The human genome(in numbers) Haploid cells(gametes) contain -3 1 X 109 and diploid(somatic cells: -62x 10 bp DNA Laid end-to-end the chromosomal dna in each diploid cell would extend 2 meters The total length of chromosomal DNA in the human body (~50X1012cels-100X109km Distance from Sun to Neptune 4.55X109km Neptunes orbit around the sun 28.6X109km
The human genome (in numbers) • Haploid cells (gametes) contain ~ 3.1 x 109 and diploid (somatic) cells: ~ 6.2 x 109 bp DNA • Laid end-to-end, the chromosomal DNA in each diploid cell would extend ~ 2 meters • The total length of chromosomal DNA in the human body (~50 x 1012 cells) ~ 100 x 109 km Distance from Sun to Neptune: ~ 4.55 x 109 km Neptune’s orbit around the sun ~ 28.6 x 109 km
Composition of the human genome 1.1%~4% <2% ~44% 32% ~45% ~65% mitochondrial genome 16.6kb nuclear genome highly conserved sequences poorly conserved sequences protein-coding genes transposon-based repeats RNA genes, regulatory sequences heterochromatin other sequences
Composition of the human genome 16.6 kb
Composition of transposon-based repeats 45%of the human genome LINEs LINE-1 family ~600,000 autonomous nonautonomous LINE-2 family 370,000 ORF1 ORF2(poD LINE-3 family 44,000→P SINES 6-8 kb Alu family ~1,200,000 MIR ~450,000 100-400bp ∥|R3 85,000 retrovirus-like(LTR transposons) LTR HERV families ~240,000 P gag pol (env) LTR (gag) LTR MaLR 285,000 6-11kb 1.5-3kb DNA transposon fossils MER1(Charlie) ~213,000 transposase MER2 (Tigger 68000 2-3kb others 60,000 80 bp-3 kb ORF open reading frame, gag= viral capsid protein; pol= reverse transcriptase, env=envelope protein, LTR= long terminal repeat
Composition of transposon-based repeats (~45% of the human genome) ORF = open reading frame, gag = viral capsid protein; pol = reverse transcriptase, env = envelope protein, LTR= long terminal repeat
Composition of major classes of high-copy number tandemly repeated DNA (6.5% of human genome Chromosomal Class Array size Repeat unit location Satellite dna hundreds of kb alphoid DNA 171bp centromeric β(Sa3 A family) 68b heterochromatin Satellite 1 25-48bp Satelitte 2 ATTCC/GGAAT Satellite 3 ATTCC/GGAAT Minisatellite dNA 0.1-20kb Telomeric TTAGGG telomeres Hypervariable 9-64bp euchromatin Microsatellite DNA <100 bp often 1-4 bp widely dispersed Diverged forms of this sequence; **primarily"constitutive heterochromatin as opposed to faculatitive heterochromatin
Composition of major classes of high-copy number tandemly repeated DNA (6.5% of human genome) Class Array size Repeat unit Chromosomal location Satellite DNA a(alphoid DNA) b(Sau3A family) Satellite 1 Satelitte 2 Satellite 3 hundreds of kb 171 bp 68 bp 25-48 bp ATTCC/GGAAT* ATTCC/GGAAT centomeric heterochromatin** “ “ “ Minisatellite DNA Telomeric Hypervariable 0.1-20 kb TTAGGG 9-64 bp telomeres euchromatin Microsatellite DNA <100 bp often 1-4 bp widely dispersed *Diverged forms of this sequence; **primarily “constitutive” heterochromatin as opposed to “faculatitive” heterochromatin
Structures of human chromosomes Metaphase y and x chromosomes (scanning electron micrograph)
Structures of human chromosomes Metaphase Y and X chromosomes (scanning electron micrograph)