RES7 Bio Glossary

8/21/2019 RES7 Bio Glossary

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cells Cells in the islets of Langerhans that release glucagon in

response to low blood glucose levels.

Acetylcholine A neurotransmitter (transmitter substance) found in cholinergicsynapses.

Acetylcholinesterase An enzyme in the synaptic cleft that breaks down thetransmitter substance acetylcholine.

Actin A protein found in muscle cells. It is the main component of thethin filaments.

Action potential A brief reversal of the resting potential across the cell surface

membrane of a neurone. All action potentials have a value of!"m#.

Adenyl cyclase $he enzyme found inside cells% associated with hormonereceptors% that converts A$& to cA'&.

Afferent Incoming or leading towards.

Allele An alternative version of a gene.

All or nothing efers to the fact that a neurone either conducts an actionpotential or it does not.

Allotransplantation $ransplantation of organs between individuals of the samespecies% for eample transplantation of a human heart intoanother human.

Amplification (DNA) $he making of multiple copies of the same short section of*+A. $he process of &C is used in automatic amplification of*+A sections.

Anabolic steroids *rugs that mimic the action of steroid hormones and increasemuscle growth.

Anabolism $ype of metabolism, biochemical reactions that synthesiselarge molecules from smaller molecules. $his re-uiresenergyA$&.

Antagonistic /orking against each other in a pair.

Annealing $he term used to describe hydrogen0bond formation betweencomplementary base pairs when sections of single0stranded*+A or +A 1oin together. Annealing is seen whencomplementary sticky ends 1oin and where *+A probes attachto a complementary *+A section.

GlossaryGlossary


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Antidiuretic hormone(ADH)

$he hormone made in the hypothalamus and released from thepituitary gland that acts on the collecting ducts in the kidneys to

increase the reabsorption of water into the blood.

Apical dominance $he growing apical bud at the tip of the shoot inhibits growth oflateral buds further down the shoot.

Apoptosis &rogrammed cell death. An orderly process by which cells dieafter they have undergone the maimum number of divisions.

Ascending limb $he limb of the loop of 2enle that carries fluid from the medullatowards the corte of the kidney.

Asepsis Literally means without contamination. In biotechnology% this

refers to lack of contamination by foreign% unwantedmicroorganisms.

Aseptic techniques Any techni-uesmanipulations of e-uipment or materials thatare designed to prevent contamination by foreign andunwanted microorganisms.

Association area A region of the cerebral corte where the information in theform of impulses from sensory areas is made sense of bycomparison with previous eperience.

AT 'olecule (nucleotide derivative) found in all living cells andinvolved in energy transfer. /hen it is hydrolysed energy isreleased.

AT synthase 3nzyme associated with stalked particles in mitochondria andchloroplasts. It catalyses the 1oining of A*& and inorganicphosphate to make A$&.

Audus microburette See photosynthometer.

Autonomic ner!oussystem

$he system of motor neurones that controls the non0consciousactions of the body. $he autonomic system controls the actions

of involuntary muscles and glandsAutotroph 4rganism that makes its own food using simple inorganic

molecules% such as carbon dioide and water% and energy.&hotoautotrophs (plants% some protoctists and some bacteria)use light as the source of energy. Chemoautotrophs (somebacteria) use chemical energy.

" cells Cells in the islets of Langerhans that release insulin inresponse to high blood glucose levels.

#asement membrane A layer of connective tissue 5 mostly collagen 5 that holds an

epithelium in place.#atch culture A culture of microorganisms that takes place in a single


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fermentation. &roducts are separated from the miture at theend of the fermentation process.

#ilirubin 4ne of the waste products produced from breaking downhaemoglobin.

#iodi!ersity $he number and variety of living things to be found in the world%an ecosystem or habitat.

#iofortified Any food substance in which a particularly valuable nutrient isin higher than usual levels. Golden Rice6 is biofortified withthe accumulation of vitamin A.

#ioremediation 7se of microorganisms to remove waste products from a

location or substance. $he most important eample is wastewater (sewage) treatment.

#iotechnology 7se of microorganisms or biochemical reactions to generateuseful products.

#i!alent &air of synapsed (1oined) homologous chromosomes during

prophase and metaphase of meiosis I.

#o%man&s capsule $he cup0shaped end of a nephron tubule.

'allus A mass of undifferentiated plant cells formed by meristem

tissue etracted from the plant and grown in tissue culture.

'ardio!ascular centre egion in the medulla oblongata of the brain that controls heartrate.

'arrying capacity $he maimum population size that can be maintained over aperiod of time in a particular habitat.

'atabolism $ype of metabolism, biochemical reactions that produce smallmolecules by hydrolysis of larger molecules.

'ell metabolism $he result of all the chemical reactions taking place in the cellcytoplasm.

'entral ner!ous system $he brain and spinal cord. It has overall control over thecoordination of the nervous system.

'hemiosmosis $he flow of hydrogen ions (protons) through A$& synthaseenzymes. $he force of this flow allows the production of A$&.4ccurs across the thylakoid membranes during the light0dependent stage of photosynthesis. Also occurs across theinner mitochondrial membrane during oidative phosphorylation(in respiration).

'hemoautotrophs Seeautotrophs.


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'hiasmata(sing chiasma)

$he points where non0sister chromatids within a bivalent 1oin%where they cross over.

'hi*squared (2) test 8tatistical test that can be carried out on data that are incategories. It enables the investigator to determine how closelyan observed set of data corresponds to the epected data.

'hloroplasts 4rganelles% in plant and some protoctist cells% wherephotosynthesis occurs.

'holinergic synapse A 1unction between neurones that uses acetylcholine as theneurotransmitter.

'horionic

gonadotrophin

A hormone released by the cells of an embryo.

'hromatogram A chart produced when substances are separated bymovement of a solvent along a permeable material such aspaper or gel.

'hromosome mutation andom change to the structure of a chromosome. $here aredifferent types, inversion (a section of chromosome turnsthrough 9:";)< deletion (apart is lost)< translocation (a piece ofone chromosome becomes attached to another)< non0dis1unction (homologous chromosomes fail to separate properly

at meiosis 9 or chromatids fail to separate at meiosis =< if thishappens to a whole set of chromosomes% polyploidy results).$he shuffling of alleles in prophase 9 is notan eample ofmutation.

'lade A monophyletic taonomic group< that is% a single ancestor andall its descendants.

'ladistics A method of classifying living organisms based on theirevolutionary ancestry.

'lassical conditioning A form of learning in which two unrelated stimuli are applied toan animal% one a >normal response? (for eample salivation inthe presence of food) another unrelated (for eample theringing of a bell). After repeated eposure to both stimulitogether the animal will eventually respond with the normalresponse to the unrelated stimulus.

'losed culture A culture of microorganisms set up in a reaction vessel andthen allowed to grow without the addition of nutrients or theremoval of products or wastes.

'odominant A characteristic where both alleles contribute to the phenotype.

'oen+yme A A coenzyme that carries acetate from the link reaction of


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respiration to @rebs cycle.

'oen+ymes 'olecules that help enzymes carry out oidation or reductionreactions. $hey work like shuttles% carrying atoms or moleculesfrom one enzyme0controlled reaction to another. 'anyimportant coenzymes are involved in respiration andphotosynthesis. In respiration% many coenzymes are concernedwith removing hydrogen atoms from substrates.

'ommunity All the populations of different species that live in the sameplace at the same time% and who can interact with each other.

'omparati!e genomemapping

$he comparison of *+A se-uences coding for the productionof proteinspolypeptides and regulatory se-uences in the

genomes of different organisms of different species.Comparisons include the search for se-uences that makesome organisms pathogenic whilst related organisms are not.

'ompetition A struggle between individuals for resources (like food orwater) that are not present in amounts ade-uate to satisfy theneeds of all the individuals who depend on those resources.

'omplementary genes enes that interact together to govern the epression of asingle characteristic.

'on-ugation (inbacteria)

Bacterial cells can 1oin together and pass plasmid *+A fromone bacterial cell to another. $his process can take placebetween bacteria of different species and is of concern in termsof passing plasmid0located genes for antibiotic resistance.

'onser!ation 'aintenance of biodiversity% including diversity betweenspecies% genetic diversity within species% and maintenance of avariety of habitats and ecosystems.

'onsumers Living organisms that feed on other living organisms.

'ontinuous culture A culture of microorganisms set up in a reaction vessel to

which substrates are added and from which products areremoved as the fermentation process continues.

'ontinuous !ariation enetic variation% also called -uantitative variation% where thereis a wide range of phenotypic variation within the population.$here are no distinct categories. It is controlled by many genes.3amples include height in humans.

'oppicing Cutting a tree trunk close to the ground to encourage newgrowth.

'o*transporter proteins &roteins in the cell surface membrane that allow the facilitated

diffusion of simple ions to be accompanied by transport of a


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larger molecule such as glucose.

'otyledons ood store in seeds of dicotyledonous plants. In some plants%these appear above the soil after germination and act as thefirst leaves.

'ross*bridge In voluntary muscle% the 1oining of a myosin head group to anactin thin filament in the presence of calcium ions.

'rossing o!er /here non0sister chromatids echange alleles during prophaseI of meiosis.

'yto/ines Cell0signalling molecules.

Deamination $he removal of the amine group from an amino acid to produceammonia.

Decomposers 4rganisms that feed on dead organic matter% releasingmolecules% minerals and energy that then become available toother living organisms in that ecosystem.

Dehydrogenation emoval of hydrogen atoms from a substrate molecule.

Depolarisation $he loss of polarisation across a membrane 5 when themembrane loses its resting potential.

Descending limb $he limb of the loop of 2enle that carries fluid from the cortetowards the medulla of the kidney.

Deto0ification Conversion of toic substances% such as alcohol% to less toicsubstances.

Diabetes mellitus A condition in which the patient is unable to control bloodglucose levels.

Dialysis $reatment for patients with kidney failure% in which metabolicwastes and ecess salts and water are removed from theblood.

Dialysis fluid $he fluid used in dialysis< it consists of a comple solution thatmatches the composition of body fluids.

Dialysis membrane A partially permeable membrane that separates the dialysisfluid from the patient?s blood in a dialysis machine.

Diffusion 'ovement of molecules down their concentration gradient. Itmay be through a partially permeable membrane.

Digest 2ydrolyse a large molecule to smaller molecules.

Diploid 2aving two sets of chromosomes (eukaryotic cell or organism).*enoted by =n.


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Discontinuous !ariation Also called -ualitative variation. enetic variation where thereare distinct phenotypic categories. 7sually controlled by one

gene. 3amples include cystic fibrosis% shape of earlobes inhumans and height in pea plants.

Distal con!olutedtubule

$he coiled portion of the nephron between the loop of 2enleand the collecting duct.

DNA ligase An enzyme capable of catalysing a condensation reactionbetween the phosphate group of one nucleotide and the sugargroup of another. $his results in *+A backbone moleculesbeing 1oined together and is an essential part of recombinant*+A procedures.

DNA mutation A change to the *+A structure. 'ay be substitution of onebase pair for another< inversion of a base triplet< deletion of abase pair or triplet of bases (on both strands)< addition of abase pair or triplet of bases (on both strands)< or a triplenucleotide repeat 5 a stutter.

Dominant Characteristic in which the allele responsible is epressed inthe phenotype even in those with heterozygous genotypes.

DRD4 ene that codes for a dopamine receptor molecule.

cosystem All the living organisms and all the non0living components in aspecific habitat% and their interactions.

ctotherms 4rganisms that rely on eternal sources of heat andbehavioural activities to regulate their body temperature.

fferent 4utgoing or leading away from.

lectron acceptors Chemicals that accept electrons from another compound. $heyare reduced while acting as oidising agents.

lectron carriers 'olecules that transfer electrons.

lectrophoresis A method used to separate molecules in a miture based ontheir size. $he method relies on the substances within themiture having a charge. /hen a current is applied% chargedmolecules are attracted to the oppositely charged electrode.$he smallest molecules travel fastest through the stationaryphase (a gel0based medium) and in a fied period of time willtravel furthest% so the molecules separate out by size. $hemethod is particularly important in separating *+A fragments ofdifferent sizes in *+A se-uencing and profiling (fingerprinting)procedures.

ndocrine gland A gland that secretes hormones directly into blood capillaries.


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ndocytosis $he transport of large molecules or fluids into the cytoplasm ofthe cell% by the invagination (folding inwards) of the cell surface

membrane to form a vesicle.

ndothelium $he tissue which lines the inside of a blood vessel or nephron.

ndotherms 4rganisms that can control production and loss of heat tomaintain their body temperature.

nergy $he ability to do work. rom the reek energos% meaningactive work.

n!elope *ouble membrane. *ouble lipid bilayer.

n!ironmentalresistance

$he combined action of biotic and abiotic factors that limits thegrowth of a population.

pistasis $he interaction of genes concerned with the epression of onecharacteristic. 4ne gene may mask the epression of anothergene.

pithelium $he tissue that covers the outside of a structure.

u/aryotes 4rganisms with eukaryotic cells 5 protoctists% fungi% plants andanimals.

!olution $he process of gradual change in the inherited traits passedfrom one generation to the net within a population. It results inthe formation of new species.

0cretion $he removal of metabolic waste (waste from the reactionsinside cells) from the body.

0ergonic Chemical or biochemical reaction that releases heat energy.

0ocrine gland A gland that secretes substances into a duct.

0ocytosis A mechanism of secretion from a cell involving vesicles that

fuse to the cell surface membrane and release their contents tothe outside. It uses A$&.

0plant A piece of tissue taken from a particular plant (which includesmeristematic tissue) then sterilised in order to grow a callus intissue culture micropropagation.

4acilitated diffusion *iffusion that is enhanced by the action of protein channels orcarriers in the cell membrane.

4ermentation (9) $he process of anaerobic respiration in microorganisms%used to yield specific products. or eample% the anaerobic

respiration of yeast is used in the fermentation of grapes toproduce wine.


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(=) $he process of culturing any microorganism in order togenerate a specific product% either aerobically or anaerobically.

All industrial biotechnological processes using wholemicroorganisms are referred to as fermentation.

4ertilisation usion of male and female gamete nuclei.

4ight or flight response $he set of responses in an animal that accompany theperception of threat. $he response is driven by the sympatheticnervous system and sets the body at a higher level of capacityto respond to the threat< for eample increased respiration ratein muscles and increased blood flow to muscles to prepare foreplosive muscle action necessary to fight or run away.

4irst messenger A hormone that acts as a message in the bloodstream.

6ametes 8pecialised se cells. In many organisms the gametes arehaploid and are produced by meiosis.

6as chromatography A techni-ue used to separate substances in a gaseous state.

6ene A length of *+A that codes for one (or more)polypeptidesproteins. 8ome genes code for +A and regulateother genes.

6ene pool $otal genetic information possessed by the reproductivemembers within a population of organisms.

6ene therapy In humans% any therapeutic techni-ue where the functioningallele of a particular gene is placed in the cells of an individuallacking functioning alleles of that particular gene. Can be used totreat some recessive conditions but not dominant conditions suchas 2untington disease.

6enerator potential A small depolarisation of the membrane in a receptor cell.

6enetic drift Also called allelic drift. $he change in allele fre-uency in a

population% as some alleles pass to the net generation andsome disappear. $his causes some phenotypic traits tobecome rarer or more common.

6enetic engineering $he branch of biotechnology characterised by the obtaining ofa particular gene% either by removal from a donor organism?sgenome using restriction enzymes or by manufacture% usuallyfrom m+A transcript using reverse transcriptase enzyme.4nce obtained% the gene is inserted into the genome of arecipient organism 5 often of a different species from the donororganism. $he inserted gene is transcribed into protein% so

giving the recipient organism a characteristiccapacity that it didnot have previously. 8uch organisms are referred to as being


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transgenic or genetically modified.

6enetic fingerprinting(genetic profiling)

$he use of *+A fragmentation and electrophoresis givesbanding patterns that are uni-ue to each individual. 8amples of*+A% for eample from crime scenes% are fragmented using arange of restriction enzymes% and% because each individual?s*+A has differences% the number and size of fragmentsproduced is slightly different. 3lectrophoresis and staining ofthe *+A gives a banded pattern that can be compared withother samples of *+A treated with the same set of restrictionenzymes.

6enetic mar/ers Antibiotic resistance genes held on bacterial plasmids are used

as genetic markers to identify the bacteria that have taken upthe re-uired gene. $he gene is inserted into a plasmid thatcarries a resistance to a particular antibiotic. If a bacterium cangrow on the particular antibiotic% then the plasmid% and so there-uired gene% is present in the bacterium.

6enetic !ariation #ariation of genetic information in a gene pool.

6enome All the genetic information within an organismcell.

6enome sequencing $he techni-ue used to give the base se-uence of *+A of aparticular organism. $he se-uencing reaction can only identify

up to around 9""" base pairs of se-uence in a fragment. Inorder to se-uence the whole genome% overlapping fragmentsare se-uenced% then reassembled by computer software inorder to generate the original se-uence detail.

6enomics $he study of the whole set of genetic information in the form ofthe *+A base se-uences that occur in the cells of organisms ofa particular species.

6enotype Alleles present within cells of an individual% for a particulartraitcharacteristic.

6erm line gene therapy $his involves placing the gene into embryonic cells. $histechni-ue is not currently legal and is deemed unethical.

6lomerulus A small network of capillaries found inside the Bowman?scapsule.

6lucagon A hormone released by the D cells in the islets of Langerhansin the pancreas 5 it causes the blood glucose level to rise byconverting glycogen in liver cells to glucose.

6lycerate*$*phosphate

(6)

Intermediate compound produced during the Calvin cycle in the

light-independent stage of photosynthesis.


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6lycolysis 'etabolic pathway.$he first stage of respiration. It is anaerobicand occurs in the cytosol (cytoplasm). Although anaerobic% it

involves oidation as substrate molecules are dehydrogenated.

6olden 8ice9 A variety of rice that is genetically engineered to carry largeamounts of the vitamin A precursor beta0carotene. $he riceappears golden brown% unlike its non0engineered relative%which is white in colour.

6rana(sing granum)

8tacks of thylakoid membranes% found in a chloroplast.

Habitat $he place where an organism or population of organisms lives.

Haemodialysis A form of treatment for kidney patients in which blood is takenfrom a vein and passed through a dialysis machine so thatechange can occur across an artificial partially permeablemembrane.

Hairpin countercurrentmultiplier

An arrangement of a tubule or blood vessel involving a 9:";bend so that the fluid in one end of the tubule flows back pastthe fluid at the other end. $his arrangement facilitates theechange of materials by ensuring that there is a concentrationgradient all along the tubule.

Half*life $he time taken for the concentration of a substance to drop tohalf its original value.

Haploid 3ukaryotic cell or organism having only one set ofchromosomes. *enoted by n.

Hardy:;einbergprinciple

$he concept that both genotype fre-uencies and genefre-uencies will stay constant from generation to generation%within a large interbreeding population where mating is random%there is no mutation and no selection or migration.

Hayflic/ constant $he number of times that a normal body cell divides beforeundergoing apoptosis. $he number of divisions is about E".

Hemi+ygous Cell or individual having only one allele for a particular gene.

Hepatic portal !ein An unusual blood vessel that has capillaries at both ends 5 itcarries blood from the digestive system to the liver.

Hepatocytes Liver cells.

Heterotroph 4rganism that gains its nutrients from comple organicmolecules. It digests them to simpler% soluble molecules and

then respires some of them to obtain energy% or uses theproducts of digestion to synthesise the organic molecules it


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needs. 2eterotrophs are consumers in food chains. &arasitesand saprotrophs are also heterotrophs. Animals% some bacteria

and some protoctists are heterotrophs.

Hetero+ygous 3ukaryotic cell or organism that has two different alleles for aspecific gene.

Hierarchy (social) /ithin a group individuals have a place in the order ofimportance within the group. $his is often shown by individualshigher up in the hierarchy receiving more food or having rightsof access to mate with other individuals.

Homeobo0 genes enes that control the development of the body plan of anorganism.

Homeostasis $he maintenance of a constant internal environment despiteeternal changes.

Homeotic selectorgenes

$hese direct the development of individual body segments.$hey are master genes that control other regulatory genes.

Homo+ygous 3ukaryotic cell or organism that has two identical alleles for aspecific gene.

Hormone A molecule released into the blood that acts as a chemical

messenger.

Ho0 clusters roups of homeobo genes. 'ore comple organisms havemore 2o clusters. $his is probably due to a mutation thatduplicated the 2o clusters.

Human chorionicgonadotrophin (h'6)

A hormone released by the human embryo. Its presence in apregnant woman?s urine can be detected to confirm pregnancy.

Hydrolysis 8plitting of large molecules into smaller molecules with additionof water.

Hyperglycaemia A high blood glucose concentration.

Hyperpolarised $he condition of a membrane that is more highly polarised thanthe usual resting state. $he resting potential is lower thanusual.

Hypertension A condition in which the resting blood pressure (particularly thediastolic pressure) is raised for prolonged periods.

Hypoglycaemia A low blood glucose concentration.

Hypostasis /here two alleles interact to control the epression of one

characteristic one is epistatic and one is hypostatic. /here ahomozygous recessive allele at the first locus (place on a


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chromosome) prevents the epression of another allele at asecond locus% the alleles at the first locus are epistatic and the

alleles at the second locus are hypostatic.

Hypothalamus A portion of the brain that contains various receptors thatmonitor the blood. Also involved in controlling the autonomicnervous system.


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=imiting factor A variable that limits the rate of a particular process. If thefactor is increased then the process will take place at a faster

rate. /here the rate of a natural process is affected by anumber of factors% the limiting factor is the one whosemagnitude limits the rate of the process.

=in/age enes for different characteristics that are present at differentloci on the same chromosome are linked.

=in/ reaction 8tage of aerobic respiration that links glycolysis with the @rebscycle. In eukaryote cells it occurs in the mitochondrial matri.

=ocal currents 'ovements of ions along a neurone close to the cell surfacemembrane% caused by influ or efflu of ions through themembrane.

=ocus 8pecific position on a chromosome% occupied by a specificgene.

?aternal chromosome 'ember of a homologous pair of chromosomes that originallycame from the female gamete.

?edulla oblongata A portion of the brain (the brain stem) that contains centres forthe control of various unconscious bodily functions and via theautonomic nervous system.

?eiosis $ype of nuclear division. A reduction division. $he chromosomenumber is halved. It involves two divisions. It produces cellsthat are genetically different from each other and from theparent cell.

?eristem rowth points in a plant where immature cells are still capableof dividing.

?etabolic %aste /aste substances that may be toic or are produced in ecessby the chemical reactions inside cells.

?icropropagation A form of artificial vegetative propagation using sterile eplanttissue grown to form a callus culture from which many newplants are grown by separation and growth of small parts of thecallus. &articularly useful in generating vast numbers ofgenetically identical plants following the genetic engineering ofa particular gene into the callus.

?icro!illi 'icroscopic folds of the cell surface membrane that increasethe surface area of the cell.

?onoclonal antibodies Antibodies that are identical because they have been produced

by cells that are clones of one original cell.


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?onogenic Characteristic coded for by one gene.

?onophyletic A monophyletic group is one that includes an ancestralorganism and all its descendent species.

?orphogen A substance that controls the pattern of tissue development. Itis produced in a particular region of a developing organism. Itdiffuses to other cells% which then enter a specificdevelopmental pathway.

?otor area An area of the cerebral corte within which the neurones areresponsible for driving motor functions.

?otor unit efers to the innervation of a cluster of muscle fibres by a

single motor neurone. $he number of muscle fibres within amotor unit is governed by the level of manipulation re-uired inthe muscle. 'uscles responsible for very fine motor functionshave as few as three muscle fibres in a motor unit. 'usclesre-uiring less fine motor control may have over ="" musclefibres in a motor unit.

?utation 8tructural change to genetic material 5 either to a gene or to achromosome.

?utualism A relationship between two organisms from which both benefit.

?yelin A fatty sheath around a neurone that consists of many layers ofthe plasma membranes of 8chwann cells.

?yogenic Contraction of the muscle is generated from within the muscleitself. $he term is used to describe the contraction of the heart%which is controlled by the action of the sinoatrial node.

?yosin $he protein that forms the thick filament in muscle cells. $hisprotein has head groups that form the cross0bridges associatedwith muscular contraction.

NAD Coenzyme involved in respiration. It removes hydrogen atomsfrom substrates. It becomes reduced +A*% which carrieshydrogen atoms (protons and electrons).

NAD Coenzyme involved in photosynthesis. It accepts hydrogenatoms from photolysis of water during the light0dependentstage and carries them to the light0independent stage.

Natural selection 'echanism for evolution. 4rganisms that are well adapted totheir environment are more likely to survive and reproduce%passing on the alleles for the favourable characteristics.

Necrosis *isorderly% often accidental cell death.


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Negati!e feedbac/ A process in which any change in a parameter brings about thereversal of that change so the parameter is kept fairly constant.

Nephrons $ubules in the kidney that are used to produce urine.

Neurosecretory cells Cells in the hypothalamus that are similar to neurones butrelease a hormone into the blood instead of a transmittersubstance into a synapse.

Neurotransmitter A transmitter substance 5 a chemical that is released from thepresynaptic membrane of one neurone to pass a signal toanother neurone.

Niche $he role that a species plays in an ecosystem.

Nitrogen fi0ation Conversion of nitrogen gas into a form which is usable byplants% such as nitrate or ammonium ions.

Non*dis-unction ailure of members of a homologous pair of chromosomes% orof a pair of chromatids% to separate during nuclear division.

Non*reproducti!ecloning

Also known as therapeutic cloning. $he use of stem cells inorder to generate replacement cells% tissue or organs% whichmay be used to treat particular diseases or conditions ofhumans. or eample% the use of stem cells to generate

replacement heart cells in patients suffering from myocardialinfarction (heart attack).

@perant conditioning Also known as trial0and0error learning. $he term is used todescribe learning that takes place in animals given punishmentor reward to reinforce the performance of a particular operation.'ost famously% this type of learning is seen in rats and pigeonsin a >8kinner bo?% where operation of a lever rewards theanimal with a food pellet.

@peron A unit consisting of genes that work together under the controlof an operator gene. An eample is the lac operon% whichconsists of two structural genes and an operator gene.4perons were first discovered in prokaryotes but later found ineukaryotes.

@rganelles 8tructures within cells. 3ach carries out a specific function.

@rnithine cycle A process that occurs inside liver cells to convert ammonia tourea.

@smoreceptors eceptor cells that monitor the water potential of the blood anddetect any changes.

@smoregulation $he control and regulation of the water potential of the bloodand body fluids.


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@0idation Chemical reaction involving loss of electrons% gain of oygen orloss of hydrogen atoms.

@0idati!ephosphorylation

$he formation of A$&% in the presence of oygen% bychemiosmosis.

@0ytocin A hormone released by the posterior pituitary gland to facilitatebirth and breastfeeding.

ancreas A small organ in the abdomen that secretes digestive fluids andhormones.

ancreatic duct A duct leading from the pancreas to carry digestive 1uices to thesmall intestine.

araphyletic group A classification group for living organisms that includes themost recent ancestor but not all of the descendants.

artially permeablemembrane

A membrane that is permeable to certain substances% such aswater% but is not permeable to other substances.

aternal chromosome 'ember of a pair of homologous chromosomes that originallycame from the male gamete.

eripheral ner!oussystem

$he sensory and motor neurones connecting the centralnervous system to the sensors and effectors around the body.

eritoneal dialysis A form of treatment for kidney patients in which dialysis fluid ispumped into the body cavity so that echange can occuracross the peritoneal membrane.

hagocytosis 3ndocytosis of large solid molecules into a cell.

henotype 4bservable characteristics of an organism.

hotoautotroph SeeAutotroph.

hotolysis 3nzyme0catalysed reaction where water molecules are split%using light energy. It occurs in photosystem II% during the light0dependent stage of photosynthesis.

hotophosphorylation ormation of A$& in the presence of light energy. It takes placein thylakoid membranes of chloroplasts% during the light0dependent stage of photosynthesis. $here are two types, cyclicphotophosphorylation and non0cyclic photophosphorylation.

hotosyntheticpigments

Chemicals that absorb light energy. ound in thylakoidmembranes% in photosystems. 3ach pigment absorbs energy

associated with light of a specific wavelength. 3amplesinclude chlorophyll a% chlorophyll b% carotenoids and


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anthophylls.

hotosynthometer Apparatus to measure rate of photosynthesis by collecting andmeasuring the volume of oygen produced in a certain time.

hotosystems roup of photosynthetic pigments in the thylakoid membrane.Consists of a primary reaction centre and accessory pigments.

hylogenetic group roup of organisms that share evolutionary ancestry.

odocyte A specialised cell that makes up the lining (endothelium) of theBowman?s capsule. &odocytes have finger0like processes.$hey aid ultrafilitration as fluid entering the renal capsule fromthe blood goes through the gaps in these processes% making

ultrafiltration more efficient as the podocytes do not provide abarrier to filtration.

olarised 'embrane with a potential difference across it.

olygenic Characteristic coded for by many genes. 3amples includeheight and intelligence in humans. &olygenic characteristics aremore influenced by environmental factors than are monogeniccharacteristics.

olypeptide Large polymer molecule made of many amino acids 1oined by

peptide bonds.

olyploid 3ukaryotic organisms or cell with more than two sets ofchromosomes.

opulation All of the organisms of one species% who live in the same placeat the same time% and who can breed together.

opulation genetics $he study of the gene pools and the allele and genotypefre-uencies of populations of organisms.

ositi!e feedbac/ A process in which any change in a parameter brings about an

increase in that change.

osterior pituitarygland

$he hind part of the pituitary gland% which releases A*2.

o%er stro/e $he term describes the action of the myosin head in muscularcontraction. $he head group attached to the actin filament tiltsbackwards% pulling the thick filament to overlap further with thethin filament. 3nergy from A$& is used up in the power stroke.

recursor Literally means >coming before?. In biology% a precursormolecule is one which is used in order to form another more

useful molecule. or eample% beta0carotene is the precursor


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molecule for vitamin A.

rimary metabolite Any metabolite which is formed as part of the normal growth ofa microorganism. *uring growth the lipids% proteins%carbohydrates and waste products generated by themicroorganism in order to grow in numbers are described asprimary metabolites.

rimary pigmentreaction centre

The primary photosynthetic pigments in a photosystem act asreaction centres. In PSI the primary pigment reaction centre isa molecule of chlorophyll a that has a peak absorption of !" nm. This means that its greatest absorption is of light with awavelength of !"nm. In PSII the primary pigment reactioncentre is a molecule of another type of chlorophyll a that has anabsorption peak of #""nm.

rimer (DNA) 8hort single0stranded se-uences of *+A% around 9" bases inlength. $hey are needed% in se-uencing reactions andpolymerase chain reactions% to bind to a section of *+Abecause the *+A polymerase enzymes cannot bind directly tosingle0stranded *+A fragments.

roducers Autotrophic organisms (plants% some protoctists and somebacteria) that convert light energy to chemical energy% whichthey then supply to consumers.

roducti!ity &rimary productivity is the rate of production of new biomass byproducers. It is the energy captured by their chlorophyll andused to synthesise organic molecules. $his minus the energyreleased via their respiration is the net primary productivity 5the energy available to heterotrophs through consumption ofproducers? biomass.

rogrammed cell death Seeapoptosis.

rotein A macromolecule. A polymer of many amino acids 1oined by

peptide bonds. 'ay also be called a polypeptide.

rotoctist 3ukaryotic organism classified as belonging to the kingdom&rotoctista. $his kingdom includes organisms that do not fitintocannot be classified as belonging to the other fourkingdoms. It includes algae% protozoa and slime moulds. 8omemembers of this phylum are photosynthetic. 8ome haveundulipodia and some have cilia.

roton moti!e force orce produced as hydrogen ions flow% through A$& synthasechannels% down their concentration gradient. $he force causes

A*& and &ito combine and form A$&.roto*oncogene ene that can undergo mutations to become an oncogene%


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which induces tumour formation (cancer).

uadrat A s-uare frame used for sampling in fieldwork.

8ecessi!e Characteristic in which the allele responsible is only epressedin the phenotype if there is no dominant allele present.

8ecombinant DNA A section of *+A% often in the form of a plasmid% which isformed by 1oining *+A sections from two different sources.

8eduction Chemical reaction involving the gain of electrons% gain ofhydrogen atoms or loss of oygen atoms.

8efractory period $he short period of time after firing during which it is more

difficult to stimulate a neurone.

8eplica plating $he process of growing bacteria on an agar plate% thentransferring a replica of that growth to other plates using asterile velvet pad. $he replica plates usually contain differentantibiotics. Analysis of growth patterns on the replica platesgives information about the genetic properties of the growingbacteria.

8esponse $he reaction to a stimulus.

8esting potential $he potential difference or voltage across the neurone cellmembrane while the neurone is at rest.

8estriction en+yme An enzyme originally derived from bacteria% in which it has arole in defence against infection by viruses. $he enzymescatalyse a hydrolysis reaction that breaks the phosphate5sugarbackbone of the *+A double heli. $he two backbones areusually broken at slightly different points on the restriction site%leaving a staggered cut known as a sticky end. $he restrictionsite for each restriction enzyme is uni-ue.

8estriction site $he specific location on a stretch of *+A which is the target

site of a restriction enzyme. estriction sites are around eightbases long.

8e!erse transcriptase An enzyme originally derived from retroviruses. $he enzymecatalyses the construction of a *+A strand using an m+Astrand as a template. 3ffectively the reverse of transcription.

8ibulose bisphosphate(8u#)

E0carbon compound% present in small amounts in stroma ofchloroplasts. It is a carbon dioide acceptor. It is regeneratedfrom triose phosphate.

8ibulose bisphosphatecarbo0ylase (rubisco) 3nzyme that catalyses the carboylation (addition of carbondioide) to ribulose bisphosphate.


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8NA interference *escribes the process in which short fragments of single0stranded +A bind to complementary regions on m+A

molecules and in doing so form sections of double0strandedm+A which cannot be translated. $he binding of theinterfering +A section often triggers cellular destruction of them+A. $he term gene silencing is used to mean that +Ainterference can prevent the formation of the product of aparticular gene within a cellorganism. +A interference hasbeen shown to operate in natural regulation of gene epressionas well as in the targeted silencing of genes in the laboratory.

Baltatory efers to way in which the action potential appears to 1umpfrom node to node.

Baprotrophs 4rganisms (like bacteria and fungi) that feed by secretingenzymes onto food% and absorbing digested nutrients acrosstheir outer walls.

Barcomere In voluntary muscle% the span between one H0line and the netH0line. $he H0line is the central part of the I band% whichalternates with the A band. $he sarcomere is the smallest unitof contraction of voluntary muscle% consisting of the thick andthin filaments responsible for muscular contraction.

Becond messenger A chemical inside the cell released in response to a hormonebinding to the cell surface membrane% e.g. cA'&.

Becondary metabolite A metabolite produced by a microorganism% usually in the latterstages of growth as the culture ages. 8econdary metabolitesare not specifically re-uired for the organism to grow. $heyusually have antibiotic properties.

Begmentation genes enes that control the development of polarity (which end ishead and which end is tail) in organisms.

Belection pressure 3nvironmental factor that confers greater chances of surviving

and reproducing on some members of the population than onothers.

Belecti!e reabsorption $he absorption of certain selected molecules back into theblood from the fluid in the nephron tubule.

Bensory area An area of the cerebral corte within which the neuronesassociated with receiving sensory information from thereceptors are found. $hese neurones often pass information toassociation areas in order to make sense of the incominginformation.

Be0 lin/age ene with its locus on one of the se chromosomes% or J. Asthere are few genes on the J chromosome% in humans% most


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se0linked genes are on the chromosome. 2owever% thereare some genes on the J chromosome% notably the gene 8y

that stimulates development of the testes and subse-uentdevelopment of the embryo into a male. $here is also a J 8$(short tandem repeat on the J chromosome) used in genealogy*+A testing. (+ote that in some organisms it is not thepresence of a J chromosome that controls development into amale. or eample in Drosophila it is the number of chromosomes% 9 for male and = for female. In turtles% se isdetermined by incubation temperature of the eggs.) In birds%butterflies and moths% males are (or HH) and females areJ (H/). In grasshoppers and crickets females are andmales are 4 (1ust one chromosome). In bees and wasps%

diploid individuals are female and haploid individuals are male.3arthworms and some snails are hermaphrodite (have bothmale and female anatomies). 8ome organisms% such asoysters and some fish% can change se during their life cycle.

Be0ual reproduction &roduction of new organisms involving fusion of nuclei frommale and female gametes% usually from unrelated individuals.Increases genetic variation in the population.

Binoatrial node (BAN)or sinus node

$he region of the heart right atrial muscle wall% about K mmwide% 9Emm long and 9mm deep% which consists of specialisedmuscle fibres (cells) that have no contractile filaments butconnect directly to atrial muscle fibres. Any ecitation (electricalactivity) starting in the 8A+ spreads immediately to the rest ofthe atrial wall. 2ence the pacemaker controls the synchronisedrate of beating of the whole heart. (Artificial pacemakers arebattery0powered devices% usually inserted under the skin andconnected via wires in the subclavian vein and vena cava tothe heart muscle.)

Bocial beha!iour Behaviour of organisms of a particular species living together ingroups with relatively defined roles for each member of the

group.

Bodium:potassiumpumps

&rotein carriers embedded in the membranes of some cells%which use energy from A$& to move sodium ions andpotassium ions in opposite directions simultaneously% againsttheir concentration gradients. $hey are chemically gated ionchannels.

Bomatic cell genetherapy

Involves the placing of the gene in adult differentiated cells.3amples include the placing of C$ genes into therespiratory system cells of individuals with cystic fibrosis.

Bomatic cell nucleartransfer

$he techni-ue of cloning organisms involving the removal ofthe nucleus from an adult% differentiated cell% which is then


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2$

placed into the enucleated egg cell taken from a donororganism. $he cell formed is placed into a surrogate mother in

order to develop. $he resulting organism is a clone of theorganism which provided the adult% differentiated cell nucleus.

Bpecies $he biological speciesconcept is a group of similar organismsthat can interbreed and produce fertile offspring. $hephylogenetic speciesconcept is a group of organisms withsimilar morphology% physiology% embryology and behaviour% andthat all occupy the same ecological niche.

Btabilising selection A type of natural selection in which the allele and genotypefre-uency within populations stays the same because the

organisms are already well adapted to their environment.

Btem cells 7ndifferentiated cells. 3mbryonic stem cells are totipotent andare able to differentiate into any type of specialised cell found inorganisms of that species. 7mbilical stem cells and adult stemcells may become specialised into a more limited range of celltypes.

Btimulus Any change in the environment of an organism that causes aresponse.

Btomata

(sing stoma)

&ores between guard cells in the epidermis of leaves.

Btroma luid0filled matri of chloroplasts. $his is where the light0independent stage of photosynthesis takes place.

Bubstrate*le!elphosphorylation

ormation of A$& from A*& and &iduring glycolysis and the@rebs cycle.

Buccession A directional change in a community of organisms over time.

Bummation $he way that several small potential changes can combine toproduce one larger change in potential difference across aneurone membrane.

Bynaptic /nob $he swelling at the end of a neurone where it forms a 1unction(synapse) with another neurone.

Byno!ial -oint A type of 1oint in the skeleton characterised by the presence ofa synovial membrane that produces synovial fluid to lubricatethe 1oint. 8ynovial 1oints are found where a large movementrange is re-uired% such as the elbow and the hip.

Target cells Cells that have receptors embedded in the plasma membrane

that are complementary in shape to specific hormonemolecules. 4nly these cells will respond to that specific


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hormone.

Ta0on(pl ta0a)

roup of organisms used in a hierarchical classification.3amples are @ingdom% &hylum% Class% 4rder% amily.

Threshold potential A potential difference (usually 5E"m#)across the membrane. Ifthe depolarisation of the membrane does not reach thethreshold potential then no action potential is created. If thedepolarisation reaches the threshold potential then moresodium ion channels open and an action potential is created.

Thyla/oid Inner membrane in chloroplast. 8ite of photosystems and A$&synthase.

Tissue A group of cells% with a common origin and similar structures%which performs a particular function< for eample% blood% bone%epithelium% muscle% nervous tissue% ylem and phloem.

Tissue culture Also called micropropagation. $he cloning of isolated cells orsmall pieces of plant tissue in special culture solutions% undercontrolled aseptic conditions.

Totipotent stem cells 8tem cells that can differentiate into any type of specialisedcells found in organisms of that species.

Transcription $he formation of an +A molecule% using a length of *+A as atemplate. Complementary base pairing is used. $he enzyme+A polymerase catalyses the reaction.

Transect A line taken through a habitat% which helps with systematicsampling of changes across a habitat.

Transformation Bacteria that take up *+A from their surroundings (e.g. fromdead bacteria) are transformed.

Translation 8tage of proteinpolypeptide synthesis in which the amino acidsare assembled at ribosomes. $he order in which the amino

acids are 1oined together% by peptide bonds% is determined bythe se-uence of codons on the m+A% which is itselfdetermined by the se-uence of nucleotide triplets on the codingstrand of a length of *+A (gene). $he genetic code istranslated.

Triose phosphate (T) K0carbon compound formed when a molecule of glyceratephosphate is reduced% during the Calvin cycle in the light0independent stage of photosynthesis.

Trophic le!el $he level at which an organism feeds in a food chain.

Tropism A directional growth response in which the direction of the


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response is determined by the direction of the eternalstimulus.

Cltrafiltration iltration at the molecular level in the glomerulus of kidneys.8ome molecules are filtered out of the blood of the glomerulusinto the renal capsule. 'olecules with relative molecularmasses above M""" are retained in the blood capillaries.

Crea An ecretory product formed from the breakdown of ecessamino acids.

ector Carrier. In *+A technology% refers to the agent that carries apiece of *+A from one cell into another% e.g. a bacterialplasmid.

egetati!e propagation Aseual reproduction in plants making use of specialisedvegetative structures that grow to form new and separateindividual organisms.

oltage*gated channels Channels in plasma membranes that allow the passage of ions.$hey respond to changes in potential difference (voltage)across a membrane and% as a result% open or close.

Eenotransplantation $he transplantation of cells or organs from one species into thebody of an organism of another species.

Fygote Cell formed% during seual reproduction% from the fusion of twogametes.

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RES7 Bio Glossary