Organization of DNA
the complete genetic makeup of an organism, its total DNA sequence
Genome*
Genes*units of heredity that are passed on from
parent to offspringdetermine, in whole or in part, a genetic
traitsegments of DNA responsible for the
production of a functional proteinevery person has two copies of each
gene, one inherited from each parent
Complexity and GenomeNo correlation between complexity of organism and …
• # of protein-coding genes (rice)• genome size (example lungfish)• # of protein-coding genes and genome size
• genes are not evenly spread along chromatin or chromosomes
Organization of genetic information*
• Viral• RNA or DNA, ss or ds, linear or circular
• Bacterial• DNA, ds, usually circular• found in one area = nucleoid• often have Plasmids (small extra-chromosomal DNA)
• Eukaryotic• DNA, ds, linear ds =double-stranded, ss=single-stranded
Eukaryotic chromosomes
Because we have A LOT of DNA in each cell it needs to be packaged in a specific way
Packing of DNA into chromosomes (1)*
Level 1Winding of DNA around histones to
create a nucleosome structure.
Level 2Nucleosomes connected by strands
of linker DNA like beads on a string.
Packing of DNA into chromosomes (2)*
Level 3Packaging of nucleosomes into 30-
nm chromatin fiber.
Level 4Formation of looped domains.
Packing of DNA into Chromosomes(big picture)
Packing of DNA into Chromosomes(big picture)
Isn’t that a lot of proteins ?*
Chromatin:- about twice as much protein as DNA
Two major types of proteins:1. Histones2. Non-histones
Isn’t that a lot of proteins ?
Two major types of proteins:1. Histones- abundant, basic proteins with a positive
charge that bind to DNA- evolutionarily conserved
2. Non-histones- all the other proteins associated with DNA- differ markedly in type and structure
Your ChromosomesChromosomes are compact molecules of DNAA human set of chromosomes contains 23 pairs23rd pair are your
sex chromosomesKaryotype
http://www.youtube.com/watch?v=ubq4eu_TDFc&list=PLF9969C74FAAD2BF9&index=1