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Dounce Homogenizer
Invented by and named for Alexander Dounce , a Dounce homogenizer or "Douncer", is a cylindrical glass tube, closed at one end, with two glass pestles of carefully specified outer diameters, intended for the gentle homogenization of eukaryotic cells (e.g. mammalian cells). Dounce homogenizers are still commonly used today to isolate cellular organelles. The two Dounce homogenizer pestles (known as the "loose" or "A" and "tight" or "B" pestles), have a carefully specified outer diameter, relative to the inner diameter of the cylinder. The "A" (loose) pestle has a clearance from the cylinder wall of (~0.0025 - 0.0055 in.) while the "B" (tight) pestle has a clearance of (~0.0005 - 0.0025 in.). This allows for tissue and cells to be lysed by shear stress with minimal (if any) degree of heating, thereby leaving extracted organelles or heat-sensitive enzyme complexes largely intact. Typically, a soft tissue (e.g. mammalian liver) is cut or broken into smaller pieces and placed into th ...
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Tissue Glass Dounce Homogenizer-03
Tissue may refer to: Biology * Tissue (biology), an ensemble of similar (or dissimilar in structure but same in origin) cells that together carry out a specific function * ''Triphosa haesitata'', a species of geometer moth ("tissue moth") found in North America * ''Triphosa dubitata'', a species of geometer moth ("tissue") found in Afro-Eurasia Paper products * Tissue paper, a type of thin, gauzy translucent paper used for wrapping and cushioning items ** Facial tissue, tissue paper used for cleaning the face ** Japanese tissue, tissue paper from Japan made of vegetable fibers ** Toilet paper, tissue paper used for cleaning the anus ** Wrapping tissue, tissue paper used for wrapping and cushioning items Other * Aerial tissue Aerial silks (also known as aerial contortion, aerial ribbons, aerial tissues, fabric, ribbon, or ''tissu'') is a type of performance in which one or more artists perform aerial acrobatics while hanging from a specialist fabric. The fabric may ..., an ac ...
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Alexander Dounce
Alexander Latham Dounce (December 7, 1909 – April 24, 1997) was an American professor of biochemistry. Among his fields of study were the isolation and purification of cellular organelles, protein crystallization, enzymes (specifically catalase), DNA binding proteins, and the chemical basis of protein synthesis. He also invented the Dounce homogenizer, which was named after him. Biography Alexander Dounce was born on December 7, 1909, in New York. He began his undergraduate studies at Hamilton College but later moved to Cornell University, where he also did his doctoral studies in the lab of James B. Sumner, a pioneer in protein crystallization. Dounce received his PhD in organic chemistry in 1935, the title of his thesis being "''Study of dihydrofurans and the dehydration rearrangement of 2,3-ethylenic 1,4-diols''". According to Marshall W. Nirenberg, another biochemist who knew Dounce personally, "during his ounce'sfinal doctoral exam when his doctoral committee got toge ...
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FASEB J
''The FASEB Journal'' is a scientific journal related to experimental biosciences, promoting scientific progress and education. It is published by the Federation of American Societies for Experimental Biology The Federation of American Societies for Experimental Biology (FASEB) is a non-profit organization that is the principal umbrella organization of U.S. societies in the field of biological and medical research. This organization organizes academ ..., that was founded in 1912, originally by three societies (29 as of January 2019 ). References Publications established in 1912 Biology journals Monthly journals Academic journals published by learned and professional societies 1912 establishments in the United States {{biology-journal-stub ...
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Homogenization (biology)
Homogenization, in cell biology or molecular biology, is a process whereby different fractions of a biological sample become equal in composition. It can be a disease sign in histopathology, or an intentional process in research: A homogenized sample is equal in composition throughout, so that removing a fraction does not alter the overall molecular make-up of the sample remaining, and is identical to the fraction removed. Induced homogenization in biology is often followed by molecular extraction and various analytical techniques, including ELISA and western blot. Methods Homogenization of tissue in solution is often performed simultaneously with cell lysis. To prevent lysis however, the tissue (or collection of cells, e.g. from cell culture) can be kept at temperatures slightly above zero to prevent autolysis, and in an isotonic solution to prevent osmotic damage. If freezing the tissue is possible, cryohomogenization can be performed under "dry" conditions, and is often the m ...
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Eukaryotic Cells
Eukaryotes () are organisms whose Cell (biology), cells have a cell nucleus, nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the Three-domain system, three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard (archaea), Asgard archaea. This implies that there are only Two-domain system, two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass (ecology), biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as Flagellated cell, flagellated phagotrophs. The ...
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Shear Stress
Shear stress, often denoted by (Greek: tau), is the component of stress coplanar with a material cross section. It arises from the shear force, the component of force vector parallel to the material cross section. ''Normal stress'', on the other hand, arises from the force vector component perpendicular to the material cross section on which it acts. General shear stress The formula to calculate average shear stress is force per unit area.: : \tau = , where: : = the shear stress; : = the force applied; : = the cross-sectional area of material with area parallel to the applied force vector. Other forms Wall shear stress Wall shear stress expresses the retarding force (per unit area) from a wall in the layers of a fluid flowing next to the wall. It is defined as: \tau_w:=\mu\left(\frac\right)_ Where \mu is the dynamic viscosity, u the flow velocity and y the distance from the wall. It is used, for example, in the description of arterial blood flow in which case which ther ...
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Lysis Buffer
A lysis buffer is a buffer solution used for the purpose of breaking open cells for use in molecular biology experiments that analyze the labile macromolecules of the cells (e.g. western blot for protein, or for DNA extraction). Most lysis buffers contain buffering salts (e.g. Tris-HCl) and ionic salts (e.g. NaCl) to regulate the pH and osmolarity of the lysate. Sometimes detergents (such as Triton X-100 or SDS) are added to break up membrane structures. For lysis buffers targeted at protein extraction, protease inhibitors are often included, and in difficult cases may be almost required. Lysis buffers can be used on both animal and plant tissue cells. Choosing a buffer The primary purpose of lysis buffer is isolating the molecules of interest and keeping them in a stable environment. For proteins, for some experiments, the target proteins should be completely denatured, while in some other experiments the target protein should remain folded and functional. Different prote ...
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Saccharomyces Cerevisiae
''Saccharomyces cerevisiae'' () (brewer's yeast or baker's yeast) is a species of yeast (single-celled fungus microorganisms). The species has been instrumental in winemaking, baking, and brewing since ancient times. It is believed to have been originally isolated from the skin of grapes. It is one of the most intensively studied eukaryotic model organisms in molecular biology, molecular and cell biology, much like ''Escherichia coli'' as the model bacteria, bacterium. It is the microorganism behind the most common type of fermentation (biochemistry), fermentation. ''S. cerevisiae'' cells are round to ovoid, 5–10 micrometre, μm in diameter. It reproduces by budding. Many proteins important in human biology were first discovered by studying their Homology (biology), homologs in yeast; these proteins include cell cycle proteins, signaling proteins, and protein-processing enzymes. ''S. cerevisiae'' is currently the only yeast cell known to have Berkeley body, Berkeley bo ...
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Zymolyase
Zymolyase (also known as lyticase) is an enzyme mixture used to degrade the cell wall of yeast and form spheroplasts. Essential activities of zymolyase include β-1,3-glucan laminaripentao-hydrolase activity and β-1,3-glucanase activity. A common source of zymolyase is the Actinobacteria ''Arthrobacter luteus''. Commercial sources of zymolyase may have some residual protease activity. Fungi susceptible to zymolyase can be found in the order Saccharomycetales. Saccharomycetales genera that zymolyase is known to have activity against include: '' Eremothecium'', '' Candida'', ''Debaryomyces'', '' Eremothecium'', ''Endomyces'', ''Hansenula'', ''Hanseniaspora'', ''Kloekera'', ''Kluyveromyces'', '' Lipomyces'', ''Metschikowia'', ''Pichia'', ''Pullularia'', ''Saccharomyces'', ''Saccharomycopsis'', ''Schizosaccahromyces'', ''Torulopsis ''Candida'' is a genus of yeasts and is the most common cause of fungal infections worldwide. Many species are harmless Commensalism, commensals or ...
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Cell Biology
Cell biology (also cellular biology or cytology) is a branch of biology that studies the structure, function, and behavior of cells. All living organisms are made of cells. A cell is the basic unit of life that is responsible for the living and functioning of organisms. Cell biology is the study of structural and functional units of cells. Cell biology encompasses both prokaryotic and eukaryotic cells and has many subtopics which may include the study of cell metabolism, cell communication, cell cycle, biochemistry, and cell composition. The study of cells is performed using several microscopy techniques, cell culture, and cell fractionation. These have allowed for and are currently being used for discoveries and research pertaining to how cells function, ultimately giving insight into understanding larger organisms. Knowing the components of cells and how cells work is fundamental to all biological sciences while also being essential for research in biomedical fields such as ...
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Biochemistry
Biochemistry or biological chemistry is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all areas of the life sciences are being uncovered and developed through biochemical methodology and research. Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis which allows biological molecules to give rise to the processes that occur within living cells and between cells,Karp (2009), p. 2. in turn relating greatly to the understanding of tissues and organs, as well as organism structure and function.Miller (2012). p. 62. Biochemistry is closely related to molecular biology, which is the study of the molecular mechanisms of biological phenomena.As ...
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