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