Unit 5 Biology notesContents Section 9.1 Sensory Reception....................................................................................3Section 9.2 Nervous Control.......................................................................................4Section 9.3 Control of heart rate.................................................................................5Section 9.4 Role of receptors......................................................................................6Section 10.1 Coorination...........................................................................................!Section 10.2 Neurons................................................................................................10Section 10.3 "he nerve i#pulse................................................................................11Section 10.5 "he spee of a nerve i#pulse...............................................................12Section 10.6$10.% Structure an function of the synapse $ "rans#ission across a synapse.........................................................................................................................13Section 11.1 Structure of s&eletal #uscle.................................................................15Section 11.2 ' contraction of s&eletal #uscle...............................................................1%Section 12.1 (rinciple of ho#eostasis......................................................................19Section 12.2 ' "her#ore)ulation..................................................................................20Section 12.3$12$4 *or#ones an the re)ulations of +loo )lucose$,ia+etes an its control..........................................................................................................................22Section 13.1 "he principles of fee+ac& #echanis#s..............................................24Section 13.2 "he oestrous cycle................................................................................25Section 14.1 Structure of ri+onucleic aci................................................................26Section 14.2 (olypeptie synthesis transcription an splicin)..............................2%Section 14.3 (olypeptie synthesis translation......................................................2!Section 14.4 -ene #utation......................................................................................29Section 15.1 "otipotency an cells specialisation.....................................................31Section 15.2 Re)ulation of transcription an translation..........................................32Section 16.1 (roucin) ,N. fra)#ents...................................................................33Section 16.2 /n vivo )ene clonin) the use of vectors.............................................34Section 16.3 /n vitro )ene clonin) the poly#erase chain reaction........................36Section 16.4 0se of reco#+inant ,N. technolo)y..................................................3%Section 16.5 ' -ene therapy.........................................................................................3!Section 16.6 1ocatin) an se2uencin) )enes............................................................40Section 16.% ' Screenin) for clinically i#portant )enes..............................................42Section 16.! -enetic fin)erprintin)..........................................................................43Section 9.1 Sensory Reception . sti#ulus is a etecta+le chan)e in the internal or e3ternal environ#ent of an or)anis# that prouces a response. "he a+ility to respon to a sti#ulus increases an or)anis#4s chances of survival. Receptors transfer the ener)y of a sti#ulus into a for# that can +e processe +y the or)anis# an leas to a response. "he response is carrie out +y 5effectors6 7hich can inclue cells8 tissues8 or)ans an syste#s.Taxis . si#ple response that4s irection is eter#ine +y the irection of the sti#ulus.n or)anis# can respon irectly to a chan)e in the environ#ent +y #ovin) its +oy either91.: "o7ar the sti#ulus ;positive ta3is:2.: .7ay fro# the sti#ulus ;ne)ative ta3is:Kinesis Results in an increase of rano# #ove#ents ae up of pairs of nerves that ori)inate either fro# the +rain or the spinal corThe peripheral nervous system"his is ivie into9 Sensory neurons 7hich carry i#pulses a7ay fro# receptors to the CNS >otor neurons 7hich carry nervous i#pulses fro# the CNS to effectors"he spinal cor is a colu#n of nervous tissueA reflex involuntary response to a sti#ulus ;you o stop to consier an alternative:"he path7ay of neurons involve in a refle3 is calle a refle3 arc.Refle3 arcs contain ?ust 3 neurons91i)ht causes a protein that a affects )ro7th factor to #ove to the left sie of the plant causin) that sie to )ro7 #ore rapily. >ore )ro7th on the left sie causes the plant to +en to7ars the source of li)ht. 1.: . sensory neuron2.: .n inter#eiate neuron3.: . #otor neuron"here are several sta)es of a refle3 arc9 1.: Sti#ulus2.: Receptor3.: Sensory neuron4.: Synapse5.: Coorinator ;inter#eiate neuron:6.: Synapse%.: >otor neuron!.: @ffecter 9.: ResponseImportance of the reflex arc Involuntary oes not re2uire the ecision #a&in) po7er of the +rains Arain can overrie the response if necessary (rotects the +oy fro# har#ful sti#uli Effective from birth oes not nee to +e learnt Short pathay fe7er synapsesSynapses slo7Neurons fastSection 9.3 Control of heart rateThe Autonomic nervous systemControls su+conscious activities of #uscles an )lans*as t7o #ain ivisions9The sympathetic nervous syste# Spees up activities an thus allo7s us to cope 7ith stressful situations ;fi)ht or fli)ht response:The parasympathetic nervous system /nhi+its effects an slo7s o7n activities. "his allo7s ener)y to +e conserve. Controls uner nor#al restin) conitions"he t7o ivisions are antagonistic #eanin) that their effects oppose one another!ontrol of heart rateChan)es of the heart rate are controlle +y a re)ion of the +rain calle the #eulla o+lon)ata 7hich has t7o #ain ivisionsost )ate potassiu# channels re#ain open potassiu# ions #ove out of the a3on o7n their che#ical )raient >ost )ate soiu# channels re#ain closeThe action potential "e#porary reversal of the char)e of the #e#+rane fro# ;'65#E to F65#E:. Bhen the p. is F65#E the a3on is sai to +e epolarise ost heat )aine throu)h internal #eta+olic activities "e#perature ran)e '35 44 oC Co#pro#ise +et7een hi)her te#perature 7here enHy#es 7or& #ore rapily an the a#ount of ener)y neee ;hence foo: to #aintain that te#perature!onserving an# gaining heat in response to a col# environment1on) ter# aaptations9S#all S.9E ration "herefore #a##als an +irs in col environ#ents are relatively lar)eS#aller e3tre#ities ;e.). ears: thic& fur8 feathers or fat reserves to insulate the +oyRapi chan)es93asoconstriction reucin) the ia#eter of arteries$arteriolesShivering in voluntary rapi #ove#ents an contractions that prouce he ener)y fro# respiration%aising hair ena+les a thic& layer of still air to +uil up 7hich acts as a )oo insulator.4ehavioural mechanisms +athin) in the sun5ecrease# seating6oss of heat in response to a arm environment1on) ter# aaptations91ar)e S.9E ratio so s#aller ani#als are foun in 7ar#er cli#ates1ar)er e3tre#ities1i)ht coloure fur to reflect heat3aso#ilation .rterioles increase in ia#eter8 #ore +loo reaches capillaries8 #ore heat is therefore raiate a7ayIncrease# seating *eat ener)y is re2uire to evaporate s7eat ;7ater:. @ner)y for this co#es fro# the +oy. "herefore8 re#oves heat ener)y to evaporate 7ater6oer bo#y hair *air erector #uscles rela3. *airs flatten8 reuces the insulatin) layer of air8 so #ore heat can +e lost to the environ#ent 4ehavioural mechanisms see&in) shae8 +urro7s8 etc!ontrol of bo#y temperature>echanis#s to control +oy te#perature are coorinate +y the hypothala#us in the +rain"he hypothala#us has a ther#ore)ulatory centre ivie into t7o parts9. heat )ain centre 7hich is activate +y a fall in +oy te#perature.n a heat loss centre 7hich is activate +y an increase in te#perature"he hypothala#us #easures the te#perature of +loo passin) throu)h it"her#oreceptors in the s&in also #easure the te#perature/#pulses sent to the hypothala#us are sent via the autono#ic nervous syste#"he core te#perature in the +loo is #ore i#portant that the te#perature sti#ulatin) s&in "her#oreceptorsSection 12.3&12& +or$ones an" the regulations of ,loo" glucose&-ia,etes an" its control*or#ones are prouce +y )lans ;enocrine )lans: 7hich secrete the hor#ones into the +loo"he hor#ones are carrie in the +loo plas#a to the tar)et cells to 7hich they act. "hetar)et cells have co#ple#entary receptors on the cell surface #e#+rane *or#ones are affective in s#all 2uantities set have 7iesprea an lon)'lastin) affectsSo#e hor#ones 7or& via the seconary #essen)er #oel91.: "he hor#one ;the first #essen)er: +ins to receptors on the cell surface #e#+rane8 for#in) a hor#one'receptor co#ple32.: "he hor#one'receptor co#ple3 activates an enHy#e insie the cell that prouces a seconary #essen)er che#ical3.: "he seconary #essen)er acts 7ithin the cell prouces an a series of chan)esAoth )luca)on an arenaline 7or& +y the seconary #essen)er #oelAdrenaline as a secondary messen!er1.: "he hor#one arenaline for#s a hor#one'receptor co#ple3 an therefore activates an enHy#e insie the cell #e#+rane2.: "he activate enHy#e the converts ."( to cyclic .>( 7hich acts as the seconary #essen)er3.: Cyclic .>( then activates several other enHy#es that can convert )lyco)en to)lucose"he )roup of hor#one proucin) cells in the pancreas are &no7n as the islets of lan)erhansAlpha cells a larger an prouce glucagon4eta cells an smaller an prouce insulin4loo# glucose an# variations in its levelAloo )lucose co#es fro# three #ain sources9,irectly fro# the iet resultin) fro# the +rea&o7n of car+ohyrateCro# the +rea&o7n of )lyco)en ;-lyco)enolysis: -lyco)en is store in the liver an in #uscle cellsCro# )luconeo)enises prouction of ne7 )lucose fro# sources other than car+ohyrate an )lyco)en. @.). protein$a#ino acis an )lycerolInsulin an# beta cells in the pancreasAeta cells in the pancreas can etect an increase in )lucose concentration in the +loo an therefore release insulinBhen +oun to receptors on the plas#a #e#+rane of cells8 insulin +rin)s a+out9 . chan)e in the tertiary structure of the )lucose transport protein channels8 causin) the# to chan)e shape so as to allo7 #ore )lucose into the cell /ncreasin) the nu#+er of carrier #olecules in the cell surface #e#+rane .ctivatin) enHy#es involve in convertin) )lucose to fat$)lyco)enAy chan)in) the shape of )lucose transport proteins an causin) an increase in the a#ount of )lucose enterin) cells8 the rate of respiration increasesGlucagon an# alpha cellsBhen alpha cells etect a fall in +loo )lucose concentration that release )luca)on.lpha cells increase +loo )lucose concentration +y9 .ctivatin) an enHy#e that converts )lyco)en to )lucose .n +y increasin) the conversion of a#ino acis$)lycerol to )lucose.renaline can inactivate enHy#es that convert )lucose to )lyco)enTypes of #iabetes"ype # $insulin dependent% utations can turn proto'onco)enes into onco)ens.