BMS1062 Chapter : BMS1062: Molecular Biology: Higher order genetics + Transcription and RNA processing
6 Jul 2013
School
Department
Course
Professor
Document Summary
Each chromosome consists of a single linear dna molecule. Eukaryotic = diploid (two copies of each chromosome) Prokaryotes = haploid (one copy per cell) Dna must be highly compacted to fit into the cell (see chromatin above) Chromatin can be divided into two types: euchromatin: less densely packed, can be transcribed, takes up most of the nucleus, heterochromatin: very densely packed, not transcribed, often found at centromeres. During mitosis and meiosis becomes 5-10 times more densely packed less tightly packed between mitotic cycles. Basic structure of chromatin composed of: equal mass of dna and histone proteins, core region comprising two copies of the histone proteins h2a, h2b, h3, h4, (histones are small basic proteins, one associated histone h1 protein. Chromatin remodelling is an important regulator of gene expression: transcription is repressed when gene promoter and activator regions wound in nucleosome, section of dna in nucleosome controlled by, histone protein tail acetylation, swi-snf protein complex.
