Transcript 10/16 - link

•Homework #2 is due 10/18
•Bonus #1 is due 10/25
The order of Hox genes parallels the order of body
parts in which they are expressed
Fig 12.10
How are genomes organized?
25,000
12
How does the organization of a genome
affect its function?
Map of human chromosome 20
Fig 13.13
http://www.ncbi.nlm.nih.gov/mapview/maps.cgi?ORG=human&CHR=X&MAPS=i
deogr[Xpter:Xqter],genes[1.00:153692391.00]
Comparison of Fugu and human huntingtin gene:
(green indicates transposons prevalent in human version)
7.5 X
bigger
both have 67
exons, connected
by lines
(puffer fish)
Figure 7-113 Molecular Biology of the Cell, 4th ed by Alberts et al
(Adapted from S. Baxendale et al., Nat. Genet. 10:67–76, 1995.)
rRNA is arranged in
repeated transcription
units
Most cells in an
organism have the
same DNA.
Which cells have
different DNA?
DNA is rearranged
in B-cells during
antibody production
Each B-cell
produces a
unique antibody
DNA
rearrangements in
B-cells allow each
B-cell to produce a
unique antibody
Some genes have several similar sequences within the
genome: known as a gene family
Hemoglobin (carries O2 in the blood) is comprised of a
gene family in humans
Different members of the hemoglobin gene family are
expressed at different developmental stages
Fig 19.17
Fetal Hb
binds O2
more
strongly than
maternal Hb
Pseudogenes have the structure of a gene,
but are not expressed.
Fig 19.18
Recently Mobilized Transposons in the
Human and Chimpanzee Genomes (2006)
Ryan E. Mills et al. The American Journal of
Human Genetics 78: 671-679
and
Which transposable elements are active in
the human genome? (2007) Ryan E. Mills et
al. Trends in Genetics 23: 183-191
Transposons: mobile DNA
Transposons
comprise much of
human DNA
From “Biology 7th ed.”
by Campbell et al
fig 19.14
Retrotransposons
move via an
RNA
intermediate
Fig 14.13
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are needed to see this picture.
Tbl 1
Recently
Mobilized Transposons
in the Human and
Chimpanzee Genomes
(2006) Ryan E. Mills et
al. The American
Journal of Human
Genetics 78: 671-679
Humans and
chimpanzees
shared a
common
ancestor
about 6
million years
ago
human
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are needed to see this picture.
chimp
Fig 3
Recently
Mobilized Transposons
in the Human and
Chimpanzee Genomes
(2006) Ryan E. Mills et
al. The American
Journal of Human
Genetics 78: 671-679
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Tbl 2
Recently Mobilized Transposons in the Human and Chimpanzee Genomes (2006) Ryan E. Mills et al.
The American Journal of Human Genetics 78: 671-679
Fig 1
Which transposable elements are active in the human genome? (2007) Ryan E. Mills et al. Trends in
Genetics 23: 183-191
Conclusions:
•Transposons may play a role in evolution
•More abundant transposons in humans
show “recent” transposon activity
Conclusions:
•Transposons may play a role in evolution
•More abundant transposons in humans
show “recent” transposon activity
What affect do transposons have in humans?
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Fig 3
Recently Mobilized Transposons in the Human and Chimpanzee Genomes (2006) Ryan E. Mills et al. The
American Journal of Human Genetics 78: 671-679
Does transposition cause disease?
Tbl 1
Which transposable elements are active in the human genome? (2007) Ryan E. Mills et al. Trends in
Genetics 23: 183-191
The coding capacity of L1 was not fully
recognized until an active copy with
intact ORFs ‘jumped’ into the factor VIII
gene and caused hemophilia.
Diseases caused by transposon insertion:
•Duchenne muscular dystrophy
•Coffin-Lowry syndrome
•Fukuyama-type congenital muscular dystrophy
(FCMD)
•colon cancer
•chronic granulomatous disease
•X-linked dilated cardiomyopathy
•familial hypocalciuric hypercalcemia and neonatal
severe hyperparathyroidism
•neurofibromatosis type 1
Which transposons are mobile?
Active human transposons have been
estimated to generate about one new
insertion per 10–100 live births
Comparative genomics also has been used to
identify recently mobilized transposons in
genetically diverse humans. For example, over 600
recent transposon insertions were identified by
examining DNA resequencing traces from 36
genetically diverse humans.
QuickTime™ and a
TIFF (Uncompressed) decompressor
are needed to see this picture.
Which transposons are mobile?
Tbl 1
Which transposable elements are active in the human genome? (2007) Ryan E. Mills et al. Trends in
Genetics 23: 183-191
Conclusions:
•Transposons may play a role in evolution
•More abundant transposons in humans
show “recent” transposon activity
•Transposons are still active, and can cause
mutations and disease.