DNA Structure and Function
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Transcript of DNA Structure and Function
By Ristiana Nugrahani0402514041
Structure and Function of DNA
Sejarah Penemuan DNA
The Structure and Function of DNA
1869Friedrich Miescher:
Di dalam inti sel darah putih
terdapat senyawa mengandung
fosfat (NUKLEIN)
Akhir abad 19 memisahkan
DNA dan RNA
1930anP. Lavene, W. Jacobs, dkkRNA (gugus
gula ribosa + 4 basa nitrogen)DNA (gugus
gula deoksiribosa)
1928Frederick
GriffitPercampuran sel tipe S
dan R transformasi
Oswald Avery, Colin MacLeod, Mackyn McCarty
Molekul penyebab
transformasi adalah DNA
1952A.D Hershey & Martha Case:
Mmolekul yang masuk ke dalam sel
adalah DNA
DNA Material genetik di dalam sel, pembawa informasi
yang diturunkan keturunannya dalam
bentuk kodon
DNA STRUCTuRE
The Structure and Function of DNA
What are the structures and functions of DNA and RNA?
DNA:
Shown here in its uncondensed form
Carries genetic information that defines many of an organism’s traits (including behaviours)
and its predisposition for certain diseases.
DNA Structure and Function
The Structure and Function of DNA
• In the early 1919s, Phoebus Levene proposed that both were made up of individual units called nucleotides.
• Each nucleotide was composed of one of four nitrogen-containing bases, a sugar, and a phosphate group.
Determining the Chemical Composition and Structure of DNA
The Structure and Function of DNA
Nucleotides in RNA have the same basic structure, except a ribose sugar group is used. The sugar groups differ by a hydroxyl group at the 2′ carbon. Both DNA and RNA contain the same purine bases and the cytosine pyrimidine base. However, thymine is only present in DNA, and uracil is only present in RNA.
Chargaff’s Rule
The Structure and Function of DNA
• There is variation in the composition of nucleotides in different species.
• Regardless of the species, DNA maintains certain nucleotide proportions. That is, the amount of A and T nucleotides are equal and the amount of C and G nucleotides are equal.
The Scientist Discovery: DNA Structure
The Structure and Function of DNA
• 1951 Linus Pauling discovered that many proteins have helix-shaped structures.
• 1950 Rosalind Franklin and Maurice Wilkins: DNA has a helical structure. The nitrogen bases are on the inside of the DNA helix, and the sugar-phosphate backbone is on the outside.
• 1950 Watson and Crick : a twisted ladder, which they called a double-helix. The
sugar-phosphate molecules make up the sides or “handrails” of the ladder, and the bases make up the “rungs” of the ladder by protruding inwards.
Different sequences of base pairs accounts for the differences between species.
The Modern DNA Model
The Structure and Function of DNA
The Structure and Function of DNA
• To relate DNA’s primary structure (how nucleotides are linked) and secondary structure (how two strands of nucleotides form a double helix) to DNA function, it is necessary to consider:
• how DNA is organized in the cell, and • how its genome (the total genetic material of an organism)
is arranged into distinct functional regions on DNA
• The functional unit of DNA is a gene, which is a specific sequence of DNA that codes for proteins and RNA molecules.
• The majority of DNA in an organism’s genome does not contain genes and, instead, has non-coding regions. These regions may contain regulatory sequences, which are sections of DNA that regulate the activity of genes.
DNA FUNCTION
The Structure and Function of DNA
Organisasi Gen pada Prokariot
• Terdiri satu unit DNA untai ganda yang sirkuler
• Terkondensasi dalam nukleoid• Bersifat Monoploid (satu bahan
genetik utama)• E. Coli 4.600 kb• Material genetik terikat pada membran
sel sebelah dalam • Memiliki plasmid sirkular yang
membawa gen tertentu
The Structure and Function of DNA
Organisasi Gen pada Prokariot
• Plasmid Material genetik tambahan• DNA untai ganda sirkuler• Membawa gen tertentu yang
membawa keuntungan• Ukuran lebih kecil dari genetik utama• Plasmid ColV-K30 E. Coli 2 kb• Plasmid CAM Pseudomonas 230
kb• Bereplikasi secara bebas
The Structure and Function of DNA
• Panjang DNA > Panjang sel• Perlu pengemasan dengan cara
membuat molekul DNA terkondensasi membentuk butiran padat
• Diameter setiap butiran 12 nm• Setiap butiran terdiri dari DNA
berpilin (supercoiled dan looping)
• DNA binding protein• Terdapat linker DNA
memisahkan DNA Binding protein dengan tidak
Pengemasan DNA pada Prokariot
The Structure and Function of DNA
• Promoter ( pengatur ekspresi genetik)• Bagian struktural (membawa kode-kode genetik)• Terminator (Penghentian proses transkripsi)• Gen bakteri tidak mengandung intron
Organisasi Gen dalam Genom Prokaryot
The Structure and Function of DNA
• GEN INDEPENDEN Ekspresinya tidak tergantung ekspresi gen lain
• UNIT TRANSKRIPSI sekelompok gen gen berdekatan dan di ekspresikan bersama
• mengkode tRNA dan rRNA• KELOMPOK GEN berdekatan dengan lokus dan
hasil ekspresi gen diperlukan bersama dalam fisiologis dikendalikan secara independen
• OPERON GEN Gen berdekatan yang ekspresinya dikendalikan oleh promoter yang sama
3 kelompok Organisasi Gen Prokaryot
The Structure and Function of DNA
Organisasi Gen pada Eukariot
•Lebih kompleks•Double helix linear•Ukuran genom lebih besar•Material genetik dalam nukleus
disebut kromosom•Jumah kromosom bervariasi•Terdapat DNA ekstraseluler
(Mitokondria dan Kloroplas)•Replikasi DNA mitokondri secara
independen
The Structure and Function of DNA
Pengemasan DNA Eukariot
The Structure and Function of DNA
ORGANISASI GEN EUKARIOT
• Terdapat intron dan ekson• Informasi genetik terdapat pada dua untai ganda DNA
yang mengandung Coding Region maupun Noncoding Region
• Genn Eukariot dibagi menjadi 3 kelas :Gen Kelas I gen-gen yang mengkode pembentukan rRNA 5,8s, rRNA 18S, dan rRNA 28 S
Gen Kelas II gen-gen yang mengkode semua sintesis molekul proein, sebelumnya ditranskripsi menjadi mRNAditranslasi
Gen Kelas I gen-gen yang mengkode pembentukan tRNA dan rRNA 5S
The Structure and Function of DNA
ORGANISASI GENOM VIRUS
Genom bervariasi: DNA untai tunggal, DNA untai ganda, RNA untai tunggal, RNA untai ganda
Genom berupa Asam nukleat linear atau sirkuler
Memiliki keunikan asam nukleatContoh: Bakteriofage E. Coli memiliki
basa Sitosin dalam bentuk hydroxymethylcytosin
Genom bakteriofag Bacillus subtilis Hydroxymethylurasil
The Structure and Function of DNA
Tipe Asam Nukleat Struktur Asam
Contoh Virus Sel Inang
DNA Untai-tunggal Linear Parvovirus Manusia
Sirkular Bakteriofag M13Bakteriofag ϕX174
Bakteri E. coli
DNA Untai-ganda Linear Bakteriofag T4Vius Epstein-Barr
E. coliManusia
Sirkular Bakteriofag PM2
Polyomavirus
Pseudomonas aeruginosa BAL-31Manusia
RNA Untai-tunggal Linear Bakteriofag MS2TMV
E. ColiTanaman tembakau
RNA untai-ganda Linear Bakteriofag ϕ6Cypovirus
P. PhaseolicaInsekta
TIPE ASAM NUKLEAT VIRUS
The Structure and Function of DNA
• SEKIAN.......• Terimakasih......