F₁ generation The first filial generation, the generation produced by an initial cross between two distinct types of parents. MORE INFORMATION
F₂ generation The second filial generation, the generation produced by interbreeding of individuals belonging to the F₁ generation. In general, the Fn generation is produced by interbreeding of individuals belonging to the Fn-1 generation. MORE INFORMATION
faciocervical /FASH-ee-oh-SIR-vick-əl/ Pertaining to the face and neck.
faciolingual /FASH-ee-oh-LING-yoo-əl/ Pertaining to the face and tongue.
facioplasty /FASH-ee-oh-PLAST-ee/ Facial plastic surgery.
FACS Fluorescence-activated cell sorter. See: flow cytometry.
FADH2 Reduced form of flavin adenine dinucleotide.
fallopian tubes /fə-LOPE-ee-ən/ Ducts by which ova pass from the ovaries to the uterus.
fauces /FAW-seez/ The region where the mouth interfaces with the pharynx — faucial /FAW-see-əl/
faucial reflex /FAW-see-əl/ Gagging caused by contact with the fauces.
faucitis /fə-SIGHT-əs/ Inflammation of the fauces.
FBPase Fructose bisphosphatase.
febricity /fə-BRISS-ə-dee, fee-/ State of being feverish.
febrifuge /FEB-rə-fyooj/ A fever-reducing agent.
febrile /FEB-brəl, FEEB-, -brial/ Feverish.
febris /FEB-brəs, FAY-brəs/ Fever.
fecal (Brit:faecal) /FEE-kəl/ Of or pertaining to feces.
fecal coliform bacteria (often shortened to: fecal coliforms) /FEE-kəl KOLE-ə-form/ Coliform bacteria originating in feces (such as Escherichia). Some coliform bacteria (e.g. those of the genera Enterobacter, Klebsiella, and Citrobacter) are not of fecal origin. Coliform bacteria are rod-shaped, gram-negative, non-spore forming bacteria that ferment lactose with the production of acid and gas when incubated at 35-37°C. They occur widely in the environment in water, soil and vegetation. Fecal coliforms are always present in the feces of warmblooded animals. Although bacteria of this kind are not ordinarily the cause of serious illness, they are used as an indicator of the presence of other pathogenic organisms of fecal origin that are not as easily detected.
feces (plural only) /FEE-seez/ Excrement (bodily waste ejected from the intestines).
fecula (pl feculae) /FEK-yə-lə/ Sediment.
feedback inhibition A condition in which a process producing a particular product tends to occur at a slower rate when that product is present at high concentration.
felid /FEEL-əd/ (1) member of the family Felidae; a cat; (2) pertaining to the family Felidae.
Felidae /FEEL-ə-DEE/ The mammalian family that contains the cats.
femtoliter (fL) /FEM-tə-LEET-er/ One million-billionth (10⁻¹⁵) of a liter.
femtosecond (fs) /FEM-tə-SECK-und/ One million-billionth (10⁻¹⁵) of a second.
femur /FEE-mer/ (1) in humans, the largest bone in the body; it connects the knee and hip; (2) in animals, the bone of the proximal portion of the hind limb. ANTERIOR VIEW OF HUMAN FEMUR | POSTERIOR VIEW OF HUMAN FEMUR
ferment /fur-MENT/ To undergo, or cause to undergo, fermentation.
fermentation A catabolic process that produces a characteristic product such as lactic acid or ethanol. Without an electron transport chain, fermentation makes a limited amount of ATP from glucose. See: respiration.
ferredoxins (Fd) Iron-sulfur proteins mediating electron transfer. There are many different types of ferredoxins that participate in a wide variety of metabolic reactions.
fertility factor See: F factor.
fetal /FEET-əl/ Of or pertaining to the fetus.
fever /FEEV-ur/ Elevated body temperature; specifically, the medical definition of fever in a human being is any temperature at or above 100.4 degrees (38C).
feverish /FEEV-ur-ish/ Having a fever.
FH Familial hypercholesterolemia.
fibroblast /FIBE-rə-blast/ A cell that secretes the necessary constituents of extracellular fibers.
filamentous /fil-ə-MENT-əs/ Thready, threadlike; also: bearing or covered with threadlike structures ("filaments").
finger protein A protein with a zinc finger that allows the protein to bind DNA. A zinc finger has the consensus sequence
where the subscripts indicate the number of residues present. The motif is named for the finger-like loop of amino acids that protrudes from the zinc binding site (known as the "Cys₂/His₂ finger" (pronounced "siss-two-hiss-two").
fingerprinting In genetics, the identification of multiple specific alleles uniquely identifying an individual. Also known as DNA fingerprinting.
finished DNA sequence High-quality, low error, gap-free DNA sequence of the human genome. Achieving this ultimate 2003 HGP goal requires additional sequencing to close gaps, reduce ambiguities, and allow for only a single error every 10,000 bases, the agreed-upon standard for HGP finished sequence. See also: sequencing, draft sequence.
FISH See: fluorescence in situ hybridization.
flabellum /flə-BELL-əm/ A fan-shaped part.
flaccid /FLA-səd/ Lacking tension; said of walled cells in an isotonic environment.
flagellin /flə-JEHL-ən/ The main protein component of bacterial flagella.
flatworm A flat worm belonging to the phylum Platyhelminthes.
flavin adenine dinucleotide (FAD) A redox cofactor that exists in both a reduced and oxidized state. In the oxidized state (FAD₊) it accepts electrons and becomes reduced, then, in its reduced state (FADH2), it acts as a reducing agent, donating electrons. Many oxidoreductases (known as "flavoenzymes") will function only when FAD is present.
flavin mononucleotide (FMN) or riboflavin-5'-phosphate, is the usual form in which riboflavin (vitamin B₂) is found in cells. It functions as a prosthetic group in conjunction with oxidoreductases such as NADH dehydrogenase. Riboflavin kinase produces FMN from riboflavin.
flavoproteins Dehydrogenases containing flavin. They play a key role in the cellular respiration of plants and animals.
flow cytometry /sigh-TOM-ə-tree)/ Analysis of cells or chromosomes by evaluating their light absorption or fluorescent properties as they stream through a laser beam. A machine that carries out this process is known as a fluorescence-activated cell sorter (FACS).
flow karyotyping Use of flow cytometry to analyze and separate chromosomes.
fluidram A measure of volume used in pharmacology (being the same as the volume of 57.1 grains of distilled water = 3.70 cc).
flukes (1) the two parts or lobes that make up the triangular tail of a whale (now often used in singular to refer to the entire fin, composed of both lobes); (2) flatworms of the class Trematoda.
fluorescence /flə-RESS-əns, floh-/ The emission of electromagnetic radiation (usually visible light) by a substance, that has absorbed radiation of some other wavelength.
fluorescence in situ hybridization (FISH) A technique that vividly paints chromosomes or portions of chromosomes with fluorescent molecules. It uses fluorescein tags to detect hybridization of probes. The method can be used both with metaphase chromosomes and with interphase chromatin; useful for identifying chromosomal abnormalities and for gene mapping.
fluorescence-activated cell sorter (FACS) See: flow cytometry.
fluorescent /flə-RESS-ənt, floh-/ Exhibiting fluorescence.
fluorine (F) /FLOO-ə-reen or FLOOR-een/ A gaseous chemical element. Atomic weight 18.9984; atomic number 9. When in its pure elemental form, fluorine bonds with itself to form diatomic fluorine, F₂. However, F₂ is extremely reactive — more reactive than any other element, so much so that it will burn hydrocarbons at room temperature without any energy input, such as the spark required to initiate oxygen combustion under similar circumstances. Elemental fluorine is therefore a poisonous, perilous substance. Fluorine is not necessary to life, but trace amounts in the diet are effective in preventing tooth decay. PERIODIC TABLE
folic acid (also folacin) /FOH-lik/ A B vitamin (B₉) present in such foods as liver, green vegetables, and yeast. A lack of folic acid in the diet causes anemia because it is essential in the production of erythrocytes. In the liver it is converted to dihydrofolic acid and then into tetrahydrofolate.
folium (pl folia) /FOH-lee-əm/ A leaflike structure.
folivorous /foh-LIV-ver-əs/ Leaf-eating.
follicle /FALL-ə-kəl/ Any small, bulbous group of cells forming a cavity.
follicle-stimulating hormone (FSH) /FALL-lik-əl/ A hormone secreted by the gonadotrope cells of the pituitary gland (i.e., a gonadotropin) in vertebrates. Its function is much broader than its name suggests. Although FSH does stimulate the production of ovarian follicles, it also plays an important role in growth, development of the sexual organs, and spermatogenesis.
fomentation /fo-men-TAY-shən/ The application of a hot, moist substance for the relief of pain or discomfort.
fomes /FOH-meez/ A substance that transmits infection.
fontanel or fontanelle /FONT-ə-nel/ The large gap in the bony structure of the skull found at the peak of the skull in fetal and newborn infants.
foramen (pl foramina) /for-AY-mən/ A hole, opening, or orifice in a bone (or that connects two cavities of an organ).
foramen magnum /for-AY-mən MAWG-noom/ The large opening in the base of the skull (piercing the occipital bone) through which the spinal cord passes.
fossil /FAW-səl/ (1) n. The remains, or traces, of an ancient organism preserved in the earth; (2) adj. Being, or pertaining to, such remains or traces.
fossiliferous /faw-səl-LIF-er-əs/ fossil-bearing, containing fossils.
fossorial /faw-SORE-ee-əl/ Suited for digging; living in burrows.
F plasmid See: F factor.
fragmentation A mode of vegetative reproduction in which an organism breaks, or is broken, into pieces and the separate pieces go on to live as distinct individuals.
frameshift mutation A mutation that causes a reading frame shift for all codons downstream of the mutation.
freemartin A female fraternal twin that develops male traits due to the influence in the uterus of male hormones from its male sibling when the fetal circulations are continuous (the term is usually used in connection with cattle, although the condition occurs, too, in sheep, goats and pigs).
fringillid Belonging to a family, Fringillidae, of small seed-eating finches, of which the canaries, siskins, and similar birds are members.
Fritillaria A genus of lilies much studied in the field of cytogenetics because of their very large chromosomes. Lilies of this genus have the highest C-values among plants, ranging up to F. assyriaca, in which a haploid nucleus contains 127.4 pg of DNA.
frontal /FRUN-təl/ (1) of or pertaining to the front; (2) lying at the front.
frontal bone The bone underlying the forehead.
frontal lobe One of the two anterior lobes of the brain that underlie the forehead. Taken together, the two frontal lobes are the frontal region.
fructose-1-phosphate (F1P) The product of phosphorylation of fructose catalyzed by hepatic fructokinase. MOLECULAR STRUCTURE
fructose-6-phosphate (F6P also Neuberg ester) Fructose sugar phosphorylated on carbon 6. Fructose 6-phosphate is part of the glycolysis metabolic pathway. It is produced by isomerisation of glucose 6-phosphate. The β-D-form of F6P is abundant in cells. MOLECULAR STRUCTURE
frugivorous /froo-GIV-er-əs/ Fruit-eating.
fruit The ripe ovary of a flower.
fruit fly See: Drosophila.
fruit sugar An alternative name for fructose.
functional group Organic chemistry: any of various specific groups of atoms, as the acyl group or hydroxyl group, that engage in similar chemical reactions even when they are components of distinct molecules.
fungal /FUN-gəl/ Of or pertaining to fungi.
fungus (pl fungi) /FUN-gəs, pl: FUN-jigh, -jee/ An organism belonging to Kingdom Fungi. Fungi are eukaryotes that form spores, as do plants, but that lack chloroplasts. The cells of most fungi grow as filamentous structures ("hyphae"), which may contain multiple nuclei, and grow from their tips. The most familiar fungi are mushrooms and toadstools, but the category also includes microorganisms such as yeasts and molds. A primary distinguishing characteristic of fungi is the presence of chitin in the cell walls, which in plants contain cellulose instead. PICTURE (Lycoperdon perlatum) | PICTURE (Amanita muscaria) | PICTURE (Laetiporus sulphureus) | PICTURE (budding yeast) | PICTURE (Penicillium)
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