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Unsolved Problems In Biology
This article lists notable unsolved problems in biology. General biology Evolution and origins of life *Origin of life. Exactly how, where, and when did life on Earth originate? Which, if any, of the many hypotheses is correct? What were the metabolic pathways used by the earliest life forms? How did genetic code originate? What was the molecular mechanism that allows the association of the amino acids with their triplet codons? What were the biochemical paths from individual bio-building blocks like amino acids or nucleic acids to functional polymers such as proteins and DNA? * Origin of sexual reproduction. What were the fundamental selective forces responsible for the origin of sexual reproduction? * Maintenance of sexual reproduction. What are the fundamental selective forces maintaining sexual reproduction? * Origins of viruses. Exactly how and when did different groups of viruses originate? *Morphology problem. How are neural tissues formed in specific ways in differ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Unsolved Problems
List of unsolved problems may refer to several notable List of conjectures, conjectures or open problems in various academic fields: Natural sciences, engineering and medicine * List of unsolved problems in astronomy, Unsolved problems in astronomy * List of unsolved problems in biology, Unsolved problems in biology * List of unsolved problems in chemistry, Unsolved problems in chemistry * List of unsolved problems in geoscience, Unsolved problems in geoscience * List of unsolved problems in medicine, Unsolved problems in medicine * List of unsolved problems in neuroscience, Unsolved problems in neuroscience * List of unsolved problems in physics, Unsolved problems in physics Mathematics, statistics and information sciences * List of unsolved problems in mathematics, Unsolved problems in mathematics * List of unsolved problems in statistics, Unsolved problems in statistics * List of unsolved problems in computer science, Unsolved problems in computer science * List of unsolved prob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycerophospholipid
Glycerophospholipids or phosphoglycerides are glycerol-based phospholipids. They are the main component of biological membranes in eukaryotic cells. They are a type of lipid, of which its composition affects membrane structure and properties. Two major classes are known: those for bacteria and eukaryotes and a separate family for archaea. Structures Glycerophospholipids are derived from glycerol-3-phosphate in a de novo pathway. The term glycerophospholipid signifies any derivative of glycerophosphoric acid that contains at least one ''O''- acyl, or ''O''-alkyl, or ''O''-alk-1'-enyl residue attached to the glycerol moiety. The phosphate group forms an ester linkage to the glycerol. The long-chained hydrocarbons are typically attached through ester linkages in bacteria/eukaryotes and by ether linkages in archaea. In bacteria and procaryotes, the lipids consist of diesters commonly of C16 or C18 fatty acids. These acids are straight-chained and, especially for the C18 membe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polypeptide
Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty amino acids are called oligopeptides, and include dipeptides, tripeptides, and tetrapeptides. Peptides fall under the broad chemical classes of biological polymers and oligomers, alongside nucleic acids, oligosaccharides, polysaccharides, and others. Proteins consist of one or more polypeptides arranged in a biologically functional way, often bound to ligands such as coenzymes and cofactors, to another protein or other macromolecule such as DNA or RNA, or to complex macromolecular assemblies. Amino acids that have been incorporated into peptides are termed residues. A water molecule is released during formation of each amide bond.. All peptides except cyclic peptides have an N-terminal (amine group) and C-terminal (ca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Folding
Protein folding is the physical process by which a protein, after Protein biosynthesis, synthesis by a ribosome as a linear chain of Amino acid, amino acids, changes from an unstable random coil into a more ordered protein tertiary structure, three-dimensional structure. This structure permits the protein to become biologically functional or active. The folding of many proteins begins even during the translation of the polypeptide chain. The amino acids interact with each other to produce a well-defined three-dimensional structure, known as the protein's native state. This structure is determined by the amino-acid sequence or primary structure. The correct three-dimensional structure is essential to function, although some parts of functional proteins Intrinsically unstructured proteins, may remain unfolded, indicating that protein dynamics are important. Failure to fold into a native structure generally produces inactive proteins, but in some instances, misfolded proteins have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ketamine
Ketamine is a cyclohexanone-derived general anesthetic and NMDA receptor antagonist with analgesic and hallucinogenic properties, used medically for anesthesia, depression, and pain management. Ketamine exists as its S- (esketamine) and R- (arketamine) two enantiomers and has antidepressant action likely involving additional mechanisms than NMDA antagonism. At anesthetic doses, ketamine induces a state of dissociative anesthesia, a trance-like state providing pain relief, sedation, and amnesia. Its distinguishing features as an anesthestic are preserved breathing and airway reflexes, stimulated heart function with increased blood pressure, and moderate bronchodilation. As an anesthetic, it is used especially in trauma, Emergency medical services, emergency, and Pediatrics, pediatric cases. At lower, sub-anesthetic doses, it is used as a treatment for pain and treatment-resistant depression. Ketamine is legally used in medicine but is also tightly controlled due to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thalidomide
Thalidomide, sold under the brand names Contergan and Thalomid among others, is an oral administered medication used to treat a number of cancers (e.g., multiple myeloma), graft-versus-host disease, and many skin disorders (e.g., complications of leprosy such as skin lesions). Updated as required. Thalidomide has been used to treat conditions associated with HIV: aphthous ulcers, HIV-associated wasting syndrome, diarrhea, and Kaposi's sarcoma, but increases in HIV viral load have been reported. Common side effects include sleepiness, rash, and dizziness. Severe side effects include tumor lysis syndrome, blood clots, and peripheral neuropathy. Thalidomide is a known human teratogen and carries an extremely high risk of severe, life-threatening birth defects if administered or taken during pregnancy. It causes skeletal deformities such as Amelia (birth defect), amelia (absence of legs and/or arms), absence of bones, and phocomelia (malformation of the limbs). A single dose of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lithium (medication)
Certain lithium compounds, also known as lithium salts, are used as psychiatric medication, primarily for bipolar disorder and for major depressive disorder. Lithium is taken orally (by mouth). Common side effects include increased urination, shakiness of the hands, and increased thirst. Serious side effects include hypothyroidism, diabetes insipidus, and lithium toxicity. Blood level monitoring is recommended to decrease the risk of potential toxicity. If levels become too high, diarrhea, vomiting, poor coordination, sleepiness, and ringing in the ears may occur. Lithium is teratogenic and can cause birth defects at high doses, especially during the first trimester of pregnancy. The use of lithium while breastfeeding is controversial; however, many international health authorities advise against it, and the long-term outcomes of perinatal lithium exposure have not been studied. The American Academy of Pediatrics lists lithium as contraindicated for pregnancy and lactat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mechanism Of Action
In pharmacology, the term mechanism of action (MOA) refers to the specific biochemical Drug interaction, interaction through which a Medication, drug substance produces its pharmacological effect. A mechanism of action usually includes mention of the specific molecular targets to which the drug binds, such as an enzyme or receptor (biochemistry), receptor. Receptor sites have specific affinities for drugs based on the chemical structure of the drug, as well as the specific action that occurs there. Drugs that do not bind to receptors produce their corresponding therapeutic effect by simply interacting with chemical or physical properties in the body. Common examples of drugs that work in this way are antacids and laxatives. In contrast, a Mode of action, mode of action (MoA) describes functional or anatomical changes, at the cellular level, resulting from the exposure of a living organism to a substance. Importance Elucidating the mechanism of action of novel drugs and medicati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
TRAPP Complex
TRAPP (TRAnsport Protein Particle) is a protein involved in particle transport between organelles. Protein folding and the Endoplasmic Reticulum (ER) Proteins that are destined for the plasma membrane or export to the extracellular environment in eukaryotic cells are translated on ribosomes that sit on the rough endoplasmic reticulum (RER). Most proteins are co-translationally transported into the ER (i.e., while the ribosome is translating the mRNA code into a polypeptide, the polypeptide is simultaneously inserted via the translocon pore into the ER). The ER provides an environment that helps nascent polypeptides fold into and become functional or partially functional proteins. The ER provides an oxidizing environment (for formation of disulfide bonds) and the necessary chaperones (folding assisting agents that are not part of the final protein). Numerous exported proteins form disulfide bonds—covalent bonds that stabilize the protein structure in harsh extracellular environment ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Theory
In biology, cell theory is a scientific theory first formulated in the mid-nineteenth century, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells. Cells are the basic unit of structure in all living organisms and also the basic unit of reproduction. Cell theory has traditionally been accepted as the governing theory of all life, but some biologists consider non-cellular entities such as viruses living organisms and thus disagree with the universal application of cell theory to all forms of life. History With continual improvements made to microscopes over time, magnification technology became advanced enough to discover cells. This discovery is largely attributed to Robert Hooke, and began the scientific study of cells, known as cell biology. When observing a piece of cork under the scope, he was able to see pores. This was shocking at the time as it was believ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Golgi Apparatus
The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic Cell (biology), cells. Part of the endomembrane system in the cytoplasm, it protein targeting, packages proteins into membrane-bound Vesicle (biology and chemistry), vesicles inside the cell before the vesicles are sent to their destination. It resides at the intersection of the secretory, lysosomal, and Endocytosis, endocytic pathways. It is of particular importance in processing proteins for secretion, containing a set of glycosylation enzymes that attach various sugar monomers to proteins as the proteins move through the apparatus. The Golgi apparatus was identified in 1898 by the Italian biologist and pathologist Camillo Golgi. The organelle was later named after him in the 1910s. Discovery Because of its large size and distinctive structure, the Golgi apparatus was one of the first organelles to be discovered and observed in detail. It was d ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Size
Cell most often refers to: * Cell (biology), the functional basic unit of life * Cellphone, a phone connected to a cellular network * Clandestine cell, a penetration-resistant form of a secret or outlawed organization * Electrochemical cell, a device used to convert chemical energy to electrical energy * Prison cell, a room used to hold people in prisons Cell may also refer to: Arts, entertainment, and media Fictional entities * Cell (comics), a Marvel comic book character * Cell (''Dragon Ball''), a character in the manga series ''Dragon Ball'' Literature * ''Cell'' (novel), a 2006 horror novel by Stephen King * "Cells", poem, about a hungover soldier in gaol, by Rudyard Kipling * ''The Cell'' (play), an Australian play by Robert Wales Music * Cell (music), a small rhythmic and melodic design that can be isolated, or can make up one part of a thematic context * Cell (American band) * Cell (Japanese band) * ''Cell'' (album), a 2004 album by Plastic Tree * ''Cells'', a 19 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
