FS1 INTRODUCTION TO DNA GENES AND CHROMOSOMES
:
PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
DNA o tai s the i st u io s fo g o th a d de elop e t i hu a s a d all li i g thi gs. Ou DNA is
pa kaged i to h o oso es that o tai all of ou ge es.
I su
ar
DNA sta ds for Deo ri oNu lei A id hi h is ade up of er lo g hai s of
he i al leters : Ade i e A , Gua i e G , Th i e T a d C tosi e C
DNA o tai s the i stru io s for our ge es
Ge es are the i stru io s for
ells a d od
I hu a s,
aki g protei s. Protei s do the ork ithi our
ost ge es are arra ged o
THE GENETIC BOOK OF LIFE
I hu a s ge ei i fo aio , also k o
as ou
ge o e, a e des i ed as the Book of Life . This
ook a
e thought of as ei g ade up of t o
olu es, ea h olu e of the ook is gi e to a pe so
o e of thei pa e ts Figure . .
Figure . : The hu a ge o e so ei es alled the
Book of Life
hro oso es that are fou d i the u leus of ells.
‘eadi g a pe so s ge ei
. :
ook of life Figure
O e olu e of the ook is i he ited f o
othe a d the othe f o the fathe
the
Both olu es o tai
hapte s ea h,
e ui ale t to the pai s of h o oso es i
hu a
od
ells that o tai ge ei
i fo aio
The
hapte s h o oso es a e ade
up of a u e of e ipe pages odi g DNA
o ge es a d i - et ee
o - odi g pages
of DNA
So e of the
hile othe s
h o oso es
thousa ds of
hile othe s a
Ge es a e se io s of DNA that ode fo the
p otei s ou od eeds to fu io
I - et ee
o - odi g se io s of DNA
ha e a ious jo s, ot all of hi h e
u de sta d
Ca eful e a i aio of the o ds ithi
ge es sho s that all the o ds a e ade up
of th ee lete s t iplets su h as AGT, GGT,
ACT, CAA et .
The e a e fou lete s used i
ook. The a e A, T, C & G.
hapte s o tai
a pages
o l ha e a fe . So e
a e la ge a d o tai
a
ge es a d o - odi g DNA
e u h s alle
the ge ei
Just as eadi g the o ds o the page of a ook
allo s a u de sta di g of the autho s essage,
the od is a le to ead the t iplets i ge es to
ake the p otei eeded fo ou ells to o k.
.ge ei s.edu.au
Updated
Page of
Ju e
:
PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
Ou ells do t eed all the i st u io s all the
i e. Pages of ou ge ei ook a e losed a d
the eope ed he eeded. Ea h t pe of ell
a ha e dife e t pa ts of the ge ei
ook
ope ed o shut e ause dife e t ells do dife e t
jo s i ou od . Whi h ge es a e tu ed o o
of a
e i lue ed
ou diet, he i al
e posu e, e e ise, agei g a d essages f o
othe ge es i the od .
Figure . : Chro oso es are like stri gs of ge es
Figure . : Ge ei ter i olog a d the Book of Life
DNA, GENES AND CH‘OMOSOMES IN THE BODY
Ou odies a e ade up of illio s of ells. Ea h
ell o tai s a o plete op of a pe so 's ge ei
ook of life.
Ch o oso es a e thought of as ei g ade
up of st i gs of ge es DNA that odes fo
p otei s
ith o - odi g DNA et ee the .
The h o oso es, i ludi g the ge es, a e ade
up of a he i al su sta e alled DNA
Deo i oNu lei A id .
Figure . : Diagra
Chro oso es
The e a e
u leus of od
of a hu a
h o oso es
ells:
ell
o tai ed i
the
Of these,
a e f o the othe 's egg a d
a e f o the fathe 's spe
The h o oso es a e e lo g st a ds of DNA,
oiled up like a all of st i g as sho
i Figure
. .
Whe the egg a d the spe joi togethe at
the i e of o epio , the i st ell of the
a is fo ed. This ell is opied to ake all
of the ells of the a
Ch o oso es a e fou d i the u leus of all od
ells e ept fo ed lood ells hi h ha e o
u leus a d the efo e do
ot
o tai
h o oso es.
The
a s
od
ells
h o oso es, ade up of
the pa e ts Figure . .
As e age a d g o , ou
di idi g to fo
e ells.
A othe pla e i the ell he e DNA is fou d is i
e s all o pa t e ts alled ito ho dria the
e eg
e t es of the ell that a e fou d
s ate ed outside the u leus Figure . . The
DNA i
ito ho d ia is u h s alle a d has e
litle o - odi g DNA.
o
ha e
pai s, just like
ells a e o i uall
Du i g this di isio p o ess, ea h of the lo g thi
h o oso es oils up ightl , so that ea h of the
i di idual h o oso es i the u leus e o e
od-shaped st u tu es a d a e see he usi g
a i os ope.
.ge ei s.edu.au
Updated
Page of
Ju e
:
PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
Figure . : At o epio the sper
a d egg o
i e
I a ge ei tesi g la o ato the h o oso es
a e olou ed stai ed ith spe ial d es to
p odu e disi i e a di g pate s a d li ed up
i size o de . This p odu es hat e all a
kar ot pe. These pate s allo the la o ato to
he k the size a d st u tu e of ea h
h o oso e.
Figure
.
sho s a
a ded h o oso e
ka ot pe he e ea h h o oso e has ee
u e ed f o
the la gest
h o oso e
u e
to the s allest h o oso e u e
a d a a ged i pai s i o de of size. These
u e ed h o oso es a e alled autoso es.
The e a e t o h o oso es that ha e ee
gi e the la els X a d Y. These a e the se
hro oso es. It is these se h o oso es that
dete i e hethe the h o oso es ha e o e
f o a ale o a fe ale.
I
fe ales, ells i
the
od ha e
h o oso es
autoso es plus t o opies of
the X h o oso e . The a e said to ha e a
46,XX kar ot pe. Eggs fe ale ep odu i e ells
a e dife e t as the o l o tai half of the
h o oso es
ade up of
u e ed
h o oso es a d a X h o oso e .
I
ales, ells i the od ha e
h o oso es
autoso es plus a X a d a Y h o oso e .
The a e said to ha e a 46,XY kar ot pe. Spe
ale ep odu i e ells a e dife e t as the
o l o tai half of the h o oso es
ade
up of
u e ed h o oso es a d a X
h o oso e or a Y h o oso e .
Figure . : Chro oso e pi ture kar ot pe fro
,XY.
a
ale
Ge es
The DNA aki g up ea h h o oso e is usuall
oiled up ightl . If e i agi e it st et hed out, it
ould look like eads o a st i g Figure . :
Ea h of these eads is alled a ge e
Ea h ge e is a
p otei
Thousa ds of
h o oso e
Bet ee the ge es a e seg e ts of
odi g DNA.
i st u io
ge es
fo a spe ii
ake
up
ea h
o -
Si e the h o oso es o e i pai s, the e a e
also t o opies of ea h of the ge es. The
e epio to this ule applies to the ge es a ied
o the se h o oso es, X a d Y.
Si e
e ha e o l o e op of the X
h o oso e, the ha e o l o e op of all the
ge es a ied o the X h o oso e. Wo e
ha e t o opies of the X h o oso e i thei
ells a d so the ha e t o opies of all the ge es
a ied o the X h o oso e.
To adjust fo the fa t that o e ha e t o X
h o oso es ith lots of ge es hile e ha e
o l o e, o e of the o a s X h o oso es is
s it hed of o i a i ated i ea h of thei ells.
The e a e e fe ge es o the Y h o oso e
a d thei ole is ai l to ake a pe so
ale, so
the a e ot eeded i fe ale ells.
.ge ei s.edu.au
Updated
Page of
Ju e
:
PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
DNA
The e a e o e
ea h pe so .
lo aio
o
ito ho d ial
plus the o ge o e.
,
ge es fou d i the DNA of
Ea h ge e has its o
spe ii
a
h o oso e o
o
the
DNA a d the ge es odi g DNA
odi g DNA ake up that pe so s
The DNA ode is ade up of e lo g hai s
of fou
asi
uildi g lo ks
u leoide
ases alled Ade i e A , Gua i e G ,
Th i e T a d C tosi e C
A h o oso e o sists of t o of these DNA
hai s u i g i opposite di e io s. The
ases pai up to fo
the u gs of a ladde
t isted to fo
a dou le heli
Figures . & .
Pai i g of the ases follo s a pate
he e
ase A a o l pai ith ase T a d ase G
a o l pai
ith ase C. ‘oughl th ee
illio of these ase pai s of DNA ake up
the hu a ge o e
Ou DNA ode is ade up of a o i aio
of th ee of these fou he i al lete s alled
a t iplet.
Ea h th ee-lete o d triplet tells the
ell to p odu e a pa i ula a i o a id,
the uildi g lo ks of p otei s
The se ue e of th ee-lete
o ds i
the ge e e a les the ells to asse le
the a i o a ids i the o e t o de to
ake up a p otei
O l a out % of the e i e DNA i the
hu a ell is ade up of ge es that
o tai the i fo aio odes fo aki g
p otei s
The e ai i g
% of DNA does ot
o tai the i fo aio fo p otei s a d
used to e alled ju k DNA. This o odi g DNA sepa ates ge es f o ea h
othe alo g the h o oso es a d the e
is i easi g e ide e that it has a ole i
tu i g ge es o a d of. This o odi g DNA the efo e has a o t ol
fu io ithi the ge o e.
Figure . : The DNA ases pair up to
ake ge es
Figure . : The DNA heli
DNA VA‘IATIONS
We all ha e s all a iaio s i ou ge ei ode.
That is h e a e all u i ue. E e ide i al t i s
ha e so e a iaio s i thei DNA
the i e
the a e o . Be ause e i he it ou ge es f o
ou pa e ts, e e s of the sa e fa il sha e
thei DNA i ludi g its a iaio s.
The e a e ha ges i the se ue e of lete s
i the ge e essage; u leoide ase/s A, G, T o
C a e issi g alled a deleio o ase/s a
e added alled a i se io a d these a e of
o e o a DNA ases.
Va iaio s i the ode a o u du i g ou life fo
a a iet of easo s i ludi g e posu e to
adiaio , e tai he i als o
ha e. Agei g
is a o
o
ause of ge ei
a iaio .
Th oughout ou li es, ou ells a e o i uall
ei g epla ed.
So e a iaio s i the ge ei i fo aio do ot
see to ake a dife e e to the fu io of
ou ells. These t pes of DNA a iaio s a e uite
o
o .
.ge ei s.edu.au
Updated
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PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
Othe DNA a iaio s a e asso iated ith a
i eased ha e of a health o diio , fo
e a ple dia etes o a e .
Si e e ha e t o opies of ea h ge e, if o e
op has a utaio a d the othe op is
o ki g, the e a ot de elop a p o le s.
So e DNA a iaio s a
ea the ge e
i st u io is i o e t so a fault p otei is ade
o the o t ol s it h is ha ged. A a iaio i a
ge e that eates a fault is alled a pathoge i
aria t o utaio .
We a e all o
so ei es these a
p o le .
A DNA utaio a ause a p o le fo o e ell
t pe ut ot a othe , si e ot all ells use all of
the possi le p otei s.
I othe ases, a e ge e a iaio a a ise i
a egg o spe
ell. This is alled a de ovo
ha ge.
Whe a DNA ha ge auses a fault p otei i
ells that eed that p otei , it usuall esults i
disease s pto s that a so ei es e
e og ised as a ge ei o diio .
ith DNA
utaio s a d
e e ei ial o ause o
Whe a ge e a iaio is p ese t i egg o spe
ells, it a e passed o to hild e i he ited .
The pe so a isi g f o that egg o spe
ell ill
e the i st i the fa il to ha e the DNA ha ge
hi h a the
e passed do
to his o he
hild e a d futu e ge e aio s.
Ge es o tai re ipes for the ody to ake protei s - the Book of Life
is like a re ipe ook for our odies
.ge ei s.edu.au
Updated
Page of
Ju e
PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
DNA o tai s the i st u io s fo g o th a d de elop e t i hu a s a d all li i g thi gs. Ou DNA is
pa kaged i to h o oso es that o tai all of ou ge es.
I su
ar
DNA sta ds for Deo ri oNu lei A id hi h is ade up of er lo g hai s of
he i al leters : Ade i e A , Gua i e G , Th i e T a d C tosi e C
DNA o tai s the i stru io s for our ge es
Ge es are the i stru io s for
ells a d od
I hu a s,
aki g protei s. Protei s do the ork ithi our
ost ge es are arra ged o
THE GENETIC BOOK OF LIFE
I hu a s ge ei i fo aio , also k o
as ou
ge o e, a e des i ed as the Book of Life . This
ook a
e thought of as ei g ade up of t o
olu es, ea h olu e of the ook is gi e to a pe so
o e of thei pa e ts Figure . .
Figure . : The hu a ge o e so ei es alled the
Book of Life
hro oso es that are fou d i the u leus of ells.
‘eadi g a pe so s ge ei
. :
ook of life Figure
O e olu e of the ook is i he ited f o
othe a d the othe f o the fathe
the
Both olu es o tai
hapte s ea h,
e ui ale t to the pai s of h o oso es i
hu a
od
ells that o tai ge ei
i fo aio
The
hapte s h o oso es a e ade
up of a u e of e ipe pages odi g DNA
o ge es a d i - et ee
o - odi g pages
of DNA
So e of the
hile othe s
h o oso es
thousa ds of
hile othe s a
Ge es a e se io s of DNA that ode fo the
p otei s ou od eeds to fu io
I - et ee
o - odi g se io s of DNA
ha e a ious jo s, ot all of hi h e
u de sta d
Ca eful e a i aio of the o ds ithi
ge es sho s that all the o ds a e ade up
of th ee lete s t iplets su h as AGT, GGT,
ACT, CAA et .
The e a e fou lete s used i
ook. The a e A, T, C & G.
hapte s o tai
a pages
o l ha e a fe . So e
a e la ge a d o tai
a
ge es a d o - odi g DNA
e u h s alle
the ge ei
Just as eadi g the o ds o the page of a ook
allo s a u de sta di g of the autho s essage,
the od is a le to ead the t iplets i ge es to
ake the p otei eeded fo ou ells to o k.
.ge ei s.edu.au
Updated
Page of
Ju e
:
PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
Ou ells do t eed all the i st u io s all the
i e. Pages of ou ge ei ook a e losed a d
the eope ed he eeded. Ea h t pe of ell
a ha e dife e t pa ts of the ge ei
ook
ope ed o shut e ause dife e t ells do dife e t
jo s i ou od . Whi h ge es a e tu ed o o
of a
e i lue ed
ou diet, he i al
e posu e, e e ise, agei g a d essages f o
othe ge es i the od .
Figure . : Chro oso es are like stri gs of ge es
Figure . : Ge ei ter i olog a d the Book of Life
DNA, GENES AND CH‘OMOSOMES IN THE BODY
Ou odies a e ade up of illio s of ells. Ea h
ell o tai s a o plete op of a pe so 's ge ei
ook of life.
Ch o oso es a e thought of as ei g ade
up of st i gs of ge es DNA that odes fo
p otei s
ith o - odi g DNA et ee the .
The h o oso es, i ludi g the ge es, a e ade
up of a he i al su sta e alled DNA
Deo i oNu lei A id .
Figure . : Diagra
Chro oso es
The e a e
u leus of od
of a hu a
h o oso es
ells:
ell
o tai ed i
the
Of these,
a e f o the othe 's egg a d
a e f o the fathe 's spe
The h o oso es a e e lo g st a ds of DNA,
oiled up like a all of st i g as sho
i Figure
. .
Whe the egg a d the spe joi togethe at
the i e of o epio , the i st ell of the
a is fo ed. This ell is opied to ake all
of the ells of the a
Ch o oso es a e fou d i the u leus of all od
ells e ept fo ed lood ells hi h ha e o
u leus a d the efo e do
ot
o tai
h o oso es.
The
a s
od
ells
h o oso es, ade up of
the pa e ts Figure . .
As e age a d g o , ou
di idi g to fo
e ells.
A othe pla e i the ell he e DNA is fou d is i
e s all o pa t e ts alled ito ho dria the
e eg
e t es of the ell that a e fou d
s ate ed outside the u leus Figure . . The
DNA i
ito ho d ia is u h s alle a d has e
litle o - odi g DNA.
o
ha e
pai s, just like
ells a e o i uall
Du i g this di isio p o ess, ea h of the lo g thi
h o oso es oils up ightl , so that ea h of the
i di idual h o oso es i the u leus e o e
od-shaped st u tu es a d a e see he usi g
a i os ope.
.ge ei s.edu.au
Updated
Page of
Ju e
:
PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
Figure . : At o epio the sper
a d egg o
i e
I a ge ei tesi g la o ato the h o oso es
a e olou ed stai ed ith spe ial d es to
p odu e disi i e a di g pate s a d li ed up
i size o de . This p odu es hat e all a
kar ot pe. These pate s allo the la o ato to
he k the size a d st u tu e of ea h
h o oso e.
Figure
.
sho s a
a ded h o oso e
ka ot pe he e ea h h o oso e has ee
u e ed f o
the la gest
h o oso e
u e
to the s allest h o oso e u e
a d a a ged i pai s i o de of size. These
u e ed h o oso es a e alled autoso es.
The e a e t o h o oso es that ha e ee
gi e the la els X a d Y. These a e the se
hro oso es. It is these se h o oso es that
dete i e hethe the h o oso es ha e o e
f o a ale o a fe ale.
I
fe ales, ells i
the
od ha e
h o oso es
autoso es plus t o opies of
the X h o oso e . The a e said to ha e a
46,XX kar ot pe. Eggs fe ale ep odu i e ells
a e dife e t as the o l o tai half of the
h o oso es
ade up of
u e ed
h o oso es a d a X h o oso e .
I
ales, ells i the od ha e
h o oso es
autoso es plus a X a d a Y h o oso e .
The a e said to ha e a 46,XY kar ot pe. Spe
ale ep odu i e ells a e dife e t as the
o l o tai half of the h o oso es
ade
up of
u e ed h o oso es a d a X
h o oso e or a Y h o oso e .
Figure . : Chro oso e pi ture kar ot pe fro
,XY.
a
ale
Ge es
The DNA aki g up ea h h o oso e is usuall
oiled up ightl . If e i agi e it st et hed out, it
ould look like eads o a st i g Figure . :
Ea h of these eads is alled a ge e
Ea h ge e is a
p otei
Thousa ds of
h o oso e
Bet ee the ge es a e seg e ts of
odi g DNA.
i st u io
ge es
fo a spe ii
ake
up
ea h
o -
Si e the h o oso es o e i pai s, the e a e
also t o opies of ea h of the ge es. The
e epio to this ule applies to the ge es a ied
o the se h o oso es, X a d Y.
Si e
e ha e o l o e op of the X
h o oso e, the ha e o l o e op of all the
ge es a ied o the X h o oso e. Wo e
ha e t o opies of the X h o oso e i thei
ells a d so the ha e t o opies of all the ge es
a ied o the X h o oso e.
To adjust fo the fa t that o e ha e t o X
h o oso es ith lots of ge es hile e ha e
o l o e, o e of the o a s X h o oso es is
s it hed of o i a i ated i ea h of thei ells.
The e a e e fe ge es o the Y h o oso e
a d thei ole is ai l to ake a pe so
ale, so
the a e ot eeded i fe ale ells.
.ge ei s.edu.au
Updated
Page of
Ju e
:
PM
Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
DNA
The e a e o e
ea h pe so .
lo aio
o
ito ho d ial
plus the o ge o e.
,
ge es fou d i the DNA of
Ea h ge e has its o
spe ii
a
h o oso e o
o
the
DNA a d the ge es odi g DNA
odi g DNA ake up that pe so s
The DNA ode is ade up of e lo g hai s
of fou
asi
uildi g lo ks
u leoide
ases alled Ade i e A , Gua i e G ,
Th i e T a d C tosi e C
A h o oso e o sists of t o of these DNA
hai s u i g i opposite di e io s. The
ases pai up to fo
the u gs of a ladde
t isted to fo
a dou le heli
Figures . & .
Pai i g of the ases follo s a pate
he e
ase A a o l pai ith ase T a d ase G
a o l pai
ith ase C. ‘oughl th ee
illio of these ase pai s of DNA ake up
the hu a ge o e
Ou DNA ode is ade up of a o i aio
of th ee of these fou he i al lete s alled
a t iplet.
Ea h th ee-lete o d triplet tells the
ell to p odu e a pa i ula a i o a id,
the uildi g lo ks of p otei s
The se ue e of th ee-lete
o ds i
the ge e e a les the ells to asse le
the a i o a ids i the o e t o de to
ake up a p otei
O l a out % of the e i e DNA i the
hu a ell is ade up of ge es that
o tai the i fo aio odes fo aki g
p otei s
The e ai i g
% of DNA does ot
o tai the i fo aio fo p otei s a d
used to e alled ju k DNA. This o odi g DNA sepa ates ge es f o ea h
othe alo g the h o oso es a d the e
is i easi g e ide e that it has a ole i
tu i g ge es o a d of. This o odi g DNA the efo e has a o t ol
fu io ithi the ge o e.
Figure . : The DNA ases pair up to
ake ge es
Figure . : The DNA heli
DNA VA‘IATIONS
We all ha e s all a iaio s i ou ge ei ode.
That is h e a e all u i ue. E e ide i al t i s
ha e so e a iaio s i thei DNA
the i e
the a e o . Be ause e i he it ou ge es f o
ou pa e ts, e e s of the sa e fa il sha e
thei DNA i ludi g its a iaio s.
The e a e ha ges i the se ue e of lete s
i the ge e essage; u leoide ase/s A, G, T o
C a e issi g alled a deleio o ase/s a
e added alled a i se io a d these a e of
o e o a DNA ases.
Va iaio s i the ode a o u du i g ou life fo
a a iet of easo s i ludi g e posu e to
adiaio , e tai he i als o
ha e. Agei g
is a o
o
ause of ge ei
a iaio .
Th oughout ou li es, ou ells a e o i uall
ei g epla ed.
So e a iaio s i the ge ei i fo aio do ot
see to ake a dife e e to the fu io of
ou ells. These t pes of DNA a iaio s a e uite
o
o .
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Fa t Sheet 1 | AN INT‘ODUCTION TO DNA, GENES AND CH‘OMOSOMES
Othe DNA a iaio s a e asso iated ith a
i eased ha e of a health o diio , fo
e a ple dia etes o a e .
Si e e ha e t o opies of ea h ge e, if o e
op has a utaio a d the othe op is
o ki g, the e a ot de elop a p o le s.
So e DNA a iaio s a
ea the ge e
i st u io is i o e t so a fault p otei is ade
o the o t ol s it h is ha ged. A a iaio i a
ge e that eates a fault is alled a pathoge i
aria t o utaio .
We a e all o
so ei es these a
p o le .
A DNA utaio a ause a p o le fo o e ell
t pe ut ot a othe , si e ot all ells use all of
the possi le p otei s.
I othe ases, a e ge e a iaio a a ise i
a egg o spe
ell. This is alled a de ovo
ha ge.
Whe a DNA ha ge auses a fault p otei i
ells that eed that p otei , it usuall esults i
disease s pto s that a so ei es e
e og ised as a ge ei o diio .
ith DNA
utaio s a d
e e ei ial o ause o
Whe a ge e a iaio is p ese t i egg o spe
ells, it a e passed o to hild e i he ited .
The pe so a isi g f o that egg o spe
ell ill
e the i st i the fa il to ha e the DNA ha ge
hi h a the
e passed do
to his o he
hild e a d futu e ge e aio s.
Ge es o tai re ipes for the ody to ake protei s - the Book of Life
is like a re ipe ook for our odies
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