Biology question and answer
Who was Macleod, John James Richard ?
Macleod, John James Richard (1876–1935) Scottish Physiologist John James Richard Macleod was born on September 6, 1876, in Cluny, near Dunkeld, Perthshire, Scotland, to the Rev. Robert Macleod. Macleod went to the grammar school at Aberdeen and later entered the Marischal College of the University of Aberdeen to study medicine. In 1898 he worked for a year at the Institute for Physiology at the University of Leipzig, and the following year he was appointed demonstrator of physiology at the London Hospital Medical School.
In 1903 he was appointed professor of physiology at the Western Reserve University at Cleveland, Ohio, in the United States. In 1918 he became professor of physiology at the University of Toronto, Canada, and served as director of the physiological laboratory and as an associate dean of the faculty of medicine. In 1928 he was appointed Regius professor of physiology at the University of Aberdeen, a position he held until his death.
For his work on the discovery of insulin with Frederick BANTING, he was awarded the Nobel Prize in physiology or medicine for 1923.
Macleod conducted research in carbohydrate metabolism, focusing especially on diabetes, and published some 37 papers on carbohydrate metabolism and 12 papers on experimentally produced glycosuria (sugar in the urine).
He wrote 11 books and monographs, including Recent Advances in Physiology (with Sir Leonard Hill) (1905); Physiology and Biochemistry of Modern Medicine; Diabetes: Its Pathological Physiology (1925); Carbohydrate Metabolism and Insulin (1926); and the Vanuxem lectures, published in 1928 as the Fuel of Life. He died on March 16, 1935.
What is macroevolution ?
Evolution that deals with largescale and complex changes such as the rise of species, mass extinctions, and evolutionary trends.
What is macromolecule ?
A large molecule of high molecular mass composed of more than 100 repeated monomers, single chemical units of lower relative mass; a polymer. DNA, proteins, and polysaccharides are examples of macromolecules in living systems; a large complex molecule formed from many simpler molecules.
What is macrophages ?
Blood cells that are able to ingest a wide variety of particulate materials. They are a type of PHAGOCYTE.
What is magnetic circular dichroism ?
magnetic circular dichroism (MCD) A measurement of CIRCULAR DICHROISM of a material that is induced by a magnetic field applied parallel to the direction of the measuring light beam. Materials that are achiral still exhibit MCD (the Faraday effect), since the magnetic field leads to the lifting of the degeneracy of electronic orbital and spin states and to the mixing of electronic states. MCD is frequently used in combination with absorption and CD studies to affect electronic assignments. The three contributions to the MCD spectrum are the A-term, due to Zeeman splitting of the ground and/or excited degenerate states; the B-term, due to field-induced mixing of states; and the C-term, due to a change in the population of molecules over the Zeeman sublevels of a paramagnetic ground state. The C-term is observed only for molecules with ground-state paramagnetism, and becomes intense at low temperatures; its variation with field and temperature can be analyzed to provide magnetic parameters of the ground state, such as spin, g-factor, and zero-field splitting. Variable-temperature MCD is particularly effective in identifying and assigning electronic transitions originating from paramagnetic CHROMOPHOREs.
What is magnetic resonance imaging (MRI) ?
The visualization of the distribution of nuclear spins (usually water) in a body by using a magnetic field gradient (NMR IMAGING). A similar technique, but less widely used, is to visualize the distribution of paramagnetic centers (EPR imaging).
What is magnetic susceptibility ?
For paramagnetic materials, the magnetic susceptibility can be measured experimentally and used to give information on the molecular magnetic dipole moment, and hence on the electronic structure of the molecules in the material. The paramagnetic contribution to the molar magnetic susceptibility of a material, χ, is related to the molecular magnetic dipole moment m by the Curie relation: χ = constant m2/T.
What is magnetotactic ?
Ability to orient in a magnetic field.
What is major histocompatibility complex (MHC) ?
A large cluster of genes on chromosome 6 in humans, encoding cell-surface proteins that play several roles in the immune system. Several classes of protein such as MHC class I and II proteins are encoded in this region. In humans, these are known as human leukocyte antigens (HLA). Class I protein molecules are designated HLA A, B, or C. Class II molecules are designated DP, DQ, or DR.
The ability of T lymphocytes to respond only when they “see” the appropriate antigen in association with “self” MHC class I or class II proteins on the antigenpresenting cells is called MHC restriction.
What is malaria ?
A tropical disease caused by a protozoa of the genus Plasmodium (Plasmodium falciparum) and transmitted to humans by the bite of mosquitoes of the genus Anopheles.
What is malignant ?
Term used to designate a cancerous condition.
What is Mallophaga ?
One of the insect orders, known as chewing lice, with three families, Menoponidae, Philopteridae, and Trichodectidae, and made up of the chewing lice, characterized by flattened, wingless bodies, chewing mouthparts, and gradual metamorphosis. Commonly found on dogs and cats.
What is Malpighian tubule ?
An excretory organ in arthropods (insects) that correspond functionally to the kidneys of vertebrates. The tubules maintain internal salt and water balance and remove wastes such as urea; uric acid; urates of sodium, calcium, and ammonia; leucin; and various salts of calcium and potassium (oxalates, carbonates, and phosphates). Most of the nitrogen excreted is in the form of uric acid. Opens into the posterior section of the alimentary canal (gut). In some insects, such as Mermeleon formicarius, Chrysopa perla, and Euplectrus bicolor, the Malpighian tubules produce a substance just before the time of pupation that is spun out of the anus in the form of silk threads, with which the cocoon is woven.
What is Mammalia ?
A class of warm-blooded animals that have three characteristics not shared by other animals: body hair; the production of milk for nourishment of their infants by mammary glands (teats), which are modified sweat glands; and the three middle ear bones (malleus, incus, and stapes). Placental mammals have a vascular-connected placenta formed between the embryo and mother (e.g., humans, bears, whales). Aplacental mammals do not (e.g., marsupials and monotremes). Most mammals also have differentiated teeth. Found on land and sea, there are around 5,000 species placed in 26 orders.
What is mange ?
A partial or complete lack or removal of hair resulting from various disorders or conditions. Also a form of dermatitis caused by species of mites (for example, Sarcoptes scabiei causes sarcoptic mange or scabies). Also called alopecia.
What is mantle ?
A membranous or muscular outer form of tissue that surrounds the visceral mass in a mollusk and secretes the shell and periostracum, the outermost layer of shell that provides protection.
What is marine ?
Refers to sediments or environments in seas or ocean waters.
What is marsupial ?
An aplacental mammal whose young are born undeveloped and complete their embryonic development not inside the body of the mother but, rather, inside a maternal pouch called a marupium, located on the outside of the body, in which the young attach to the mother’s nipples. Kangaroos, wombats, bandicoots, opossums, and Koala bears are examples. Found only in Australia, Tasmania, New Guinea, and a few nearby islands, except for the opossum, which is the only North American marsupial.
What is Mastigophora ?
A phylum composed of the most primitive type of protozoans. Usually parasitic, they have many flagella for movement, and some can form pseudopodia, used for food engulfing or movement, called flagellates. They live inside host organisms to obtain nutrients and cause diseases such as trichomoniasis, giardiasis, trypanosomiasis, and leishmaniasis.
What is matrilineal ?
Societies in which descent is traced through mothers rather than through fathers. Property is often passed from mothers to daughters, and the custom of matrilocal residence may be encouraged. Many Native American nations are matrilineal.
What is matrix ?
Often described as a scaffolding, support, or cell growth director (intercellular); it is a complex network of nonliving fibrous material of the connective tissues that acts as structural support. Examples include the skin, cartilage, bone, tendon, and muscle.
What is matter ?
Any substance that has inertia and occupies physical space; can exist as solid, liquid, gas, plasma, foam, or Bose–Einstein condensate.
What is mean ?
A statistical method used to indicate a point on the scale of measures where the population is centered. The mean is the average of the scores in a population.
What is mechanoreceptor ?
A specialized sensory receptor that responds to mechanical stimuli, e.g., tension, pressure, or displacement. Examples include the inner-ear hair cells, carotid sinus receptors, and muscle spindles.
Who was Mechnikov, Ilya Ilyich ?
Mechnikov, Ilya Ilyich (1845–1916) Russian Zoologist Ilya Ilyich Mechnikov was born on May 16, 1845, in a village near Kharkoff in Russia to an officer of the Imperial Guard, who was a landowner in the Ukraine steppes.
Mechnikov went to school at Kharkoff and was interested in natural history. He attended the University of Kharkoff to study natural sciences. After graduating at Kharkoff, he went to study marine fauna at Heligoland, and then to the University of Giessen, the University of Göttingen, and the Munich Academy. In 1865, while he was at Giessen, he discovered intracellular digestion in one of the flatworms. At Naples he prepared a thesis for his doctorate on the embryonic development of the cuttle-fish Sepiola and the crustacean Nelalia.
In 1882, in a private laboratory he set up, he discovered the phenomenon of phagocytosis. In 1888 he went to Paris, where Louis Pasteur gave him a laboratory and an appointment in the Pasteur Institute, where he remained for the rest of his life.
Apart from his work on phagocytosis, Mechnikov published many papers on the embryology of invertebrates. These included work on the embryology of insects, published in 1866, and, in 1886, his studies of the embryology of medusae. At the Pasteur Institute in Paris, Mechnikov was engaged in work associated with the establishment of his theory of cellular immunity. He published several papers and two volumes on the comparative pathology of inflammation (1892), and in 1901 he published a treatise entitled L’Immunité dans les Maladies Infectieuses (Immunity in infectious diseases). In 1908 he was awarded, together with Paul EHRLICH, the Nobel Prize in physiology or medicine.
He later proved that syphilis can be transmitted to monkeys and took up the study of the flora (lacticacid-producing bacteria) of the human intestine and developed a theory that senility is due to poisoning of the body by the products of certain of these bacteria.
Mechnikov received many distinctions, among which were the honorary D.Sc. of the University of Cambridge, the Copley Medal of the Royal Society of which he was a foreign member, the honorary memberships of the Academy of Medicine in Paris and the Academies of Sciences and of Medicine in St. Petersburg. In addition, he was a corresponding member of several other societies and a foreign member of the Swedish Medical Society. He died on July 16, 1916.
What is mediator modulator ?
An object or substance by which something is mediated, such as:
Concerning mediators of immediate hypersensitivity, the most important include histamine, leukotriene (e.g., SRS-A), ECF-A, PAF, and serotonin. There also exist three classes of lipid mediators that are synthesized by activated mast cells through reactions initiated by the actions of phospholipase A2. These are prostaglandins, leukotrienes, and platelet-activating factors (PAF).
What is medicinal chemistry ?
A chemistry-based discipline, also involving aspects of biological, medical, and pharmaceutical sciences. It is concerned with the invention, discovery, design, identification, and preparation of biologically active compounds; the study of their METABOLISM; the interpretation of their mode of action at the molecular level; and the construction of STRUCTURE-ACTIVITY RELATIONSHIPS.
What is medulla oblongata ?
One part of the brain stem, along with the midbrain, pons, and reticular formation; connects the brain to the spinal cord through the foramen magnum. Nerve tissue that deals with vital functions in respiration, circulation (heart rate, blood flow), and vasomotor; controls reflexes such as coughing, sneezing, swallowing, vomiting, and gagging.
What is medusa ?
One of two basic life cycles of Cnidaria (i.e., hydra, jellyfish, anemones, and corals), the other being polyps. The medusa form is a free-swimming, floating, umbrellalike, flat, mouth-down version. Polyps’ forms are sessile. Body parts on both forms are similar. Most medusa have separate sexes. The eggs are fertilized after they are shed into the water and usually grow into polyp form that, in a form of asexual reproduction, may break into multiple medusas.
What is megapascal (MPa) ?
A unit of pressure. 1 MPa = 1,000,000 Pa (pascal). 1 megapascal (MPa) = 10 bars. A value of 1 bar is approximately equal to one atmosphere of pressure.
What is meiosis ?
The reductive division of diploid cells in ovaries and testes that produce gametes (sperm and ova). Two divisions with several stages take place that result in the production of four daughter cells, each of which contain half (haploid) of the original number of chromosomes.
What is melanism ?
A medical condition usually seen in the skin, characterized by abnormal deposits of melanin.
What is membrane potential ?
The difference in electrical charge (voltage difference) across the cell membrane due to a slight excess of positive ions on one side and of negative ions on the other; potential inside a membrane minus the potential outside. A typical membrane potential is –60 mV, where the inside is negative relative to the surrounding fluid, and resting membrane potentials are typically found between –40 and –100 mV.
What is memory cell ?
Cells (lymphocytes) that have been exposed to specific antigens and remain in the body after an immune response to attack those same antigens if reexposed to them in the future. Memory cells are subsets of T and B cells.
who was Mendel, Gregor Johann ?
Mendel (1822–84) was an Austrian botanist and monk who was the first to lay the groundwork for the foundation of the science of genetics, using his now famous experiments with breeding peas at his monastery. His groundbreaking research paper “Experiments in Plant Hybridization,” was read at a meeting on February 8, 1865. He concluded that genes were not blends of parental traits, but instead were separate physical entities passed individually in specific proportions from one generation to the next.
What is Menkes’ disease ?
A sex-linked inherited disorder, causing defective gastrointestinal absorption of copper and resulting in copper deficiency early in infancy.
What is menstrual cycle ?
The cyclical growth and destruction of the female endometrium each month; a stage of the female reproductive cycle. As an egg matures and is released monthly, hormones such as estrogen stimulate the thickening of the endometrium. Progesterone stops the growth of the endometrium and prepares the body for pregnancy. If it does not occur, the endometrium becomes a bloody discharge through the cervix into the vagina, thus ending the menstrual period.
What is meristem ?
A group of plant cells that can divide indefinitely and can provide new cells for the plant as long as it lives.
What is meroblastic cleavage ?
meroblastic cleavage (incomplete cleavage) is a type of cleavage where only part of the fertilized egg, the blastodisc, goes through division, usually leaving a large concentration of yolk in the egg; observed in avian development.
What is mesentery ?
A membrane fold (peritoneum) suspending, attaching, and anchoring various organs to the body cavity, such as the small intestine and spleen; provides blood, lymphatic vessels, and nerve supply to and from the organs. The term mesentery is used generically describing peritoneal extensions not only from the intestine but from all abdominal and pelvic organs.
What is mesoderm ?
The middle (mesos) of three germ layers (endo- and ectoderms are the other two) of the early embryo during gastrulation, early mammalian embryonic development, that gives rise to blood, cartilage, circulatory system, connective tissue, gonads, kidneys, and muscle. Three regions of the mesoderm are responsible for specific parts: the epimere or dorsal mesoderm forms somites, discrete clumps of mesoderm, which forms the connective tissue layer of the skin, most of the bony skeleton, and most of the striated musculature (each somite is further split into dermotome, myotome, and sclerotome segments); the mesomere or intermediate mesoderm, which differentiate into the kidney and urogenital structures; and the hypomere, which differentiate into limbs, peritoneum, gonads, heart, blood vessels, and mesenteries.
What is mesophyll ?
Plant tissue that forms the inner or middle cells of the leaf and lies between the upper and lower epidermis. It contains two types of chlorenchyma cells (cells that contain chlorophyll): the long and vertically arranged palisade cells, the upper layer, which are on top of the round and loosely packed spongy cells in the lower layer, where most of the gas exchange occurs and where photosystem II is most active. It is in both the palisade and spongy cells that photosynthesis takes place by way of chloroplasts.
What is mesotrophic lake ?
Any lake with a moderate nutrient supply.
What is Mesozoic era ?
A geological time that extends from the end of the Paleozoic era (230 million years ago) to the beginning of the Cenozoic era (about 65 million years ago). Subdivided into the Triassic, Jurassic, and Cretaceous periods, which includes the age of the dinosaurs.
What is messenger RNA (mRNA) ?
An RNA molecule that transfers the coding information for protein synthesis from the chromosomes to the ribosomes. Fragments of ribonucleic acid serve as templates for protein synthesis by carrying genetic information from a strand of DNA to ribosomes for translation into a protein. The information from a particular gene or group of genes is transferred from a strand of DNA by constructing a complementary strand of RNA through transcription. Transfer RNA (tRNA), composed of three nucleotide segments attached to specific amino acids, correctly match with a template strand of mRNA, lining up the correct order of amino acids and bonding them, via translation in the ribosome with rRNA (ribosomal RNA), to form a protein.
What is met ?
A qualifying prefix indicating the oxidized form of the parent protein, e.g., methemoglobin.
What is metabolism ?
The entire physical and chemical processes involved in the maintenance and reproduction of life in which nutrients are broken down to generate energy and to give simpler molecules (CATABOLISM), which by themselves may be used to form more complex molecules (ANABOLISM).
What is In the case of heterotrophic organisms, the energy evolving from catabolic processes is made available for use by the organism. ?
In medicinal chemistry, the term metabolism refers to the biotransformation of xenobiotics and particularly DRUGs.
What is metabolite ?
Any intermediate or product resulting from METABOLISM.
What is metalloenzyme ?
An ENZYME that, in the active state, contains one or more metal ions that are essential for its biological function.
What is metallo-immunoassay ?
A technique in which ANTIGEN-ANTIBODY recognition is used, with attachment of a metal ion or metal complex to the antibody. The specific absorption or (radioactive) emission of the metal is then used as a probe for the location of the recognition sites.
What is metallothionein ?
A small, cysteine-rich protein that binds heavy metal ions, such as zinc, cadmium, and copper in the form of CLUSTERs.
What is metamorphosis ?
The change and reorganization of the tissues and body shape during the development of an animal from larva to adult. Metamorphosis can be complete or incomplete, i.e., lacking a pupal stage. Simple or gradual metamorphosis is an incomplete metamorphosis with no pupa and with young immature forms looking similar to the adult minus wings.
What is metanephridium ?
Excretory organ or tubule surrounded by capillaries in invertebrates (e.g., annelid worms) in which nephrostomes, the internal ciliated funnel-shaped opening, collects body fluids and nitrogenous compounds and discharges at the other end, the nephridiopore. Also reabsorbs fatty acids, water, and amino acids back into circulation.
What is metaphase ?
A development stage in mitosis or meiosis. Characterized by chromosomes aligning along the equatorial plane of the cell.
What is metapopulation ?
Groups of local species populations where each group occupies separate habitat patches that often are connected by corridors allowing migration between them.
What is metastasis ?
The spread of cancer cells from one part of the body to another.
What is Metazoa ?
The kingdom that includes all multicellular organisms. It includes vertebrates and invertebrates.
What is methane mono-oxygenase ?
A METALLOENZYME that converts methane and dioxygen to methanol using NADH as coSUBSTRATE. Two types are known, one containing a dinuclear oxo-bridged iron center; the other is a copper protein.
What is methanogens ?
Strictly ANAEROBIC ARCHAEA that are able to use a variety of SUBSTRATES (e.g., dihydrogen, formate, methanol, methylamine, carbon monoxide, or acetate) as electron donors for the reduction of carbon dioxide to methane.
What is me-too drug ?
A compound that is structurally very similar to already known DRUGs, with only minor pharmacological differences.
Who was Meyerhof, Otto Fritz ?
Meyerhof, Otto Fritz (1884–1951) German Physiologist, Chemist Otto Fritz Meyerhof was born on April 12, 1884, in Hannover to Felix Meyerhof, a merchant, and Bettina May. He went to the Wilhelms Gymnasium (classical secondary school) in Berlin, leaving at age 14 only to have kidney problems two years later, which kept him confined for a long period. He eventually studied medicine at Freiburg, Berlin, Strassburg, and Heidelberg and graduated in 1909. From 1912 he worked at the University of Kiel, becoming a professor in 1918.
Meyerhof conducted experiments on the energy changes in cellular respiration. For his discovery of the fixed relationship between the consumption of oxygen and the metabolism of lactic acid in the muscle, he was awarded, together with the English physiologist A.V. HILL, the Nobel Prize in physiology or medicine in 1922. In 1925 Meyerhof successfully extracted the enzymes that convert glycogen to lactic acid from the muscle. He introduced the term glycolysis to describe the anaerobic degradation of glycogen to lactic acid, and showed the cyclic nature of energy transformations in living cells. This metabolic pathway of glycolysis— conversion of glucose to lactic acid—is now known as the Embden-Meyerhof pathway, after Meyerhof and Gustav George Embden.
During World War II, he went to the United States and became research professor of physiological chemistry, a position created for him by the University of Pennsylvania and the Rockefeller Foundation. He died from a heart attack on October 6, 1951.
What is Michaelis-Menten kinetics ?
The dependence of the initial rate of conversion of a SUBSTRATE (S) of the product (P) by an ENZYME or other catalyst (E).
What is microevolution ?
The smallest scale of evolution; changes within a species; a change in allele or genotype frequencies over time.
What is microfilament (actin filament) ?
A minute solid helical rod—about 7 nm in diameter, composed of the protein actin found in most eukaryotic cell cytoplasm—that makes up part of the cytoskeleton and often is found in association with microtubules. Plays a role in cell mobility, cytokinesis, and, with myosin, part of the contractile mechanism of skeletal muscle. One of three protein filaments of the cytoskeleton, along with microtubules and intermediate filaments. The cytoskeleton provides structural support for the cell and movement of organelles, chromosomes, as well as the cell itself.
What is micronutrient ?
A compound essential for cellular growth, being present in concentrations in minute amounts in the growth medium.
What is microtubule ?
A lengthy hollow cylindrical structure composed of the protein tubulin. One of three protein filaments of the cytoskeleton, along with microfilaments and intermediate filaments, it is also found in cilia, flagella, and centrioles. The cytoskeleton provides structural support for the cell and movement of organelles, chromosomes, as well as the cell itself. Microtubules also form the spindle fibers of mitosis.
What is microvillus ?
Very small hairlike or fingerlike projection from the surface of some types of epithelial cells, particular those in the small intestine, where they serve to increase surface area.
What is middle lamella ?
The gel-like pectin layer between adjacent plant cell walls that binds or cements the plant cells together; in woody tissues, lignin replaces pectin.
What is mimicry ?
The ability of an individual to look or share similar traits of an individual of a different species to protect it from predation. It can be in the form of protective coloration, imitation of characteristics, or deception. Two forms of mimicry are common. BATESIAN MIMICRY is where the mimic, which is palatable to a predator, resembles an unpalatable species; and MÜLLERIAN MIMICRY is where two or more unpalatable species have a reduced predation rate due to their similarity, so that predators avoid them to a greater degree than they would individually. The viceroy butterfly, which mimics the monarch, is an example of Batesian mimicry, while the queen butterfly (Danaus gilippus), which is a poisonous butterfly, mimics the poisonous monarch and is an example of Müllerian mimicry.
What is mineral ?
A naturally occurring homogeneous solid, inorganically formed, with a definite chemical composition, usually crystalline in form, and an ordered atomic arrangement, e.g., quartz.
What is mineralocorticoid ?
Any of the group of C21 (21 carbon) corticosteroids, principally aldosterone, that are predominantly involved in the regulation of electrolyte and water balance through their effect on ion transport in epithelial cells of the renal tubules. This results in retention of sodium and loss of potassium. Some also possess varying degrees of glucocorticoid activity. Their secretion is regulated principally by plasma volume, serum potassium concentration, and angiotensin II and, to a lesser extent, by anterior pituitary ACTH (adrenocorticotropic hormone).
What is minimum dynamic area ?
The smallest area of habitat necessary to sustain a viable population.
What is minimum viable population (MVP) ?
The smallest isolated population having the best chance of surviving for x years, regardless of natural catastrophes or future demographic, environmental, and genetic variables.
Who was Minot, George Richards ?
Minot, George Richards (1885–1950) was American Pathologist George Richards Minot was born on December 2, 1885, in Boston, Massachusetts, to James Jackson Minot, a physician, and Elizabeth Whitney. He attended Harvard University and received a B.A. degree in 1908, an M.D. in 1912, and an honorary degree of Sc.D. in 1928. In 1915 he was appointed assistant in medicine at the Harvard Medical School and the Massachusetts General Hospital. From 1928 to 1948 he was professor of medicine at Harvard and director of the Thorndike Memorial Laboratory, Boston City Hospital.
What is Earlier research revealed that anemia in dogs, induced by excessive bleeding, is reversed by a diet of raw liver. In 1926 Minot and William MURPHY found that ingestion of a half pound of raw liver a day dramatically reversed pernicious anemia in human beings. He received (with George WHIPPLE and William Murphy) the Nobel Prize for physiology or medicine in 1934 for the introduction of a raw-liver diet in the treatment of pernicious anemia, which up to that time was almost always a fatal disease. Today, 10,000 lives a year are saved in the United States alone because of this discovery. ?
With chemist Edwin Cohn, they prepared liver extracts that, when taken orally, constituted the primary treatment for pernicious anemia until 1948, when vitamin B was discovered. Minot died on February 25, 1950, in Brookline, Massachusetts.
What is Miocene ?
A geological age that extends from the end of the Oligocene epoch (22.5 million years ago) to the beginning of the Pliocene epoch (5 million years ago).
What is missense mutation ?
One of four types of point mutations. A point mutation is when a triplet of three nucleotides (codon) has the base sequence permanently changed. A missense mutation is when a change in the base sequence converts a codon from one amino acid to a codon for a different amino acid. The other three point mutations are nonsense (codon for a specific amino acid is converted to a chain-terminating codon), silent (converts a codon for an amino acid to another codon that specifies the same amino acid), and frameshift (nucleotide is deleted or added to the coding portion of a gene) mutations.
What is Mississippian age ?
The first of the two geologic ages of the Carboniferous period, extending from about 345 to 310 million years ago. The Pennsylvanian is the second (310 to 280 million years ago).
What is mites ?
Mites and ticks belong to the order Acari and are the most diverse and abundant of all arachnids. Very small in size, usually less than a millimeter in length, they are ubiquitous, found in almost every part of the world, and account for 30,000 species in at least 50 families. Many are parasitic and cause disease.
What is mitochondria ?
Cytoplasmic organelles of most eukaryotic cells, they are surrounded by a double membrane and produce ADENOSINE 5’-TRIPHOSPHATE as useful energy for the cell by oxidative PHOSPHORYLATION. The proteins for the ATP-generating electron transport of the respiration chain are located in the inner mitochondrial membrane. Mitochondria contain many ENZYMEs of the citric acid cycle and for fatty acid ßoxidation. They also contain DNA, which encodes some of their proteins, the remainder being encoded by nuclear DNA.
What is mitochondrial matrix ?
Each mitochondrion is surrounded by a double membrane. The aqueous matrix is bounded within the inner membrane and contains ribosomes and oxidative enzymes.
What is mitosis ?
The cell division process in eukaryotic cells that replicates chromosomes so that two daughter cells get equally distributed genetic material from a parent cell, making them identical to each other and the parent. It is a four-step process that includes prophase (prometaphase), metaphase, anaphase, and telophase. Interphase is the time in the cell cycle when DNA is replicated in the nucleus.
What is mixed valency ?
This is one of several names, such as “mixed oxidation state” or “nonintegral oxidation state,” used to describe COORDINATION compounds and CLUSTERs in which a metal is present in more than one level of oxidation. The importance in biology is due to the often-complete delocalization of the valence electrons over the cluster, allowing efficient electrontransfer processes.
What is mobbing ?
The display of a flock of small birds attacking a larger predatory bird to keep it away from nests, a defensive posturing.
What is model ?
A synthetic COORDINATION entity that closely approaches the properties of a metal ion in a protein and yields useful information concerning biological structure and function. Given the fact that the term is also loosely used to describe various types of molecular structures, constructed, for example, in the computer, the term BIOMIMETIC is more appropriate.
What is modern synthesis ?
The neo-Darwinism theory of evolution. A modern theory about how evolution works at the level of genes, phenotypes, and populations.
What is molarity ?
The number of moles of solute dissolved in 1 liter of solution.
What is mold ?
Molds are naturally occurring clusters of microscopic fungi that reproduce by releasing airborne spores. Certain individuals with a mold allergy will develop asthma and nasal symptoms if they breathe in these spores. Many people are allergic to mold. Mold spores are carried in the air and can be present all year long. Mold is most prevalent indoors, in damp locations and in bathrooms, washrooms, fabrics, rugs, stuffed animals, books, wallpaper, and other “organic” materials. Outdoors, mold lives in the soil, on compost, and on damp vegetation.
What is mole (mol) ?
An amount of substance that contains as many items (such as ions, molecules, etc.) as the number of atoms in exactly 12 grams of carbon (C). The number of molecules contained is equal to 6.022 × 1023 (602,200,000,000,000,000,000,000), known as Avogadro’s number. Thus a mole is anything that has Avogadro’s number of items in it.
What is molecular formula ?
The formula of a compound in which the subscripts give the actual number of each element in the formula.
What is molecular graphics ?
The visualization and manipulation of three-dimensional representations of molecules on a graphical display device.
What is molecular modeling ?
A technique for the investigation of molecular structures and properties using computational chemistry and graphical visualization techniques in order to provide a plausible three-dimensional representation under a given set of circumstances.
What is molecule ?
The smallest unit in a chemical element or compound that contains the chemical properties of the element or compound. They are made of atoms held together by chemical bonds that form when they share or exchange electrons. They can vary in complexity from a simple sharing of two atoms, such as oxygen, O2, to a more complex substance such as nitroglycerin, C3H5(NO3)3.
What is molt ?
The process of periodically losing old skin or exoskeleton and replacing it with a new one. Reptiles shed their skin, birds shed feathers, and butterflies molt several times during their development.
What is ?
What is molybdenum cofactor (Moco) ?
The molybdenum complex of the MOLYBDOPTERIN PROSTHETIC GROUP (LIGAND). In the molybdenum COFACTOR, the minimal COORDINATION of the Mo atom is thought to be provided by the chelating dithiolenato group of the molybdopterin and either two oxo or one oxo and one sulfide ligands.
What is molybdopterin ?
The PROSTHETIC GROUP associated with the Mo atom of the MOLYBDENUM COFACTOR found in all molybdenum-containing ENZYMEs except NITROGENASE. Many of the enzymes catalyze twoelectron redox reactions that involve the net exchange of an oxygen atom between a SUBSTRATE and water. The molybdopterin prosthetic group contains a pterin ring bound to a dithiolene functional group on the 6-alkyl side chain. In bacterial enzymes a NUCLEOTIDE is attached to the phosphate group.
What is Monera ?
The large prokaryotic kingdom that includes archaebacteria, eubacteria, and cyanobacteria, members of which were the first forms of life over 3.5 billion years ago. All bacteria belong to the kingdom Monera.
What is ?
Who was Moniz, António Caetano de Abreu Freire Egas ?
Moniz, António Caetano de Abreu Freire Egas (1874–1955) Portuguese Neuroscientist António Caetano de Abreu Freire Egas Moniz was born in Avanca, Portugal, on November 29, 1874, to Fernando de Pina Rezende Abreu and Maria do Rosario de Almeida e Sousa. He received his early education from his uncle before joining the Faculty of Medicine at Coimbra University. He continued his education in Bordeaux and Paris, received his doctor’s degree in medicine in 1899, and became professor at Coimbra in 1902. In 1911 he became the new chair in neurology at Lisbon and stayed there until his death.
Moniz also participated in politics in 1903, serving as a deputy in the Portuguese parliament until 1917, when he became Portuguese ambassador to Spain. In 1917 he was appointed minister for foreign affairs and was president of the Portuguese delegation at the Paris Peace Conference in 1918.
Aside from politics, Moniz discovered cerebral angiography and prefrontal leucotomy (lobotomy). He was awarded a Nobel Prize in medicine in 1949 for developing the first psychosurgery procedure, frontal leucotomy, and a surgical interruption of nerve fibers that connect the frontal or prefrontal areas of the cerebral cortex of the brain. He published a number of books, including Physiological and Pathological Aspects of Sex Life, 1901; Neurology in War, 1917; A Year of Politics, 1920; Diagnostics of Cerebral Tumours and Application of Arterial Encephalography, 1931; Tentative Methods in the Treatment of Certain Psychoses, 1936; Prefrontal Leucotomy: Surgical Treatment of Certain Psychoses, 1937; Clinical Cerebral Angiography, 1938; Cerebral Arteriography and Phlebography, 1940; On the Side of Medicine, 1940; How I Came to Perform Leucotomy, 1948; and even History of Playing-Cards, 1942.
Moniz received numerous honors during his career and is considered the father of modern psychosurgery. He died on December 13, 1955, in Lisbon.
What is monoamine ?
Small organic molecule containing both a carboxyl group and an amino group bonded to the same carbon atom, e.g., histamine, serotonine, epinephrine, and norepinephrine.
What is monoclonal ?
Literally, coming from a single clone. A clone is the progeny of a single cell. In immuno logy, monoclonal generally describes a preparation of antibody that is monogenous, or cells of a single specificity.
What is ?
What is monoclonal antibodies ?
Laboratory-produced antibodies, which can be programmed to react against a specific antigen in order to suppress the immune response.
What is monocot ?
Monocotyledonae, a subclass of the angiosperms, that has as characteristics an embryo containing one cotyledon, parallel leaf veins, pollen with single furrow or pore, stem vascular bundles scattered, secondary growth absent, adventitious roots, and flower parts in multiples of three. Monocots comprise some one-quarter of all flowering plants in the world, about 65,000 species divided among 9 families: Gramineae, Liliaceae, Iridaceae, Orchidaceae, Palmae, Pandanaceae, Agavaceae, Bromeliaceae, Musaceae. Includes lilies, orchids, palms, and grasses. Economically important monocots such as corn, rice, wheat, barley, sugar cane, pineapples, dates, and bananas make up much of the food supply.
Monocots reproduce sexually. The flowering plants contain female carpels and male stamens. Monocots are primarily tropical, with the exception of the lilies, asparagus, and gumflower.
What is monoculture ?
The practice of raising only one species on a large land area. Makes planting and harvesting easier with a large machine like a combine.
What is monocyte ?
A white blood cell that can ingest dead or damaged cells (through phagocytosis) and provide immunological defenses against many infectious organisms. Monocytes migrate into tissues and develop into macrophages.
What is monoecious ?
Plants having separate male and female flowers on the same plant, e.g., cucumbers, American beech, black walnut, and corn. Opposite of DIOECIOUS.
What is monogamy ?
The practice of having one mate at a time, lifelong pair bonding.
What is monogyny ?
In social insects, having one queen per nest, as with ants.
What is monohybrid cross ?
A cross that involves two parents that differ in only one trait.
What is monomer ?
A basic building block or small organic molecule that makes up a polymer when combined with identical or similar monomers through polymerization. Polymers are important substances in organisms, e.g., proteins are polymers.
What is mono-oxygenase ?
An ENZYME that catalyzes the INSERTION of one atom of oxygen, derived from O2, into an aromatic or aliphatic compound. The reaction is coupled to the oxidation of a coSUBSTRATE such as NAD(P)H or 2-oxoglutarate.
What is monophyletic ?
Refers to a group of organisms that includes the common ancestor and all descendants of this common ancestor. The group of organisms is also called a clade.
What is monosaccharide ?
A simple sugar such as fructose or glucose that cannot be decomposed by hydrolysis; colorless crystalline substances with a sweet taste that have the same general formula, CnH2nOn. They are classified by size according to the number of carbon atoms in the chain, such as dioses, two carbon-ring backbone; trioses, three carbon-ring backbone; heptose with seven carbon-ring backbone, etc. Further classified as aldoses (when carbonyl group is an aldehyde) or ketoses (contains a carbonyl [keto] group in its straight-chain form).
What is monotreme ?
An egg-laying mammal that feeds its young with milk once hatched. Only two forms exist in the world, and both live in Australia: theshort-beaked echidna (the spiny anteater) and the duck-billed platypus.
What is montane ?
A biological zone of altitude found in mountains, above the tree line, and usually based on at least 500 m (1,600 ft.) elevation.
Who was Morgan, Thomas Hunt ?
Morgan, Thomas Hunt (1866–1945) was American Zoologist Thomas Hunt Morgan was born on September 25, 1866, in Lexington, Kentucky, to Charlton Hunt Morgan. He received a B.S. at the University of Kentucky in 1886 and completed postgraduate work at Johns Hopkins University, where he studied morphology with W. K. Brooks and physiology with H. Newell Martin.
In 1890 he obtained a Ph.D. degree at Johns Hopkins University for his work on the evolutionary relationships of pycnogonids (sea spiders).
In 1891 he became associate professor of biology at Bryn Mawr College for women, Pennsylvania, where he stayed until 1904, then becoming professor of experimental zoology at Columbia University, New York. He remained there until 1928, when he was appointed professor of biology and director of the G. Kerckhoff Laboratories at the California Institute of Technology, at Pasadena. Here he remained until 1945. During his later years he had his private laboratory at Corona del Mar, California.
Morgan’s early work on genetic linkage with Drosophila melanogaster (the fruit fly) was put forward as a theory of the linear arrangement of the genes in the chromosomes. He described the phenomena of linkage and crossing over, which he explained in Mechanism of Mendelian Heredity (1915). He was the first to show that variation derives from numerous small mutations. His work also established the use of drosophila as a model for genetic research gene-mapping efforts. For his discoveries concerning the role played by the chromosome in heredity, he was awarded the Nobel Prize in 1933. Morgan is considered a cofounder, along with William Bateson, of modern genetics.
He also wrote several important genetics books: Heredity and Sex (1913), The Physical Basis of Heredity (1919), Embryology and Genetics (1924), Evolution and Genetics (1925), The Theory of the Gene (1926), Experimental Embryology (1927), and The Scientific Basis of Evolution (1935). He died on December 4, 1945.
The Morgan is now the unit of measurement of distances along all chromosomes in flies, mice, and humans. The University of Kentucky honored Morgan by naming its school of biological science after him
What is morphogen ?
A diffusible protein molecule present in embryonic tissues that, through a concentration gradient, can influence the development process of a cell; different morphogen concentrations specify different cell fates.
What is morphogenesis ?
The development of body shape and organization of an embryo from fertilized egg to adult.
What is morphological species concept ?
A way to classify organisms in the same species if they appear identical by anatomical criteria. Recognizing a species based initially on appearance; the individuals of one species look different from the individuals of another.
What is morphometrics ?
A branch of mathematics that focuses on the study of the metrical and statistical properties of shapes and the changes of geometric objects both organic or inorganic. Biologically relevant when dealing with species that have morphs that appear radically different.
What is morphotype ?
Reference to a particular morphological appearance of an organism or group.
What is mosaic development ?
A pattern of development in which body parts are determined from an early stage of cell division; the blastomere fate is established at a very early stage in development. Cells develop more or less independently and are largely unaffected by each other or the environment. When and what the cell becomes is under tight genetic control.
What is mosaic evolution ?
When different anatomical, physiological, and behavioral features evolve at different rates and at different times. Human evolution and language are examples.
What is mosquitoes ?
An organism belonging to the dipteran suborder, Nematocera, the more primitive group of flies that also includes groups such as crane flies, midges, gnats, and black flies. This is a large, abundant, and well-known family (Culicidae) whose members are pests to humans and who, with their long proboscises for feeding on the blood of mammals, are vectors for disease. Aedes aegypti (L.) is a vector for yellow fever and dengue fever, Anopheles punctipennis (Say) is the vector for malaria, and Culex pipiens (L.) is the vector for filariasis and encephalitis.
What is Mössbauer effect ?
Resonance absorption of gamma radiation by specific nuclei arranged in a crystal lattice in such a way that the recoil momentum is shared by many atoms. It is the basis of a form of spectroscopy used for studying COORDINATED metal ions. The principal application in bioinorganic chemistry is 57Fe. The parameters derived from the Mössbauer spectrum (isomer shift, quadrupole splitting, and the HYPERFINE coupling) provide information about the oxidation, spin, and COORDINATION state of the iron.
What is moth ?
Any of numerous insects of the order Lepidoptera. The nocturnal counterpart to the butterfly. Whereas moths rest with wings in various positions, butterflies rest with the wings folded over the back.
What is motif ?
A pattern of amino acids in a protein SEQUENCE that has a specific function, e.g., metal binding.
What is motor neuron ?
A neuron that sends messages from the central nervous system (brain or spinal cord) to smooth muscles, cardiac muscle, or skeletal muscles. There are upper-motor neurons that lie entirely within the central nervous system and cause movement because they terminate on a lower motor neuron; the lower motor neurons cell body lies in the central nervous system, and their axons leave the central nervous system through a foramen (hole in a bone for nerves and blood vessels) and terminate on an effector (e.g., muscle).
What is motor unit ?
A single motor neuron and the entire complement of muscle cells that receive synaptic connections from it.
What is MPF (M-phase promoting factor) ?
A protein complex containing cyclin and a cyclin-dependent protein kinase that triggers a cell to enter mitosis (M phase). Cyclin B increases prior to mitosis, combines with the cyclindependent protein kinase, and forms an active MPF complex. The MPF phosphorylates lamin, a structural protein of the nuclear envelope that assists in maintaining the nuclear shape, among other substrates, causing the dissolution of the nuclear envelope, which triggers the initial phases of mitosis. Formerly called maturation-promoting factor.
What is M phase ?
Mitosis in eukaryote cells; when a cell divides into two daughter cells, each with the identical chromosomes as the parent cell.
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