Glossary of Terms
Entropy: the degree of disorder or randomness of a system.
Glossary
Actin: a protein filament within the sarcomeres of muscle cells.
Adhesin: A molecular component of the surface of a microorganism that is involved in adhesion to a substratum or cell. Adhesion to a specific host tissue usually is a preliminary stage in pathogenesis, and adhesins are important virulence factors.
Acidophile: A microorganism that has its growth optimum between about pH 0 and 5.5.Aerobe: An organism that grows in the presence of atmospheric oxygen.
Aflatoxin: A polyketide secondary fungal metabolite that can cause cancer.
Agar: A complex sulfated polysaccharide, usually extracted from red algae, that is used as a solidifying agent in the preparation of culture media.
Akinetes: Specialized, nonmotile, dormant, thick-walled resting cells formed by some cyanobacteria.
Algicide: An agent that kills algae.
Alleles: Alternative forms of a genetic characteristic.
Amensalism: A symbiotic relationship in which one organism is harmed or inhibited and the other is unaffected.
Anabolism: the process of synthesizing large molecules by joining smaller molecules together.
Anaerobic: organisms that thrive in an oxygen-free environment.
Anaphase: stage in mitosis and meiosis where chromosomes begin moving to opposite ends (poles) of the cell.
Anatomy: the study of the structure and relationship between body parts.
Annotation: The process of determining the location of specific genes in a genome map after it has been produced by nucleic acid sequencing.
Antagonistic hormones: hormones that act to return body conditions to within acceptable limits from opposite extremes.
Anterior: Situated before or toward the front.
Antigen: any molecule, usually a protein or polysaccharide, that can be identified as foreign or nonself. It may be a toxin, or a part of the protein coat of a virus, or a molecule unique to the plasma membranes.
Apoptosis - genetically programmed cell death
Aquaculture – the farming of marine and fresh water organisms.
Atoll – a coral reef that develops as a ring around a central lagoon.
Autosome: All chromosomes except those involved in sex determination. Humans have 22 pairs of autosomes and the X and Y sex chromosomes (XX for females, YY for males).
Alveoli: microscopic air sacs that are surrounded by a rich network of blood vessels in mammalian lungs that function in gas exchange; the air sacs are at the end of the bronchioles.
ATP (adenosine triphosphate) a common source of activation energy for metabolic reaction.
Axon: the long extension of a neuron.
Basophils: the white blood cells that function in allergic responses.
Bioaccumulation: the process whereby pollutants are taken up, retained and concentrated in the cells of plants and animals.
Biology: is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy.
Bioluminescence – the production of light by living organisms.
Biomass: the total dry weight of food at each level of the food pyramid.
Biosphere: the blanket of living things that surrounds the substratum of the earth.
Bowman's capsule: an enlarged cuplike structure below the nephron in the human kidney.
Catabolism: The metabolic breakdown of complex molecules into simpler ones, often resulting in a release of energy.
Cecum: a blind sac that is the meeting point of the small and large intestines.
Cells: the fundamental units of living things
Centriole: a cylinder-like organelle that assists in chromosomal migration during mitosis.
Centrosome: The organelle located near the nucleus in the cytoplasm that divides and migrates to opposite poles of the cell during mitosis, and is involved in the formation of mitotic spindle, assembly of microtubules, and regulation of cell cycle progression; the region pertaining to the organelle.
Chelicerae: one of the anterior pair of appendages of an arachnid often specialized as fangs
Chemosynthesis: The process whereby chemical energy is used to make organic compounds from inorganic compounds. One example is the oxidation of ammonia to nitrite by nitrifying bacteria.
Chromatid: homologous chromosomes joined to each other at the centromere; present during the prophase of mitosis.
Cistron: A length of chromosomal DNA representing the smallest functional unit of heredity, essentially identical to a gene.
Cladophora: A genus of green algae found in large numbers in the gills of fish that died from asphyxiation.
Cofactor: The nonprotein component of an enzyme; it is required for catalytic activity.
Cones: photoreceptor cells that respond to bright light and color and transmit sharp images.
Cristae: the folds of the inner mitochondrial membrane.
Cytochromes: molecules that accept and release electrons in an electron transport system.
Cytokinesis: is the process in which the cytoplasm of a single eukaryotic cell is divided to form two daughter cells.
Cytosol: a fluid matrix of water and dissolved substances such as proteins and nutrients.
Denaturation is a process in which proteins or nucleic acids lose their tertiary structure and secondary structure by application of some external stress or compound.
Dermal Tissue: the tissue that functions to protect the plant from injury and water loss and covers the outside of the plant.
Dermis: the second layer of skin.
Diastole: a relaxation event of either the atria or ventricles.
Diencephalon: connects the cerebrum to the brain stem.
Diffusion: the net movement of substances from an area of higher concentration to an area of lower concentration.
Diploid: Having a full set of genetic material consisting of paired chromosomes. One of each pair of chromosomes comes from each parent.
Disaccharide: a carbohydrate consisting of two linked sugar molecules.
Double Helix: term used to describe the structure of DNA.
Ectoderm: one of three germ layers that develops into the skin and nervous system.
Effluent: Industrial or urban waste discharged into the environment.
Electrophoresis: A method of separating large molecules-such as DNA fragments or proteins-from a mixture of similar molecules.
Endocytosis: is the process by which cells absorb molecules (such as proteins) from outside the cell by engulfing them with their cell membrane.
Endoderm: one of three germ layers that develops into the gastrointestinal tract.
Endolymph: is the fluid contained in the membranous labyrinth of the inner ear. It is also called Scarpa's fluid, after Antonio Scarpa.
Entropy: the degree of disorder or randomness of a system.
Enzyme: A protein that acts as a catalyst, speeding the rate at which a biochemical reaction proceeds but not altering the direction or nature of the reaction. All cellular metabolism is controlled by enzymes.
Eosinophils: white blood cells whose functions are uncertain.
Epistasis - when one gene controls the expression of another gene.
Epithelial tissue acts as a covering and lining on the outside surfaces of the body and lines the internal organs or secretes hormones or other products.
Epiphysis: the rounded end of a long bone
Erythrocytes: the red blood cells; disk-shaped cells produced in the bone marrow that have no nucleus; their cytoplasm is filled with hemoglobin to transport oxygen.
Eubacteria: modern bacteria
Eutrophication: Enrichment of a water body with nutrients, resulting in excessive growth of phytoplankton seaweeds, or vascular plants, and often depletion of oxygen.
Exocytosis: is the durable process by which a cell directs the contents of secretory vesicles out of the cell membrane.
Exon: A segment of a gene that contains instructions for making a protein. In many genes the exons are separated by "intervening" segments of DNA, known as introns, which do not code for proteins; these introns are removed by splicing to produce messenger RNA.
Flagella: structure that protrudes from the cell membrane and makes wavelike movements. Classified by length and number per cell, flagella are long and few. A single flagellum propels sperm. Structurally flagella consists of microtubules arranged in a "9 + 2" array.
Gametangium: A structure that contains gametes or in which gametes are formed.
Ganglia: clusters of cell bodies in the peripheral nervous system.
Genome: The full set of genes present in a cell or virus; all the genetic material in an organism; a haploid set of genes in a cell.
Ghrelin: a gastrointestinal hormone produced by epithelial cells lining the fundus of the stomach; appears to be a stimulant for appetite and feeding, but is also a strong stimulant of growth hormone secretion from the anterior pituitary.
Glomerulus: a ball of capillaries that comprises Bowman's capsule in the human kidney.
Glucagon: a hormone produced in the pancreas that stimulates the breakdown of glycogen to glucose in the liver.
Glycogen: A highly branched polysaccharide containing glucose, which is used to store carbon and energy.
Glycolysis: the subdivision of cellular respiration in which glucose molecules are broken down to form pyruvic acid molecules.
Gross (macroscopic) anatomy: the study of body parts visible to the naked eye.
Guanine: A purine derivative, 2-amino-6-oxypurine, found in nucleosides, nucleotides, and nucleic acids.
Gustation: The act or sensation of tasting.
Halophile: A microorganism that requires high levels of sodium chloride for growth.
Haploid: A cell with half the usual number of chromosomes, or only one chromosome set. Sex cells are haploid.
Hapten: a molecule not immunogenic by itself but that, when coupled to a macromolecular carrier, can elicit antibodies directed against itself.
Helicases: Enzymes that use ATP energy to unwind DNA ahead of the replication fork.
Hemopoiesis: the process that produces the formed elements of the blood and takes place in the red bone marrow of long bones.
Hemostasis: the stoppage of bleeding through vascular spasm, platelet plug, or coagulation.
Hypothesis: A tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation.
Hypotonic: lacking muscle tone: with low or diminished muscle tone or tension or lower in osmotic pressure: with a lower osmotic pressure than another fluid.
Histology: the study of tissues at the microscopic level.
Histones: nuclear proteins that coil DNA molecules
Homeostasis: The ability or tendency of an organism or cell to maintain internal equilibrium by adjusting physiological processes.
Holdfast: A structure produced by some bacteria and algae that attaches the cell to a solid object.
Holoenzyme: A complete enzyme consisting of the apoenzyme plus a cofactor.
Homologies: Similarities in DNA or protein sequences between individuals of the same species or among different species.
Homeostasis: the process in which the internal environment exists at a steady-state equilibrium despite changes in the external environment.
Hypertonic: excessively tense: describes a body part such as a muscle or artery that is under unusually high tension or having higher osmotic pressure: describes a fluid that has a higher osmotic pressure than another fluid.
Hypha: The unit of structure of most fungi and some bacteria; a tubular filament.
Hypodermis: the layer between the dermis and the underlying tissues and organs.
Hypotension: Abnormally low blood pressure, commonly considered to be levels below 100 diastolic and 40 systolic.
Hypotonic: lacking muscle tone: with low or diminished muscle tone or tension or lower in osmotic pressure: with a lower osmotic pressure than another fluid.
Hypoxic: Having a low oxygen level.
Inducer: A small molecule that stimulates the synthesis of an inducible enzyme.
Interferons (IFNs): are proteins made and released by lymphocytes in response to the presence of pathogens—such as viruses, bacteria, or parasites—or tumor cells. They allow communication between cells to trigger the protective defenses of the immune system that eradicate pathogens or tumors.
Insertion: the muscle end that attaches to the moving structure.
Integrator: a control center (often the brain).
Intron: A noncoding intervening sequence in a split or interrupted gene, which codes for RNA that is missing from the final RNA product.
Isogenic: Of the same genotype.
Isomeres: Molecules with the same chemical formula, but atoms are arranged differently.
Isotonic: Of equal pressure; having the same concentration of solutes as the blood: an isotonic saline solution, Pysiology. of or involving muscular contraction in which the muscle remains under relatively constant tension while its length changes.
Isotope: One of two or more atoms that have the same atomic number (the same number of protons) but a different number of neutrons.
Karyotype: A photomicrograph of an individual's chromosomes arranged in a standard format showing the number, size, and shape of each chromosome type.
Leptin: (from the Greek leptos, meaning thin) is a protein hormone with important effects in regulating body weight, metabolism and reproductive function.
Limbic System: a network of neurons that extends over a wide range of areas of the brain. Imposes an emotional aspect to behaviors, experiences, and memories.
Lipids: a class of substances that are insoluble in water (and other polar solvents) but are soluble in nonpolar substances (like ether or chloroform).
Liposome: A spherical particle formed by a lipid bilayer enclosing an aqueous solution. It may be use to administer chemotherapeutic agents or in diagnostic testing.
Lymph: a watery fluid derived from plasma that seeps out of the blood system capillaries and mingles with the cells.
Lymphocytes: white blood cells (leukocytes) that provide an immune response that attacks specific kinds of nonself cells and foreign substances.
Lysis: Breaking apart of cells.
Lysogeny: The state in which a phage genome remains within the baterial host cell after infection and reproduces along with it rather than taking control of the host and destroying it.
Macromolecule: A very large molecule, such as a polymer or protein, consisting of many smaller structural units linked together
Macronucleus: The larger of the two nuclei in ciliate protozoa. It is normally polyploid and directs the routine activities of the cell.
Macrophage (mak_ro-føaj) The name for a large mononuclear phagocytic cell, present in blood, lymph, and other tissues. Macrophages are derived from monocytes. They phagocytose and destroy pathogens; some macrophages also activate B cells and T cells.
Meiosis: is the process by which the number of chromosomes in a cell nucleus is halved during the formation of germ cells (eggs and sperm)
Melatonin: a hormone that helps regulate the biological clock (sleep-wake cycles).
Mesenchyme: or mesenchymal connective tissue, is an example of reticular connective tissue, a type of loose connective tissue, which is derived from all three germ layers and located within the embryo.
Mesoderm: one of three germ layers that develops to become the muscles and other internal organs
Metabolism: the set of chemical reactions that happen in living organisms to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually divided into two categories. Catabolism breaks down organic matter, for example to harvest energy in cellular respiration. Anabolism uses energy to construct components of cells such as proteins and nucleic acids.
Metastasis: The transfer of a disease like cancer from one organ to another not directly connected with it.
Metamorphosis: is a biological process by which an animal physically develops after birth or hatching, involving a conspicuous and relatively abrupt change in the animal's body structure through cell growth and differentiation.
Microbiology: The study of organisms that are usually too small to be seen with the naked eye. Special techniques are required to isolate and grow them.
Monera: the kingdom that includes the bacteria and the cyanobacteria; prokaryotic organisms.
Monophyletic: descended from a common ancestor or stem cell.
Monosaccharide: the simplest kind of carbohydrate consisting of a single sugar molecule.
Morphogenesis: (from the Greek morphê shape and genesis creation, literally, "beginning of the shape"), is the biological process that causes an organism to develop its shape. It is one of three fundamental aspects of developmental biology along with the control of cell growth and cellular differentiation.
Mitochondria: carry out aerobic respiration
Mitosis is the process by which a eukaryotic cell separates the chromosomes in its cell nucleus into two identical sets in two nuclei.
Mutagen: (Latin, literally origin of change) is a physical or chemical agent that changes the genetic material, usually DNA, of an organism and thus increases the frequency of mutations above the natural background level.
Mycoplasma: is a genus of bacteria which lack a cell wall.Without a cell wall, they are unaffected by many common antibiotics such as penicillin or other beta-lactam antibiotics that target cell wall synthesis.
Mycosis: Any disease caused by a fungus.
Nephrons: filtering units that number over a million in the kidneys.
Osmosis: the tendency of a fluid, usually water, to pass through a semipermeable membrane into a solution where the solvent concentration is higher, thus equalizing the concentrations of materials on either side of the membrane.
Oviparous: Producing eggs that hatch outside the body.
Parturition: The act or process of giving birth; childbirth.
Peritoneum: thin membrane that lines the abdominal and pelvic cavities, and covers most abdominal viscera. It is composed of layer of mesothelium supported by a thin layer of connective tissue.
Phagocytes: white blood cells that wander throughout the body attacking bacteria and other foreign invaders.
Phagocytosis: process by which certain living cells called phagocytes ingest or engulf other cells or particles.
Pharmacokinetics: sometimes abbreviated as PK, (from Ancient Greek pharmakon "drug" and kinetikos "to do with motion" The process by which a drug is absorbed, distributed, metabolized, and eliminated by the body.
Phenotype: The outward physical characteristics of an organism.
Phospholipids: a class of lipids that are a major component of all cell membranes as they can form lipid bilayers.
Physiology: the study of the function of body parts and the body as a whole.
Plasmid: A circular, double-stranded unit of DNA that replicates within a cell independently of the chromosomal DNA. Plasmids are most often found in bacteria and are used in recombinant DNA research to transfer genes between cells.
Platyhelminthes: The flatworms, known in scientific literature as Platyhelminthes or Plathelminthes (from the Greek, platy, meaning "flat" and, helminth-, meaning worm) are a phylum of relatively simple bilaterian, unsegmented, soft-bodied invertebrate animals.
Pluripotency: in the broad sense refers to "having more than one potential outcome." In biological systems, this can refer either to cells or to biological compounds. From the Latin pluri=many, potent=power, capacity. A pluripotent cell can create all cell types except for extra embryonic tissue, unlike a totipotent cell, (tot=all), which can produce every cell type including extra embryonic tissue.
Pneumothorax: (a term for collapsed lung) occurs when air leaks into the space between your lungs and chest wall, creating pressure against the lung.
Polymerase: an enzyme that acts like a molecular assembly line to build new strands of DNA.
Polypeptide: A molecule made up of a string of amino acids. A protein is an example of a polypeptide.
Polyphyletic: derived from more than one ancestral type
Proteins: The active molecules in all cells. Proteins control biochemical reactions and determine the physical structure of organisms.
Receptor: a molecule most often found on the surface of a cell, which receives chemical signals originating externally from the cell. Through binding to a receptor, these signals direct a cell to do something—for example to divide or die, or to allow certain molecules to enter or exit.
Reductionism: an approach to understanding the nature of complex things by reducing them to the interactions of their parts, or to simpler or more fundamental things.
Remodeling: the process of creating new bone and removing old bone.Ribosome: The small cellular structure in which RNA translates the genetic code into proteins.
Rods: photoreceptors that are most sensitive to light and more numerous than cones. The provide vision in dim light and are more capable of detecting movement.
Salinophiles are bacteria that thrive in salty environments.
Saprophyte: An organism that takes up nonliving organic nutrients in dissolved form and usually grows on decomposing organic matter.
Septate: Divided by a septum or cross wall; also with more or less regular occurring cross walls.
Sheath: A hollow tubelike structure surrounding a chain of cells and present in several genera of bacteria.
Somatic cells: Any cell in the body except sex cells.
Speciation is the evolutionary process by which new biological species arise.
Spirillum: a rigid, spiral-shaped bacterium
Spirochete: A flexible, spiral-shaped bacterium with periplasmic flagella.
Strain: A population of organisms that descends from a single organism or pure culture isolate.
Symbiosome: The final nitrogen-fixing form of Rhizobium that is active within root nodule cells.
Synapse (synaptic cleft): a gap that separates the neuron from a muscle cell or another neuron.
Systole: a contraction event of either the atria or ventricles.
Telomere is a region of repetitive DNA sequences at the end of a chromosome, which protects the end of the chromosome from deterioration or from fusion with neighboring chromosomes.
Thrombopoiesis: The process of blood clot formation, the formation of blood platelets.
Transcription: The process by which DNA passes genetic information to RNA. Transcription is the first step in producing proteins.
Transdermal - Through or by way of the skin
Transformation: is the genetic alteration of a cell resulting from the uptake, genomic incorporation, and expression of environmental genetic material.
Tropism: The movement of living organisms toward or away from a focus of heat, light, or other stimulus.
Uracil: A base; one of the molecular components of RNA. Bonds only with adenine (U-A).
