Lecture 4

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25 Mar 2012
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Lecture 4 Jan. 23/12
Genomes and Chromosomes (P1)
Genome and organism relationships
Genome: organism’s heredity information, encoded in DNA (RNA for viruses)
Organism complexity/size have no relation with genome size
No relation between entire genome size and gene size
No relation between number of proteins and genome size
Sections of the genome
Only 1.5% of genome codes for proteins
50% of genome is repetitive
Other 48.5% is not fully understood, not “junk DNA
I.E. Introns
Segments of DNA that do not code for protein, removed before translation
DNA packaging
Prokaryotes
Nucleoid
Condensed (folded/twisted) protein/DNA with no nuclear membrane
+vely charged amines shield charges on DNA so it will not fold on itself
Nucleoid-associated proteins (NAPs) help folding/twisting
DNA supercoiling caused by topoisomerase, twists double helix even more
Eukaryotes
Nucleus, E genome >>> P genome
E genome is packed into cells through chromosomes
Chromosome composed of chromatin
Chromatin: single, long DNA molecule and its associated proteins
Chromatin only in E genome
In Situ hybridization
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