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Dipeptide - ansA molecule consisting of two amino acids joined by a peptide bond. Endocytosis - ansThe process of taking materials into a cell by surrounding them with plasma membrane, which pinches off to form a vesicle inside the cell. This is an active process requiring ATP. Exchange surface - ansA specialised area adapted to make it easier for molecules to cross from one side of the surface to the other. Family - ansTaxonomic group used in the classification of living organisms. Contains related genera. Fermenter - ansA vessel used to grow microorganisms in large numbers. Gamete - ansSex cells, usually haploid (one set of chromosomes). Fuse during sexual reproduction to form zygotes (diploid). Gene pool - ansThe sum total and variety of all the genes in a population or species at a given time. Glycosidic bond - ansThe covalent bond formed when carbohydrate molecules are joined together in condensation reactions. Habitat - ansThe place where an organism or population lives. It includes the climatic, topographic and edaphic factors as well as the plants and animals that live there. Haem - ansThe iron-containing prosthetic group found in haemoglobin. Haemoglobinic acid - ansThe acid produced when haemoglobin takes up hydrogen ions. Haemolysis - ansThe rupturing of animal cell surface membranes, and subsequent release of their contents, when cells placed in a solution of higher water potential and water enters by osmosis. Health - ansComplete mental, physical and social wellbeing. Histone - ansType of protein associated with DNA in eukaryotes. DNA is wound around them to form chromatin. Hormone - ansChemicals made in endocrine glands that are carried in the blood to target cells/tissues/organs. They act as chemical messengers. Hydrocarbon chain - ansA chain of carbon atoms bonded together with hydrogen atoms bonded onto the carbons. Immune response - ansA response to an antigen, which involves the activation of lymphocytes. Immunological memory - ansAbility of the immune system to respond very quickly to antigens that it recognises as they have entered the body before. Incidence - ansThe number of new cases of a disease in a certain time period. Induced fit (hypothesis) - ansThe theory of enzyme action in which the enzyme molecule changes shape to fit the substrate molecule more closely as it binds to it. Interferon - ansA group of factors with non-specific antiviral activity. They also affect the immune system. Intracellular - ansInside the cell. Ion - ansAn atom (or group of atoms) carrying a positive or a negative charge. Ionic bond - ansAttraction between oppositely charged ions. Keratin - ansFibrous protein found in skin, hair and nails. Leucocytes - ansWhite blood cells.
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Lipids - ansA diverse group of chemicals that includes triglycerides, fatty acids and cholesterol. Lock-and-key hypothesis - ansThe simple theory of enzyme action where the active site is directly complementary to the substrate molecule. Lumen - ansA cavity surrounded by a cell wall in cells, such as xylem vessels, which have lost their cell contents. Also used for the central cavities of blood vessels. Lymphocyte - ansA type of white blood cell activated as part of the immune response. Lysosomes - ansMembrane-bound vesicles made by pinching off from the Golgi body. They usually contain digestive enzymes. Macrophages - ansLarge, phagocytic, amoeba-like white blood cells that engulf, ingest and destroy bacteria, damaged cells and worn-out red blood cells. Magnification - ansThe number of time greater an image is than the object. Messenger RNA (mRNA) - ansA type of RNA polynucleotide involved in protein synthesis. Carries the information coding for a polypeptide from the nucleus to the ribosomes in the cytoplasm. Microtubule motors - ansProteins associated with microtubules. The proteins can move along microtubules. Kinesin moves towards the (+) end of the microtubules and dynein moves towards the (-) end. Mitosis - ansNuclear division that results in the formation of cells that are genetically identical to the parent cell. Monoculture - ansA crop of plants of a single species bred to be very similar. Monocyte - ansLarge, phagocytic white blood cell. Monomer - ansA small molecule that is one of the units bonded together to form a polymer. Monosaccharide - ansA simple sugar molecule. The monomer of polysaccharides. Morbidity - ansThe proportion of people in a population who are ill with a particular disease at any one time. Mortality - ansThe number of people who die from a disease in a certain time period. Mucus - ansA slimy substance secreted by goblet cells in animal epithelial tissues. It is made up mostly of glycoproteins and protects and/or lubricates the surface on to which it is secreted. Mutation - ansA change in the structure of DNA, or in the structure and number of chromosomes. Mycelium - ansThe mass of filaments (hyphae) that make up the body of a fungus. Natural selection - ansThe mechanism for evolution in which the best-adapted organisms in a population can outcompete those that are less well-adapted. Niche - ansThe exact role of an organism in the ecosystem - its use of the living and non- living components of the ecosystem. Non-competitive inhibitor - ansAn inhibitor of an enzyme-controlled reaction that binds to the enzyme molecule in a region away from the active site. Nuclear envelope - ansThe double membrane structure surrounding the nucleus in eukaryotic cells. Nucleotide - ansThe monomer of nucleic acids consisting of a phosphate, a sugar and an organic base.
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Photosynthesis - ansProcess by which plants, some bacteria and some protoctists make food using carbon dioxide, water and sunlight energy. Phylogeny - ansThe evolutionary relationships between organisms. Phylum - ansA taxonomic group used in classification of living organisms. Contains similar classes. Pinocytocis - ansThe process of endocytosis involving the bulk movement of liquids into a cell. Pits (or bordered pits) - ansThin areas in the lignified walls of xylem tissue cells that allow communication between adjacent cells. Plaque - ansFatty material built up under the endothelium of an artery. Plasma cells - ansMature B-lymphocytes (white blood cells) that secrete a specific kind of antibody. Plasma proteins - ansProteins made in the liver that are found in the non-cellular fraction of the blood. Plasmid - ansSmall, circular piece of DNA present in some bacterial cells. May have genes for antibiotic resistance and can also be used as vectors in genetic engineering. Plasmodesma(ta) - ansA fine strand of cytoplasm that links the protoplasm of adjacent cells through a thin area of cell wall called a pit. Plasmolysis - ansDetachment of the plasma membrane from the cell wall as the cytoplasm shrinks when water is lost from a plant cell. Platelets - ansFragments of cells in the blood that play a part in blood clotting. Pluripotent - ansStem cells capable of differentiating to become a limited number of cell types found in the organism (e.g. cells of an early embryo). Polymer - ansA large molecule made up of many/repeating similar, smaller molecules (monomers) covalently bonded together. Polynucleotide - ansA polymer consisting of many nucleotide monomers covalently bonded together (DNA and RNA are examples). Polypeptide - ansA polymer consisting of many amino acid monomers covalently bonded together. Polysaccharide - ansA polymer consisting of many monosaccharide monomers covalently bonded together. Potometer - ansApparatus used to measure water uptake in a leafy shoot and so to estimate rate of transpiration. Precipitate - ansA suspension of small solid particles in a liquid, produced by a chemical reaction. Prevalence - ansThe number of people with a particular disease at a certain time. Primary defences - ansThe defences that prevent the entry of a pathogen into the body. Primary structure - ansThe sequence of amino acids found in a protein molecule. Prokaryote - ansAn organism with cells that do not contain a true nucleus. Prophase - ansThe phase of mitosis where the chromosomes become visible as a pair of sister chromatids joined at the centromere. Prosthetic group - ansA non-protein organic molecule that forms a permanent part of a functioning protein molecule.
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Protease - ansAn enzyme capable of digesting proteins. Protein - ansA polymer consisting of many amino acid monomers covalently bonded together. Pulmonary circulation - ansThe circulation of the blood through the lungs. Pulmonary vein - ansThe vein carrying oxygenated blood from the lungs to the left atrium of the heart. Purine - ansAdenine and guanine - nitrogenous bases consisting of a double ring structure. Purkyne tissue (Purkinje tissue) - ansSpecialised tissue (muscle fibres) in the septum of the heart that conducts the electrical stimulus from the sinoatrial node to the ventricles. Pyrimidine - ansThymine, cytosine and uracil - nitrogenous bases consisting of a single ring structure. Quadrat - ansA square frame used for sampling in field work. Qualitative - ansA study is that does not involve quantity (numbers). For example, simple observations to see if a particular species lives in a selected area. Quantitative - ansA study involving quantity (numbers). For example, if you count the number of individuals of a species in a selected area. Quaternary structure - ansProtein structure where a protein consists of more than one polypeptide chain e.g. Haemoglobin and insulin. Receptor sites - ansProtein or glycoprotein molecules on cell surfaces, used for attachment of specific substances such as hormones or viruses. Reducing sugar - ansA carbohydrate monomer or dimer that gives a positive result in Benedict's test because it is able chemically to reduce copper sulfate in solution. Reduction - ansChemical reaction involving the gain of electrons or the addition of hydrogen. Resolution - ansThe ability to distinguish two separate points as distinct from each other. Respiration - ansThe process in which energy is released from complex molecules, such as glucose, within cells and transferred to molecules of ATP. Ribose - ansThe 5-carbon (pentose) sugar found in RNA nucleotides. Ribosomal RNA (rRNA) - ansThe nucleic acid found in ribosomes. Ribosome - ansThe organelle on which proteins are synthesised inside the cell. Risk factor - ansA factor that increases the chance that you may develop a particular disease. RNA - ansA single-stranded polynucleotide molecule that exists in three forms. Each form plays a part in the synthesis of proteins within cells. Root hair cells - ansCells in the epithelium of roots that have long extensions to increase surface area for the absorption of water and minerals. Secondary defences - ansDefences that attempt to kill or inactivate pathogens that have already invaded the body. Secondary structure - ansThe local coiling or folding parts of a protein molecule due to the formation of hydrogen bonds formed as the protein is synthesised. E.g. a-helix and b-pleated sheets. Secretion - ansThe release of a substance made inside the cell using the process of exocytosis. Selection pressure - ansAn external pressure that drives evolution in a particular direction. Semi-conservative replication - ansThe replication of a DNA strand where the replicated double helix consists of one old strand and one newly synthesised strand.
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Sustainable development - ansDevelopment that does not cause excessive harm to the surrounding environment. The local biodiversity and people can continue to live and operate alongside the development. Sympatric - ansSpeciation that occurs within one area - some factor other than geographical separation has prevented free interbreeding between members of the species. Symplast pathway - ansThe route taken by water through the cytoplasm of cells in a plant. Systemic circulation - ansThe circulation that carries blood around the body, excluding the circulation to the lungs. Systole - ansThe stage of the heart cycle in which heart muscle contracts to pump blood. Taxon (pl: taxa) - ansA taxonomic group, such as a class or a family, used to aid classification. Taxonomy - ansThe study of the principles behind classification. Telophase - ansFinal phase of mitosis. Two new nuclear envelopes form around the two new nuclei. Tendinous cords - ansString-like tendons used to attach the atrioventricular valves of the heart to the sides of the ventricle wall. Sometimes called heart strings. Tertiary structure - ansThe overall three-dimensional shape of a protein molecule. Involves hydrogen bonding, disulfide bridges, ionic bonds and hydrophobic interactions. Testosterone - ansSteroid hormone made in the testes. Thrombus - ansA blood clot. Thylakoid - ansFlattened membrane sacs in chloroplasts, which hold the pigments used in photosynthesis and are the site of the light reactions. A stack of thylakoids forms a granum. Thymine - ansA nitrogen-containing organic base found in DNA. It pairs with adenine. Tissue - ansA group of similar cells that perform a particular function. Tissue fluid - ansThe fluid, derived from blood plasma, that surrounds the cells in a tissue. Totipotent - ansUndifferentiated cell that is capable of differentiating into any kind of specialised cell. Trachea - ansThe windpipe leading from the back of the mouth to the bronchi. Transcription - ansThe assembly of an mRNA molecule that is a copy of the DNA coding strand (and complementary to the template strand). Transect - ansA line through a habitat used to help take samples and study the habitat. Transfer RNA (tRNA) - ansA type of polynucleotide involved in protein synthesis. It transports amino acids to the ribosomes to be added to the growing polypeptide chain. Transgenic - ansOrganism that has genetic material from another organism, usually by genetic engineering. Translocation - ansThe movement of sucrose and other substances up and down a plant. Transmission - ansThe way in which a microorganism or other pathogen travels from one host to another. Transpiration - ansThe loss of water vapour from the aerial parts of a plant due to evaporation. Triglyceride - ansA molecule consisting of a glycerol molecule and three fatty acid molecules covalently bonded together.
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Turgid - ansDescribes a cell that is full of water as a result of entry of water due to osmosis such that pressure of the cell wall prevents more water entering. Ultrastructure - ansThe detailed structure of the internal components of cells as revealed by the electron microscope rather than by the light microscope. Uracil - ansA nitrogen-containing organic base found in RNA. Pairs with adenine. Urea - ansChemical made in the liver from amine groups from deaminated amino acids and carbon dioxide. It is toxic and is removed from the body in urine. Vaccine - ansA preparation of antigens given to provide artificial immunity. Vacuolar pathway - ansThe pathway taken by water in plants as it passes from cell to cell via the cell cytoplasm and vacuole. Variable - ansCondition in an experimental investigation. Can be independent (altered by the experimenter) or dependent (respond to changes in the independent variable). Variation - ansThe differences between individuals. Vascular tissue / bundle - ansThe transport tissue in a plant - usually found as a bundle containing both xylem and phloem. Vector - ansAn organism that carries a disease-causing organism (pathogen) from one host to another. Also describes an agent (such as a plasmid) that can transfer genetic material. Vena cava - ansEither of two large veins that carry deoxygenated blood from the body back to the heart. Ventilation - ansBreathing - movement of diaphragm and rib cage that bring air into and out of the lungs. Ventricles - ansThe lower chambers in the heart. Vesicle - ansA membrane-bound sac found in cells and used to transport materials around the cell. Villi - ansFolds in the wall of an organ or tissue that increase surface area. Vitamin - ansChemical needed in small amounts for healthy metabolism. Some organisms can make them, some organisms have to obtain them in the diet. Water potential (Y) - ansA measure of the ability of water molecules to move freely in solution. Decreased by the presence of solutes. Water vapour potential - ansThe potential energy of water vapour in a gas - it is used to indicate how much water vapour is present. Xerophyte - ansA plant specially adapted to living in dry areas. Xylem - ansA plant tissue containing vessels (and other cells) that are used to transport water in a plant and provide support. Zygote - ansDiploid cell made from fusion of male and female gametes. Abundance - ansThe frequency of occurrence of plants in a sampled area, such as a quadrat. Activation energy - ansThe level of energy required to enable a reaction to take place. Enzymes reduce the amount of energy required to allow a reaction to proceed. Active immunity - ansImmunity that is acquired by activation of immune system. Active site - ansThe area on an enzyme molecule to which the substrate binds. Adhesion - ansForce of attraction between molecules of two different substances. a-helix - ansA protein secondary structure - a right-handed spiral held in place by hydrogen bonds between adjacent C=O and NH groups.
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Carrier protein - ansA protein found in membranes, which is capable of carrying a specific molecule or ion through the membrane by active transport. Calibration - ansTo use known concentrations of a substance in a solution to make a standard curve on a graph. This can be used to determine the amount of that substance in solutions of unknown concentration. Centromere - ansThe region of a chromosome where two sister chromatids are joined together, and where the spindle fibre attaches during cell division. Cellulose - ansA carbohydrate polymer (of b-glucose) that forms plant cell walls. Atrioventricular node (AVN) - ansA patch of tissue in the septum of the heart that conducts the electrical stimulus from the atria in the heart through to the Purkyne fibres. Cartilage ring - ansA flexible ring of cartilage that holds the airways open. Chromatin - ansMaterial staining dark red in the nucleus during interphase. It consists of nucleic acids and proteins. Condenses into chromosomes during prophase of nucler division. Benedict's test - ansTest for reducing sugars. Sample is heated to 80ÂșC with reagent. If a reducing sugar is present, the reagent changes from blue to red precipitate. Cardiac cycle - ansThe sequence of events making up one heartbeat. Anomalous - ansDescribes a result/data point that does not appear to fit the pattern of the other results. Clones - ansGenetically identical cells or individuals. Chloride shift - ansThe movement of chloride ions into red blood cells to balance the loss of hydrogencarbonate ions. Adaptation - ansFeature of a living organism that increases its chances of survival, for example thick fur on an animal that lives in a cold habitat. Centriole - ansAn organelle from which the spindle fibres develop during cell division in animal cells. Antigen - ansA foreign molecule (which may be protein or glycoprotein) that can provoke an immune response. Artificial selection - ansAlso called selective breeding - the process of improving a variety of crop plant or domesticated animal by breeding from individuals with desired characteristics. Cohesion - ansThe attraction between water molecules due to hydrogen bonding. Cambium - ansPlant tissue in the stem and root that contains dividing cells. Anaphase - ansIn mitosis, the stage when the newly separated chromatids are pulled towards opposite poles of the nuclear spindle. Carnivore - ansAn animal that eats meat. Cell surface membrane - ansAlso known as the Plasma membrane. Cartilage - ansA flexible, slightly elastic connective tissue. Cytokines - ansHormone-like proteins produced by vertebrates, which are used for communication between cells, allowing some cells to regulate the activities of others. Cytoskeleton - ansThe network of protein fibres and microtubules found within the cell that gives structure to the cell and is responsible for the movement of many materials within it. Cholesterol - ansA lipid molecule (not a triglyceride) found in all cell membranes and involved in the synthesis of steroid hormones.
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Casparian strip - ansA strip of waterproof material (suberin) in the cell walls of root endodermis cells. It blocks the apoplast pathway. Bronchioles - ansAirways in the lungs that lead from the bronchi to the alveoli. Buffer - ansA chemical system that resists changes in pH by maintaining a constant level of hydrogen ions in solution. Certain chemicals dissolved in the solution are responsible for this. Constrict - ansTo make narrow. For example, in the narrowing of blood vessels. Clonal expansion - ansThe division of selected cells by mitosis to increase their numbers. Clonal selection - ansThe selection of cells (of the immune system) with a specific receptor site. These cells will undergo expansion as part of the immune response. Cytokinesis - ansThe division of the cell, following nuclear division, to form two new cells. Chromosome - ansA linear DNA molecule wrapped around histone proteins found in the nucleus. Become visible in prophase of cell division. Crenation - ansState of animal cells when they have been immersed in a solution of lower water potential and have lost water by osmosis and become shrivelled. Catalyst - ansA substance that increases the rate of a reaction but does not take part in the reaction, and so is re-usable. Carcinogen - ansA substance that causes cancer. Cristae - ansThe folds found in the inner membrane of a mitochondrion. Stalked particles containing ATP synthase are found here. Binomial system - ansA system of naming living things using two Latin words - the genus name and the specific name. Continuous variation - ansVariation where there is a range of intermediates, such as height, hair colour and intelligence in humans. Affected by multiple genes and environment Electrocardiogram - ansTrace (graph) showing the electrical activity of the heart muscle (atria and ventricles) during a cycle. Ciliated epithelium - ansLining cells that have cilia on their cell surface. Domain - ansClassification level introduced by Carl Woese dividing the kingdom Prokaryotae into two and placing all Eukaryotes into a third. Connective tissue - ansA type of tissue that consists of separate cells held together by a ground substance (matrix). Cofactor - ansA molecule or ion that helps an enzyme to work. It may be an inorganic ion or an enzyme. Enzyme - ansA protein molecule that acts as a biological catalyst. Discontinuous variation - ansVariation between living organisms within a species, where there are discrete categories and no intermediates, e.g. blood groups A, B, AB or O in humans. Disease - ansA departure from full health. Covalent bond - ansA chemical bond formed by the sharing of one or more electrons between two atoms. Bohr shift / Bohr effect - ansThe effect of carbon dioxide concentration on the affinity of haemoglobin for oxygen. Disaccharide - ansA molecule consisting of two monosaccharide sugars joined by a glycosidic bond.
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Diaphragm - ansA sheet of muscular and fibrous tissue separating the chest cavity from the abdominal cavity. Cell signalling - ansProcesses that lead to communication and coordination between cells. Hormones binding to their receptors on the cell surface membrane are an example. Deoxygenated - ansBlood with haemoglobin that carries no or little oxygen. Cytosine - ansA nitrogen-containing organic base found in nucleic acids. It pairs with guanine in DNA. Condensation - ansA type of chemical reaction in which two molecules are joined together by means of a covalent bond to form a larger molecule, and at the same time a water molecule is released. Dilate - ansTo make wider. For example, when the lumens of blood vessels become wider. Dissociation - ansThe separation of a molecule into two molecules, atoms or ions without breakage of a covalent bond. For example, the release of oxygen from oxyhaemoglobin. Conservation ex situ - ansConservation in areas other than the natural habitat. Cotransporter - ansA protein in a cell membrane that allows movement of one molecule when linked to the movement of another molecule in the same direction by active transport. Emulsion - ansA suspension of one material in another as droplets, because it does not dissolve. For example, fat droplets dispersed in water. Endodermis - ansA ring of cells between the cortex of a root and the area housing the xylem and phloem. DNA - ansA polymer of nucleotide molecules that form the instructions for the synthesis of proteins found within organisms. These nucleotides contain the 5-carbon sugar deoxyribose. Epidemiology - ansThe study of patterns of disease and the factors that influence their spread. Enzyme-substrate complex - ansThe intermediate structure formed when a substrate molecule binds to an enzyme molecule. Deamination - ansRemoval of amine (NH2) group from an amino acid Endothelium - ansA tissue that lines the inside of a structure, such as a blood vessel. Evolution - ansProcess by which the present diversity of living organisms arose from simple primitive organisms, with new species arising by natural selection. Diastole - ansThe period when the heart muscle in the ventricles is relaxing and blood pressure is at its lowest. Elastic tissue - ansTissue containing the protein elastin, which is able to stretch and recoil. Coenzyme - ansAn organic non-protein molecule that binds temporarily with substrate to an enzyme active site. It is essential for enzyme activity. Calibration - ansTo determine the value of intervals of a scale on an instrument, such as a thermometer. Chloroplast - ansAn organelle found in plants, which contains chlorophyll and is responsible for photosynthetic activity in the plant. Classification - ansThe organisation of living organisms (or other items) into groups according to their shared similarities. Collagen - ansA structural fibrous protein found in connective tissue, bones, skin and cartilage. It accounts for 30% of body protein.
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Competitive inhibitor - ansA substance that reduces the rate of an enzyme-controlled reaction by binding to the enzyme's active site. Diffusion - ansThe net movement of molecules or ions in a gas or liquid from an area of high concentration to an area where they are less concentrated. Channel protein - ansA protein pore that spans a membrane, through which very small ions and water soluble molecules may pass. Dissociation curve - ansThe curve on a graph showing the proportion of haemoglobin that is saturated with oxygen at different oxygen tensions. Division of labour - ansAny system where different parts perform specialised functions, each contributing to the functioning of the whole. Double circulatory system - ansA transport system in which blood travels twice through the heart for each complete circulation of the body. Conservation in situ - ansConservation in the natural habitat. Diploid - ansCells or organisms that have two copies of each chromosome in their nuclei. End-product inhibition - ansThe regulation of metabolic pathways where the last product in a sequence of enzyme-controlled reactions becomes an inhibitor of one of the enzymes earlier in the sequence. Environmental impact assessment - ansAn assessment of the damage that may be caused to the (local) environment by a proposed development. Double helix - ansDescribes the structure of DNA, a twisted helix of two strands with bases joining the strands. Ester bond - ansThe bond formed when fatty acid molecules are joined to glycerol molecules in condensation reactions. Erythrocytes - ansRed blood cells. Differentiation - ansThe development and changes seen in cells as they mature to form specialised cells. Extinction - ansThe death of the last individual in a species. Endoplasmic reticulum (ER) - ansA series of membrane-bound, flattened sacs extending from the outer nuclear membrane through the cytoplasm. Comes in rough and smooth forms. Epithelium - ansA tissue that covers the outside of a structure. Extracellular - ansOutside the cell - for example describes enzymes that work outside the cell. Diffusion gradient - ansThe difference in molecular concentration that allows diffusion to occur. Exocytosis - ansThe process of removing materials from the cell by fusing vesicles containing the material with the plasma membrane. Eukaryote - ansAn organism having cells with a nucleus and membrane-bound organelles. Enzyme-product complex - ansThe intermediate structure in which product molecules are bound to an enzyme molecule. Fertiliser - ansA substance added to soil to enhance the growth of plants. Flaccid - ansA term used to describe plant tissue where the cells have lost turgor and are not firm. Epidemic - ansDescribes a disease that spreads to many people quickly and affects a large proportion of the population.
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Haploid - ansA cell or organism that has one set of chromosomes/one copy of each chromosome. Glycolipid - ansA lipid with carbohydrate molecules attached. Fluid mosaic (model) - ansThe model of cell membrane structure proposed by Singer and Nicholson - a phospholipid bilayer with proteins 'floating' in it. Food tests - ansSimple procedures that show the presence of various biological molecules in samples or structures. Interleukin - ansCell-signalling chemicals. Some are involved in activating cells of the immune system. A type of cytokine. Hydrogen bond - ansA weak bond formed between partially charged atoms. It is seen in water molecules, and is important in the secondary and tertiary structure of proteins. Hydrolysis - ansA reaction in which a molecule is broken down into two smaller molecules by the addition of a water molecule and the breaking of a covalent bond. Lacteal - ansA blind-ending branch of the lymph system found in each villus of the small intestine. Heterotroph - ansOrganism that gains nutrients from complex organic molecules. These molecules are digested by enzymes to simple soluble molecules. Kinetic energy - ansEnergy of movement. Glycoprotein - ansA protein with carbohydrate molecules attached. Genetic erosion - ansThe loss of genetic variation due to (artificial) selection. Kingdom - ansTaxonomic group. Living organisms are grouped into one of five: Prokaryotae, Protoctista, Fungi, Plantae and Animalia. Fat - ansMixture of lipids, mainly triglycerides with saturated fatty acids, that is solid at body temperature. Act as an energy store, insulation, waterproofing and may give buoyancy. Interphase - ansThe phase of the cell cycle where synthesis of new DNA and organelles takes place. Monokines - ansChemical produced by monocytes to signal to other cells. Also called lymphokines. Homologous - ansChromosomes in diploid organisms that have the same genes at the same loci and that pair up during meiosis. Can also refer to structures that have a common evolutionary origin. Microtubules - ansComponents of the cell cytoskeleton. Involved in mitosis, cytokinesis and movement of vesicles within cells. Initial reaction rate - ansRate of reaction at the beginning before a significant amount of product has been formed or reactant used up. Hydrostatic pressure - ansPressure created by a fluid pushing against the sides of a container. Myogenic - ansDescribes muscle tissue (heart muscle) that generates its own contractions. Meiosis - ansNuclear division that results in the formation of cells containing half the number of chromosomes of the adult cell. Memory cells - ansB and T cells that remain in the body after an immune response. Their presence enables a much faster and greater second immune response. Keratinocytes - ansCells that make keratin.
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Fibrous protein - ansA protein with a relatively long, thin structure, which is insoluble in water and metabolically inactive, often having a structural role within the organism. Marker-assisted selection - ansUsed by animal and plant breeders to help select individuals with the desired genotype. The desired gene is linked to a section of DNA that is easy to identify in a young individual. Monophyletic - ansA group of organisms that share a common ancestor and therefore belong to the same classification group. Omnipotent - ansAnother word for totipotent. Nucleic acid - ansA polymer of nucleotide molecules. Diversity - ansTerm used to describe a large range of species in an area or a population of organisms that have significant genetic variation. Metabolism - ansAll the chemical reactions that take place in an organism. Osmosis - ansThe movement of water molecules from a region of higher water potential to a region of lower water potential across a partially permeable membrane. Lymphatic system - ansA system of lymph nodes and lacteals with lymph fluid. Myoglobin - ansA respiratory pigment (protein) with a higher affinity for oxygen than haemoglobin. Metaphase - ansThe phase of mitosis where the chromosomes line up at the equator of the spindle. Microvilli - ansFolds in the membrane of a cell that increase its surface area. Maltose - ansA disaccharide molecule consisting of two a-glucose molecules bonded together. Limiting factor - ansA variable that limits the rate of a process. If it is increased, then the rate of the process will increase. Macromolecule - ansA very large molecule. Intercostal muscles - ansMuscles between the ribs, responsible for moving the rib cage during breathing. Fibrillation - ansA state in which the chambers in the heart contract out of rhythm. Inhibition/inhibitor - ansThe slowing of an enzyme-controlled reaction by a molecule that slows down or prevents the formation of enzyme-substrate complexes. Plasma membrane or cell surface membrane - ansThe membrane that surrounds every cell, forming the selectively permeable boundary between the cell and its environment. Gene - ansA length of DNA that carries the code for the synthesis of one (or more) specific polypeptide(s). Mitochondrion - ansThe organelle found in cells in which most of the ATP synthesis occurs. It is the site of aerobic respiration. Meristem cells - ansUndifferentiated plant cells capable of rapid cell division. Natural immunity - ansImmunity acquired through exposure to disease during the normal course of life. Hydrophobic - ansWater-repelling (water-hating). Neutrophils - ansPhagocytic white blood cells. They engulf and digest bacteria. They have a many-lobed nucleus, and a granular cytoplasm due to the large numbers of lysosomes present.
