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Hershey–Chase Experiment
The Hershey–Chase experiments were a series of experiments conducted in 1952 by Alfred Hershey and Martha Chase that helped to confirm that DNA is genetic material. While DNA had been known to biologists since 1869, many scientists still assumed at the time that proteins carried the information for inheritance because DNA appeared to be an inert molecule, and, since it is located in the nucleus, its role was considered to be phosphorus storage. In their experiments, Hershey and Chase showed that when bacteriophages, which are composed of DNA and protein, infect bacteria, their DNA enters the host bacterial cell, but most of their protein does not. Hershey and Chase and subsequent discoveries all served to prove that DNA is the hereditary material. Hershey shared the 1969 Nobel Prize in Physiology or Medicine with Max Delbrück and Salvador Luria for their "discoveries concerning the genetic structure of viruses". Historical background In the early twentieth century, biolo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Hershey Chase Experiment
Hershey may refer to: People * Hershey (name), a list of people with the surname, given name or nickname Places * Hershey, Nebraska, a village * Hershey, Pennsylvania, an unincorporated community, home to the chocolate company * Hershey, Cuba, also known as Camilo Cienfuegos, a village in Mayabeque province Companies and organizations * The Hershey Company, North American chocolate manufacturer ** Hershey bar, a Hershey product * Hershey Creamery Company, an unrelated ice cream manufacturer * Hershey Development, a slot machine manufacturer, and parent company of Jennings & Co. * Hershey Electric Railway, from Havana to Matanzas, Cuba * Hershey Trust Company, Milton Hershey's trust * Hershey Entertainment and Resorts Company, Hershey, Pennsylvania: ** Hershey Park ** The Hershey Story Schools * Hershey School of Musical Art, Chicago, Illinois * Hershey High School (Pennsylvania), Hershey, Pennsylvania Sports * Hershey Open, a PGA golf tournament from 1933 to 1941, played ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Maclyn McCarty
Maclyn McCarty (June 9, 1911 – January 2, 2005) was an American geneticist, a research scientist described in 2005 as "the last surviving member of a Manhattan scientific team that overturned medical dogma in the 1940s and became the first to demonstrate that genes were made of DNA." He had worked at Rockefeller University "for more than 60 years." 1994 marked 50 years since this work's release. McCarty devoted his life as a physician-scientist to studying infectious disease organisms, and was best known for his part in the monumental discovery that DNA Deoxyribonucleic acid (; DNA) is a polymer composed of two polynucleotide chains that coil around each other to form a double helix. The polymer carries genetic instructions for the development, functioning, growth and reproduction of al ..., rather than protein, constituted the chemical nature of a gene. Uncovering the molecular secret of the gene in question — that for the capsular polysaccharide of pneumococcal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Plasmolysis
Plasmolysis is the process in which cells lose water in a hypertonic solution. The reverse process, deplasmolysis or cytolysis, can occur if the cell is in a hypotonic solution resulting in a lower external osmotic pressure and a net flow of water into the cell. Through observation of plasmolysis and deplasmolysis, it is possible to determine the tonicity of the cell's environment as well as the rate solute molecules cross the cellular membrane. Etymology The term plasmolysis is derived from the Latin word ‘plasma’ meaning ‘matrix’ and the Greek word ‘lysis’, meaning ‘loosening’. Turgidity A plant cell in hypotonic solution will absorb water by endosmosis, so that the increased volume of water in the cell will increase pressure, making the protoplasm push against the cell wall, a condition known as turgor. Turgor makes plant cells push against each other in the same way and is the main line method of support in non-woody plant tissue. Plant cell walls resi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme, pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
DNase
Deoxyribonuclease (DNase, for short) refers to a group of glycoprotein endonucleases which are enzymes that catalyze the hydrolytic cleavage of phosphodiester linkages in the DNA backbone, thus degrading DNA. The role of the DNase enzyme in cells includes breaking down extracellular DNA (ecDNA) excreted by apoptosis, necrosis, and neutrophil extracellular traps (NET) of cells to help reduce inflammatory responses that otherwise are elicited. A wide variety of deoxyribonucleases are known and fall into one of two families ( DNase I or DNase II), which differ in their substrate specificities, chemical mechanisms, and biological functions. Laboratory applications of DNase include purifying proteins when extracted from prokaryotic organisms. Additionally, DNase has been applied as a treatment for diseases that are caused by ecDNA in the blood plasma. Assays of DNase are emerging in the research field as well. Types The two main types of DNase found in animals are known as deox ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Lysis
Lysis ( ; from Greek 'loosening') is the breaking down of the membrane of a cell, often by viral, enzymic, or osmotic (that is, "lytic" ) mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a ''lysate''. In molecular biology, biochemistry, and cell biology laboratories, cell cultures may be subjected to lysis in the process of purifying their components, as in protein purification, DNA extraction, RNA extraction, or in purifying organelles. Many species of bacteria are subject to lysis by the enzyme lysozyme, found in animal saliva, egg white, and other secretions. Phage lytic enzymes (lysins) produced during bacteriophage infection are responsible for the ability of these viruses to lyse bacterial cells. Penicillin and related β-lactam antibiotics cause the death of bacteria through enzyme-mediated lysis that occurs after the drug causes the bacterium to form a defective cell wall. If the cell wall is completely lost and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Centrifugation
Centrifugation is a mechanical process which involves the use of the centrifugal force to separate particles from a solution according to their size, shape, density, medium viscosity and rotor speed. The denser components of the mixture migrate away from the axis of the centrifuge, while the less dense components of the mixture migrate towards the axis. Chemists and biologists may increase the effective gravitational force of the test tube so that the precipitate (pellet) will travel quickly and fully to the bottom of the tube. The remaining liquid that lies above the precipitate is called a supernatant or supernate. There is a correlation between the size and density of a particle and the rate that the particle separates from a heterogeneous mixture, when the only force applied is that of gravity. The larger the size and the larger the density of the particles, the faster they separate from the mixture. By applying a larger effective gravitational force to the mixture, like ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Agitator (device)
An agitator is a machine, device or Mechanism (engineering), mechanism to put something into Motion (physics), motion by wikt:shaking, shaking or wikt:stirring, stirring. There are several types of agitation machines, including washing machine agitators (which rotate back and forth) and magnetic agitators (which contain a magnetic bar rotating in a magnetic field). Agitators can come in many sizes and varieties, depending on the application. In general, agitators usually consist of an impeller and a shaft. An impeller is a rotor located within a tube or conduit attached to the shaft. It helps enhance the pressure in order for the flow of a fluid be done. Modern industrial agitators incorporate process control to maintain better control over the mixing process. Washing machine agitator In a top load washing machine the agitator projects from the bottom of the wash basket and creates the wash action by rotating back and forth, rolling garments from the top of the load, down to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Progeny (genetic Descendant)
In biology, offspring are the young creation of living organisms, produced either by sexual or asexual reproduction. Collective offspring may be known as a brood or progeny. This can refer to a set of simultaneous offspring, such as the chicks hatched from one clutch of eggs, or to all offspring produced over time, as with the honeybee. Offspring can occur after mating, artificial insemination, or as a result of cloning. Human offspring ( descendants) are referred to as children; male children are sons and female children are daughters (see Kinship). Overview Offspring contains many parts and properties that are precise and accurate in what they consist of, and what they define. As the offspring of a new species, also known as a child or f1 generation, consist of genes of the father and the mother, which is also known as the parent generation. Each of these offspring contains numerous genes which have coding for specific tasks and properties. Males and females both contrib ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
T2 Phage
T, or t, is the twentieth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''tee'' (pronounced ), plural ''tees''. It is derived from the Semitic Taw 𐤕 of the Phoenician and Paleo-Hebrew script (Aramaic and Hebrew Taw ת/𐡕/, Syriac Taw ܬ, and Arabic ت Tāʼ) via the Greek letter τ (tau). In English, it is most commonly used to represent the voiceless alveolar plosive, a sound it also denotes in the International Phonetic Alphabet. It is the most commonly used consonant and the second-most commonly used letter in English-language texts. History '' Taw'' was the last letter of the Western Semitic and Hebrew alphabets. The sound value of Semitic ''Taw'', the Greek alphabet Tαυ (''Tau''), Old Italic and Latin T has remained fairly constant, representing in each of these, and it has also kept its original basic shape in most of these alphabets. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
Radionuclide
A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferred to one of its electrons to release it as a conversion electron; or used to create and emit a new particle (alpha particle or beta particle) from the nucleus. During those processes, the radionuclide is said to undergo radioactive decay. These emissions are considered ionizing radiation because they are energetic enough to liberate an electron from another atom. The radioactive decay can produce a stable nuclide or will sometimes produce a new unstable radionuclide which may undergo further decay. Radioactive decay is a random process at the level of single atoms: it is impossible to predict when one particular atom will decay. However, for a collection of atoms of a single nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
