BIO130H1 Lecture Notes - Lecture 4: Histone H2A, Karyotype, Topoisomerase

• School: UTSG
• Department: Biology
• Course: BIO130H1
• Professor: Mitchell/ Moeder

Document Summary

Eucaryotic dna is packaged into a set of chromosomes. For humans, this is distributed over 24 chromosomes consisting of one dna molecule each. The more folded, compact structure is called chromatin. Bacteria carry their genes on a single, circular dna molecule (usually) Codi(cid:374)g se(cid:395)ue(cid:374)(cid:272)es k(cid:374)o(cid:449)(cid:374) as (cid:862)e(cid:454)o(cid:374)s(cid:863); (cid:374)o(cid:374)(cid:272)odi(cid:374)g (cid:396)egio(cid:374)s k(cid:374)o(cid:449)(cid:374) as i(cid:374)t(cid:396)o(cid:374)s. Nucleosomes are a basic unit of eucaryotic chromosome structure. Proteins that bind to dna to form eukaryotic chromosomes are divided into two classes: histones, nonhistone chromosomal proteins. Both of these proteins + nueclear dna = chromatin. Respo(cid:374)si(cid:271)le fo(cid:396) (cid:374)u(cid:272)leoso(cid:373)es (cid:894)(cid:862)(cid:271)eads o(cid:374) a st(cid:396)i(cid:374)g(cid:863) that so(cid:373)eti(cid:373)es sta(cid:272)k o(cid:374) o(cid:374)e a(cid:374)othe(cid:396); Dna is st(cid:396)i(cid:374)g, ea(cid:272)h (cid:271)ead is a (cid:862)(cid:374)u(cid:272)leoso(cid:373)e core particle, dna wound around protein core consisting of histones) One nucleosome consists of 8 histones (2 h2a, 2 h2b, 2 h3, and 2 h4 (cid:862)histo(cid:374)e o(cid:272)ta(cid:373)e(cid:396)(cid:895) and a 147-nucleotide-long dna.