DNA - Basic structure
Parts of DNA
Phosphate group + sugar + Base (nitrogenous base)
Difference between sugar of DNA and RNA
DNA has deoxyribose sugar(1 OH group attached to sugar and RNA has ribose sugar (2 OH groups)
Nucleotide and nucleoside
Nucleotide = Phosphate group + Base + sugar
Nucleoside = Base and sugar
Types of Nitrogenous base
Purines and Pyrimidines
Purines consists of
Pure As Gold = Adenine and Guanine
Pyrimidine consists of
CUT the pyramids
Uracil (only in RNA)
Purine nucleosides are
Adenosine and Guanosine
Pyrimidine nucleosides are
Cytidine, Uridine and Thymidine
Adenosine monophosphate, Guanosine MP
How is DNA packed inside nucleus ?
In the form of chromatin which is further condensed to form chromosomes
What is a nucleosome ?
DNA coiled twice around an octamer of Histone composed of (H2A, H2B, H3, H4) x2 with linker H1 protein.
Positive and Negative charge of Chromatin
Positive charged = Lysine and Arginine of Histone which bind to negative charge of phosphate group of DNA
Types of chromatin
Euchromatin and heterochromatin
Which chromatin is active in transcription?
Euchromatin as it is relaxed and less condensed
Which chromatin is inactive?
Heterochromatin , highly condensed
Nucleolus of cell contains which chromatin
Barr Body is a form of
DNA methylation leads to activation or inactivation.
Inactivation so no transcription - silenced
70% of human DNA is methylated
DNA methylation occurs in which region of DNA
CpG islands where Cytosine is methylated that makes DNA mute/ transcriptionally inactive.
Histone methylation makes DNA active or mute
Acetylation of Histone causes
Activation — transcription active
And vice versa
Drug induced Lupus is caused by
HIP = Hydralazine, Isoniazid and Procainamide
Diagnosis of Drug induced Lupus is done by
Anti- Histone Ab
In SLE we check anti-dsANA Ab
Histone deacetylase inhibitor drug is used in
Huntington disease as the silenced gene can be activated
Which antiepileptic drug is found to have histone acetylase inhibitor effect?