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CELL REPRODUCTION:
MITOSIS & MEIOSIS
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OVERVIEW
• DNA replication
• Overview o cell !ivi"ion
• Mito"i"
• Meio"i"
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DNA REPLICATIONOcc#r" !#rin$ interp%a"e o cellccle
' DNA (olec#le #ntwi"te!
Eac% parent "tran! "erve" a"te(plate or new "tran!
) * new DNA (olec#le"+
eac% , ol! & , new
) "e(i-con"ervative replication
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En.(e" /rea0 1 /on!" /etween *"tran!"
) #nwin!" & e2po"e" n#cleoti!e /a"e"
3ree n#cleoti!e" pair wit% e2po"e!/a"e"
Eac% parent "tran! %a" new one(a!e on it
) twi"t to$et%er to or( !o#/le %eli2
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DNA REPLICATION IN A
LITTLE MORE DETAIL 4S#$ar-p%o"p%ate /ac0/one" o * DNA "tran!" r#n
in oppo"ite !irection"
56 en!) P%o"p%ate $ro#p on "#$ar6" C
76 en!
) 8O1 $ro#p on "#$ar6" C
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) ' !a#$%ter "tran!"nt%e"i.e! contin#o#"l
) Ot%er !a#$%ter "tran!"nt%e"i.e! !i"9ointe!l
DNA polymerase adds nucleotides to 3’ends only
Daughter strand grows in 5’ to 3’ direction
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REPLICATION EN;MES:
1ELICASESCatal.e /rea0in$ o 1 /on!" "o !o#/le %eli2 can
#nwin!
Wor0 wit% "(all protein" to prevent rewin!in$ oparent "tran!"
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REPLICATION EN;MES:DNA POL;MERASES
Catal.e a!!ition o ree n#cleoti!e" to e2po"e! /a"e"on eac% "tran!
Al"o %ave proorea!in$ a/ilitie"
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REPLICATION EN;MES:
DNA LI
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TRANSCRIPTION VS= DNAREPLICATION
Tran"cription
Onl part o DNA
"tran! #nwo#n!
RNA pol(era"e a!!" n#cleoti!e"
to $rowin$ "tran!
Re"#lt" in ' ree
(RNA "tran!
DNA replication
W%ole DNA (olec#le #nwo#n!
DNA pol(era"e a!!" n#cleoti!e" to
$rowin$ "tran!
Re"#lt" in * !o#/le-%eli2 DNA
(olec#le"
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Mi"ta0e" occ#r t%at can /e let%al i not ca#$%te=$= wron$ /a"e-pairin$
DNA proorea!in$ (ec%ani"(" >2 (o"treplication error" & /rea0" in "tran!"
?proorea! & correct (i"(atc%e"@
Repair en.(e" repair "o(e c%an$e" /
"nippin$ o#t !a(a$e! "ite" or (i"(atc%e"
I (i"(atc% can6t /e >2e!+ replication i" "toppe!
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CELL DIVISION: AN
OVERVIEWParent" repro!#ce to pro!#ce new $eneration o cell"
or (#lticell#lar or$ani"(
O"prin$ in%erit" all inor(ation & (eta/olic(ac%iner ro( parent
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PROBAR;OTIC CELL
DIVISIONPro0arotic cell" repro!#ce a"e2#all
) /inar >""ion
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EUBAR;OTIC CELL
DIVISIONDNA in e#0arotic cell" i" in n#cle#"
E#0arotic cell" can6t !ivi!e / >""ion
M#"t cop & pac0a$e DNA into ' n#cle#" /eore
ctopla"( can "plit
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TWO T;PES O3 CELL DIVISION
Mito"i":
• Pro!#ce" * $eneticall i!entical cell"
• 1appen" t%ro#$%o#t /o!
Meio"i":
• Pro!#ce" $eneticall !ierent cell"
• Cell" onl %ave , o $enetic ino
• 1appen" onl in $ona!"
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MITOSISOne part o t%e cell ccle
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T1E CELL C;CLE
T%e perio! ro( one cell !ivi"ion to ne2t
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INTERP1ASE: T1E LON
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Interphase
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S: S;NT1ESIS P1ASEDNA !#plicate!
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C%ro(o"o(e & cop ) "i"ter c%ro(ati!"
Koine! at centro(ere
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Cell" "ta in
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Sa(e ccle len$t% or "a(e tpe o cell"
Dierent ccle len$t%" or !ierent tpe" o cell"
e=$= cell" in re! /one (arrow !ivi!e ever "econ!
e=$= nerve cell" "ta in
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Ater
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C1ROMOSOME NUMER
1#(an" %ave c%ro(o"o(e"
) !iploi! ?*n@
* o eac% tpe oc%ro(o"o(e
) one "et ro( (ot%er+one ro( at%er
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D#rin$ (ito"i":
Eac% *n parent cell pro!#ce" two *n !a#$%ter cell"
Eac% !a#$%ter cell %a" eac% pair o c%ro(o"o(e"
) *7 pair"
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D#rin$ (ito"i"+ * "i"ter c%ro(ati!" ?!#plicate!c%ro(o"o(e"@ "eparate
Eac% /eco(e" in!epen!ent c%ro(o"o(e t%at en!" #p in '
o !a#$%ter cell"
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T1E MITOTIC SPINDLEPre"ent in ever cell
Ma!e o (icrot#/#le"
) c%an$e len$t% / a!!ition or
re(oval o t#/#lin "#/#nit"
Ori$inate" ro( pair o centriole"
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Earl in cell !ivi"ion+ !#plicate!c%ro(o"o(e i" con!en"e! )
coil" #p
DNA win!" twice aro#n! %i"tone"
) n#cleo"o(e
Beep" c%ro(o"o(e" or$ani.e!!#rin$ n#clear !ivi"ion
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LATE INTERP1ASE
PRE-PROP1ASE
O#t"i!e o n#cle#"+ * centriole" !#plicate"elve"
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EARL; PROP1ASEIn"i!e n#cle#":
C%ro(o"o(e" /e$in to con!en"e
O#t"i!e n#cle#":
Spin!le /e$in" to or(
N#clear envelope /e$in" to all apart
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LATE PROP1ASEN#clear envelope co(pletel all" apart
Spin!le >/re" ro( eac% pole attac% to"i"ter c%ro(ati!" o eac% c%ro(o"o(e
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METAP1ASE
C%ro(o"o(e" line #p %alwa /etween
"pin!le pole"
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ANAP1ASESi"ter c%ro(ati!" o eac% c%ro(o"o(e"eparate & (ove to oppo"ite pole"
?(otor protein" attac%e! to 0inetoc%ore"!ra$ c%ro(ati!" alon$ (icrot#/#le"@
Spin!le pole" p#"%e! apart / $rowin$(icrot#/#le"
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TELOP1ASE' o eac% tpe oc%ro(o"o(e reac%e" eac%
"pin!le pole
) * i!entical $ro#p" oc%ro(o"o(e" at eac% cell pole
C%ro(o"o(e" !econ!en"e
N#clear envelope or(" aro#n!eac% cl#"ter o c%ro(o"o(e") two n#clei+ eac% wit% *n J o
c%ro(o"o(e"
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C;TOBINESISCtopla"( o cell !ivi!e"
Re"#lt" in * !a#$%ter cell"+ eac% wit% "a(en#(/er o c%ro(o"o(e" a" parent cell
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C;TOBINESIS IN ANIMAL
CELLSContractile rin$ (ec%ani"(
1alwa /etween cell6"pole"+ pla"(a (e(/rane
con"trict" ) cleava$e#rrow
?ATP ener$ ca#"e"contraction o actin>la(ent"@
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C;TOBINESIS IN PLANT
CELLSCell plate or(ation
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SUMMAR; O3 MITOSIS
N#clear & cell#lar !ivi"ion t%at(aintain" c%ro(o"o(e J
U"e! or $rowt%+ repair+ a"e2#alrepro!#ction
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Cell !ivi"ion & DNA replication re$#late! "o t%at:
DNA onl replicate! once /eore cell !ivi"ion
Cell" t%at never !ivi!e !o not replicate DNA
Cell" !on6t tr to replicate DNA i lac0 t%e ener$ & raw
(aterial" to co(plete proce""
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CELLULAR CONTROLS
OVER MITOSISAnc%ora$e !epen!enceAni(al cell" (#"t /e in contact wit% a
"oli! "#race to !ivi!e
Den"it-!epen!ent in%i/ition
Crow!e! cell" "top !ivi!in$
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CELL C;CLE
C1ECBPOINTSCell cycle has checkpoints:
– Structure of chromosomal DNA monitored
– Completion of phases monitored
– Determines if good time for cell division
Rely on internal & eternal cues
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CANCER & CELL DIVISION
If immune system doesn!t recogni"e &destroy a cancerous cell# it may divide
multiple times & form a tumor
$enign
Cells remain locali"ed
%alignantSpreads to other parts of ody & disrupts
function
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W1; DON6T CANCER CELLS 3OLLOW T1E RULES
Don6t e2%i/it !en"it-!epen!ence
1ave !eective control ""te("
I$nore over-ri!e c%ec0point"
So(e "nt%e"i.e own $rowt% actor" "o contin#e !ivi!in$
Divi!e in!e>nitel
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T;PES O3 CANCERSCarcino(a"
Internal & e2ternal coverin$" o /o! e=$= "0in
Sarco(a"
S#pportive ti""#e" e=$= /one & (#"cle
Le#0e(ia" & L(p%o(a"
loo!-or(in$ ti""#e" e=$= /one (arrow+ "pleen+ l(p%
no!e"
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WA;S TO TREAT
CANCERI not "evere:
S#r$ical re(oval o t#(or
Ra!iation t%erap
?!a(a$e" DNA o cancer cell" to $reater !e$ree t%annor(al cell"@
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I "evere:
C%e(ot%erap
U"e" !r#$" to !i"r#pt cell !ivi"ion
e=$= Paclita2el ree.e" t%e (itotic "pin!le at
(etap%a"e
e=$= Vin/la"tin prevent" "pin!le or(ation
Al"o aect" rapi!l-!ivi!in$ nor(al cell" e=$=inte"tinal linin$+ i((#ne cell"+ %air ollicle cell"
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Donor cell & e$$ cell place! ne2t to eac%ot%er in c#lt#re !i"% & electricall
"ti(#late!
Cell" #"e & enter (ito"i"
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MITOSIS VS= MEIOSISMito"i":
• Occ#r" in "o(atic cell"
• Re"#lt" in * $eneticall i!entical cell"
•
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ASEQUAL VS= SEQUAL
REPRODUCTIONA"e2#al repro!#ction:In!ivi!#al (a0e" (#ltiple o"prin$ wit%
i!entical DNA
Se2#al repro!#ction:
Allow" or variet in %erita/le trait"
A!aptive in c%an$in$ environ(ent"
Meio"i" or(ation o $a(ete" ertili.ation
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T1E EUBAR;OTIC
C1ROMOSOMEDo#/le-"tran!e! DNA & a""ociate!protein"
C%ro(o"o(e" !#plicate! !#rin$interp%a"e'nduplicated Duplicated
Centromere
Sister chromatids
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C1ROMOSOME NUMERAl(o"t ever cell in /o! %a" * co(plete "et" o
c%ro(o"o(e"
One "et ro( (ot%er+ one ro( at%er
* "et" ) !iploi! ?*n@
Eac% cell %a" * ver"ion" o eac% $ene
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1o(olo$o#" c%ro(o"o(e"
Pair o c%ro(o"o(e" t%at carr $ene" or "a(e %erita/letrait"
E2cept "e2 c%ro(o"o(e" ?Q or ;@
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ALLELEOne o t%e variant or(" o a $ene at apartic#lar ?loc#"@ location on a c%ro(o"o(e
Dierent allele" pro!#ce variation in in%erite!c%aracteri"tic" ?e=$= %air & ee colo#r+ etc=@
a"i" or evol#tion: en!le"" co(/ination" oallele" lea! to variation" in trait"
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SO W1AT IS MEIOSIS
N#clear !ivi"ion t%at %alve"c%ro(o"o(e J
Occ#r" onl in "e2 ?repro!#ctive@ cell"
'"t "tep in or(ation o $a(ete" ? or@
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1#(an" are !iploi! ?*n@ wit% c%ro(o"o(e"?*7 *7 %o(olo$o#" c%ro(o"o(e"@
Meio"i" %alve" c%ro(o"o(e n#(/er "o !a#$%ter cell"?$a(ete"@ are %aploi! ?n@ wit% *7 c%ro(o"o(e"
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D#rin$ (eio"i"+ one cell $oe" t%ro#$% * !ivi"ion" toen! wit% or(ation o cell"+ all wit% %aploi! ?n@
n#clei
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INTERP1ASE
Sa(e a" in (ito"i":
Cell $row" & !#plicate" ctopla"(icco(ponent"
DNA i" replicate!
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PROP1ASE IC%ro(o"o(e" con!en"e
Cro""in$-over occ#r" /etween
%o(olo$o#" c%ro(o"o(e"
Centriole" (ove to oppo"ite "i!e" on#clear envelope
N#clear envelope /e$in" to all apart
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CROSSIN< OVERW%en c%ro(o"o(e" con!en"e !#rin$ prop%a"e+
%o(olo$o#" c%ro(o"o(e" "tic0 ver clo"el to$et%er& or( a tetra!
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Maternal & paternal c%ro(o"o(e" "wap$ene"
) e2c%an$e "e$(ent" o $enetic ino
1o(olo$o#" c%ro(o"o(e" /eco(e (i2t#reo (aternal & paternal ino
chiasma
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METAP1ASE I
1o(olo$#e" o c%ro(o"o(e" tet%ere!/ (icrot#/#le" at oppo"ite "pin!le pole"
C%ro(o"o(e" line #p alon$ e#ator ocell
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ANAP1ASE I
C%ro(o"o(e" p#lle! apart & (ove towar!"re"pective pole"
Pole" (ove #rt%er apart
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TELOP1ASE I
Ctopla"( !ivi!e"
Re"#lt" in * %aploi! cell"
?onl %ave ' o eac% pair o %o(olo$o#"c%ro(o"o(e"@
C%ro(o"o(e" "till !#plicate!
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PROP1ASE II
New (itotic "pin!le or(" in eac%cell
C%ro(ati!" o eac% c%ro(o"o(e/eco(e tet%ere! to oppo"ite pole"
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METAP1ASE II
C%ro(o"o(e" line #p alon$ e#ator o cell
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ANAP1ASE II
C%ro(ati!" "eparate & (ove towar!" oppo"itepole"
Spin!le pole" p#"%e! apart
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TELOP1ASE II
N#clear envelope or(" aro#n! eac% c%ro(o"o(ecl#"ter
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C;TOBINESISCtopla"( !ivi!e"
Re"#lt" in %aploi! ?n@ !a#$%ter cell"
C%ro(o"o(e" are #n!#plicate!
MEIOSIST1IN
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MEIOSIST1IN
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MEIOSIS & TRAIT
VARIATIONCan occ#r via:
• Cro""in$ over
• Ran!o( ali$n(ent o
c%ro(o"o(e" at (etap%a"e I
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A= CROSSIN< OVERE2c%an$e" o allele-containin$ "e$(ent" occ#r"/etween non-"i"ter c%ro(ati!" ?i=e= /etween(aternal & paternal c%ro(o"o(e"@
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= METAP1ASE I
ALI
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W%ic% %al o %o(olo$o#" c%ro(o"o(epair en!" #p at w%ic% pole i" totall
ran!o(
**7 ?+7+G@ po""i/le co(/o" o
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3ROM
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MALE
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3EMALE
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W%en ' oocte !ivi!e" ater (eio"i" I+one !a#$%ter cell ?* oocte@ $et" (o"t
o ctopla"(
Ot%er cell ?'"t polar /o!@ i" ver "(all
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Ater (eio"i" II+ one o * oocte6"!a#$%ter cell" i" *n! polar /o! ?al"o ver
"(all@
Ot%er $et" (o"t o ctopla"( an! !evelop"
into ov#( ?e$$@
'"t polar /o!6" !a#$%ter cell" are /ot%
polar /o!ie"
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Polar /o!ie" event#all !e$enerate
Sole #nction: to en"#re ov#( i" %aploi!
Ov#( $et" (o"t o ctopla"( & (eta/olic (ac%iner
I" a/le to "#pport earl cell !ivi"ion" o new in!ivi!#alater ertili.ation
3ERTILIATION: W1EN *
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3ERTILIATION: W1EN *
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SUMMAR; O3 MEIOSIS
N#clear !ivi"ion t%at %alve" c%ro(o"o(e n#(/er
Re"#lt" in n (ale & e(ale $a(ete" t%at can #"e!#rin$ ertili.ation to pro!#ce *n o"prin$
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C1ROMOSOMAL
ANORMALITIESA/nor(al c%ro(o"o(e structure:
rea0a$e o c%ro(o"o(e lea!" torearran$e(ent" t%at aect $ene" on t%at
c%ro(o"o(e
A/nor(al c%ro(o"o(e number:
C%ance event" occ#r /eore or ater cell!ivi"ion t%at re"#lt in wron$ c%ro(o"o(e J
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C1AN
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?A@ INVERSIONS
ro0en ra$(ent reattac%e" to ori$inal c%ro(o"o(e /#t in rever"e !irection
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?@ DELETIONS3ra$(ent o c%ro(o"o(e i" lo"t
Ca#"e "evere p%"ical & (entalpro/le("
e=$= cri !# c%at
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?C@ DUPLICATIONS3ra$(ent ro( one c%ro(o"o(e 9oin" to a "i"ter
c%ro(ati! or %o(olo$o#" c%ro(o"o(e
Can %ave "evere eect"
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I c%ro(o"o(al c%an$e" occ#r in "per( or e$$ cell":) (a ca#"e con$enital !i"or!er"
I c%ro(o"o(al c%an$e" occ#r in "o(atic cell":
) can lea! to !evelop(ent o cancer
?w%ic% i" w% cancer i" $enerall not %erita/le@
1ERITALE C1AN
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C1ROMOSOME J
C%ance event" occ#r /eore or ater cell !ivi"ion t%atre"#lt in wron$ c%ro(o"o(e J
Con"e#ence" can /e (inor or let%al
Mo"t c%an$e" in c%ro(o"o(e n#(/er occ#r /eca#"e o
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Mo"t c%an$e" in c%ro(o"o(e n#(/er occ#r /eca#"e onon-!i"9#nction
) ' pair o c%ro(o"o(e" !o not "eparate !#rin$(ito"i" or (eio"i"
Ane#ploi!:
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p
Nor(al J ± ' c%ro(o"o(e
e=$= tri"o( *' ?Down Sn!ro(e@
Polploi!:
7n+ n+ etc=
Nor(al in (an plant" & ani(al"
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J o "e2 c%ro(o"o(e" can al"o /e a/nor(al
E=$= QO+ QQQ+ QQ;+ Q;;
Will ret#rn to t%i" w%en coverin$ in%eritance