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Pre-mRNA
A primary transcript is the single-stranded ribonucleic acid (RNA) product synthesized by Transcription (genetics), transcription of DNA, and processed to yield various mature RNA products such as mRNAs, tRNAs, and rRNAs. The primary transcripts designated to be mRNAs are modified in preparation for Translation (biology), translation. For example, a precursor mRNA (pre-mRNA) is a type of primary transcript that becomes a messenger RNA (mRNA) after Post-transcriptional modification, processing. Pre-mRNA is synthesized from a DNA template in the cell nucleus by transcription (genetics), transcription. Pre-mRNA comprises the bulk of heterogeneous nuclear RNA (hnRNA). Once pre-mRNA has been completely Post-transcriptional modification, processed, it is termed "mature messenger RNA", or simply "messenger RNA". The term hnRNA is often used as a synonym for pre-mRNA, although, in the strict sense, hnRNA may include nuclear RNA transcripts that do not end up as cytoplasmic mRNA. There ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alternative Splicing
Alternative splicing, alternative RNA splicing, or differential splicing, is an alternative RNA splicing, splicing process during gene expression that allows a single gene to produce different splice variants. For example, some exons of a gene may be included within or excluded from the final RNA product of the gene. This means the exons are joined in different combinations, leading to different splice variants. In the case of protein-coding genes, the proteins translated from these splice variants may contain differences in their amino acid sequence and in their biological functions (see Figure). Biologically relevant alternative splicing occurs as a normal phenomenon in eukaryotes, where it increases the number of proteins that can be encoded by the genome. In humans, it is widely believed that ~95% of multi-exonic genes are alternatively spliced to produce functional alternative products from the same gene but many scientists believe that most of the observed splice variants ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mature Messenger RNA
Mature messenger RNA, often abbreviated as mature mRNA is a eukaryotic RNA transcript that has been spliced and processed and is ready for translation in the course of protein synthesis. Unlike the eukaryotic RNA immediately after transcription known as precursor messenger RNA, mature mRNA consists exclusively of exons and has all introns removed. Mature mRNA is also called "mature transcript", "mature RNA" or "mRNA". The production of a mature mRNA molecule occurs in 3 steps: # Capping of the 5' end # Polyadenylation of the 3' end # RNA Splicing of the introns Capping the 5' End During capping, a 7-methylguanosine residue is attached to the 5'-terminal end of the primary transcripts.This is otherwise known as the GTP or 5' cap. The 5' cap is used to increase mRNA stability. Further, the 5' cap is used as an attachment point for ribosomes. Beyond this, the 5' cap has also been shown to have a role in exporting the mature mRNA from the nucleus and into the cytoplasm. P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intron
An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. The word ''intron'' is derived from the term ''intragenic region'', i.e., a region inside a gene."The notion of the cistron .e., gene... must be replaced by that of a transcription unit containing regions which will be lost from the mature messenger – which I suggest we call introns (for intragenic regions) – alternating with regions which will be expressed – exons." (Gilbert 1978) The term ''intron'' refers to both the DNA sequence within a gene and the corresponding RNA sequence in RNA transcripts. The non-intron sequences that become joined by this RNA processing to form the mature RNA are called exons. Introns are found in the genes of most eukaryotes and many eukaryotic viruses, and they can be located in both protein-coding genes and genes that function as RNA ( noncoding genes). There are four main types of introns: tRNA introns, group I introns, group I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transcription (genetics)
Transcription is the process of copying a segment of DNA into RNA for the purpose of gene expression. Some segments of DNA are transcribed into RNA molecules that can encode proteins, called messenger RNA (mRNA). Other segments of DNA are transcribed into RNA molecules called non-coding RNAs (ncRNAs). Both DNA and RNA are nucleic acids, which use base pairs of nucleotides as a complementary language. During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand called a primary transcript. In virology, the term transcription is used when referring to mRNA synthesis from a viral RNA molecule. The genome of many RNA viruses is composed of negative-sense RNA which acts as a template for positive sense viral messenger RNA - a necessary step in the synthesis of viral proteins needed for viral replication. This process is catalyzed by a viral RNA dependent RNA polymerase. Background A DNA transcription unit encoding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA Polymerase
In molecular biology, RNA polymerase (abbreviated RNAP or RNApol), or more specifically DNA-directed/dependent RNA polymerase (DdRP), is an enzyme that catalyzes the chemical reactions that synthesize RNA from a DNA template. Using the enzyme helicase, RNAP locally opens the double-stranded DNA so that one strand of the exposed nucleotides can be used as a template for the synthesis of RNA, a process called transcription. A transcription factor and its associated transcription mediator complex must be attached to a DNA binding site called a promoter region before RNAP can initiate the DNA unwinding at that position. RNAP not only initiates RNA transcription, it also guides the nucleotides into position, facilitates attachment and elongation, has intrinsic proofreading and replacement capabilities, and termination recognition capability. In eukaryotes, RNAP can build chains as long as 2.4 million nucleotides. RNAP produces RNA that, functionally, is either for protei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Exon
An exon is any part of a gene that will form a part of the final mature RNA produced by that gene after introns have been removed by RNA splicing. The term ''exon'' refers to both the DNA sequence within a gene and to the corresponding sequence in RNA transcripts. In RNA splicing, introns are removed and exons are covalently joined to one another as part of generating the mature RNA. Just as the entire set of genes for a species constitutes the genome, the entire set of exons constitutes the exome. History The term ''exon'' is a shortening of the phrase ''expressed region'' and was coined by American biochemist Walter Gilbert in 1978: "The notion of the cistron... must be replaced by that of a transcription unit containing regions which will be lost from the mature messengerwhich I suggest we call introns (for intragenic regions)alternating with regions which will be expressedexons." This definition was originally made for protein-coding transcripts that are spliced before b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleotide
Nucleotides are Organic compound, organic molecules composed of a nitrogenous base, a pentose sugar and a phosphate. They serve as monomeric units of the nucleic acid polymers – deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), both of which are essential biomolecules within all Life, life-forms on Earth. Nucleotides are obtained in the diet and are also synthesized from common Nutrient, nutrients by the liver. Nucleotides are composed of three subunit molecules: a nucleobase, a pentose, five-carbon sugar (ribose or deoxyribose), and a phosphate group consisting of one to three phosphates. The four nucleobases in DNA are guanine, adenine, cytosine, and thymine; in RNA, uracil is used in place of thymine. Nucleotides also play a central role in metabolism at a fundamental, cellular level. They provide chemical energy—in the form of the nucleoside triphosphates, adenosine triphosphate (ATP), guanosine triphosphate (GTP), cytidine triphosphate (CTP), and uridine triph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uridine Monophosphate
Uridine monophosphate (UMP), also known as 5′-uridylic acid ( conjugate base uridylate), is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside uridine. UMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase uracil; hence, it is a ribonucleotide monophosphate. As a substituent or radical its name takes the form of the prefix uridylyl-. The deoxy form is abbreviated dUMP. Covalent attachment of UMP (e.g., to a protein such as adenylyltransferase) is called uridylylation (or sometimes uridylation). Biosynthesis Uridine monophosphate is formed from orotidine 5′-monophosphate (orotidylic acid) in a decarboxylation reaction catalyzed by the enzyme orotidylate decarboxylase. Uncatalyzed, the decarboxylation reaction is extremely slow (estimated to occur on average one time per 78 million years). Adequately catalyzed, the reaction takes place once per second, an increase of 1017-fold. In humans, th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Guanosine Monophosphate
Guanosine monophosphate (GMP), also known as 5′-guanidylic acid or guanylic acid (conjugate base guanylate), is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside guanosine. GMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase guanine; hence it is a ribonucleotide monophosphate. Guanosine monophosphate is commercially produced by microbial fermentation. As an acyl substituent, it takes the form of the prefix guanylyl-. ''De novo'' synthesis GMP synthesis starts with D-ribose 5′-phosphate, a product of the pentose phosphate pathway. The synthesis proceeds by the gradual formation of the purine ring on carbon-1 of ribose, with CO2, glutamine, glycine, aspartate and one-carbon derivatives of tetrahydrofolate donating various elements towards the building of the ring. As inhibitor of guanosine monophosphate synthesis in experimental models, the glutamine analogue DON can be used.''Ahluwalia GS et al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytidine Monophosphate
Cytidine monophosphate, also known as 5'-cytidylic acid or simply cytidylate, and abbreviated CMP, is a nucleotide that is used as a monomer in RNA. It is an ester of phosphoric acid with the nucleoside cytidine. CMP consists of the phosphate group, the pentose sugar ribose, and the nucleobase cytosine; hence, a ribonucleoside monophosphate. As a substituent it takes the form of the prefix cytidylyl-. Metabolism CMP can be phosphorylated to cytidine diphosphate by the enzyme CMP kinase, with adenosine triphosphate or guanosine triphosphate donating the phosphate group. Since cytidine triphosphate is generated by amination of uridine triphosphate, the main source of CMP is from RNA being decomposed by RNAse. See also * Deoxycytidine monophosphate * Nucleoside * Oligonucleotide Oligonucleotides are short DNA or RNA molecules, oligomers, that have a wide range of applications in genetic testing, Recombinant DNA, research, and Forensic DNA, forensics. Commonly made in the labor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenosine Monophosphate
Adenosine monophosphate (AMP), also known as 5'-adenylic acid, is a nucleotide. AMP consists of a phosphate group, the sugar ribose, and the nucleobase adenine. It is an ester of phosphoric acid and the nucleoside adenosine. As a substituent it takes the form of the prefix adenylyl-. AMP plays an important role in many cellular metabolic processes, being interconverted to adenosine triphosphate (ATP) and adenosine diphosphate (ADP), as well as allosterically activating enzymes such as myophosphorylase-b. AMP is also a component in the synthesis of RNA. AMP is present in all known forms of life. Production and degradation AMP does not have the high energy phosphoanhydride bond associated with ADP and ATP. AMP can be produced from ADP by the myokinase (adenylate kinase) reaction when the ATP reservoir in the cell is low: : 2 ADP → ATP + AMP Or AMP may be produced by the hydrolysis of one high energy phosphate bond of ADP: : ADP + H2O → AMP + Pi AMP can also be forme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
