DNA Structure and Analysis Chapter 9

9 | DNA STRUCTURE AND ANALYSIS DNA  serves as the genetic material except in viruses right handed double helix  ( James-Crick  James-Crick model) Strand are anti!arallel and are held together through h"drogen bond : A - -T (2 H bonds) o G - - - C ( 3 H bonds) o structure is for toring and ex!reing the genetic in#ormation

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RNA ingle tranded serves as the genetic material in some $irue Chromoome •

contain gene gene cont !henot"!ic trait that stru struct ctur ures es that that contain contrroi oing ng the !henot"!ic that are are transm transmitt itted ed throug through h gamete  o%!ring contains both a nuceic acid and a protein component 

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&ene •

in!uences the form and characteristics of each individua o  genetic material 

9'( | T)E &ENETIC *ATERIAL *ATERIAL *UST E+)I,IT -.UR C)ARACTERISTICS (' Re!l Re!lic icat atio ion n "undamenta propert# of a iving organisms Doubling the amount  of the genetic material  *ut be e/uall" !artitioned  into the daughter ces o -ormation o# the gamete  aso re!licate and !artition the genetic material$ on# getting ½ of  the original genetic material %*eioi •

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0' Storag Storage e o# in#orm in#ormati ation on moecue has to act as a re!oitor" o# genetic in#ormation  that ma# or ma# not be expressed b# the ce in &hich it resides' a' Ex' Turn on and o in bacteria and higher animas i' acteria acteria * speci+c speci+c environ environmenta menta conditi conditions ons ii' ii' Huma Human n * me mean anin in gen genes es •

1' Ex!re Ex!reio ion n o# o# in#or in#ormat mation ion basis of the process of information !o& &ithin the ce Trancri!tion o# DNA 1 RNA molecule are s#nthesi,ed: mRNA, rRNA and tRNA o  mRNA- transate transated d into !rotein2 produ product ct of a speci+c speci+c gene and direct the "nthei o# a o di%erent !rotein Tranltion chemica chemica informati information on in m.A m.A directs directs the contruction o# a chain o# amino   acids caed o  polypeptides$  polypeptides$ &hich fod into a protein' •

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3ariation b" mutation

*utation a change in the chemical com!oition o# DNA / alteration is refected during transcription and translation that aects a specic protein can be !aed  to the future generations o genetic variation aso incude the alterations of  chromosome number and rearrangements within and bet4een chromoome !ro$iding a ne4 ra4 material  for the process of evoution o

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9'0 &enetic *aterial •

| Until (9956 .ber$ation -a$ored 7rotein a the

0ince there is a great diversit# of proteins in abundant ces

-riedrich *iecher

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Iolated cell nuclei and deri$ed an acid ubtance  containing 1.A caed nuclein DNA lac8 di$erit" necessar# to store extensive genetic information  The concusion &as based on 7hoebu A Le$ene 4/ 1.A contained approximate# e5ua amounts of 6 simiar moecues caed nuceotides' o o  Tetranucleotide hypothesis

Er4ann Charga%  • •

0ho&ed that 7evene &as incorrect 8ost organisms do not contain precise# e5ua proportions of the 6 nuceotides

9'1 | E$idence -a$oring DNA a the &enetic *aterial 4a -irt .btained During the Stud" o# ,acteria and ,acterio!hage •

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9s&ad Aver#$ Coin 8ac7eod and 8ac#n 8cCart# pubished principe; 1.A &as carrier of the genetic information 1.A &as the responsibe on in heredit#

the chemica nature of a transforming

TRANS-.R*ATI.N EARLY STUDIES -rederic8 &ri:#th •

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s &as initianted in 2? @xperimented in Diploccocus pneumonia o 0ome are $irulent train and some are a$irulent train 3irulent train o Have the !ol"accharide ca!ule Are not engufed easi# / mutip# and causes oneumoniae o "orm mooth colonie ;S<  &ith shin# surface on an agar cuture pate o A$irulent do not have the po#saccharide capsue o Readil" engul#  and detro"ed b# the phagoc#tic ces in the anima>s circuator# s#stem o o  roduces rough colonie ;R  ) Bf heated$ did not cause pneumonia o Diplococcus ma# be one of do,ens of dierent t#pes caed erot"!e S!eci=cit" is due to the detailed chemical tructure   of the  !ol"accharide contituent o#  o the thic8 $ lim" ca!ule'

)eated IIIS ;$irulent< > li$ing IIR; a$irulent
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)enr" Da4on • •

0ho&ed that transformation coud occur in vitro * tube containing on# bacteria ces' Bnection to the mice is not necessar# for transformation to occur'

Lionel B' Allo4a" • •

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Re=ned the in $itro ex!eriment  using extracts from 0 ces added to iving  ces  The soube +trate from the heat-=ied BBB0 ces &as as e%ecti$e inducing tran#ormation as &ere the intact ces' 1id not vie& transformation as a genetic event but a ph#sioogica modi+cation

TRANS-.R*ATI.N A$er"6 *acLeod and *cCart" Ex!eriment • •

9btained the transforming principe in a high# puri+ed state * 1.A Chec= "igure 3 for summar# •

Soluble =ltrate -derived(retained the abiit# to induce transformation of t#pe BB aviruen ces

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7reoteae- protein-digesting en,#me

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Ribonucleae@ .A digesting en,#me

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ut &hen deox#ribonucease &as used$ the transforming activit# present in the +trate &as destro#ed'

Concusion in 66 pubication: “The evidence presented supports the belied that a nucleic acid o deo!ribose t!pe is the undamental unit o the transorming orinciple o "neumococcu t!pe ###$   Transforming principes interacts &ith the BB ce and gives rise to a coordinated en,#matic reactions that cuminates in the s#nthesis of the t#pe BBB0 capsuar po#saccharide •

Tran#ormation i heritable and the !roce a%ect the genetic material' T)E )ERS)EY@C)ASE E+7ERI*ENT E' coli and a bacterio!hage T 0 7hage or bacterio!hage o  virus consists of a protein coat surrounding a core of 1.A' o @xterna structure is composed of a hexagona head pus a tai Adsorbs to the bacteria ce and some component of the phage enters the ce' o o ira information  commandeers;- responsibe for the vira reproduction manipuating the ceuar machiner# of the host

(' T0 !hage conit o# a!!roximatel"  !rotein and  DNA 0' In#ection i initiated b" ador!tion o# the !hage b" it tail =ber to the bacterial cell 1' The !roduction i# ne4 $iru occur 4ithin the bacterial cell' •

sed radioisotopes to foo& the moecuar components of phages during infection 10 7 F label DNA 1.A contains phosphorus but not sufur o 1

S Flabel !rotein o roteins contain sufur bot not phosphorus •

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@'coi ces are +rst gro&n in the presence of either radioactive isotope and the infected &ith T2 virus$ the progen# ohage &i then be abeed &ith a 1.A core or a abed rotein coat'  The radioactive phages can be isoated and infect unabeed bacteria 

abeed phage and unabeed bacteria &ere mixed

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adsorption compex &as formed as the phages attached their tai +bers to the bacteria &a 3 comexes &ere isoated and subected to shear forceusing a bender 6 force stripped o( the attached phages/ ana#,ed separate# D radioisotopes &ere traced E ?

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 1.A - bacteria ce

0 protein- remaBned outside' FghostsF bacteria ces &ere #sed as ne& phages &ere produced$ the progen# contained 32 but not 3D0 3D

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rotein of the coat remains outside the host ce and is not invoved in the production of ne& phages 1.A enters the host ce and directs the phage reproduction

&enetic material in !hage T0 i DNA6 and not !rotein

TRANS-ECTI.N E+7ERI*ENTS •

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D?$ @' coi &as treated &ith the en,#me l"oG"me6 the outer &a of the ce can be removed &ithout destro#ing the bacterium' 8a=ing them na=ed$ containing on# the ce membranes as the outer boundar# of ce o o 0tructures are caed as !roto!lat or !hero!lat'  Iohn 0pi,i,en and 1ean "raser sed protopasts and &ere abe to initiate the phage mutipication &ith distrupted T2 partices' o A virus did not have to be intact for infection to occur o

 Transfection o rocess of infection b# on# the vira acid sed on# puri+ed 1.Afrom bacteriophages o

DNA er$e a the genetic material in all organim

9'5 | Indirect and Direct E$idence Su!!ort the Conce!t that DNA I the &enetic *aterial in Eu8ar"ote Indirect E$idence Ditribution o# DNA •

 The genetic materia shoud be found &here it functions .uceus as part of the chromosomes o 1.A and protein ut proteins are aso abundant in the cutopasm 8itochondria and choropasts both perform genetic functions/ 1.A is present 1.A is found on# &here primar# genetic function is =no&n to occur  

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Correlation bet4een the !loid";6n6 0n etc'< o# cell and the /uantit" o# the molecule that #unction a the genetic material occur' •

.o consistent correation occurs bet&een gametes and dipoid ces for proteins

Indirect E$idence *utagenei Ultr$iolet ;U3< light 9ne of the agents capabe od inducing mutations in the genetic materia Action !ectrum o 9btained &hen data are potted  ight as mutagenic agent is obtained Abor!tion !ectrum o
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The molecule er$ing a the genetic material i ex!ected to aborb at the 4a$elength ho4n to be mutagenic'

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v ight is most mutagenic at the &aveength ( λ< of about 2E4 nm oth 1.A and .A absorb  ight at 2E4 nm roteins absorb at around 2J4 nm but no mutagenic eects are observed

Direct E$idence Recombinant DNA tudie

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0egments of eu=ar#otic 1.A corresponding to speci+c genes are isoated and spiced into bacteria 1.A

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Compex can be inserterted into a bacteria ce genetic expression is monitored

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introduction of eu=ar#otic gene

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presence of corresponding eu=ar#otic preotein product demonstrates direct# the 1.A is functiona in the bacteria ce

As the bacterium divides$ the eu=ar#otic 1.A repicates aong the host 1.A

eatrice 8int, • •

1emonstrated the 1.A encoding the human -gobin protein 8icroinected to a fertii,ed mouse egg

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7ater found to be present and expressed in adut mouse tissue and it is transmitted to and expressed in the mouse>s progen#  The mouses are caed to be TRANS&ENIC ANI*ALS

9' | RNA er$e a the &enetic *aterial in Some 3iru • •

irus coreK .A  Tobacco mosaic virus (T8) 0pread on its eaves o o 7esions &ere caused b# the vira infection

Norman 7ace and Sol S!iegelman •

.A from phage L can be isoated and repacted in vitro'

RNA re!licae o @n,#me that causes repication •

etrovirus epicate in an unusua &a# o .A serves as a tempate for s#nthesis of the compementar# 1.A moecue o rocess is caed as the re$ere trancri!tion o Re$ere trancri!tae 1.A po#merase that direct the direction of .A- dependent 1.A po#merase  The 1.A intermediate can be incorporated into the genome of the host ce 1.A transcription- copies of the retrovira .A chromosome are produced Bncudes HB- human immunode+cienc# virus  That causes aids and .A tumor virus o   

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