Family The taxonomic category between order and tribe, but if no tribe exists, then it is the category between order and genus. Also a social unit related by marriage, descent, or kinship.
Farsightedness A condition in eyesight where distant objects can be seen better than objects that are closer. It is the inability of images to focus properly on the retina of the eye. The eye is too short or the cornea is too flat, so that the images focus beyond the retina and cause close objects to appear blurry. Also called hyperopia or presbyopia, when the lens of the eye begins to lose elasticity (normal aging process).
Fat (general) Any substance made up of lipids or fatty acids that supply calories to the body and can be found in solid or liquid form (e.g., margarine, vegetable oil); three fatty acids linked to a glycerol molecule form fat.
Fat (triacylglycerol) Triacylglycerols are storage lipids, comprising three fatty acids attached to a glycerol molecule, found mostly stored in adipose (fat) cells and tissues. They are highly concentrated regions of metabolic energy. Because there are abundant reduced CH groups available in fats for oxidation-required energy production, they are excellent storage containers of energy. Fats can be found in plants, animals, and animal plasma lipoproteins for lipid transport. Formerly known as triglyceride.
Fatty acid Fatty acids are the components of two lipid types mostly found in cells in the form of large lipids or small amounts in free form: storage fats and structural phospholipids. They consist of long hydrocarbon chains of varying length (from four to 24 carbon atoms), containing a terminal carbonyl group at one end and may be saturated (has only a single carbon-to-carbon bond) or unsaturated (one or more double or triple carbon-to-carbon bonds). The number and location of double bonds also vary for the different fatty acids. More than 70 different kinds have been found in cells. Saturated fatty acids have higher levels of blood cholesterol, since they have a regulating effect on its synthesis, but unsaturated ones do not have that effect and thus they are more often promoted nutritionally. Some fatty acids are palmitic acid, palmitoleic acid, alpha-linolenic acid, eleostearic acid, linoleic acid, oleic acid, and elaidic acid. Three fatty acids linked to a glycerol molecule form fat.
Fauna All wild birds and all wild animals (both aquatic and terrestrial); includes wild mammals, reptiles,amphibians, and aquatic and nonaquatic invertebrate animals, and all such wild animals’ eggs, larvae, pupae, or other immature stage and young.
Feedback inhibition (end-product inhibition) A way for the end product of a cell’s biosynthetic pathway to stop the activity of the first enzymes in that pathway, thereby controlling the enzymatic activity; it stops the synthesis of the product.
Female Sex classification by gender. The individual in a sexually reproducing species that produces eggs. Female mammals, for example, nourish their young with milk. In humans, females have two X chromosomes.
FeMo-cofactor An inorganic cluster that is found in the FeMo protein of the molybdenum-nitrogenase and is essential for the catalytic reduction of N2 to ammonia. This cluster contains Fe, Mo, and S in a 7:1:9 ratio. The structure of the cofactor within the FeMo protein can be described in terms of two cuboidal subunits, Fe4S3 and MoFe3S3 bridged by three S2- ions and "anchored" to the protein by a histi-dine bound via an imidazole group to the Mo atom and by a cysteine bound via a deprotonated SH group to an Fe atom of the Fe4S3 subunit. The Mo atom at the periphery of the molecule is six-coordinate and, in addition to the three sulfido ligands and the histidine imidazole, is also bound to two oxygen atoms from an (R)-homocitrate molecule.
Fermentation The anaerobic decomposition of complex organic substances by microorganisms such as bacteria, molds, or yeast, called ferments, on a fermentation substrate that produce simpler substances or some other desired effect, such as the yielding of ethanol and carbon dioxide from yeast for commercial purposes, the production of ATP and energy production, and the development of antibiotics and enzymes. Fermentation is used by microflora of the large intestine to break down indigestible carbohydrates.
Large fermentors are used to culture microorganisms for the production of some commercially valuable products such as bread, beer, wine, and other beverages.
Ferredoxin A protein containing more than one iron and acid-labile sulfide that displays electron-transfer activity but not classical enzyme function.
Ferriheme An iron(III) porphyrin coordination complex.
Ferritin An iron storage protein consisting of a shell of 24 protein subunits encapsulating up to 4,500 iron atoms in the form of a hydrated iron(III) oxide.
Ferrochelatase An enzyme that catalyzes the insertion of iron into protoporphyrin ix to form heme. The mammalian enzyme contains an iron-sulfur cluster.
Ferroheme An iron(II) porphyrin coordination complex.
Ferromagnetic If there is coupling between the individual magnetic dipole moments of a paramagnetic sample, spontaneous ordering of the moments will occur at low temperatures. If this ordering results in an electronic ground state in which the moments are aligned in the same direction (parallel), the substance is said to be "ferromagnetic." If the ordering results in an electronic ground state in which the moments are aligned in opposite directions, the substance is said to be "antiferromagnetic."
Fertilization The combining of two gametes from different sexes to form a zygote, e.g., the penetration of sperm into the egg and the resulting combining of genetic material from both that develops into an embryo. The process involves karyogamy, the fusion of nuclei of both gametes, and plasmogamy, the fusion of cytoplasm. Each gamete contains a haploid set of chromosomes, with the resulting nucleus containing a diploid set of chromosomes. Fertilization can also be self-induced by the fusion of male and female gametes from the same euploid (nucleus of a cell contains exact multiples of the haploid number of chromosomes) organism; cross fertilized by the fusion of male and female gametes from different euploid individuals; or double fertilized, in which two separate sperm cells unite with two cells in the embryo sac to form the zygote and endosperm, such as in angiosperms.
Colored scanning electron micrograph (SEM) of sperm clustered around a human egg (ovum) during fertilization. The rounded egg (at center) is seen on human tissue. Sperm attached to its surface appear as fine hairlike structures; each sperm has a rounded head and a long tail. They are penetrating the thick spongy surface of the zona pellucida of the egg, a surface layer that attracts sperm to the egg and enables the sperm to attach. The human female usually produces a single large egg, and only one of the millions of male sperm may penetrate the egg’s wall to fuse with the egg nucleus. Once fertilized, the egg begins its process of growth by cell division.
In agriculture, fertilization means the application of nutrients, a fertilizer, to soil in order to promote growth and development of domestic or crop plants.
Fetus An unborn offspring in the postembryonic stage where the major features of the organism can be seen.
Factor A bacterial plasmid, which is a piece of DNA that is able to replicate independently of the chromosome, that allows a prokaryote (cell with no nucleus) to join together with and pass DNA. An epi-some that can replicate by itself or in integrated form and move from one bacterium to another while conjugating. A circular piece of DNA that can replicate independently of the bacterial chromosome or integrate and replicate as part of the chromosome.
Fiber A long-walled plant cell that is often dead at maturity, is lignified, and reinforces the xylem of angiosperms, giving elasticity, flexibility, tensile strength, and mechanical support to plant structure. Also part of sclerenchyma tissue, which is thickened cell walls of lignin, composed of both sclereids, short cells, and the longer fibers, and lacking a living protoplast when mature.
In human nutrition, fiber is a carbohydrate that resists the action of digestive enzymes and passes through the human digestive system virtually unchanged, without being broken down into nutrients. There are insoluble fibers, found in wholegrain products and vegetables, that help the digestive system by moving stools through the digestive tract by keeping them soft. Soluble fiber slows the digestive process and is water-soluble. Found in beans, fruits, and oat products, it is thought to help lower blood fats and blood glucose (sugar).
Fiber is also a slender, elongated natural or synthetic filament capable of being spun into yarn, e.g., cotton.
Fibiger, Johannes Andreas Grib (1867-1928) Danish Pathologist Johannes Andreas Grib Fibiger was born in Silkeborg, Denmark, on April 23, 1867, to C. E. A. Fibiger, a local medical practitioner, and Elfride Muller, a writer.
Fibiger studied under bacteriologists Robert koch and Emil von Behring, and from 1891 to 1894 he was assistant to Professor C. J. Salomonsen at the department of bacteriology at the University of Copenhagen. He received his doctorate from the University of Copenhagen in 1895 based on research into the bacteriology of diphtheria.
He was appointed prosector at the university’s Institute of Pathological Anatomy (1897-1900), principal of the Laboratory of Clinical Bacteriology of the Army (1890-1905), and in 1905 became the director of the central laboratory of the army and consultant physician to the Army Medical Service.
Fibiger’s early research dealt with diphtheria and tuberculosis, and he developed laboratory methods for growing the causing bacteria as well as a serum to protect against the disease. Fibiger achieved the first controlled induction of cancer in laboratory animals, after research in studying tumors in the stomachs of animals, by feeding mice and rats with cockroaches infected with a worm. His work led others to pursue the research on chemical carcinogens and led to the development of modern cancer research.
Fibiger was a founding member and joint editor of the Acta Pathologica et Microbiologica Scandinavica, and coeditor of Ziegler’s Beitrage zur pathologischen Anatomie und zur allgemeinen Pathologie. He received the 1927 Nobel Prize in physiology or medicine for his work on cancer, specifically for his "discovery of the Spiroptera carcinoma." Fibiger died on January 30, 1928, in Copenhagen.
Fibril A small or microscopic thread of cellulose that is part of the cellulose matrix of plant cell walls. The contractile unit of a muscle cell or a bundle of filaments in a striated muscle cell; the thin fibrous structure of a nerve; a long fine hair or fiber; many fibrils bundle together to form a fiber. Makes up the smallest unit of paper fibers. Also a linear feature in the H alpha chromosphere of the Sun, found near strong sunspots and plages or in filament channels. Fibrils parallel strong magnetic fields.
Fibrin An insoluble stringy protein derived from fib-rinogen that facilitates blood clotting by forming threads and creating the mesh around the clot. A blood clot is also called a fibrin clot. Coagulation begins usually with an injury to some part of the body. The body forms a clot from a mixture of the blood protein fibrin and platelets. After the bleeding stops, a blood protein dissolves the clot by breaking down the fibrin into tiny fragments.
Fibroblast (fibrocyte) A flat, elongated, branched, irregular and motile cell type found in vertebrate connective tissue that produces extracellular collagen and elastin fibers; spindlelike with long cytoplasmic extensions at each end and with oval, vesicular nuclei; most abundant cell type found in the skin. Fibroblasts differentiate into chondroblasts that secrete cartilage matrix, collagenoblasts that proliferate at chronic inflammation sites, and osteoblasts that secrete bone matrix. They form the fibrous tissues in the body, tendons, and aponeuroses, the shiny, broad sheets of connective tissue that bind muscle fibers together to form muscles, as well as supporting and binding tissues.
Fight-or-flight reaction The reaction in the body when faced with a sudden and unexpected threat or stress. The reaction is immediate to either run or stay and fight. In humans, a sudden release of the hormones epinephrine and norepinephrine increases blood flow to the muscles and increases blood pressure. The resulting increase in muscle strength and mental ability prepares the body for either reaction that is chosen. In other animals such as the wood thrush (Hylocichla mustelina), flight is preferred over fight.
Filial generation (offspring generation) The successive generations of progeny in a controlled series of crosses, beginning with two specific parents (the P generation), and intercrossing the progeny of each new generation. F1 is the first offspring or filial generation between any two parents, the first generation of descent; F2 is the second (grandchildren); and so on.
Filter feeding The filtering of suspended food particles from a water current by using gill rakers or similar organs.
Fingerprinting In genetics, the identification of multiple specific alleles on a person’s DNA to produce a unique identifier for that person; used in forensics. There are six steps to DNA fingerprinting. First the DNA must be isolated and removed from the cells of the animal or plant. Then special enzymes, called restriction enzymes, are used to cut the DNA at specific places, and the DNA are sorted by size. The DNA pieces are then transferred to a nylon sheet, which is then probed. The fingerprint is generated by adding tagged probes to the nylon sheet, and each probe sticks in only one or two specific places, wherever the sequences match. The final DNA fingerprint is created by using several different probes, with the resulting end product looking like a grocery store bar code. DNA fingerprinting is increasingly being used in criminal cases, and people have been freed from prison based on DNA fingerprinting.
Finsen, Niels Ryberg (1860-1904) Danish Physician Niels Ryberg Finsen was born on December 15,1860, in the capital city Thorshavn in the Faroe Islands (Denmark) to Johanne Froman and Hannes Steingrim Finsen, an Icelandic family that could trace its ancestry back to the 10th century and occupied many of the highest positions in the administration of the Faroe Islands. He received his early education in schools at Thorshavn and then at Herlufsholm in Denmark.
In 1882 Finsen went to Copenhagen to study medicine. After taking his final examination in 1890, he became prosector of anatomy at the University of Copenhagen until 1893. He continued with private tutoring of medical students to make a moderate income.
By 1883 he was diagnosed with Pick’s disease, characterized by progressive thickening of the connective tissue of certain membranes in the liver, the heart, and the spleen, with long-term impairment of the functions of these organs. He also developed symptoms of heart trouble and ascites, and became more and more of an invalid until finally during his last years he was confined to a wheelchair. It did not prevent him from making contributions to medicine.
He was instrumental in discovering the effects of light—and in particular ultraviolet light (then called red light)—as phototherapy against diseases such as lupus vulgaris in 1893. In 1895 he made a great breakthrough that established his international reputation by introducing the revolutionary carbon-arc treatment (Finsen’s therapy) of lupus. In 1896 he founded the Finsen Medical Light Institute (now the Finsen Institute) in Copenhagen.
He received the Nobel Prize in physiology or medicine on December 10, 1903, for his work in treating diseases with light.
Among the many publications by Finsen, two are especially noteworthy: Om Lysets Indvirkninger paa Huden (On the effects of light on the skin) appeared in 1893, and the classical treatise Om Anvendelse i Medicinen af koncentrerede kemiske Lysstraaler (The use of concentrated chemical light rays in medicine) was published in 1896. The results of much of his research are contained in the communications published by his institute. Finsen tried to combat his illness in various ways, including keeping a diet poor in salt during his last years. This led to his last publication, a thorough study of En Ophobning af Salt i Organismen (An accumulation of salt in the organism) in 1904.
In 1899 he became Knight of the Order of Dan-nebrog, and a few years later the Silver Cross was added. He was a member or honorary member of numerous societies in Scandinavia, Iceland, Russia, and Germany. He received a Danish gold medal for merit, and in 1904 the Cameron Prize was given to him from the university of Edinburgh.
In 1892 Finsen married Ingeborg Balslev, the daughter of Bishop Balslev at Ribe. They had four children. Finsen died on September 24, 1904.
Firefly Commonly called a lightning bug, they are neither flies nor bugs. They belong to the order Coleoptera, family Lampyridae, which are beetles. These small flying beetles produce their own light, from a chemical called luciferase, from structures in their abdomen. Females of some species, which are wingless, and many larvae also produce light and are called glowworms. Fireflies can be seen in early summer (late May), appearing at dusk. Males and females attract each other with a flashing green light in their abdomens. The wingless females flash from the ground and the males look for them. There are more than 2,000 species of firefly in temperate and tropical environments worldwide.
First law of thermodynamics Simply put, energy can neither be created nor destroyed, only transformed or transferred from one molecule to another; in effect, the total amount of energy in the universe is constant. Also known as the Law of Conservation of Energy. Thermodynamics is the study of the conversion of energy between heat and other forms, e.g., mechanical.
Fission (binary fission) Asexual reproduction or division of a single-celled individual, such as a prokaryote, into two new single-celled individuals of equal size and genetic composition, without mitosis occurring. From the Latin fissilis, meaning "easily split."
Fixation The complete prevalence of one gene form (allele), resulting in the total exclusion of the other. Genes that confer a reproductive advantage generally go to fixation.
Fixed action pattern (FAP) A series of innate behavior patterns (a fixed action) in response to a specific stimulus (called a sign stimulus or innate releaser) that continues until the response is completed. FAPs are genetic and not individually learned. For example, a group of spined larvae of the buck moth (Hemileuca maia) will all instantly raise their bodies and thrash back and forth when a predator (bird) approaches.
Flaccid Limp, soft condition, e.g., walled cells are flaccid in isotonic surroundings; low turgid pressure; opposite of turgid.
Flagellum A long whiplike structure that is used to propel certain kinds of prokaryote and eukaryote cells. The cells can have an individual flagellum or a few flagella per cell. In prokaryote organisms the flagellum is composed of a protein called flagellin. In the eukary-ote organism, it is longer than a cilium but has the same construction of nine outer double microtubules and two inner single microtubules.
