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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

  • Purine nucleotides

    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.

    13 Nucleosome Stock Photos, Pictures & Royalty-Free Images - iStock

  • 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

    Euchromatin vs Heterochromatin: Differences and Similarities – Genetic  Education

  • 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?



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