Struktur dna
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Transcript of Struktur dna
DNA
• Material genetik pada mahluk hidup adalah Asam nukleat (DNA atau RNA)yaitu suatu polimer nukleotida yg berperanan dlm penyimpanan serta pemindahan informasi genetik
Transformation• Fred Griffith menggunakan strain
bakteri S.pneumoniae virulen tipe S and nonvirulent tipe R
Smooth Streptococcus
pneumoniae (pneumococci)
Rough Streptococcus
pneumoniae (pneumococci)
台大農藝系 遺傳學601 20000
Chapter 2 slide 5
Peter J. Russell, iGenetics: Copyright © Pearson Education, Inc., publishing as Benjamin Cummings.
Griffith’s transformation experiment
6
Transformation• Dia menemukan bhw strain tipe R
dapat menjadi virulent ketika mengambil DNA (transformasi) dari strain tipe S yg sudah mati
• Penelitian ini menunjukkan bahwa DNA adalah adalah material genetik
Peter J. Russell, iGenetics: Copyright © Pearson Education, Inc., publishing as Benjamin Cummings.
Oswald T. Avery’s Transformation Experiment - 1944
Determined that “IIIS” DNA was the genetic material responsible for Griffith’s results (not RNA).
Support for Avery
• They radiolabeled the protein coat with 35S and the DNA with 32P in order to “see” which of the molecules actually entered the cell and produced more phage.
DNA/RNA
• Asam nukleat terdapat dlm 2 bentuk, yaitu asam deoksiribosa (DNA) dan asam ribosa (RNA).
• Pd sel eukariot, DNA terdapat di dlmnukleus,
• pada sel prokariot, terdpt dlmsitoplasma dalam bentuk nukleoid.
DNATersusun atas subunit ygdisebut nukleotidaNukleotida terdiri atas: Gugus phosphate Gula berkarbon-5 Basa Nitrogen
DNA• Gula pentose (Deoxyribose) terikat ke gugus phosphat (PO4) groups melalui ikatan phosphodiester
• Ikatan antara molekul deoxiribosa dengan basa-basa nitrogen disebut ikatan glikosida
18
Nukleotida DNA
O=P-OO
PhosphateGroup
NNitrogenous base(A, G, C, or T)
CH2
O
C1C4
C3 C2
5
Sugar(deoxyribose)
O
19
Gula Pentosa• Tersusun atas 5 atom karbon yg
dinotasi 1’ - 5’
CH2
O
C1C4
C3 C2
5
Sugar(deoxyribose)
20
Basa2 Nitrogen
• Double ring PURINAdenine (A)Guanine (G)
• Single ring PYRIMIDINThymine (T)Cytosine (C) T or C
A or G
Pasangan-basa• Purin hanya berpasangan dgn Pirimidin
• Pasangan antara Guanin & sitosin membentuk tiga ikatan hidrogen
CG
3 H-bonds
Ikatan Hidrogen
H
H
H H
O
O
H
C
C
C C
N
N
C
TiminH
N
H
H
N
C C
C
C
N
N H
N
C
Adenin
H
O
N
H C
C C
N
N
C
Sitosin
H
H
H
N
C C
C
C
N
N H
N
C
Guanin
NH
O
H
Three Dimensional Structure of DNA
• Rosalind Franklin- X-ray crystallography of DNA- showed that DNA was in a helix with PO4 and sugars to the outside.
• James Watson and Francis Crick-took Franklin’s data- in April 23, 1953, and deduced the structure of DNA. Won the Nobel Prize along with Maurice Wilkins.
1962: Nobel Prize in Physiology and Medicine
James D.Watson
Francis H.Crick
Maurice H. F.Wilkins
What about?Rosalind Franklin
29
Untai ganda ygbersifat Antiparalel
• Satu untai tumbuh dari
5’ ke 3’ (gula)
• Untai yang lain memiliki arah yg berlawanan dari 3’ ke 5’
32
DNA Double Helix
NitrogenousBase (A,T,G or C)
“Rungs of ladder”
“Legs of ladder”
Phosphate &Sugar Backbone
Type B-DNA
Other DNA forms include:
A-DNA:Right-handed double helix with 11 bases per turn; shorter and wider at 2.2 nm diameter. Exists in some DNA-protein complexes.
Z-DNA:Left-handed double helix with 12 bases per turn; longer and thinner at 1.8 nm diameter.
Characteristics of DNA
• All chains of DNA and RNA have a 5’ PO4 end and a 3’ OH end.
• Base sequences are written in a 5’ to 3’ direction.
• Ex. 5’ pGpTpCpCpApT-OH 3’ or
- GTCCAT -
Characteristics of DNA
• Base pairs stabilize the molecule by forming H-bonds.
• Antiparallel Strands-
5’----------------3’
3’----------------5’
• Strands are complementary.
Discovery of DNA Structure
• Erwin Chargaff menunjukkan jumlah dari basa penyusun DNA ( A,T,C,G)
• Pada sel somatik:A = 30.3%T = 30.3%G = 19.5%C = 19.9%
Genome: Keseluruhan gen/DNA yang ada di
dalam sel hidup.
Gene:Urutan nukleotida yang mengkode
suatu protein.
Two types of organism: Eukaryotes;
cells contain membrane-bound
compartments, including a nucleus and organelles.
Eukaryotes include: animals, plants, fungi, and
protozoa.
Prokaryotes: Lack internal compartments
extensively.
Divided into two groups: bacteria and archaea.]