Mystery of the
Matching Marks
(Part 3)
DNA Search Lab Followup
Welcome back from your
SEARCH FOR
THE TELL-TALE TELOMERE
Let’s see what it tells us…
2
RESULTS: Can you see the telomeres?
108061
108121
108181
108241
108301
108361
108421
108481
108541
108601
108661
108721
108781
108841
108901
108961
109021
109081
109141
109201
109261
109321
agcacagacc
ggccactgcc
gttgcagccg
gaaagaaaaa
tgcattgcag
taggggtggg
cagggtcagg
agggttgggg
tggggttggg
aaccctaccc
ctaaccctaa
accctaaccc
accctaacca
ctaccctacc
ccagccccaa
ccctaaccct
cctaacccct
ccctcaccct
ccgcctttaa
ccctcagccc
cccgaagtct
taaagagaac
tgggggtcac
tggctttgtg
tgaataatca
gcccctctga
ggtgagggtg
gttggggttg
gtcagggtta
ttggggttag
gttagggtta
ctacccctac
cccaaaccct
taacacccta
taaccctaaa
ctaaccccaa
cccttaccct
aaccctaccc
accctaaccc
aaccctcacc
ggtgcccccc
gcccgcccgg
gtgcagagga
gcaactccgc
cgtaaaggtg
acaactcggg
aggttagaga
atcctgggca
agggttaggg
gggttggggt
gggttttagg
ggttaggggt
gctaaaccta
ccctaacccc
aaccctaccc
aaaccgtgac
ccctaaccct
cccctaaccc
aaccctaccc
caaccccaaa
ctagccctag
ctcaccctaa
aggtctgtgc
gtctgacctg
gaacgcagct
cctcgcaaag
gagcagcatt
gcgcatcaac
ccagttagag
gcgagattct
tttgggttgg
taggggtagg
gttaggattt
tagggttggg
accctaaccc
aacccccacc
taaccctaac
cctgaccttg
aaaccctaac
ctaaccctaa
taacccttaa
cccaacccta
ccctagccct
cccaacgtct
tgaacagaac
agaagaactc
ccgccctcgc
gcggcgcgcc
cccctaagca
ggtgaataaa
cggttcagtg
cccaaagcaa
gtttggggtt
ggtaggggta
tagggttagg
gttggggttg
ctaaccccaa
cttaaccctt
ccaaccctaa
accctgaccc
cctaaaccct
ccctacccct
ccctaacccc
acccaaccct
aaccctaacc
gtgctgagaa
gcagctccgc
tgctccgcct
gatgctctcc
ggcggaggcg
cagaggttgg
atctttcccg
cggaaaacgg
ggcgaggggc
ggggttgggg
ggggtagggt
gtaagggtta
gggttggggt
ccccaacccc
aacccttacc
ccctaaccct
ttaaccctta
aaccctaaca
aaccccaacc
taaccctaac
aacccctaac
ctcgccctaa
gaatgctgct
cgtcgcagtg
tcgcaatagc
ggctgtgtgc
cggagaggcg
3
RESULTS CLARIFIED:
108061
108121
108181
108241
108301
108361
108421
108481
108541
108601
108661
108721
108781
108841
108901
108961
109021
109081
109141
109201
109261
109321
agcacagacc
ggccactgcc
gttgcagccg
gaaagaaaaa
tgcattgcag
taggggtggg
cagggtcagg
agggttgggg
tggggttggg
aaccctaccc
ctaaccctaa
accctaaccc
accctaacca
ctaccctacc
ccagccccaa
ccctaaccct
cctaacccct
ccctcaccct
ccgcctttaa
ccctcagccc
cccgaagtct
taaagagaac
tgggggtcac
tggctttgtg
tgaataatca
gcccctctga
ggtgagggtg
gttggggttg
gtcagggtta
ttggggttag
gttagggtta
ctacccctac
cccaaaccct
taacacccta
taaccctaaa
ctaaccccaa
cccttaccct
aaccctaccc
accctaaccc
aaccctcacc
ggtgcccccc
gcccgcccgg
gtgcagagga
gcaactccgc
cgtaaaggtg
acaactcggg
aggttagaga
atcctgggca
agggttaggg
gggttggggt
gggttttagg
ggttaggggt
gctaaaccta
ccctaacccc
aaccctaccc
aaaccgtgac
ccctaaccct
cccctaaccc
aaccctaccc
caaccccaaa
ctagccctag
ctcaccctaa
aggtctgtgc
gtctgacctg
gaacgcagct
cctcgcaaag
gagcagcatt
gcgcatcaac
ccagttagag
gcgagattct
tttgggttgg
taggggtagg
gttaggattt
tagggttggg
accctaaccc
aacccccacc
taaccctaac
cctgaccttg
aaaccctaac
ctaaccctaa
taacccttaa
cccaacccta
ccctagccct
cccaacgtct
tgaacagaac
agaagaactc
ccgccctcgc
gcggcgcgcc
cccctaagca
ggtgaataaa
cggttcagtg
cccaaagcaa
gtttggggtt
ggtaggggta
tagggttagg
gttggggttg
ctaaccccaa
cttaaccctt
ccaaccctaa
accctgaccc
cctaaaccct
ccctacccct
ccctaacccc
acccaaccct
aaccctaacc
gtgctgagaa
gcagctccgc
tgctccgcct
gatgctctcc
ggcggaggcg
cagaggttgg
atctttcccg
cggaaaacgg
ggcgaggggc
ggggttgggg
ggggtagggt
gtaagggtta
gggttggggt
ccccaacccc
aacccttacc
ccctaaccct
ttaaccctta
aaccctaaca
aaccccaacc
taaccctaac
aacccctaac
ctcgccctaa
gaatgctgct
cgtcgcagtg
tcgcaatagc
ggctgtgtgc
cggagaggcg
Head
Telomere
of “extra”
chrom. 2a
Head
Telomere
of “short”
chrom. 2b
4
FUSION POINT !
Did you know… you’ve got FOSSILS in YOU !
All of you have these fossils,
in the #2 chromosome of every cell !
108361
108421
108481
108541
108601
108661
108721
taggggtggg
cagggtcagg
agggttgggg
tggggttggg
aaccctaccc
ctaaccctaa
accctaaccc
gttggggttg
gtcagggtta
ttggggttag
gttagggtta
ctacccctac
cccaaaccct
taacacccta
gggttggggt
gggttttagg
ggttaggggt
gctaaaccta
ccctaacccc
aaccctaccc
aaaccgtgac
taggggtagg
gttaggattt
tagggttggg
accctaaccc
aacccccacc
taaccctaac
cctgaccttg
ggtaggggta
tagggttagg
gttggggttg
ctaaccccaa
cttaaccctt
ccaaccctaa
accctgaccc
Telo.
2a
ggggtagggt
gtaagggtta
gggttggggt
ccccaacccc
aacccttacc
ccctaaccct
ttaaccctta
Fossils are the remains of ancient life,
and these are the telomeres of
two chromosomes from your ancient ancestor !
So, these telomeres are your very own
MOLECULAR FOSSILS !
Telo.
2b
5
CONCLUSION
PREDICTIONS: If our hypothesis was true, we
should find two telomeres there;
If NOT true, should be NO telomeres there.
Did we find telomeres there?
YES! Therefore…
Our hypothesis was supported:
Our #2 chromosome WAS formed
from the FUSION of two chromosmes
in an ancient ancestor after the
chimpanzees branched off.
6
A Peek at the Chromosomes
of Other Apes…
On the next slide, you will see the
chromosome diagrams for humans,
chimpanzees, gorillas, and orangutans,
all the :”Great Apes”
They are shown side by side
for easy comparison…
7
The Chromosomes
of Humans and Apes
Compared
For each number,
the chromosomes
are arranged in
this order
(left to right):
human, chimpanzee,
gorilla, orangutan
What is most
striking?
8
RIGHT!
They are ALL
Strikingly Similar!
And what do we know
when we find identical
or very similar patterns
on different items?
RIGHT!
They had to have a
COMMON ORIGIN
Or, in this case…
COMMON ANCESTRY
9
Based on these chromosome comparisons…
Biologists have been able to draw
a phylogenetic tree, showing
how primates are related to each other.
The following slide shows the tree
(called a “Primate Cladogram”).
See if you can point to
where the COMMON ANCESTORS
of Modern Primates
would be LOCATED on the tree…
10
Chimps Human
s
11
Chimp
s
Human
s
Did you find ALL
of the
Common Ancestors?
12
Did you notice…
All the other apes had that
“extra” chromosome, too?
This confirms that this is
the more PRIMITIVE (original)
CONDITION, so our SINGLE
#2 chromosome is the
DERIVED CONDITION
(the result of fusion)
13
MORE CONFIRMING EVIDENCE
When we compare primates
by using other features,
including DNA, different proteins,
anatomy, physiology, and fossils,
Biologists have developed similar
Cladograms (Phylogenetic Trees),
like these…
14
Based on Albumin Protein Analysis:
Based on DNA
Hybridization Analysis
See how similar
they are?
15
And here’s another one…
PRIMATE CLADOGRAM
Based on Genome
Analysis
Again, basically
the same pattern
6 mya
8 mya
13 mya
18 mya
25-30 mya
Common Ancestor
Species
Today
Humans
Bonobos
Chimpanzees
Gorillas
Orangutans
Gibbons
Old World
Monkeys
16
When all the data point to
essentially the same conclusions,
this strengthens those conclusions.
Biologically, humans are
very closely related to the apes.
In fact, chimps are closer to US,
than they are to gorillas!
Humans and chimps are even closer
than zebras are to horses!
Biologists have even recommended that
humans and chimps be in the same genus!
17
This may be hard for many to accept…
But we are very special apes,
not just “ordinary animals.”
Because of our brain and our dexterity,
humans have built amazing cultures
and environments not equaled
anywhere else in the animal kingdom.
Will we use our talents to protect and
manage our environment,
or will we get lazy and lose it all?
18
What will YOU do
with YOUR talents
to make this a better world
for everyone?
19
This is Your
BEGINNING
LESSON WRAP-UP
REALITY-CHECK QUESTIONS
MORE DNA SEARCHES
Time for a REALITY CHECK
Number your paper from 1-8
Based on the observed data…
Which are true… which are false?
• 1. All chromosomes have telomeres at both ends.
• 2. All chromosomes have telomeres in their
middles.
• 3. Identical complex patterns on different items
means they had a common origin.
• 4. A hypothesis is a prediction.
22
REALITY CHECK cont.
Which are true… which are false?
• 5. Our #2 chromosome was formed by
the fusion of 2 chromosomes in an
early ancestor.
• 6. Humans evolved from monkeys.
• 7. Humans evolved from
chimpanzees.
• 8. Humans & chimpanzees evolved
from a common ancestor.
23
DID YOU ENJOY THE SEARCH?
Here are some more DNA searches
• Go online to search a DNA database See “Chromosome Fusion” for directions
(get internet address from teacher)
• Look for the “Lost Centromere” - Did you
notice that the centromere in the “longer”
(lower) chimp chromosome disappeared? Is
there any DNA evidence for a centromere still
THERE in our #2 chromosome?
• Look for telomere DNA on the ends of
different chromosomes, different organisms.
24
END OF LESSON
ADDENDUM FOLLOWS
More Evidence: Synteny
Telomere Tid-Bits
ADDENDUM
•
•
•
•
More Evidence (Synteny)
Telomere Tid-Bits
Key to “Reality Check”
Extensions: DNA Searching
26
Confirmation: More Evidence
When we compare
ALL the DNA in
our #2
chromosome
with ALL the DNA
in the two chimp
chromosomes…*
we find that it is
all the same DNA !
*(this is “synteny”)27
However…
When we compare
ALL the DNA in
our #2 chromosome
with DNA in Dog
chromosomes…
we find that our #2
is a patchwork of DNA
from 8 different
Dog chromosomes!
(WHY?)
28
WHY?
If you said
“More time since we
branched from our
COMMON ANCESTOR
with dogs,
SO, more time for
more chromosome
changes and other
mutations,”
YOU GOT IT!
29
Telomere Tid-Bits
1. Telomeres apparently protect the ends
of our chromosomes, keeping the gene-DNA
from getting damaged.
2. Each time our chromosomes replicate
and cells divide, a little of each telomere
is lost, so they get shorter as we age!
3. This is one reason why embryonic stem cells
are preferred over adult stem cells in
stem cell research.
30
More Telomere Tid-Bits
4. There is an enzyme, telomerase, that can
replace some of the missing telomere DNA.
It’s thought that defective telomerase
could be a cause of aging problems.
5. Telomeres and telomerase are the subjects of
much research into cancer, heart disease,
brain function, and other problems of aging.
31
KEY TO REALITY CHECK
• 1. All chromosomes have telomeres at both ends.
• True
• 2. All chromosomes have telomeres in their
middles.
• False
• 3. Identical complex patterns on different items
means they had a common origin.
• True
• 4. A hypothesis is a prediction.
• False
32
KEY TO REALITY CHECK (cont.)
• 5. Our #2 chromosome was formed by the
fusion of 2 chromosomes in an early ancestor.
• True
• 6. Humans evolved from monkeys.
• False
• 7. Humans evolved from chimpanzees.
• False
• 8. Humans & chimpanzees evolved from a
common ancestor.
• TRUE!
33
EXTENSIONS: DNA SEARCHING
1. For DNA in the 2q13 region online at NCBI, go to:
http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?val=AL078621.19
Scroll down about 1/3 scroll bar distance to ORIGIN of segment.
Then about 2/3 scroll bar down, to line 108601 for fusion area.
2. To explore ENTIRE chromosome #2, or to see DNA in other
chromosomes or chromosomes of other animals, go to
http://www.ncbi.nlm.nih.gov/mapview/
Click on the species (Homo sapiens 36 for our chromosomes),
then click on the desired chromosome number.
Click area of chromosome (or blue line contig) where you want to
see the DNA (2q13 in the human chromosome #2 for the fusion area).
For detailed directions, see “Chromosome Fusion” lesson:
http://www.indiana.edu/~ensiweb/lessons/c.fus.les.html
34
EXTENSIONS: DNA SEARCHING
IDEAS for SEARCHING:
1. Take a look at the DNA in the tip ends (telomeres) of several
chromosomes to see the characteristic tandem repeats of ...ttaggg...
2. Look for the missing centromere area in chromosome #2 where
you should see remains of the centromere that was in the longer
(lower) ancestral chromosome before it fused to the shorter
chromosome. The missing centromere region should be in the
2q21.2 region.
3. Using the BLAST search tool, see if you can find fusion areas in
other chromosomes.
Do similar searches on the ENSEMBL site at:
http://www.ensembl.org/Homo_sapiens/index.html
Click on a chromosome; look for Synteny in left column, etc.
35