BIOC19H3 Lecture Notes - Lecture 3: Immunohistochemistry, Fluorophore, In Situ Hybridization
Document Summary
Objectives: differential gene expression, role of histones, histone acetylation & methylation, genetic elements, dna methylation, differential rna processing, alternative splicing, differential translation, mrna longevity, transport and localization, selective inhibition and activation, studying gene expression. Dna is present as a complex of dna and proteins (chromatin) Histones are major proteins which combined with dna form nucleosomes. Octamer of histone proteins (8 different subunits) H1 histones are attached with linker dna. Tight packaging of the dna prevents binding of tf, rna polymerase etc, Histones have a strong positive charge, whereas dna has neg charge, which is why they package well leading to no expression. Gene expression can be regulated by controlling the packaging of dna: heterochromatin: condensed chromatin, usually transcriptionally inactive because it is so tightly packed. Nothing can get to it: euchromatin: loosely packed, and transcriptionally active. Transcription can be controlled by modifying the histone (cid:494)tails(cid:495: methyl group: added by histone methyltransferases, acetyl group: added by histone acetyltransferase.
