BIOL 3301 - Genetics Ch10D - DNA Organization 08 St

8/18/2019 BIOL 3301 - Genetics Ch10D - DNA Organization 08 St

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Organization of DNA in

Eukaryotic Chromosomes• Single copies of _________________

• __________________ DNA

– Heterochromatin associate !ith centromeres

an telomeres

– "anem repeats of short an longer DNA

se#uences – "ransposa$le se#uences


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"he Comple%ity of the &enome

• Comple%ity of the genome can $eetermine $y analysis of DNA

enaturation'renaturation processes• Denaturation – the higher &C content( the

__________________________

• ______________________ofcomplementary single strans( nucleic acihy$riization


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"he Comple%ity of )iral an

*acterial &enomes• +ate of enaturation epens on

– _____________ of the solution

– ,ncu$ation temperature

– __________________ of DNA

– -erio of incu$ation

– __________ of interacting molecules


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*acterial &enomes• "o compare renaturation( nee to make their

DNA of _______________ – fragments of

DNA .a$out / k$ long0

• +eannealing at istinctly ifferent rates

• "he smaller the genome( the

_______________ renaturation


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*acterial &enomes• "he renaturation of $acterial an 1iral DNA

occurs along single( symmetrical cur1es –

___________________________________ ___________________________________


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"he Comple%ity of Eukaryotic

&enomes• "he DNA fragments of mammalian DNA

renaturate ______________________________

• )arious nucleotie se#uences in preparation ofeukaryotic DNA are present at markely ifferentconcentrations

• DNA from plant an animals usually sho!s three

rather istincti1e steps – ____________________________________________

____________________________________________ ___________________________________________


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+epetiti1e Se#uences

• Highly repeate se#uences

_______________________________0 are

a large component of eukaryotic genomes

• "hese !ere first re1eale in e%periments

that e%amine the rate of reassociation of

enature genomic DNA2


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+epetiti1e DNA

• "he repetiti1e DNA in the human genome

can $e $roken into t!o classes


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+epetiti1e DNA an Satellite

DNA• __________________ – increase ensity

• +eassociation kinetics

• _________________ DNA – shortse#uences repeate many times ' 345 ofhuman genome

• In situ _________________________6satellite DNA hy$riize to regions ofcentromeres


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"anem +epeats

• "anem repeats are an array of consecuti1erepeats2

• "hey inclue three su$classes6 ________________________________________

• "he name 7satellites7 comes from their opticalspectra


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Satellites• "he size of a satellite DNA ranges from

______________________________________

• ,n humans( a !ell kno!n e%ample is the alphoidDNA locate at the ______________________of

all chromosomes2

• ,ts repeat unit is /8/ $p an the repetiti1e regionaccounts for 9'45 of the DNA in eachchromosome2

• Other satellites ha1e a shorter repeat unit2

• :ost satellites in humans or in other organisms arelocate at the _______________________


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:ile +epetiti1e Se#uences

• :ile or moerately repetiti1e DNA

– ,nclue some _________________________

.genes encoing for r+NA0 – Noncoing tanemly repeate or intersperse(

/4'/;; $p long !ithin an $et!een genes ./'


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Minisatellites

One type of minisatellites is calle

__________________________________

• ,ts repeat unit ranges from = $p to >; $p2• "hey are locate in non'coing regions2

• "he num$er of repeats for a gi1en minisatellite

may iffer $et!een __________________________2

• "his feature is the $asis of DNA fingerprinting2


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:ile +epetiti1e Se#uences

• :icrosatellites

– Di'( tri' tetra' an pentanucleoties

– Disperse throughout genome(

_________________________

– ,n humans( most common is inucleotie

.CA0n( n ? 4 ' 4;


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Microsatellites

• :icrosatellites are also kno!n as ____________________________________ $ecause a repeat unit consists of only / to @ $p anthe !hole repetiti1e region spans less than /4; $p2

• Similar to minisatellites( the num$er of repeats fora gi1en microsatellite may iffer $et!een

__________________

• :icrosatellites can also $e use for DNAfingerprinting2


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Centromeres and Telomeres

• Centromeres an telomeres are t!o essentialfeatures of all eukaryotic chromosomes2

• Each pro1ie a uni#ue function that is a$solutelynecessary for the sta$ility of the chromosome2

• ____________ are re#uire for the segregation ofthe centromere uring meiosis an mitosis(

• "elomeres pro1ie __________________________ to thechromosome an ensure its sur1i1al2


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Centromere

• ithin the centromere region( most species ha1e

se1eral locations !here spinle fi$ers attach( an

these sites consist of DNA as !ell as protein2• "he actual location !here the attachment occurs is

calle the _______________________ an is

compose of $oth DNA an protein2

• "he DNA se#uence !ithin these regions is calle

CEN DNA – ____________________________ 2


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CEN regions of Saccharomyces

cerevisiae• CEN regions of all /@ chromosomes consist

of __________________________(

su$i1ie into three regions• +egions , an ,,,( short( highly conser1e(

consist of > an ;'>4 $p( =45 A"( critical tocentromere function


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"elomeric +egions

• -ro1ie sta$ility to the chromosome

• "!o types of DNA telomeric se#uences6

– DNA telomeric se#uences2 Short tanemrepeats( repeate B 4; times(

______________________________throughout e1olution

– "elomere'associate se#uences2 +epetiti1e(1ary among organisms(

_____________________________________


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"elomeres

• "elomeres are short nucleotie se#uences presentas tanem repeats2 "he $asic se#uence motif is4'"%Ay&z'9 an the num$er of repeats 1aries!ith species2

• "elomeres ha1e a ____________________regionat the 9 en that forms a hairpin loop at theterminus of chromosomes2

• "elomere se#uences ae to the en ofchromosome $y a special enzyme calle a ________________________________ 2


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"elomeres

• "!o types of telomeres

• ,n1ertron telomeres ha1e a protein co1alently

attache to the 4F ens of the DNA molecule.calle the 4F'terminal protein or "- for short02

• __________________ telomeres


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DNA -olymorphism

• "he term 7polymorphism" escri$es the

e%istence of ifferent forms !ithin a population(

e2g2( ifference ___________________________________2

• All tanem repeat polymorphisms coul result

from ______________________ uring meiosis

• "he microsatellite polymorphism coul also $e

cause $y _______________________________


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2 repeats

3 repeats

--------

AGACTAGACATT-------

--------

AGATTAGGCATT-------

---------(AATG)(AATG)(AATG)----------

---------(AATG)(AATG)----------

() !ength poly"orphis"

(A) #e$%ence poly"orphis"

&ig%re 2.', .. %tler (200') Forensic DNA Typing , 2n* +*ition © 200' +lseier Aca*e"ic Press


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Short "anem +epeats .S"+s0

the repeat region is variable between samples while the

flanking regions where PCR primers bind are constant

8 repeats

> repeats

AATG

Homozygote ? _____________________________________

___________ ? alleles iffer an can $e resol1e from one another


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)N"+ – )aria$le Num$er of

"anem +epeatsHyper1aria$le markers – :enelian

inheritance !ith ______________ alleles

per locus)N"+s – large comple% motifs

of repeats

:inisatellites – small motifs .


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2 / ' 6

'-TTTCCC TCAT TCAT TCAT TCAT TCAT TCAT TCACCATGGA--AAAGGG AGTA AGTA AGTA AGTA AGTA AGTA AGTGGTACCT-'

6 ' / 2

BIOL 3301 - Genetics Ch10D - DNA Organization 08 St

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