8. Asam Nukleat

8/18/2019 8. Asam Nukleat

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Asam NukleatAsam Nukleat


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Asam Nukleat (Nucleic Acid)Asam Nukleat (Nucleic Acid) Asam Nukleat:Asam Nukleat: material bersifat asam yang ditemui

pada setiap sel hidup (inti sel/nuklei)

Merupakan biopolimer dengan monomer: Nukleotida

Nukleotida terdiri atas gula, basa dan fosfat

nukleotida

nukleosida

GulaGula

Basa

PO4


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Ada dua macam asam nukleat:Ada dua macam asam nukleat:

- DNA (deoyribose nucleic acid)- DNA (deoyribose nucleic acid)

- !NA (ribose nucleic acid)- !NA (ribose nucleic acid)


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GulaGula

" "#$#%

"#"#

#" #" " "#$#%

"#

ribose deoyribose

(no ")

RNARNA DNADNA


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&asa 'urin/'yrimidin&asa 'urin/'yrimidin enyaa amina aromatik heterosiklikenyaa amina aromatik heterosiklik

DNA:DNA: AAdenine,denine, **uanine,uanine, $$ytosine,ytosine, ++hyminehymine

!NA:!NA: AAdenine,denine, **uanine,uanine, $$ytosine,ytosine, racilracil

HN

N

O

O

H

N

N

NH2

O

H

HN

N

O

O

H

CH3N

N

HN

N N

NO

H

H2N

N

N N

NNH2

H

N

N N

N

H

Uracil (U) Thymine (T) CytosinePyrimidine

1

2

34

5

6

Ganine (G)!denine (!)Prine

1

2

3

4

56 "

#

$


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NukleosidaNukleosida

Nukleosida:Nukleosida: pembangun asam nukleat yang terdiri atas D-ribosa atau %-

deoksi-D-ribosa berikatan dengan basa amina aromatik heterosiklik

dengan ikatan glikosida

anomeric

car%on

a &N&'lycosi%ond

H

H

H

H

OHOCH2

HO OH

O

O

HN

N

Uridine

&&ri%oside

racil

1

23

4

5

1


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Nukleosida pada DNANukleosida pada DNA

Basa Gula Nukleosida

Adenine (A) DeoxyriboseAdenosine

Guanine (G) DeoxyriboseGuanosine

Cytosine (C) DeoxyriboseCytidine

Thymine (T) DeoxyriboseThymidine


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Nucleosides in RNANucleosides in RNA

Base Sugar Nucleoside

Adenine (A) ribose Adenosine

Guanine (G) ribose Guanosine

Cytosine (C) ribose Cytidine

Uracil (U) ribose Uridine


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NukleotidaNukleotida Nukleotida:Nukleotida: molekul nukleosida yang teresterkan oleh asam fosfat pada

-"# monosakaridanya

N

NN

N

NH2

O

OHOH

HH

H

CH2

H

OP

O&

O&O

5

!denosine 5&mono*hos*hate(!+P)

Acycloir . A+Acycloir . A+

(Antiiral)(Antiiral)

!,idothymidine (!- !cyclo.ir

(dra/n to sho/ its

strctral relationshi*

to 2&deo0y'anosine

O

O

N

HN

HOC

HN3

H

H

HH

O

CH3

O

HHHH

HOC

H2N

HN

N

O

N

N

H2H2


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Struktur Asam NukleatStruktur Asam Nukleat

Polimer dari empat nukleotida Dihubungkan dengan ikatan gula-fosfat (fosfodiester)

nucleotide nucleotide nucleotide nucleotideP sugar

base

P sugar

base

P sugar

base

P sugar

base


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truktur 'rimer DNA - 01truktur 'rimer DNA - 01 DeoyriboNucleic Acids (DNA)

• Kerangka %-deoy-D-ribose dan fosfat dimana gugus 23-"# dan %-

deoy-D-ribose terhubung dengan ikatan fosfodiester dengan gugus

43-"# pada unit %-deoy-D-ribose yang lain

truktur 'rimer:truktur 'rimer: urutan basa sepan5ang backbone pentosephospho-

diester pada molekul DNA atau !NA

• 'embacaan dari u5ung 43 ke u5ung 23

NO

HN

&O&P&O&CH2

O

H

H

OH

HH

H

O

CH3

OP O CH2

O

&O

O&

NH

NN

N

O

NH2

O

H

H

O

HH

H

5

3

*hos*horylated5 end

ree 3 end


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“untuk penemuan struktur asam nukleat dan perananya pada transferinfromasi pada materi hidup“ (1953)

#adiah Nobel &idang 6isiologi atau 7edokteran 089%

6rancis #arry

$ompton $rick ames Deey

;atson

Maurice #ugh

6rederick ;ilkins

United Kingdom USA United Kingdom

Institute of ole!ular "iology #ar$ard Uni$ersity Uni$ersity of %ondon %ondon&

'amridge& United Kingdom 'amridge& A& USA United Kingdom

191* 19+, 191*

truktur ekunder DNA - %1truktur ekunder DNA - %1


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DNA Double HelixDNA Double Helix

DNA terdiri atas dua untainukleotida

Ikatan hidrogen (antar basa)menghubungkan dua untai dalamstruktur double-helix structure

Struktur helix mirip dengantangga spiral

Basa selalu berpasangan antaraA–T dan G-C

Kedua basa salingberkomplemen dalam kedua

untai


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Pasangan basaPasangan basa

•Dua ikatan H untuk A-T

•Tiga ikatan H untuk G-C


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DNA Double HelixDNA Double Helix


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&entuk-bentuk DNA&entuk-bentuk DNA

&-DNA

• &entuk dominan dalam larutan encer

• right-handed helix

• 7etebalan %


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truktur tersier DNA > 21truktur tersier DNA > 21

truktur +ersier :truktur +ersier : penataan tiga dimensi molekul DNA,supercoil

DNA siklis:DNA siklis: DNA untai ganda dimana u5ung 43 dan 23

tergabung dalam ikatan phosphodiester

#istone:#istone: protein, kaya asam amino lysine dan arginine,yang berikatan dengan molekul DNA

$hromatin:$hromatin: terdiri atas molekul DNA terikat disekitar

histon membentuk struktur seperti partikel bulat


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ProblemProblem

Tulis urutan komplemen potongan DNA :

-A-G-T-C-C-A-A-T-G-C- • • • • • • • • • •

• • • • • • • • • •


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JawabanJawaban

-A-G-T-C-C-A-A-T-G-C- • • • • • • • • • •

• • • • • • • • • •

-T-C-A-G-G-T-T-A-C-G-


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!ibonucleic Acids (!NA)!ibonucleic Acids (!NA)

!NA mirip dengan DNA tetapi berbeda dalam hal:

•*ula pentosa pada !NA merupakan -D-ribose tidak seperti

DNA yang menggunakan -%-deoy-D-ribose

•&asa pyrimidine pada !NA adalah uraciluracil dan cytosinebukan thymine dan cytosine

•!NA!NA merupakan untai tunggal (untai tunggal (single stranded single stranded ) bukan

double stranded


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7lasifikasi !NA7lasifikasi !NA 7lasifikasi molekul !NA berdasarkan struktur dan fungsi

Ribosomal RNA (rRNARibosomal RNA (rRNA):): !NA yang ditemukan pada ribosom, tempat sintesisprotein

+oleclar ei'ht

an'e ('mol)

Nm%er o

Ncleotides

Percenta'e

o Cell N!

mN! 25777 & 1777777 "5 & 3777 2

tN! 23777 & 37777 "3 & $4 16

rN! 35777 & 1177777 127 & 2$74 #2

Ty*e

Transfer RNA (tRNATransfer RNA (tRNA):): !NA yang

membaa asam amino tertentu ke

tempat sintesis protein di ribosom

O8ase

OHO

CH

NH3

9

tN!&O&P&O&CH2

amino acid %ondas an ester to itss*eci:c tN!

H

H H

H

CO

O

O&


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Messenger RNA (mRNA:Messenger RNA (mRNA: !NA yang membaa kode genetik dari DNA ke

ribosom untuk sintesis protein

• umlahnya sedikit dan aktu keberadaannya singkat

•single stranded

• Disintesis berdasarkan informasi yang dikode DNA

• ntai komplemen m!NA disintesis sepan5angn satu untai DNA, mulai

dari u5ung 23

• 'roses sintesis m!NA dari DNA disebut transcriptiontranscription

3&!&G&C&C&!&T&G&T&G&!&C&C&5

5&U&C&G&G&U&!&C&!&C&U&G&G

N! tem*late

mN!


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Replikasi, Transkripsi, TranslasiReplikasi, Transkripsi, Translasi

Tinjauan Singkat


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Replikasi DNAReplikasi DNA

DNA in the chromosomes replicates itselfevery cell division

Maintains correct genetic information Two strands of DNA unwind

Each strand acts like a template

New bases pair with their complementary base Two double helixes form that are copies oforiginal DNA


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DNA UnwindsDNA Unwinds

G- -C

A- -T

C- -G

T- -A

G-C A-TC-G

T-A


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DNA Copied with Base PairsDNA Copied with Base Pairs

Two copies of original DNA strand

G-C G-C

A-T A-T

C-G C-G

T-A G-A


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UUU PheUUC PheUU! ;eUUG ;e

UCU


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+he *enetic $ode+he *enetic $ode

'roperties of the $ode

• only 90 triplets code for amino acids? the remaining 2 (AA, A*, and

*A) signal chain termination• the code is degenerate, hich means that seeral amino acids are

coded for by more than one triplet@ eu, er, and Arg, for eample,

are each coded for by si triplets

• for the 04 amino acids coded for by %, 2, or = triplets, it is only the

third letter of the codon that aries@ *ly, for eample, is coded for by

**A, ***, **$, and **

• there is no ambiguity in the code? each triplet codes for one and only

one amino acid

i DNA i DNA


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eBuencing DNAeBuencing DNA

!estriction endonuclease:!estriction endonuclease: an enCyme that catalyCes hydrolysis of a

particular phosphodiester bond ithin a DNA strand

• oer 0


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eBuencing DNAeBuencing DNA

'olyacrylamide gel electrophoresis:'olyacrylamide gel electrophoresis: a techniBue so sensitie that it is

possible to separate nucleic acid fragments differing from one another in

only a single nucleotide

• Maam-*ilbert method:Maam-*ilbert method: a method deeloped by Allan Maam and

;alter *ilbert? depends on base-specific chemical cleaage

• Dideoy chain termination method:Dideoy chain termination method: deeloped by 6rederick anger

• *ilbert and anger shared the 08F< Nobel priCe for biochemistry for

their Gdeelopment of chemical and biochemical analysis of DNA

structure@H

• During replication, the seBuence of nucleotides in one strand

is copied as a complementary strand to form the second

strand of a double-stranded DNA

• ynthesis is catalyCed by DNA polymerase

• DNA polymerase ill catalyCe synthesis in itro using single-

stranded DNA as a template, proided that (0) the fourdeoynucleotide triphosphate (dN+') monomers and (%) a

primer are present

• 'rimer:'rimer: an oligonucleotide capable of forming a short section

of double-stranded DNA (dsDNA) by base-pairing ith its

complement on a single-stranded DNA (ssDNA)

!eplication!eplication

in Iitroin Iitro

! li ti i Iit!eplication in Iitro


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5


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15P32

16<32

9 8eta *article9 Gamma ra

Dideoy $hain +erminationDideoy $hain +ermination

En this method, the folloing are mied

• single-stranded DNA of unknon seBuence and primer? then

diided into four reaction mitures

+o each reaction miture is then added

• the four dN+', one of hich is labeled in the 43 end ith

phosphorus-2%

• DNA polymerase

• one of the four ddN+'s

after gel electrophoresis of each reaction miture

•

a piece of film is placed oer the gel• gamma rays released by '-2% darken the film and create a

pattern of the resoled oligonucleotide

• the base seBuence of the complement to the original strand is

read directly from bottom to top of the deeloped film


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! G C T

;ar'er ra'ments

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8. Asam Nukleat