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CRISPR-associated Transposons
CRISPR-associated transposons or CASTs are mobile genetic elements ( MGEs) that have evolved to make use of minimal CRISPR systems for RNA-guided transposition of their DNA. Unlike traditional CRISPR systems that contain interference mechanisms to degrade targeted DNA, CASTs lack proteins and/or protein domains responsible for DNA cleavage. Specialized transposon machinery, similar to that of the well characterized Tn7 transposon A transposable element (TE), also transposon, or jumping gene, is a type of mobile genetic element, a nucleic acid sequence in DNA that can change its position within a genome. The discovery of mobile genetic elements earned Barbara McClinto ..., complexes with the CRISPR RNA (crRNA) and associated Cas proteins for transposition. CAST systems have been characterized in a wide range of bacteria and make use of variable CRISPR configurations including Type I-F, Type I-B, Type I-C, Type I-D, Type I-E, Type IV, and Type V-K. MGEs remain an important part ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mobile Genetic Elements
Mobile genetic elements (MGEs), sometimes called selfish genetic elements, are a type of genetic material that can move around within a genome, or that can be transferred from one species or replicon to another. MGEs are found in all organisms. In humans, approximately 50% of the genome are thought to be MGEs. MGEs play a distinct role in evolution. Gene duplication events can also happen through the mechanism of MGEs. MGEs can also cause mutations in protein coding regions, which alters the protein functions. These mechanisms can also rearrange genes in the host genome generating variation. These mechanisms can increase fitness by gaining new or additional functions. An example of MGEs in evolutionary context are that virulence factors and antibiotic resistance genes of MGEs can be transported to share genetic code with neighboring bacteria. However, MGEs can also decrease fitness by introducing disease-causing alleles or mutations. The set of MGEs in an organism is called a mobil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CRISPR
CRISPR (; acronym of clustered regularly interspaced short palindromic repeats) is a family of DNA sequences found in the genomes of prokaryotic organisms such as bacteria and archaea. Each sequence within an individual prokaryotic CRISPR is derived from a DNA fragment of a bacteriophage that had previously infected the prokaryote or one of its ancestors. These sequences are used to detect and destroy DNA from similar bacteriophages during subsequent infections. Hence these sequences play a key role in the antiviral (i.e. anti- phage) defense system of prokaryotes and provide a form of heritable, acquired immunity. CRISPR is found in approximately 50% of sequenced bacterial genomes and nearly 90% of sequenced archaea. Cas9 (or "CRISPR-associated protein 9") is an enzyme that uses CRISPR sequences as a guide to recognize and open up specific strands of DNA that are complementary to the CRISPR sequence. Cas9 enzymes together with CRISPR sequences form the basis of a technology ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Transposable Element
A transposable element (TE), also transposon, or jumping gene, is a type of mobile genetic element, a nucleic acid sequence in DNA that can change its position within a genome. The discovery of mobile genetic elements earned Barbara McClintock a Nobel Prize in 1983. There are at least two classes of TEs: Class I TEs or retrotransposons generally function via reverse transcription, while Class II TEs or DNA transposons encode the protein transposase, which they require for insertion and excision, and some of these TEs also encode other proteins. Discovery by Barbara McClintock Barbara McClintock discovered the first TEs in maize (''Zea mays'') at the Cold Spring Harbor Laboratory in New York. McClintock was experimenting with maize plants that had broken chromosomes. In the winter of 1944–1945, McClintock planted corn kernels that were self-pollinated, meaning that the silk (style) of the flower received pollen from its own anther. These kernels came from a long line ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CRISPR RNA
CRISPR RNA or crRNA is a RNA transcript from the CRISPR locus. CRISPR-Cas (clustered, regularly interspaced short palindromic repeats - CRISPR associated systems) is an adaptive immune system found in bacteria and archaea to protect against mobile genetic elements, like viruses, plasmids, and transposons. The CRISPR locus contains a series of repeats interspaced with unique spacers. These unique spacers can be acquired from MGEs. Pre-crRNA is formed after the transcription of the CRISPR locus and before being processed by Cas proteins. Mature crRNA transcripts contain a partial conserved section of repeat and a sequence of spacer that is complementary to the target DNA. crRNA forms an effector complex with a single nuclease or multiple Cas proteins called a Cascade (CRISPR-associated complex for antiviral defense). Once the effector complex is formed a Cas nuclease or single effector protein will cause interference guided by the crRNA match. Function Type-I Type-I CRISPR ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trans-activating CrRNA
In molecular biology, trans-activating CRISPR RNA (tracrRNA) is a small ''trans''-encoded RNA. It was first discovered by Emmanuelle Charpentier in her study of the human pathogen ''Streptococcus pyogenes'', a type of bacteria that causes harm to humanity. In bacteria and archaea, CRISPR-Cas (clustered, regularly interspaced short palindromic repeats/CRISPR-associated proteins) constitute an RNA-mediated defense system that protects against viruses and plasmids. This defensive pathway has three steps. First, a copy of the invading nucleic acid is integrated into the CRISPR locus. Next, CRISPR RNAs ( crRNAs) are transcribed from this CRISPR locus. The crRNAs are then incorporated into effector complexes, where the crRNA guides the complex to the invading nucleic acid and the Cas proteins degrade this nucleic acid. There are several CRISPR system subtypes. Type II CRISPR-Cas systems require a tracrRNA which plays a role in the maturation of crRNA. The tracrRNA is partially comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wikipedia Student Program
Wikipedia is a free online encyclopedia that is written and maintained by a community of volunteers, known as Wikipedians, through open collaboration and the wiki software MediaWiki. Founded by Jimmy Wales and Larry Sanger in 2001, Wikipedia has been hosted since 2003 by the Wikimedia Foundation, an American nonprofit organization funded mainly by donations from readers. Wikipedia is the largest and most-read reference work in history. Initially available only in English, Wikipedia exists in over 340 languages. The English Wikipedia, with over million articles, remains the largest of the editions, which together comprise more than articles and attract more than 1.5 billion unique device visits and 13 million edits per month (about 5edits per second on average) . , over 25% of Wikipedia's traffic comes from the United States, while Japan, the United Kingdom, Germany and Russia each account for around 5%. Wikipedia has been praised for enabling the democra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biotechnology
Biotechnology is a multidisciplinary field that involves the integration of natural sciences and Engineering Science, engineering sciences in order to achieve the application of organisms and parts thereof for products and services. Specialists in the field are known as biotechnologists. The term ''biotechnology'' was first used by Károly Ereky in 1919 to refer to the production of products from raw materials with the aid of living organisms. The core principle of biotechnology involves harnessing biological systems and organisms, such as bacteria, yeast, and plants, to perform specific tasks or produce valuable substances. Biotechnology had a significant impact on many areas of society, from medicine to agriculture to environmental science. One of the key techniques used in biotechnology is genetic engineering, which allows scientists to modify the genetic makeup of organisms to achieve desired outcomes. This can involve inserting genes from one organism into another, and con ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
