Class Notes (1,100,000)
CA (650,000)
York (40,000)
BIOL (2,000)
BIOL 1000 (500)
Lecture 2

BIOL 1000 Lecture Notes - Lecture 2: Histone H1, Dna Replication, Histone H2B


Department
Biology
Course Code
BIOL 1000
Professor
Nicole Nivillac
Lecture
2

This preview shows page 1. to view the full 4 pages of the document.
8. dna structure, replication & repair
!
1. Definitions+
Homologous+chromosomes:!exact!same!genes!in!the!exact!same!spots!(example:!with!pairs,!as!
opposed!to!comparing!chromosome!1!with!chromosome!2!that!are!non-homologous)!
Chromatin:!the!complex!of!DNA!+!associated!proteins!(histone!and!non-histone!proteins).!It!can!
be!euchromatin!or!heterochromatin.!
Nucleosome:!a!histone+octamer!that!DNA!wraps!around!in!eukaryotes.!
the!nucleosome!core!is!wrapped!by!the!DNA!double!helix!
there!are!2!copies!of!each!histone!protein!(H2A,!H2B,!H3!and!H4)!in!the!nucleosome!core!
the!nucleosome!contains!an!octet!of!8!histone!proteins!
Linker+DNA:!DNA!between!two!nucleosome!cores!that!is!associated!with!histone!H1.!
Cell+Cycle:!a!period!of!growth!followed!by!nuclear!division!and!cytokinesis.!
Chromosomes:!nuclear!units!of!genetic!information!that!are!divided!and!distributed!by!mitotic!
cell!division!
!
Chromatin+
The!complex!of!DNA!+!associated!proteins!(histone!and!non-histone!proteins).!
Important!for!transcription!
Euchromatin:!loosely!packed,!genes!are!active!and!transcription!is!occuring!
Heterochromatin:!densely!packed,!genes!are!inactive,!transcription!not!occuring!
!
DNA+Packing+in+Eukaryotes+
DNA!winds!around!nucleosomes!–!a!nucleosome!is!a!histone+octamer!composed!of!two!molecules!
each!of!histones!H2A,!H2B,!H3!and!H4.!Linkers!are!the!spaces!between!them.!
Binding!of!histone!H1!to!linker!DNA!causes!nucleosomes!to!package!into!a!coiled+structure!
(solenoid+or+chromatin+fiber)!
!
DNA+and+RNA+Composition+-+Nucleotides+
Nitrogenous+Base!–!ATCG!for!DNA,!AUCG!for!RNA+
Pentose+sugar!–!5-carbon!sugar,!missing!an!oxygen!for!DNA!(deoxyribose)!unlike!RNA!(ribose)+
Phosphate+group++
- DNA!is!double-stranded!but!RNA!is!single-stranded!
!
!
!
!
!
!
!
!
!
You're Reading a Preview

Unlock to view full version