proteins bind are termed enhancers. The activator regulatory proteins bind to DNA through specific enhancer sequences. Interaction of specific basal transcriptional factors with particular activator proteins is necessary for the proper positioning of RNA polymerase. The rate of transcription is regulated by the availability of these activator regulatory proteins. The repressor regulatory protein, through its regulatory domain, binds to a “silencer” sequence, located adjacent to or overlapping an enhancing sequence. As a result, the corresponding activator protein will no longer be able to bind to the enhancer sequences and will be unavailable to interact with the transcription complex, repressing transcription.

One question remaining unanswered is how a regulatory protein can affect a promoter when these proteins bind to DNA at enhancer/repressor sites located far from the promoter. The current hypothesis is that the DNA loops around so that the enhancer is positioned near the promoter. This configuration brings the regulatory domain of the protein attached to the enhancer into direct contact with the transcription factor associated with the RNA polymerase attached to the promoter.

RNA Polymerase II Elongation Control in Eukaryotes

D.H. Price, in Encyclopedia of Biological Chemistry (Second Edition), 2013

Elongation Maintenance Factors

During transcription, RNA polymerase II is aided by specific factors as it encounters numerous blocks to elongation inherent in a template sequence. During normal transcription in vivo, each nucleotide addition to an RNA chain requires ~50ms on average. However, in vitro RNA polymerase II may pause for seconds or minutes at specific sites in the absence of any accessory factors. TFIIF, a factor required for RNA polymerase II initiation, can also decrease the time that the polymerase spends at pause sites. This has the effect of increasing the overall elongation rate because, for the most part, the elongation rate is determined by how long the polymerase stops at the strongest pause sites. It has been hypothesized that the mechanism utilized by TFIIF involves an interaction-induced change in the polymerase from the paused conformation to the elongation competent form. Other factors that belong in this same class are eleven-nineteen lysine-rich leukemia and elongin, but TFIIF has the most dramatic elongation stimulatory activity. The elongation factor S-II functions by a completely different mechanism. At some sites a fraction of RNA polymerase II molecules fall into an arrested conformation from which they cannot escape unaided. At these sites the 3′ end of the nascent transcript is removed from the active site of the polymerase as the polymerase backslides along the template while maintaining an RNA:DNA hybrid. When this happens, the polymerase may remain engaged for hours or days without extending the transcript. S-II stimulates an intrinsic ribonuclease activity of the polymerase that removes the unpaired 3′ end of the transcript and puts the new 3′ end in register with the active site of the polymerase. This reactivates elongation and the polymerase has a second chance to pass the arrest site. Eventually, all polymerases can pass the arrest site, although many may require several rounds of S-II-mediated transcript cleavage. Through the combined function of both classes of factors, the elongation rate of RNA polymerase II is maintained between 1000 and 1500 nucleotides per minute.

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Circadian Rhythms and Biological Clocks, Part A

Joonseok Cha, ... Yi Liu, in Methods in Enzymology, 2015

2.4 Chromatin immunoprecipitation

The association of transcription factors, histones, and RNA polymerase II with target sites can provide important information on how they regulate gene expression. WCC rhythmically binds to the frq promoter to drive its circadian transcription (Froehlich et al., 2003; He et al., 2006). CSW-1 and CATP are required to generate a circadian rhythm of chromatin state at the frq locus to ensure proper WCC-driven transcription (Belden, Loros, et al., 2007; Cha et al., 2013). The chromatin immunoprecipitation (ChIP) assay has been widely used to determine whether a protein of interest is associated with a specific genomic region in the cell. We analyzed formaldehyde-fixed chromatin for occupancies by WCC and modified histones at the frq gene and at other clock-controlled gene loci.

To cross-link the proteins with the chromatin, add 1% formaldehyde directly into the liquid culture and incubate for 15min. To stop the cross-linking, add 125mM glycine (pH7.5) and incubate 5min. Then wash the mycelia by transferring to wash buffer (50mM HEPES, pH7.5, 137mM NaCl). Harvest the culture and grind cells in liquid nitrogen. Add 1ml of lysis buffer (50mM HEPES, pH7.5, 137mM NaCl, 1mM EDTA, 1% Triton X-100, 0.1% deoxycholate, 0.1% SDS) with protease inhibitors to around 200μl of cell powder and mix thoroughly. Sonicate the chromatin using Bioruptor (Diagenode) for 15min with a 30s:30s cycle. The sonication conditions should be adjusted based on the size of the sheared chromatin. We obtained <200-bp fragments with the conditions above. Centrifuge (10,000×g, 4°C, 15min) and transfer the supernatant to the fresh tubes. Measure the protein concentration, and dilute 1mg protein into 0.5ml lysis buffer, add preblocked Gammabind G Sepharose (GE Healthcare; incubated with 100mg/ml BSA and 100mg/ml salmon sperm DNA at 4°C with rotation for 4h), and incubate at 4°C for 1h to remove nonspecific binding. Spin down the beads (4000rpm, 2min), and transfer the supernatant to fresh tubes. Remove 50μl to assay “input,” and add appropriate antibody to the remaining chromatin. Incubate at 4°C for 4h (or overnight), add 40μl (10μl beads only) Gammabind G Sepharose, and incubate for 1h. Collect the beads (4000rpm, 2min), and wash the beads sequentially with low-salt washing buffer (0.1% SDS, 1% Triton X-100, 2mM EDTA, 150mM NaCl, 20mM Tris–HCl, pH8), high-salt washing buffer (0.1% SDS, 1% Triton X-100, 2mM EDTA, 500mM NaCl, 20mM Tris–HCl, pH8), LNDET buffer (0.25M LiCl, 1% NP40, 0.1% deoxycholate, 1mM EDTA,10mM Tris–HCl, pH8), and TE buffer (1mM EDTA, 10mM Tris–HCl, pH8).

(Video) Overview of Transcription

To elute DNA from the ChIP samples, we use Chelex 100 resin (Bio-Rad) and incubate at 94°C for 15min. Chill the samples on ice and then spin down (1000×g, 1min); the supernatant is the ChIP DNA. “Input” samples are incubated at 65°C for more than 4 hours to reverse the cross-link, and DNAs are extracted using phenol/chloroform. Quantitative real-time PCR is used to quantify the enrichment of the target site, and the efficiency of primers is verified by analysis of a dilution series of input DNAs.

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The Genetic Basis of Behavior

Bart Ellenbroek, Jiun Youn, in Gene-Environment Interactions in Psychiatry, 2016

mRNA processing

The result of RNA transcription with RNA polymerase II is a single stranded RNA sequence complementary to the entire length of the gene, usually referred to as the primary (RNA) transcript or precursor messenger RNA (pre-mRNA). This transcript, in most cases, contains both protein-coding and noncoding segments (Fig.2.7), so-called exons and introns respectively. The primary RNA transcript therefore has to undergo a series of splicing reactions in which the RNA strand is cut on the boundaries between exons and introns (splice junctions), after which the separate exons are fused together again. In the vast majority of cases, an intron starts with a GT and ends with an AG. We therefore often speak of the GT – AG (or in the case of RNA GU – AG) rule. However, although GT and AG are essential for splicing they are not sufficient by themselves. In addition, introns generally have a branch site, consisting of an adenosine located approximately 18–40 nucleotides upstream of the 3′splice site (ss), and usually followed by a polypyrimidine tract. The introns are removed in a two-step transesterification process: in the first step the 2′ –OH of the adenosine in the branch site carries out a nuclear attack on the 5′ ss, resulting in the cleavage at this site. Subsequently the free 5′ end ligates onto the adenosine leading to form the so-called lariat structure. In the second step, the 3′ end is attacked by the free 3′ –OH of the exon leading to the ligation of the 5′ of exon 1 and the 3′ of exon 2, thereby releasing the exon. Splicing is catalyzed by a large complex of proteins and small RNAs called the spliceosome. In fact, in eukaryotic cells there are two different spliceosomes: the more ubiquitous U2-dependent and the much less abundant U12-dependent spliceosome. The conformation and composition of the spliceosome are flexible and can change rapidly, allowing it to be both accurate and flexible (Will and Luhrmann,2011; Matera and Wang,2014). The U2-dependent spliceosome consists of 5different so-called ribonucleoproteins (snRNP): U1, U2, U5, and U4/U6 as well as numerous other non snRNP proteins. Each snRNP consists of a small nuclear RNA (or two in the case of U4/U6) a common set of seven Sm proteins and a variable number of additional proteins. This complexity is essential to ensure a perfect orientation of the splicing. Similar to the DNA double helix, the spliceosome complex forms many relatively weak interactions with the splice junction, resulting in a strong, highly precise splicing event. For instance, the RNA part of U1 binds to the conserved 5′ ss via the normal base-pairing rule, while the RNA part of U2 recognized the branch point (again binding via the base-pairing rule).

RNA Transcription - an overview (1)

Figure 2.7. mRNA processing.

DNA transcription leads to pre-mRNA which contains all the exons and the introns. Subsequently, through recruitment of the spliceosome the introns are excised leading to the mature mRNA. However, in most cases mRNA is further processed by adding a 7 methylguanoside to the 5 side and a long AMP tail on the 3′ end.

After the splicing out of the introns, two additional changes usually occur in the mRNA (Fig.2.7). First, a 7-methylguanoside (m7G) is linked to the first 5′nucleotide. It is thought that this capping process serves several important functions, including protecting mRNA from exonuclease attack, facilitating the transfer of mRNA from the nucleus to the cytoplasm, and enhancing the attachment of the mRNA to the 40S subunit of the ribosomes, which is essential for the final translation process (see later). Secondly, at the 3′ end of mRNA about 200 adenylate monophosphate (AMP) residues are added by the enzyme poly(A) polymerase. This poly(A) tail is thought to serve similar functions as the 5′ capping process: facilitation of the transport from the nucleus to the cytoplasm, stabilizing the mRNA molecule in the cytoplasm and enhancing the binding to the ribosomes.

An important aspect of mRNA processing is alternative splicing, which refers to the inclusion (and exclusion) of different exons in the final mRNA. It has been suggested that about 95% of all mammalian genes undergo alternative splicing. As a result, about 20,000 human protein coding genes can lead to between 250,000 and 1 million different proteins (de Klerk and 't Hoen,2015). An analysis of 15 different human cell lines showed that a single gene can lead to 25 different mRNAs, with up to 12 expressed in a single cell (Djebali etal.,2012). It is important to realize that isoforms are not always equally expressed. Some isoforms may indeed be very rare (although this does not necessarily mean they are less important: a small change in a crucial pathway may lead to big effects). Several different mechanisms can underlie alternative splicing. For example, the BDNF gene undergoes significant alternative splicing due to alternative transcription initiation. Thus at least 11 different BDNF transcripts have been identified as a result of different promoters (Aid etal.,2007). In addition, alternative splicing can involve an alternative order of exons, or the exclusion of specific exons. Alternative splicing involves the recruitment of specific RNA-binding proteins that are not part of the normal spliceosome, but can enhance or suppress splicing sites (Witten and Ule,2011).

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(Video) Transcription and Translation: From DNA to Protein

Genome and Gene Structure∗

Madhuri R. Hegde, Michael R. Crowley, in Emery and Rimoin's Principles and Practice of Medical Genetics and Genomics (Seventh Edition), 2019

4.4.4 5′-Untranslated Sequences

Shortly after initiation of mRNA transcription, a 7-methylguanosine residue is added to the 5′ end of the primary transcript (see Fig. 4.6). This 5′ cap is a characteristic of nearly every mRNA molecule [32]. Many functions have been ascribed to the cap, the most notable of which is protection of the mRNA from degradation by exonucleases. The cap may also promote splicing and nuclear export of the RNA and is recognized by the translational machinery. The 5′-UTR extends from the capping site to the beginning of the protein-coding sequence and can be several hundred base pairs in length. The 5′-UTR regions of most mRNAs contain a consensus sequence, 5′-CCA/GCCAUGG-3′, known as a Kozak consensus sequence, involved in the initiation of protein synthesis. In addition, about 5′-UTRs contain upstream AUG codons that can affect the initiation of protein synthesis and thus could serve to control expression of selected genes at the translational level.

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Proenkephalin-Derived Peptides

Patricia J. McLaughlin, in Handbook of Biologically Active Peptides (Second Edition), 2013

Processing

The PPE gene undergoes transcription, RNA processing, and translation to the preprohormone and prohormone of the same name—preproenkephalin A and proenkephalin, respectively. This prohormone undergoes further proteolysis and peptide cleavage to give rise to a variety of active proteins including [Leu5]-enkephalin, [Met5]-enkephalin, Met-enkephalin-Arg-Phe (active heptapeptide), and an octapeptide termed proenkephalin. PPE codes for six copies of [Met5]-enkephalin and one copy of [Leu5]-enkephalin, and the two pentapeptides have received the most attention for their widespread distribution and multifunctionality. The primary site for processing of these peptides is within secretory granules of the Golgi apparatus, and typically the cleavage occurs between pairs of basic amino acids such as Arg–Arg, Arg–Lys, and Lys–Lys.

Despite differences in phosphorylation and/or posttranslational processing, the enkephalins share the same four initial amino acids—tyrosine, glycine, glycine, and phenyalanine (YGGF)—with the N-terminus signifying distinctions in the resulting peptides. Processing of the prohormones is an ongoing event in order to sustain levels of rapid degradable peptides, which have been shown to biodegrade within minutes. In the case of enkephalins, hydrolysis and cleavage of the tyrosine–glycine bond is an initial catabolic step. Further degradation occurs when amino peptidase or nonspecific enkephalinases carve up the pentapeptides into 2, 3, or 4 amino acids, each of which retain some biological activity and serve as signaling entities or as precursors to inhibitory neurotransmitters.14 Two aminopeptidases termed NAP and NAP-2 are responsible for the tissue degradation of these peptides. Additionally, aminopeptidases CD10 and CD13 are specific membrane peptidases reportedly in abundance in plasma and responsible for the very short half-lives of enkephalins ranging from 2 to 5min in circulating blood.29

A discussion on the processing of opioid genes would be remiss if gene duplication from an evolutionary viewpoint was not mentioned.7 The striking similarity in the genes for POMC, prodynorphin, and proenkephalin, and their products suggests that gene duplication leads to the formation of gene families in which there was some divergence in function, as well as duplication of functional end products, throughout phylogenetic development. There are many examples showing that peptides from one or more of the opioid genes (i.e., prodynorphin and proenkephalin genes) serve the same function (e.g., as analgesic molecules) in the same or different region of the central nervous system.

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(Video) Transcription and Translation Overview

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DNA Transcription Definition, Enzymes and Function, DNA transcription Steps, and Process. Reverse Transcription. Transcription Inhibitors.

The major enzyme used in DNA transcription is RNA polymerase .. Image created with biorender.com 50 different protein transcription factors will bind to the promoter sites, on the 5′ side of the gene to be transcribed.. At the end of the termination in prokaryotes, the mRNA formed is ready for translation.. Pre-messenger RNA formation involves the initiation, elongation, and termination phases which end by forming mRNA.. In transcription only one of the DNA strands is transcribed, the strand that has the initiator sequence.. RNA polymerase is the enzyme that catalyzes the mechanism of transcription.. The promoter which is bound with transcription factors along with the RNA polymerase forms a complex.. This is the process of ending transcription, which happens when signaled by a stop sequence known as a terminator sequence.. This happens when the RNA polymerase transcribes the terminator sequence.. At the bubble, the Rho factor pulls the RNA transcript and the DNA template strand apart, releasing the RNA molecule and terminating the transcription process.. At the end of the splicing process, mature mRNA will have been made.. Another major difference is that, in prokaryotes, transcription and translation occur simultaneously while in eukaryotes, transcriptions must be complete before the translation mechanism is initiated.. Transcription inhibitors are elements that are used to inhibit the action and mechanism of the RNA polymerase enzyme, which hinders the process of transcription.

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Quantification of HCV RNA in serum of patients with chronic HCV infection (HCV antibody-positive). Of all individuals infected with hepatitis C virus (HCV), about 75% of them will develop chronic hepatitis C with ongoing viral replication in the liver and detectable HCV RNA in serum or plasma, eventually resulting in cirrhosis.. Reference Values Describes reference intervals and additional information for interpretation of test results.. Except for immunocompromised patients or patients with suspected acute hepatitis, laboratory evaluation of hepatitis C virus (HCV) infection status should begin with HCV serologic testing, including testing for the presence of HCV antibodies (see Hepatitis C: Testing Algorithm for Screening and Diagnosis in Special Instructions).. Quantification of HCV RNA in serum of patients with chronic HCV infection (HCV antibody-positive). HCV RNA Detect/Quant, S. For detection and quantification of hepatitis C viral RNA in serum before, during, and after antiviral therapy for chronic hepatitis C.. Day(s) Performed Outlines the days the test is performed.. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed.. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.. Report Available The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends.. Setup Files. Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

RNA polymerase definition. Prokaryotic and Eukaryotic RNA polymerase. Functions of RNA Polymerase. RNA polymerase I, II, III, IV, V.

Ribonucleic Acid (RNA) Polymerase (RNAP) enzyme is a multi-subunit enzyme that applies its activity in the catalyzation of the transcription process of RNA synthesized from a DNA template.. And therefore, RNA polymerase enzyme is responsible for the copying of DNA sequences into RNA sequences during transcription.. The function of RNA polymerase is to control the process of transcription, through which copying of information stored in DNA into a new molecule of messenger RNA (mRNA.). The enzyme RNA polymerase interacts with proteins to enable it to function in catalyzation of the synthesis of RNA.. The collaborator proteins assist in enabling the specific binding of RNA polymerase, assist in the unwinding of the double chemical structure of DNA, moderate the enzymatic activities of RNA polymerase and to control the speed of transcription.. RNA polymerase is an enzyme that is responsible for copying a DNA sequence into an RNA sequence, during the process of transcription.. As a complex molecule composed of protein subunits, RNA polymerase controls the process of transcription, during which the information stored in a molecule of DNA is copied into a new molecule of messenger RNA.. Prokaryotic (Bacteria, viruses, archaea) organisms have a single type of RNA polymerase that synthesizes all the subtypes of RNA, while eukaryotes (multicellular organisms) have 5 different types of RNA polymerases which perform different functions in the synthesis of different RNA molecules.. SubunitSizeFunction β150.4 kDaThe β’ + β form the catalytic center, responsible for RNA synthesis.β’155.0 kDaThe β’ + β form the catalytic center, responsible for RNA synthesis.α (αI and αII)36.5 kDaIt is made up of the enzyme assembly, and it also binds the UP sequence in the promoter.ω155.0 kDaIt confers specificity for promoter; and binds to -10 and -35 sites in the promoter.. These enzymes are much more related to bacterial RNA polymerase than to the nuclear RNA polymerase.. Animal Cell- Definition, Structure, Parts, Functions, Labeled Diagram Plant Cell- Definition, Structure, Parts, Functions, Labeled Diagram DNA Transcription (RNA Synthesis)- Article, Diagrams and Video 7 Types of RNA with Structure and Functions Cell Organelles- Definition, Structure, Functions, Diagram. RNA polymerase is used in the production of molecules that play a wide range of roles, of which one of its functions is to regulate the number and type of RNA transcript that is formed in response to the requirements of the cell.

DNA and RNA are similar yet different in just the right way to perform their functions perfectly.

Image Source: Wikimedia Commons The central dogma explains the flow of the genetic code from DNA through all three types RNA to making protein.. Figure 2: The structures of DNA and RNA, with the molecular structure of their bases.. Image Source: Wikimedia Commons Both DNA and RNA have four nitrogenous bases each—three of which they share (Cytosine, Adenine, and Guanine) and one that differs between the two (RNA has Uracil while DNA has Thymine).. The three different types of RNA associated with the central dogma are messenger RNA (mRNA), transporter RNA (tRNA) and ribosomal RNA (rRNA).. DNA is self-sufficient, providing a template for its DNA replication and the information for RNA synthesis.. Since DNA needs to maintain its integrity, it is of utmost important to ensure that it is exposed to minimal danger and to ensure this it is confined to the nucleus where several proteins are entrusted with its safety while RNA ensures that the functions of DNA are fulfilled.. RNA is transcribed from the DNA to make these proteins (the central dogma, Figure 1).. What DNA can’t do, RNA can and what DNA can do RNA can’t.

Videos

1. Protein Synthesis (Updated)
(Amoeba Sisters)
2. RNA: Transcription Overview
(Gerry Bergtrom)
3. Transcription Made Easy- From DNA to RNA (2019)
(MEDSimplified)
4. RNA Transcription Overview
(Stephanie Painchaud)
5. From DNA to protein - 3D
(yourgenome)
6. DNA replication and RNA transcription and translation | Khan Academy
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