Download - Nucleotida
DNA MoLECULE of HEREDITY
DNA/RNA structures GENETIC code Transcription
DNAOverview: Background/history
DNA structure
Genetic information in eukaryotic
A Short History
1869 - Miescher isolated DNA the first time1953 - Watson and Crick proposed the double helix as
the structure of DNA1957 - Kornberg discovered DNA polymerase1961 - Marmer and Doty discovered DNA renaturation1962 - Arber, Nathans and Smith discovered restriction
endonucleases1966 - Nirenberg, Ochoa, and Khorana figured out the
genetic code
• DNA (deoxyribonucleic acid) is a double helix: two strands of genetic material spiraled around each other.
• Everyone’s chemical structure of DNA is the same, the only difference is in the ordering of base pairs.
What is DNA?
BUILDING BLOCK of DNA
Nucleotides consist of a sugar, phosphate and nitrogenous base
Nitrogenous base of DNA
Purine nucleotides• A - Adenine• G - Guanine
Pyrimidine nucleotides
• T - Thymine• C - Cytosine
Chemical composistion of DNA
DNA strand extend from 5’ to 3’
The DNA back-bone was connected by phosphodiester bond
Strand of DNA A-A-C-T-G-A-T-A-G-G-T-C-T-A-G T-T-G-A-C-T-A-T-C-C-A-G-A-T-C
POLYNUCLEOTIDE FORMATION
DNA structure Watson-Crick double helix
The two helical polynucleotide chain coil around the common axis. The chains are antiparalel in polarity
Purine and pyrimidine bases are inside the helix, whereas the phosphate and deoxyribose units are on the outside.
DNA base composition is governed by Chargaff’s Rule
DNA has equal number of A and T residue (A-T) and equal number of G and C residue (G-C)
DNA base composition range from 25-75% G+C content.
RNA (ribonucleic acid)
Component = DNA except for nitrogenous base is replaced by Uracyl
RNA STRUCTURE
rRNA
From DNA to chromosome
Humans have 23 pairs of chromosomes.
A part of chromosome that dictates a particular trait is called a gene.
Chromatin
DNA dalam nukleus mengkombinasi dg protein (histones) chromatin.
Euchromatin: Active in genetic transcription.
Heterochromatin: Contains genes that are permanently inactivated.
GENE ORGANISATION
Operon: Is a unit of gene expression and regulation
including structural genes and control elements in DNA recognised by regulator gene product/s.
Gene organization
Gene structure in eukaryote
REGULATORy element
Promoter region where RNA polymerase bind.
Sigma factor : to ensure that the bacterial RNA polymerase binds in a stable manner to DNA only at promotors, not other site
Operator
DNA region where repressor protein binds and start to inhibit tanscription .
Enhancers Element regulator positif.
Repressor Menghambat transcripsi
Silencer Eleman DNA yang berinteraksi dengan repressors untuk
menghambat transcripsi.
Dogma of molecular biology
genome < transcriptome <proteome
1 gene 10 or more proteins
DNA Replication
Components of Replication process:
helicase DNA ligase DNA polymerase topoisomerase
VIDeO DNA rep
REPLIKASI DNAPada proses replikasi kromosom asam deoksiribonukeat, sebagai akibatnya, menjadi sepasang cetakan, dimana setiap pola cetakan merupakan komponen cetakan yang lain. Kita membayangkan bahwa sebelum terjadi duplikasi ikatan-ikatan hidrogen akan putus, dan dan kedua rantainya membuka dan terpisah. Setiap rantai kemudian berfungsi menjadi cetakan untuk pembentukan rantai pasangan yang baru, akhirnya kita akan mendapatkan dua pasang rantai,dimana kita hanya punya satu sebelumnya. Lebih jauh lagi, urutan dari pasangan-pasangan basa tersebut akan terduplikasi sama persis.
Crick, F.H.C., and J.D. Watson, The Complementary Structure of Deoxyribonucleic Acid, Proc.Roy.Soc.(A) 223 (1954), page 80.
Function of replication enzymes
DNA ligase: connect between nucleotide on the lagging strand
Topoisomerase: …. DNA polimerase:….
DNA primase : A enzym khusus utk polimerisasi nucleotide-primer RNA pd lagging strand