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Mega-telomere
A mega-telomere (also known as an ultra-long telomere or a class III telomere), is an extremely long telomere sequence that sits on the end of chromosomes and prevents the loss of genetic information during cell replication. Like regular telomeres, mega-telomeres are made of a repetitive sequence of DNA and associated proteins, and are located on the ends of chromosomes. However, mega-telomeres are substantially longer than regular telomeres, ranging in size from 50 kilobases to several megabases (for comparison, the normal length of vertebrate telomeres is usually between 10 and 20 kilobases). Telomeres act like protective caps for the chromosome. During cell division, a cell will make copies of its DNA. The enzymes in the cell that are responsible for copying the DNA cannot copy the very ends of the chromosomes. This is sometimes called the "end replication problem". If a cell did not contain telomeres, genetic information from the DNA on the ends of chromosomes would be lost ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytogenetic Telomere Arrays (2005)
Cytogenetics is essentially a branch of genetics, but is also a part of cell biology/cytology (a subdivision of human anatomy), that is concerned with how the chromosomes relate to cell behaviour, particularly to their behaviour during mitosis and meiosis. Techniques used include karyotyping, analysis of G-banded chromosomes, other cytogenetic banding techniques, as well as molecular cytogenetics such as fluorescent ''in situ'' hybridization (FISH) and comparative genomic hybridization (CGH). History Beginnings Chromosomes were first observed in plant cells by Carl Nägeli in 1842. Their behavior in animal ( salamander) cells was described by Walther Flemming, the discoverer of mitosis, in 1882. The name was coined by another German anatomist, von Waldeyer in 1888. The next stage took place after the development of genetics in the early 20th century, when it was appreciated that the set of chromosomes (the karyotype) was the carrier of the genes. Levitsky seems to ha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microchromosomes
A microchromosome (μChr) is a type of very small chromosome which is a typical component of the karyotype of birds, some reptiles, fish, and amphibians; they have yet to be found in mammals. They are less than 20 Mb in size; chromosomes which are greater than 40 Mb in size are known as macrochromosomes (MChrs), while those between 20 and 40 Mb are classified as intermediate chromosomes. Microchromosomes are characteristically very small and often cytogenetically indistinguishable in a karyotype. While originally thought to be insignificant fragments of chromosomes, in species where they have been studied they have been found to be rich in genes and high in GC content. In chickens, microchromosomes have been estimated to contain between 50 and 75% of all genes. The presence of microchromosomes makes ordering and identifying chromosomes into a coherent karyotype particularly difficult. During metaphase, they appear merely as 0.5-1.5 μm long specks. Their small size and poor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chemiluminescence
Chemiluminescence (also chemoluminescence) is the emission of light (luminescence) as the result of a chemical reaction. There may also be limited emission of heat. Given reactants A and B, with an excited intermediate ◊, : + -> lozenge -> roducts+ light For example, if is luminol and is hydrogen peroxide in the presence of a suitable catalyst we have: :\underset + \underset -> 3-APAlozenge-> + light where: * 3-APA is 3-aminophthalate * 3-APA ''◊is the vibronic excited state fluorescing as it decays to a lower energy level. General description The decay of this excited state ''◊to a lower energy level causes light emission. In theory, one photon of light should be given off for each molecule of reactant. This is equivalent to the Avogadro number of photons per mole of reactant. In actual practice, non-enzymatic reactions seldom exceed 1% QC, quantum efficiency. In a chemical reaction, reactants collide to form a transition state, the enthalpic maximum in a r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dot Blot
A dot blot (or slot blot) is a technique in molecular biology used to detect proteins. It represents a simplification of the western blot method, with the exception that the proteins to be detected are not first separated by electrophoresis. Instead, the sample is applied directly on a membrane in a single spot, and the blotting procedure is performed. The technique offers significant savings in time, as chromatography or gel electrophoresis, and the complex blotting procedures for the gel are not required. However, it offers no information on the size of the target protein. Uses Performing a dot blot is similar in idea to performing a western blot, with the advantage of faster speed and lower cost. Dot blots are also performed to screen the binding capabilities of an antibody. Methods A general dot blot protocol involves spotting 1–2 microliters of a samples onto a nitrocellulose or PVDF membrane and letting it air dry. Samples can be in the form of tissue culture sup ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EcoRI
''Eco''RI (pronounced "eco R one") is a restriction endonuclease enzyme isolated from species '' E. coli.'' It is a restriction enzyme that cleaves DNA double helices into fragments at specific sites, and is also a part of the restriction modification system. The ''Eco'' part of the enzyme's name originates from the species from which it was isolated - "E" denotes generic name which is "Escherichia" and "co" denotes species name, "coli" - while the R represents the particular strain, in this case RY13, and the I denotes that it was the first enzyme isolated from this strain. In molecular biology it is used as a restriction enzyme. ''Eco''RI creates 4 nucleotide sticky ends with 5' end overhangs of AATT. The nucleic acid recognition sequence where the enzyme cuts is G↓AATTC, which has a palindromic, complementary sequence of CTTAA↓G. Other restriction enzymes, depending on their cut sites, can also leave 3' overhangs or blunt ends with no overhangs. Structure Primary str ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HaeIII
''Hae''III is one of many restriction enzymes ( endonucleases) a type of prokaryotic DNA that protects organisms from unknown, foreign DNA. It is a restriction enzyme used in molecular biology laboratories. It was the third endonuclease to be isolated from the ''Haemophilus aegyptius'' bacteria. The enzyme's recognition site—the place where it cuts DNA molecules—is the GGCC nucleotide sequence which means it cleaves DNA at the site 5′-GG/CC-3. The recognition site is usually around 4-8 bps.This enzyme's gene has been sequenced and cloned. This is done to make DNA fragments in blunt ends. HaeIII is not effective for single stranded DNA cleavage. Properties ''Hae''III has a molecular weight of 37126. After a 2-10-fold of ''Hae''III takes place, there is overdigestion of a DNA substrate. This results in 100% being cut, more than 50% of fragments being ligated, and more than 95% being recut. Heat inactivation comes at about 80 °C for 20 minutes. The locus of the ''Hae ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Restriction Enzymes
A restriction enzyme, restriction endonuclease, REase, ENase or'' restrictase '' is an enzyme that cleaves DNA into fragments at or near specific recognition sites within molecules known as restriction sites. Restriction enzymes are one class of the broader endonuclease group of enzymes. Restriction enzymes are commonly classified into five types, which differ in their structure and whether they cut their DNA substrate at their recognition site, or if the recognition and cleavage sites are separate from one another. To cut DNA, all restriction enzymes make two incisions, once through each sugar-phosphate backbone (i.e. each strand) of the DNA double helix. These enzymes are found in bacteria and archaea and provide a defense mechanism against invading viruses. Inside a prokaryote, the restriction enzymes selectively cut up ''foreign'' DNA in a process called ''restriction digestion''; meanwhile, host DNA is protected by a modification enzyme (a methyltransferase) that modifi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slot Blot
A dot blot (or slot blot) is a technique in molecular biology used to detect proteins. It represents a simplification of the western blot method, with the exception that the proteins to be detected are not first separated by electrophoresis. Instead, the sample is applied directly on a membrane in a single spot, and the blotting procedure is performed. The technique offers significant savings in time, as chromatography or gel electrophoresis, and the complex blotting procedures for the gel are not required. However, it offers no information on the size of the target protein. Uses Performing a dot blot is similar in idea to performing a western blot, with the advantage of faster speed and lower cost. Dot blots are also performed to screen the binding capabilities of an antibody. Methods A general dot blot protocol involves spotting 1–2 microliters of a samples onto a nitrocellulose or PVDF membrane and letting it air dry. Samples can be in the form of tissue culture su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PFGE
Pulsed field gel electrophoresis is a technique used for the separation of large DNA molecules by applying to a gel matrix an electric field that periodically changes direction. Historical background Standard gel electrophoresis techniques for separation of DNA molecules provided huge advantages for molecular biology research. However, it was unable to separate very large molecules of DNA effectively. DNA molecules larger than 15–20 kb migrating through a gel will essentially move together in a size-independent manner. At Columbia University in 1984, David C. Schwartz and Charles Cantor developed a variation on the standard protocol by introducing an alternating voltage gradient to improve the resolution of larger molecules. This technique became known as pulsed-field gel electrophoresis (PFGE). The development of PFGE expanded the range of resolution for DNA fragments by as much as two orders of magnitude. Procedure The procedure for this technique is relatively similar to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Slot Blot Technique With Chicken Genomic DNA (2005)
Slot, the slot or Slots may refer to: People * Arne Slot (born 1978), Dutch footballer * Gerrie Slot (born 1954), Dutch cyclist * Hanke Bruins Slot (born 1977), Dutch politician * Tonny Bruins Slot (born 1947), Dutch association football coach who is known for his analyses of matches and opponents * Jørgen Slots, a Danish-born periodontist in the United States * Margareta Slots (died 1669), Dutch-born mistress of Gustav II Adolf of Sweden Arts, entertainment, and media * Slot (band), a Russian alternative/nu metal band * Slot, abbreviation of St. Laurence O'Toole Pipe Band, a pipe band based in Dublin, Ireland * Dance slot, an imaginary narrow rectangle along which a follower moves back and forth with respect to the leader * ''The Slot'' (TV series), an Australian television series Sport * Slot (ice hockey), the area on the hockey rink directly ahead of the goaltender between the faceoff circles on each side * Slot, a space within a formation during a game of American footba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluorescence In Situ Hybridization
Fluorescence ''in situ'' hybridization (FISH) is a molecular cytogenetic technique that uses fluorescent probes that bind to only particular parts of a nucleic acid sequence with a high degree of sequence complementarity. It was developed by biomedical researchers in the early 1980s to detect and localize the presence or absence of specific DNA sequences on chromosomes. Fluorescence microscopy can be used to find out where the fluorescent probe is bound to the chromosomes. FISH is often used for finding specific features in DNA for use in genetic counseling, medicine, and species identification. FISH can also be used to detect and localize specific RNA targets (mRNA, lncRNA and miRNA) in cells, circulating tumor cells, and tissue samples. In this context, it can help define the spatial-temporal patterns of gene expression within cells and tissues. Probes – RNA and DNA In biology, a probe is a single strand of DNA or RNA that is complementary to a nucleotide sequence o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described. Vertebrates comprise such groups as the following: * jawless fish, which include hagfish and lampreys * jawed vertebrates, which include: ** cartilaginous fish (sharks, rays, and ratfish) ** bony vertebrates, which include: *** ray-fins (the majority of living bony fish) *** lobe-fins, which include: **** coelacanths and lungfish **** tetrapods (limbed vertebrates) Extant vertebrates range in size from the frog species ''Paedophryne amauensis'', at as little as , to the blue whale, at up to . Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns. The vertebrates traditionally include the hagfish, which do no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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