Babesia /bə-BEEZH-yə or -ee-ə/ n. A genus of protozoan blood parasites transmitted by ticks; infects humans, cattle, dogs, and many other vertebrates. The resulting disease is babesiosis /bah-bə-zee-ō-səs/. LIFE CYCLE OF BABESIA MICROTI
BAC See: bacterial artificial chromosome.
bacillemia /bass-əl-EEM-ee-yə or -ee/ n. Presence of bacilli in the blood.
bacilli /bə-SILL-ī, -ee/ n. Plural of bacillus.
bacilliform /bə-SILL-ə-form/ adj. Rod-shaped.
bacillus (pl bacilli) /bə-SILL-əs; pl: ī, -ee/ n. Any rod-shaped bacterium.
backcross (1) n. a cross between a hybrid individual obtained by crossing two parental types and a second individual belonging one of those parental types; (2) v. to create a backcross individual or generation.
bacteremia /back-ter-EEM-ee-yə/ n. Presence of bacteria in the blood.
bacteria (sing bacterium) /back-TEER-ee-ə; sing: -əm/ n. (1) broadly: prokaryotes; (2) strictly: one of the two major types of prokaryotes, the other type being archaeans (more information >>) — bacterial. AGENTS OF COMMON BACTERIAL INFECTIONS
bacterial artificial chromosome (BAC) n. A vector used to clone DNA fragments in Escherichia coli cells. The fragments are typically 100- to 300-kb long (mean ~150 kb). The fragments are inserted in an F-factor plasmid found in E. coli. See also: cloning vector.
bactericide /back-TEER-ə-side/ n. Any agent that destroys bacteria. — bactericidal /back-TEER-ə-side-əl/ (also bacteriocidal /back-TEER-ee-ə-SIDE-əl/)
bacteriochlorophyll /back-TEER-yō-CHLORE-ə-fill/ (BChl) Any one of the six types (a, b, c, d, e, and g) of chlorophyll found in bacteria.
bacteriostat /back-TEER-yə-stat/ n. A substance preventing bacterial growth.
Balanidae n. The family composed of the acorn barnacles.
balanopreputial /bə-LAN-ō-pree-PYOO-shəl/ adj. Of or pertaining to the glans penis and prepuce.
Balbiani ring /BALB-ee-ahn-ee/ n. A very large puff at a particular band on a polytene chromosome.
baleen whales /BAL-een/ n. Whales that have within their mouths a sieve-like structure (the baleen) with which they obtain food by filtering small organisms from the water.
Baltica /BALT-ick-ə/ n. A separate continental plate (named for the Baltic Sea) that existed in the the Early Paleozoic. It later became part of Euramerica, then part of Pangea, and still later, part of Laurasia. Today it underlies parts of modern Scandinavia, European Russia and central Europe and the northern United Kingdom.
barium (Ba) /BEAR-ee-əm/ n. Soft metallic element (atomic weight 137.34, atomic number 86); member of alkaline earth group. PERIODIC TABLE
barium sulphate /BEAR-ee-əm SƏL-fate/ n. Compound used in x-ray examinations. When ingested, it allows visualization the gastrointestinal tract.
barospirator /BAR-ō-spear-ə-ter/ n. A device that causes respiration by means of the application of alternating high and low air pressures.
barotactic /BAR-ō-TACK-tick/ adj. Pertaining to barotaxis.
barotaxis /BAR-ō-TAX-əs/ (pl barotaxes /BAR-ō-TAX-eez/) n. A taxis in which the stimulus is pressure.
basal metabolism /BĀ-səl/ n. The quantity of energy required to maintain an organism when at complete rest.
basalt /bə-SALT/ n. Dark igneous rock (cools from a hot fluid lava or magma), which usually originates as a lava flow; contains a high percentage of magnesium and iron, and low amounts of potassium, silica, and sodium.
base n. (1) in connection with DNA and RNA, one of the purine or pyrimidine nucleotide bases of which RNA and single-stranded RNA is composed. See: adenine, cytosine, guanine, thymine, and uracil); (2) any substance that reduces a solution's hydrogen ion concentration. See: acid.
base pair (bp) n. A pair of hydrogen-bonded nitrogenous bases that join the two strands of the DNA double helix. A base pair is composed of a purine and a pyrimidine (guanine and cytosine or adenine and thymine).
base-pair substitution n. The substitution, in duplex DNA, of one pair of nucleotides for another, or the reversal of a pair of nucleotides with respect to the strands in which the two individual nucleotides reside. There are two types of base-pair substitutions: transitions, in which a purine substitutes for a purine in one strand and a pyrimidine substitutes for a pyrimidine in the other; and transversions in which a pyrimidine substitutes for a purine in one strand and a purine substitutes for a pyrimidine in the other.
base sequence analysis n. Any method for identifying the bases present in a particular nucleotide sequence.
basophil /BASE-ə-fill/ (also basophile /BASE-ə-file/) n. A leukocyte that stains dark purple with base dyes; appear in many types of inflammations, particularly allergic reactions.
Batesian mimicry /BĀT-see-ən/ n. A type of mimicry where a harmless organism looks like some other type of organism that is poisonous or harmful in some other way.
bathypelagic /bath-ə-pə-LAJ-ik/ adj. Pertaining to ocean levels that are deep but above the abyssal zone.
batrachoid /BAT-rə-koid/ (also batrachian /bə-TRACK-ee-ən/) adj. Similar to, or characteristic of, a frog or toad.
batrachophagous /bat-trə-KAWF-ə-gəs/ Frog-eating.
B cell or B lymphocytes n. A type of lymphocyte that differentiates in the bone marrow in mammals and in bursa of Fabricius in birds (the B in B cell originally stood for bursa since these cells were discovered in birds, but now generally under stood to refer to bone marrow); after contact with an antigen, B cells differentiate into antibody-secreting plasma cells.
Before Present (BP) years is a time scale used in geology, archaeology, and other branches of science to indicate the number of years back to past events. Since the present time changes, this system of time measurement has been standardized to use January 1, 1950 as the zero mark on the scale. For example, 1200 BP means 1200 years before 1950 (i.e., the year 850).
behavioral genetics n. The study of genes influencing behavior.
Beijing Man See: Homo erectus .
belemnite /bə-LEM-night/ (or belemnoid /bə-LEM-noid/) n. A member of the extinct group Belemnoidea composed of certain cephalopods similar to the modern squid and cuttlefish. They are abundant as fossils. The portion of a belemnite usually fossilized is the rear portion of the internal skeleton, the guard or rostrum, which is cylindrical and rounded or pointed on one end. Fossil range: Early Devonian–Late Cretaceous
benthic zone /BEN-thick/ The seafloor, as an environment or habitat.
beta-lactam antibiotics n. Penicillin-related antibiotics (e.g., dicloxacillin, methicillin, nafcillin, oxacillin).
bezoar /BEE-zore/ n. A solid indigestible mass forming in the intestines or stomach of an animal (including humans).
bile n. A substance produced by the liver. It contains bile salts (sodium glycocholate and sodium taurocholate) and aids in the absorption of fats by facilitating their digestion and emulsification.
bilirubin /bill-ee-ROOB-ən/ n. An orangish-yellow pigment in bile. A catabolite of hemoglobin breakdown, bilirubin is carried to the liver where it is chemically converted and excreted in the bile into the duodenum.
binary fission /BINE-er-ee/ n. The method of reproduction used by prokaryotes, in which a single parent cell divides into two daughter cells, each of which receives a single, complete copy of the parental chromosome. MORE INFORMATION
binomial /bī-NOME-ee-əl/ n. A taxonomic name, composed of two separate words, usually of Greek or Latin origin, used to indicate that the organism in question is treated as a species. MORE INFORMATION
bioclimatology /BĪ-ō-KLĪM-ə-TAWL-ə-jee/ n. The study of the influence of climate on living organisms — bioclimatologist /BĪ-ō-KLĪM-ə-TAWL-ə-jist/
bioengineering (also biological engineering) /Bī-ō-en-jə-NEAR-ing/ A hybrid field of scientific research that uses the principles of biology and the techniques of engineering to produce useful products — bioengineer /BĪ-ō-EN-jə-near/
biogeography /BĪ-ō-jee-AWG-rə-fee/ n. The study of the geographic distributions of living organisms — biogeographist /BĪ-ō-jee-AWG-rə-fist, -fəst/
bioinformatics /BĪ-ō-in-fer-MAT-iks/ n. The use of computers to manage and analyze biological data — bioinformaticist /BĪ-ō-in-fer-MAT-ə-sist/
biology /bī-AWL-ə-jee/ n. (1) the scientific study of living things and vital processes; (2) the life processes of a particular organism or class of organisms (e.g., the biology of plants); (3) the organisms living in a particular geographic region or type of environment, taken as a whole MORE INFORMATION | BRANCHES OF BIOLOGY
biomass /BĪ-ō-mass/ Material derived from living organisms, usually plants,particularly material used for the production of biofuel.
biomathematics (also mathematical biology) /BĪ-ō-math-MAT-iks/ n. An interdisciplinary field of study that attempts to model biological processes using mathematical techniques — biomathematician /BĪ-ō-math-mə-TISH-ən/
biophysics /BĪ-ō-FIZZ-icks/ n. An interdisciplinary science that applies the theories and methods of physics to biological questions — biophysicist /BĪ-ō-FIZZ-ə-sist/
biotechnology /BĪ-ō-tek-NAWL-ə-jee/ n. The practical application of biological science; particularly applied research and product development that uses recombinant DNA, cell fusion, and various other modern bioprocessing techniques — biotechnological /BĪ-ō-tek-nə-LAWJ-ə-kəl/ — biotechnologist /BĪ-ō-tek-NAWL-ə-jist/
biotic /bī-AWT-ick/ adj. Of, pertaining to, or being living things.
biparous /BIP-ə-rəs/ adj. Producing two offspring per birth.
bipedal /bī-PEED-əl/ adj. Walking upright on two legs (as does a human or a bird).
bipedalism /bī-PEED-ə-liz-əm/ n. A form of terrestrial locomotion in which four legs are used.
bisetose /bī-SEE-tōs/ adj. Having two bristles.
bisexual /bī-SEX-yoo-əl/ adj. (1) pertaining to or being a type of organism in which two different sexes occur; (2) pertaining to or being an individual having both male and female sexual organs.
bivalved /BĪ-valvd/ adj. Having a pair of hard shells that open for feeding and close for protection.
bladder See: urinary bladder.
BLAST n. A computer program that finds similar nucleotide or protein sequences in sequence data bases. BLAST stands for Basic Local Alignment Search Tool.
blastema (pl blastemas or blastemata) /blas-TEEM-ə/ n. The bud from which a regenerating limb develops.
blastocoel /BLAST-ə-seal/ n. The cavity within a blastula.
blastula /BLAST-yə-lə/ n. A hollow ball of cells that occurs early in embryonic development.
Blattaria /blə-TAR-ee-yə, -TER-/ n. The insect order that consists of the roaches.
blennostatic /blen-ə-STAT-ick/ adj. Reducing mucous secretion.
blepharoplast /BLEF-er-əh-plast/ n. Basal granule of a flagellate.
bond energy n. The amount of energy required to break a given type of chemical bond.
boreal /BORE-ee-əl/ Pertaining to, or located in the cold northern regions of the globe.
boron (B) /BORE-awn/ n. Nonmetallic chemical element; atomic weight 10.811, atomic number 5. Boron is required by plants as a nutrient, in particular for maintenance of their cell walls. It does not, however, appear to be necessary in the diets of animals. PERIODIC TABLE
Borrelia /bore-RELL-yə/ n. A genus of spirochetes, among which are the causative agents of Lyme disease (Borrelia burgdorferi), louse-borne relapsing fever (Borrelia recurrentis), and tick-borne relapsing fever (Borrelia hermsii). PHOTOMICROGRAPH OF BORRELIA BURGDORFERI
botany /BAWT-(ə)-nee/ n. The study of plants — botanist /BAWT-(ə)-nist/
botryoid /BAWT-ree-oid/ (also botryoidal /bawt-ree-OID-əl/) adj. Shaped like a bunch of grapes.
bp See: Base pair.
BP See: Before Present.
BPheo Bacteriopheophytin (same as bacteriochlorophyll less its magnesium residue).
BPTI Bovine pancreatic trypsin inhibitor; also known as aprotinin.
brachiate /BRACK-ee-ət/ adj. Having arms.
brachiate /BRACK-ee-ate/ v. To move about from one handhold to another by swinging (as does an ape) — brachiation /BRACK-ee-Ā-shən/
brachiopod /BRACK-ee-ə-pawd/ n. An animal belonging to the phylum Brachiopoda.
Brachiopoda /brack-ee-AWP-ə-də/ n. A phylum of hard-shelled invertebrates similar in appearance to bivalved mollusks, but differing from them in internal anatomy, in particular with respect to the presence of a lophophore. BRACHIOPOD MORPHOLOGY
brachydactylous /BRACK-ə-DACK-tə-ləs/ adj. Short-fingered.
brachydont /BRACK-ə-dawnt/ adj. Having short crowns and well-developed roots (said of teeth).
bradytelic /BRAID-ə-tel-ick/ adj. Pertaining to evolution that occurs at a slower than usual rate.
branchiae /BRANK-ee-ī, -ee/ n. Gills.
branchial /BRANK-ee-əl/ adj. Of or pertaining to gills.
branchiate /BRANK-ee-ət, -ate/ (also branchiferous /brang-KIF-er-rəs/) adj. Having gills.
breccia /BRECH-yə/ n. A sedimentary rock composed of coarse rock fragments embedded in a matrix of finer-grained material.
brevicaudate /brehv-ə-CAWD-date/ adj. Short tailed.
brevifoliate /brehv-ə-FŌL-ee-ət/ adj. Short leaved.
bronchus /BRAWNK-əs/ (pl bronchi /BRAWNK-ee, -ī/) n. Either of the two tubes into which the trachea divides.
Brownian motion n. Movement, visible under the microscope, of minute particles suspended in liquid; due to collisions with the surrounding molecules. MORE INFORMATION
browser n. An animal that feeds on the twigs, shoots, leaves, and fruits of bushes and trees.
bryology /bry-AWL-ə-jee/ n. The study of bryophytes.
bryophytes /BRY-ə-fĪts/ n. A group of nonvascular plants comprising the mosses, hornworts, and liverworts.
buccal /BUCK-əl/ Of or pertaining to the mouth or cheeks.
buccal cavity /BUCK-əl/ n. The mouth.
buccogingival /buck-ə-JIN-jə-vəl/ Of or pertaining to the cheeks and gums.
bucnemia /buck-NEEM-ee-yə, NEEM-yə/ n. Elephantiasis; broadly: inflammation of the leg.
budding n. A form of reproduction in which outgrowths from the parent separate from the parent and live on as separate individuals.
Bufo /BYOO-fō/ A genus of toads.
bulbourethral glands /bulb-ō-yə-REE-thrəl/ n. Cowper's glands.
bullate /BULL-ate/ adj. Like a bubble or blister.
BUN Blood urea nitrogen.
bunodont /BYOON-ə-dawnt/ adj. Being or having molar teeth with rounded cusps.
bursa/BER-sə/ (pl bursae /BER-sigh, BER-see/ or bursas /BER-səs/) n. A cushionlike sac nearby a joint. Bursae contain synovial fluid, a lubricant easing friction between tendons and bone — bursal /BER-səl/
bursate /BER-sate/ adj. Having a bursa.
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