Mystery of theMystery of the

Matching MarksMatching Marks(Part 3)(Part 3)

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DNA Search Lab Followup

Welcome back from yourSEARCH FOR

THE TELL-TALE TELOMERE

Let’s see what it tells us…

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108061 agcacagacc tgggggtcac cgtaaaggtg gagcagcatt cccctaagca cagaggttgg 108121 ggccactgcc tggctttgtg acaactcggg gcgcatcaac ggtgaataaa atctttcccg 108181 gttgcagccg tgaataatca aggttagaga ccagttagag cggttcagtg cggaaaacgg 108241 gaaagaaaaa gcccctctga atcctgggca gcgagattct cccaaagcaa ggcgaggggc 108301 tgcattgcag ggtgagggtg agggttaggg tttgggttgg gtttggggtt ggggttgggg 108361 taggggtggg gttggggttg gggttggggt taggggtagg ggtaggggta ggggtagggt 108421 cagggtcagg gtcagggtta gggttttagg gttaggattt tagggttagg gtaagggtta 108481 agggttgggg ttggggttag ggttaggggt tagggttggg gttggggttg gggttggggt 108541 tggggttggg gttagggtta gctaaaccta accctaaccc ctaaccccaa ccccaacccc 108601 aaccctaccc ctacccctac ccctaacccc aacccccacc cttaaccctt aacccttacc 108661 ctaaccctaa cccaaaccct aaccctaccc taaccctaac ccaaccctaa ccctaaccct 108721 accctaaccc taacacccta aaaccgtgac cctgaccttg accctgaccc ttaaccctta 108781 accctaacca taaccctaaa ccctaaccct aaaccctaac cctaaaccct aaccctaaca 108841 ctaccctacc ctaaccccaa cccctaaccc ctaaccctaa ccctacccct aaccccaacc 108901 ccagccccaa cccttaccct aaccctaccc taacccttaa ccctaacccc taaccctaac 108961 ccctaaccct aaccctaccc caaccccaaa cccaacccta acccaaccct aacccctaac 109021 cctaacccct accctaaccc ctagccctag ccctagccct aaccctaacc ctcgccctaa 109081 ccctcaccct aaccctcacc ctcaccctaa cccaacgtct gtgctgagaa gaatgctgct 109141 ccgcctttaa ggtgcccccc aggtctgtgc tgaacagaac gcagctccgc cgtcgcagtg 109201 ccctcagccc gcccgcccgg gtctgacctg agaagaactc tgctccgcct tcgcaatagc 109261 cccgaagtct gtgcagagga gaacgcagct ccgccctcgc gatgctctcc ggctgtgtgc 109321 taaagagaac gcaactccgc cctcgcaaag gcggcgcgcc ggcggaggcg cggagaggcg

RESULTS: Can you see the telomeres?

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RESULTS CLARIFIED:108061 agcacagacc tgggggtcac cgtaaaggtg gagcagcatt cccctaagca cagaggttgg 108121 ggccactgcc tggctttgtg acaactcggg gcgcatcaac ggtgaataaa atctttcccg 108181 gttgcagccg tgaataatca aggttagaga ccagttagag cggttcagtg cggaaaacgg 108241 gaaagaaaaa gcccctctga atcctgggca gcgagattct cccaaagcaa ggcgaggggc 108301 tgcattgcag ggtgagggtg agggttaggg tttgggttgg gtttggggtt ggggttgggg 108361 taggggtggg gttggggttg gggttggggt taggggtagg ggtaggggta ggggtagggt 108421 cagggtcagg gtcagggtta gggttttagg gttaggattt tagggttagg gtaagggtta 108481 agggttgggg ttggggttag ggttaggggt tagggttggg gttggggttg gggttggggt 108541 tggggttggg gttagggtta gctaaaccta accctaaccc ctaaccccaa ccccaacccc 108601 aaccctaccc ctacccctac ccctaacccc aacccccacc cttaaccctt aacccttacc 108661 ctaaccctaa cccaaaccct aaccctaccc taaccctaac ccaaccctaa ccctaaccct 108721 accctaaccc taacacccta aaaccgtgac cctgaccttg accctgaccc ttaaccctta 108781 accctaacca taaccctaaa ccctaaccct aaaccctaac cctaaaccct aaccctaaca 108841 ctaccctacc ctaaccccaa cccctaaccc ctaaccctaa ccctacccct aaccccaacc 108901 ccagccccaa cccttaccct aaccctaccc taacccttaa ccctaacccc taaccctaac 108961 ccctaaccct aaccctaccc caaccccaaa cccaacccta acccaaccct aacccctaac 109021 cctaacccct accctaaccc ctagccctag ccctagccct aaccctaacc ctcgccctaa 109081 ccctcaccct aaccctcacc ctcaccctaa cccaacgtct gtgctgagaa gaatgctgct 109141 ccgcctttaa ggtgcccccc aggtctgtgc tgaacagaac gcagctccgc cgtcgcagtg 109201 ccctcagccc gcccgcccgg gtctgacctg agaagaactc tgctccgcct tcgcaatagc 109261 cccgaagtct gtgcagagga gaacgcagct ccgccctcgc gatgctctcc ggctgtgtgc 109321 taaagagaac gcaactccgc cctcgcaaag gcggcgcgcc ggcggaggcg cggagaggcg

HeadTelomereof “extra”chrom. 2a

HeadTelomereof “short”chrom. 2b

FUSION POINT !

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108361 taggggtggg gttggggttg gggttggggt taggggtagg ggtaggggta ggggtagggt 108421 cagggtcagg gtcagggtta gggttttagg gttaggattt tagggttagg gtaagggtta 108481 agggttgggg ttggggttag ggttaggggt tagggttggg gttggggttg gggttggggt 108541 tggggttggg gttagggtta gctaaaccta accctaaccc ctaaccccaa ccccaacccc 108601 aaccctaccc ctacccctac ccctaacccc aacccccacc cttaaccctt aacccttacc 108661 ctaaccctaa cccaaaccct aaccctaccc taaccctaac ccaaccctaa ccctaaccct 108721 accctaaccc taacacccta aaaccgtgac cctgaccttg accctgaccc ttaaccctta

Did you know… you’ve got FOSSILS in YOU !

All of you have these fossils,in the #2 chromosome of every cell !

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 ownMOLECULAR FOSSILS !

Telo.2a

Telo.2b

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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 chromosmesin an ancient ancestor after the

chimpanzees branched off.

CONCLUSION

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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…

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The Chromosomesof Humans and Apes

Compared

For each number,the chromosomesare arranged in

this order(left to right):

human, chimpanzee,gorilla, orangutan

What is moststriking?

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RIGHT! They are ALL

Strikingly Similar!

And what do we knowwhen we find identical

or very similar patternson different items?

RIGHT!They had to have aCOMMON ORIGIN

Or, in this case…COMMON ANCESTRY

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Based on these chromosome comparisons…Biologists have been able to draw

a phylogenetic tree, showinghow 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…

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Chimps Humans

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Did you find ALLof the

Common Ancestors?

Chimps

Humans

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Did you notice…

All the other apes had that“extra” chromosome, too?

This confirms that this isthe more PRIMITIVE (original)CONDITION, so our SINGLE#2 chromosome is the DERIVED CONDITION(the result of fusion)

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When we compare primates by using other features,

including DNA, different proteins, anatomy, physiology, and fossils,

Biologists have developed similarCladograms (Phylogenetic Trees),

like these…

MORE CONFIRMING EVIDENCE

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See how similarthey are?

Based on Albumin Protein Analysis:

Based on DNA Hybridization Analysis

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And here’s another one…

PRIMATE CLADOGRAM

Based on Genome Analysis

Humans

BonobosChimpanzees

Gorillas

Orangutans

Gibbons

Old WorldMonkeys

6 mya

8 mya

13 mya

18 mya

25-30 mya

SpeciesToday

Common Ancestor

Again, basically the same pattern

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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 thathumans and chimps be in the same genus!

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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 equaledanywhere else in the animal kingdom.

Will we use our talents to protect andmanage our environment,

or will we get lazy and lose it all?

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What will YOU dowith YOUR talents

to make this a better worldfor everyone?

This is YourThis is YourBEGINNINGBEGINNING

LESSON WRAP-UP

REALITY-CHECK QUESTIONSMORE DNA SEARCHES

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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.

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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.

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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.

END OF LESSON

ADDENDUM FOLLOWSMore Evidence: Synteny

Telomere Tid-Bits

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ADDENDUM

• More Evidence (Synteny)• Telomere Tid-Bits• Key to “Reality Check”• Extensions: DNA Searching

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Confirmation: More Evidence

When we compare

ALL the DNA inour #2

chromosomewith ALL the DNA

in the two chimp

chromosomes…*

we find that it isall the same

DNA !

*(this is “synteny”)

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However…

When we compareALL the DNA in

our #2 chromosomewith DNA in Dogchromosomes…

we find that our #2is a patchwork of DNA

from 8 differentDog chromosomes!

(WHY?)

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If you said“More time since we

branched from ourCOMMON ANCESTOR

with dogs,SO, more time for

more chromosomechanges and other

mutations,”YOU GOT IT!

WHY?

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Telomere Tid-Bits

1. Telomeres apparently protect the endsof our chromosomes, keeping the gene-DNA

from getting damaged.

2. Each time our chromosomes replicateand cells divide, a little of each telomereis lost, so they get shorter as we age!

3. This is one reason why embryonic stem cellsare preferred over adult stem cells in

stem cell research.

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More Telomere Tid-Bits

4. There is an enzyme, telomerase, that canreplace some of the missing telomere DNA.

It’s thought that defective telomerasecould be a cause of aging problems.

5. Telomeres and telomerase are the subjects ofmuch research into cancer, heart disease,

brain function, and other problems of aging.

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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

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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!

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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=AL078621.19Scroll 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 tohttp://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

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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.htmlClick on a chromosome; look for Synteny in left column, etc.