 Various modes of alternative splicing Alternative splicing is the process that occurs in eukaryotes in which the splicing process of a pre-mRNA transcribed from one gene can lead to different mature mRNA molecules and therefore to different proteins.Viruses have also adapted to this biochemical process when using the protein biosynthesis apparatus. Image File history File links Download high resolution version (1280x1024, 73 KB)Diagram of the various forms of alternative splicing This is a diagram I created using Adobe Photoshop. ...
Image File history File links Download high resolution version (1280x1024, 73 KB)Diagram of the various forms of alternative splicing This is a diagram I created using Adobe Photoshop. ...
Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (IPA: ) is an organism with a complex cell or cells, in which the genetic material is organized into a membrane-bound nucleus or nuclei. ...
In genetics, splicing is a modification of genetic information after transcription, in which introns are removed and exons are joined. ...
Pre-mRNA (preliminary mRNA) is a single strand of ribonucleic acid (RNA), synthesized from the DNA in the nucleus of a cell by the process transcription. ...
The interaction of mRNA in a eukaryote cell. ...
Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus (Latin, poison) is a microscopic particle that can infect the cells of a biological organism. ...
When the pre-mRNA has been transcribed from the DNA, it includes several introns and exons. In nematodes, the mean is 4-5 exons and introns; in the fruit fly Drosophila there can be more than 100 introns and exons in one transcribed pre-mRNA. But introns and exons are not yet determined at this stage. This decision is made during the splicing process. The regulation and selection of splice sites is done by Serine/Arginine-residue proteins, or SR proteins. The use of alternative splicing factors leads to a modification of the definition of a "gene". Some have proposed that a gene should be considered as a twofold information structure: Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living things. ...
Diagram of the location of introns and exons within a gene. ...
An exon is any region of DNA within a gene, that is transcribed to the final messenger RNA (mRNA) molecule, rather than being spliced out from the transcribed RNA molecule. ...
Classes Adenophorea Subclass Enoplia Subclass Chromadoria Secernentea Subclass Rhabditia Subclass Spiruria Subclass Diplogasteria The nematodes or roundworms (Phylum Nematoda from Greek νῆμα (nema): thread + ode like) are one of the most common phyla of animals, with over 20,000 different described species (over 15,000 are parasitic). ...
Binomial name Drosophila melanogaster Meigen, 1830 [1] Drosophila melanogaster (from the Greek for black-bellied dew-lover) is a two-winged insect that belongs to the Diptera, the order of the flies. ...
SR proteins are Serine/Arginine-residue proteins which are involved in regulating and selecting splice sites in eukaryotic mRNA. Alternative splicing requires SR proteins to select which alternative splice sites should be used. ...
- A DNA sequence coding for the pre-mRNA
- An additional DNA code or other regulating process, which regulates the alternative splicing.
There are four known modes of alternative splicing: - Alternative selection of promoters: this is the only method of splicing which can produce an alternative N-terminus domain in proteins. In this case, different sets of promoters can be spliced with certain sets of other exons.
- Alternative selection of cleavage/polyadenylation sites: this is the only method of splicing which can produce an alternative C-terminus domain in proteins. In this case, different sets of polyadenylation sites can be spliced with the other exons.
- Intron retaining mode: in this case, instead of splicing out an intron, the intron is retained in the mRNA transcript. However, the intron must be properly encoding for amino acids. The intron's code must be properly expressible, otherwise a stop codon or a shift in the reading frame will cause the protein to be non-functional.
- Exon cassette mode: in this case, certain exons are spliced out to alter the sequence of amino acids in the expressed protein.
Polyadenylation is the covalent linkage of a polyadenylyl moiety to a messenger RNA (mRNA) molecule. ...
The general structure of an α-amino acid molecule, with the amine group on the left and the carboxyl group on the right. ...
In biology, a reading frame is a contiguous and non-overlapping set of three-nucleotide codons in DNA or RNA. There are 3 possible reading frames in a strand. ...
Importance in molecular genetics Alternative splicing is of great importance to genetics - it invalidates the old theory of one DNA sequence coding for one polypeptide (the "one-gene-one-protein" hypothesis). External information is needed in order to decide which polypeptide is produced, given a DNA sequence and pre-mRNA. (This does not necessarily negate the central dogma of molecular biology which is about the flow of information from genes to proteins). Since the methods of regulation are inherited, the interpretation of a mutation may be changed. Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids. ...
The central dogma of molecular biology was first enunciated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970: The central dogma of molecular biology deals with the detailed residue-by-residue transfer of sequential information. ...
In biology, mutations are changes to the genetic material (either DNA or RNA). ...
It has been proposed that for eukaryotes it was a very important step towards higher efficiency, because information can be stored much more economically. Several proteins can be encoded in a DNA sequence whose length would only be enough for two proteins in the prokaryote way of coding. Others have noted that it is unnecessary to change the DNA of a gene for the evolution of a new protein. Instead, a new way of regulation could lead to the same effect, but leaving the code for the established proteins unharmed. Kingdoms Animalia - Animals Fungi Plantae - Plants Protista A eukaryote (IPA: ) is an organism with a complex cell or cells, in which the genetic material is organized into a membrane-bound nucleus or nuclei. ...
Prokaryotes (from Old Greek pro- before + karyon nut or kernel, referring to the cell nucleus, + suffix -otos, pl. ...
In 1832, while traveling on the Beagle, naturalist Charles Darwin collected giant fossils in South America. ...
Another speculation is that new proteins could be allowed to evolve much faster than in prokaryotes. Furthermore, they are based on hitherto functional amino acid subchains. This may allow for a higher probability for a functional new protein. Therefore the adaptation to new environments can be much faster - with fewer generations - than in prokaryotes. This might have been one very important step for multicellular organisms with a longer life cycle.
A common myth is that alternative splicing is responsible for humans supposedly being the most complex animals, saying that humans perform more alternative splicing than the other animals. However, this is not the case. A study conducted on the subject found that "the amount of alternative splicing is comparable, with no large differences between humans and other animals."[1] The "record-holder" for alternative splicing is actually a Drosophila gene with 38 000 splice variants called Dscam. Type Species Musca funebris Fabricius, 1787 Drosophila is a genus of small flies whose members are often called small fruit flies, or more appropriately vinegar flies, wine flies, pomace flies, grape flies, and picked fruit-flies. ...
DSCAM and Dscam are both acronyms for Down Syndrome Cell Adhesion Molecule. ...
References - ^ http://www.nature.com/ng/journal/v30/n1/abs/ng803.html;jsessionid=BF0AED8347574D063F5E347EC693AE83
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