Gene$and$Genome$Structure$
Key$Concepts:$
1. Central$Dogma$of$Molecular$Biology$
and$GeneGcs$
2. Anatomy$of$a$gene$
3. Anatomy$of$a$genome$
Morgan$Kleiber$ Biology$2581b$
Dept.$of$Biology$ January$15/16,$2013$ DNA:$InformaGon$Storage$and$Retrieval$
DNA$stores$the$biological$informa4on$to$create$a$diverse$range$of$$
proteins$$cell$types$$4ssues$$organisms$
Advantages:$
•$ease$of$storage$(large$quanGty$of$data)$
•$can$be$copied$reliably$ DNA$stores$informaGon$“digitally”$
$A$$C$$T$$G$
Analogous$to$storing$electronic$data$such$as$music:$
1000101010101010100010
1010101010010010011101 DigiGzed$informaGon$on$your$
0101001001010101010101$ computer$hard$drive$
Music$
Sound$waves$
mp3$player$ Central$Dogma$of$Molecular$Biology$and$GeneGcs$ The$Flow$of$InformaGon$in$Biological$Systems$
5’$ 3’$ 5’$
NYterminus$
CYterminus$
Fig.$1.7$ Nature$Reviews$GeneGcs$3,$43Y52$(January$2002)$
The$Central$Dogma$of$Molecular$Biology$and$GeneGcs$Circa$2012$ What$is$a$gene?$$$
• The$basic$unit$of$biological$informaGon$
• A$specific$segment$of$DNA$at$a$specific$
locaGon$in$the$genome$(on$a$region$of$a$
chromosome)$that$serves$as$a$unit$of$
funcGon$
• Encodes$RNA$or$protein$ Anatomy$of$a$eukaryoGc$gene$
GT$ AG$ GT$ AG$
regulatory$$
flanking$region$ Exon$$
Exon$1$ 2$ Exon$3$ flanking$region$
5’$ 5’$UTR$ 3’$UTR$ 3’$
GC$ CAAT TATA$
box$ box$ box$
TranslaGon$$ TranslaGon$
Start$codon$(ATG)$
Stop$codon$ PolyYA$addiGon$
TranscripGon$$ AATAA$ site$
Start$ (TranscripGon$
stop)$
See$Fig.$20.12$ Anatomy$of$a$eukaryoGc$gene$
regulatory$$
flanking$region$ Exon$1$ Exon$$ Exon$3$
2$ flanking$region$
5’$ 5’$UTR$ 3’$UTR$ 3’$
GC$ CAAT TATA$
box$ box$ box$
TranslaGon$$ TranslaGon$ AATAA$ PolyYA$
Start$codon$(ATG)$ Stop$codon$ addiGon$site$
transcrip)on+
preYmRNA$ 5’$UTR$ 3’$UTR$
splicing/RNA+processing+
mRNA$ 5’$Cap$Y$’$UTR$ 3’$UTR$ YAAAAAA$
transla)on+
protein$ H2NY$$ YCOOH$$$
See$Fig.$20.12$ 3’$ 5’$
Anatomy$of$a$eukaryoGc$gene$
Coding$strand:$$$
• $similar$5’$$3’$sequence$as$RNA$
3’$ • $Sense$,$nonYtemplate,$or$Crick$strand$
NonYcoding$strand:$$
• used$as$a$template$to$transcribe$RNA$
• $AnGsense,$template,$or$Watson$strand$
3’$ 5’$ 5’$
DNA$coding$strand$
DNA$template$strand$
mRNA$ Genes$between$species$
A$collagen$gene$in$C.+elegans$$
Dystrophin$gene$in$H.+sapiens+
2.5$Mb$
Primary$transcript$=$~2,500,000$nt$
mRNA$=$~14,$000$nt$
Cohen$&$Muntoni,$Heart$2004;$90:835Y41.$ Fig.$8.27$ DNA,$mRNA,$and$PolypepGde$(a$C.+elegans+collagen$gene)$
Fig.$8.27$ Sequence$to$FuncGon$
Open$Reading$Frame$(ORF):$$
• $inYframe$sequence$of$DNA$that$starts$with$start$
codon$(ATG)$and$ends$with$any$of$the$three$
terminaGon$(stop)$codons$(TAA,$TAG,$TGA)$
Coding$Sequence$(CDS):$$$
• $region$of$DNA$that$is$translated$to$form$proteins$$ Fig.$1.7$
The$GeneGc$
Code$ Fig.$1.5$
Sequence$to$FuncGon$
• The$amino$acid$sequence$of$a$polypepGde$
determines$its$three$dimensional$shape$$
• Protein$shape$determines$its$biological$funcGon$ Anatomy$of$a$Genome$
What$is$a$genome?$$$
1. The$sum$total$of$
geneGc$informaGon$in$
a$parGcular$cell$or$
organism$ See$Fig.$1.12$
Anatomy$of$a$Genome$
16$Mb$
6200$genes$$
S.+cerevisiae+ 16$chr.$
A.+thaliana+
125$Mb$
~25,000$genes$$
5$chr.$
D.+melanogaster+
130$Mb$
13,900$genes$$
4$chr.$
M.+musculus+
3000$Mb$
~25,000$genes$
20$chr.$
H.+sapiens+
3.2$Gb$
~25,000$genes$$
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