mitosis regulation

8/12/2019 Mitosis Regulation

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AP Biology 2006-2007

Regulation of Cell Division


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AP Biology

Coordination of cell division

A multicellular organism needs tocoordinate cell division across

different tissues & organsu

critical for normal growt!develo"ment & maintenance coordinate timing of

cell division

coordinate rates ofcell division

not all cells can ave te

same cell cycle


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AP Biology

#2

$ #%

meta"ase"ro"ase

ana"asetelo"ase

inter"ase '#%! $! #2"ases(

mitosis '(

cyto)inesis 'C(

C

*re+uency of cell division varies ,y cell ty"eu em,ryo

cell cycle 20 minute

u s)in cells

divide fre+uently trougout life %2-2. ours cycle

u liver cells retain a,ility to divide! ,ut )ee" it in reserve

divide once every year or two

u mature nerve cells & muscle cells do not divide at all after maturity

"ermanently in #0

*re+uency of cell division


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AP Biology

Cec)"oint control system

Cec)"ointsu cell cycle controlled ,y $/P& #/

cemical signals at critical "oints

u signals indicate if )ey cellular"rocesses ave ,eencom"leted correctly


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AP Biology

Cec)"oint control system

ma3or cec)"oints4u #%5$

can DA syntesis ,egin

u #25

as DA syntesis ,eencom"leted correctly

commitment to mitosis

u s"indle cec)"oint

are all cromosomesattaced to s"indle

can sister cromatidsse"arate correctly


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AP Biology

#%5$ cec)"oint

#%5$ cec)"oint is most criticalu "rimary decision "oint

8restriction "oint9

u

if cell receives 8#/9 signal! it divides internal signals4 cell growt 'si:e(! cell

nutrition

e;ternal signals4 8growt factors9

u

if cell does notreceivesignal! it e;its cycle &

switces to #0"ase

non-dividing! wor)ing state


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AP Biology

#0"ase

&

&itosis

#%

#a" %

#0

Resting

#2

#a" 2

$

$yntesis

#0"aseu non-dividing! differentiated state

u most uman cells in #0"ase

liver cells in #0! ,ut can ,e

8called ,ac)9 to

cell cycle ,y

e;ternal cues nerve & muscle cells

igly s"eciali:ed

arrested in #0

& can

never divide


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AP Biology


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AP Biology

8#o-aead9signals

Protein signals tat "romote cell growt& divisionu internal signals

8"romoting factors9

u e;ternal signals

8growt factors9

Primary mecanism of controlu "os"orylation

)inaseen:ymes

eiter activates or inactivates cell

signals


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AP Biology

Cell cycle signals

Cell cycle controlsucyclins

regulatory "roteins

levels cycle in te cell

uCd)1s cyclin-de"endent )inases

"os"orylates cellular "roteins

wactivates or inactivates "roteinsuCd)-cyclin com"le;

triggers "assage troug differentstages of cell cycle

activated Cd)

inactivated Cd)


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AP Biology

Cyclins & Cd)s

=nteraction of Cd)1s & different cyclins triggers testages of te cell cycleu


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AP Biology

Cd) 5 #%cyclin

Cd) 5 #2cyclin 'P*(

#2

$

#%

C

#25 cec)"oint

#%5 $ cec)"oint

APC

Active=nactive

Active=nactive

=nactive

Active

mitosis

cyto)inesis

P*> itosis

Promoting *actor

APC> Ana"asePromoting Com"le;

Re"lication com"leted

DA integrity

Cromosomes attacedat meta"ase "late

$"indle cec)"oint

#rowt factors

utritional state of cell$i:e of cell


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AP Biology

Cyclin & Cyclin-de"endent )inases

CD?s & cyclin drive cell fromone "ase to ne;t in cell cycle

u "ro"er regulation of cell

cycle is so )ey to life

tat te genes for

tese regulatory"roteins ave ,een

igly conserved

troug

evolution

u te genes are ,asically

te same in yeast!

insects! "lants &

animals 'including

umans(


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AP Biology

@;ternal signals

#rowt factorsu coordination ,etween cells

u "rotein signals released ,y ,ody cellstat stimulate oter cells to divide density-de"endent ini,ition

w crowded cells sto" dividing

w eac cell ,inds a ,it of growt factorn not enoug activator left to

trigger division in any onecell

ancorage de"endence

w to divide cells must ,e attaced to asu,strate

n 8touc sensor9 rece"tors


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AP Biology

@2*

nucleuscyto"lasm

cell division

nuclear mem,rane

growt factor

"rotein )inasecascade

nuclear "ore

cromosome

Cd)cell surface

rece"tor

P

P

P

P

P

@2*R

,

R,

#rowt factor signals


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AP Biology

@;am"le of a #rowt *actor

Platelet Derived #rowt *actor 'PD#*(u made ,y "latelets in ,lood clots

u ,inding of PD#* to cell rece"tors stimulates cell

division in fi,ro,last 'connective tissue( eal wounds


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AP Biology

#rowt *actors and Cancer

#rowt factors can create cancersu "roto-oncogenes

normal growt factor genes tat

,ecome oncogenes 'cancer-causing(

wen mutated

stimulates cell growt

if switced 8/9can cause cancer

e;am"le4 RA$ 'activates cyclins(

u tumor-su""ressor genes ini,its cell division

if switced 8/**9can cause cancer

e;am"le4 "


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AP Biology

Cancer & Cell #rowt

Cancer is essentially a failureof cell division controlu unrestrained! uncontrolled cell growt

at control is lostu lose cec)"oint sto"s

u gene ""lays a )ey role in #%5$ restriction "oint

" "rotein alts cell division if it detects damaged DAw o"tions4

n stimulates re"air en:ymes to fi; DAn forces cell into #0resting stage

n )ee"s cell in #%arrest

n causes a"o"tosis of damaged cell

Acancers ave to sut down " activity

" discovered at $tony Broo) ,y Dr Arnold evine

p53 is theCell Cycle

Enforcer


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AP Biology

DA damage is caused,y eat! radiation! orcemicals

" allows cells

wit re"airedDA to divide

$te" %

DA damage iscaused ,y eat!radiation! or

cemicals

$te" % $te" 2

Damaged cells continue to divide

=f oter damage accumulates! tecell can turn cancerous

$te"

" triggers te destructionof cells damaged ,eyond re"air

AB/RA"

/RA"

a,normal

" "rotein

cancercell

$te" e " "rotein fails to sto"cell division and re"air DACell divides witout re"air to

damaged DA

Cell division sto"s! and" triggers en:ymes tore"air damaged region

$te" 2

DA re"air en:yme"

"rotein"

"rotein

" E master regulator gene


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AP Biology

Develo"ment of Cancer

Cancer develo"s only after a cell e;"eriencesF6 )ey mutations '8its9(u unlimited growt

turn ongrowt "romoter genes

u

ignore cec)"oints turn offtumor su""ressor genes '"(u esca"e a"o"tosis

turn offsuicide genes

u immortality > unlimited divisions

turn oncromosome maintenance genesu "romotes ,lood vessel growt

turn on,lood vessel growt genes

u overcome ancor & density de"endence

turn offtouc-sensor gene

It1s like anout of control

car!


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AP Biology

at causes tese 8its9

utations in cells can ,e triggered ,yu GH radiation

u cemical

e;"osure

u radiation

e;"osure

u eat

u cigarette smo)e

u "ollution

u

ageu genetics


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AP Biology

umors

ass of a,normal cellsu Benign tumor

a,normal cells remain at original site as alum"w " as alted cell divisions

most do not cause serious "ro,lems &can ,e removed ,y surgery

u alignant tumors cells leave original site

wlose attacment to near,y cells

w carried ,y ,lood & lym" system to otertissues

w start more tumors >metastasis

im"air functions of organs trougout ,ody


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AP Biology

raditional treatments for cancers

reatments target ra"idly dividing cellsu ig-energy radiation )ills ra"idly dividing cells

u cemotera"y sto" DA re"lication

sto" mitosis & cyto)inesis

sto" ,lood vessel growt

mitosis regulation

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