“Go Sally Go! Make Children!”
Can be divided into 2 stages:
- G1 Growth phase 1.
- S Synthetic phase.
- G2 Growth phase2.
- M Mitosis/Meiosis.
- C Cytokinesis.
Chromatin shows 2 types of coiling behavior:
Chromatin is made of DNA and histone proteins, in the ratio 1:1.
Histone proteins are basic proteins, rich in Lysine and Arginine.
Chromatin consists of repeating units called Nucleosomes.
It occurs in the nucleus during the G1 & G2 stage of the cell cycle.
Of the two strands of DNA only one strand called the template strand takes part in transcription.
A transcription unit in DNA consists of three regions:
Structural gene is the part of DNA from which RNA is formed.
Transcription occurs with the help of DNA dependent RNA polymerase.
Polymerization occurs in 5′ → 3′ direction.
All reference points while defining the transcription unit are made with the coding strand.
Lying towards 5′ end (upstream) of the structural gene is the promoter. It is the binding site for RNA polymerase for transcription to start.
Lying towards 3′ end (downstream) of the structural gene is the terminator, where transcription ends.