Download Comparative Genomics 2015 File

Evolution Evidence - Molecular Connection
Aim: This exercise will demonstrate how the advent of molecular evidence supports previously
established evolutionary lines and give students the opportunity to use an online database.
1. Go to the NCBI website: http://www.ncbi.nlm.nih.gov/
2. In the search bar at the top, from the scroll down menu select “gene”
3. Search for COX1 and Homo sapiens to get the gene sequence for humans
4. Select a species from the results by clicking on the COX1 link (alternatively it may go by a different
gene name) by each entry (note that there are mostly listed by genus and species names, google if
you’re not sure what the organism is.
5. Scroll down to the “Genomic Regions, transcripts and products” and click on the FASTA link in the
title bar:
6. Select and copy the DNA sequence of the whole gene including the “tag” at the beginning of the
sequence
7. In a new tab go to the following link: http://www.ebi.ac.uk/Tools/msa/clustalw2/ 8. Paste in the DNA sequence copied to your clipboard in the entry box
9. Search for the next species gene sequence then copy and paste it into the same entry box below
the first entry
10. Select a set of “DNA” in the pull down menu
11. Scroll down and click “Submit”
12. Find the percent of bases that are similar for the COX 1 gene between the two different species by
clicking on the “Result Summary” tab then finding the score:
Find the similarity between humans and the 5 species listed below. You need to search for their
scientific names (in italics) then record your results in the data table on the next page
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Rhesus Monkey: Macaca mulatta
Kangaroo: Macropus robustus
Snapping Turtle: Chelydra serpentina
Bullfrog: Lithobates catesbeianus
Tuna: Thunnus albacares
Record your results in the data table below:
Species
Number of amino acid differences
compared to human
Rhesus Monkey
Macaca mulatta
Kangaroo
Macropus robustus
Snapping Turtle
Chelydra serpentina
Bullfrog
Lithobates catesbeianus
Tuna
Thunnus albacares
The cladogram diagram below shows the relationship of selected animals based on their shared
anatomical features. For example: out of seven key traits, all of these animals have a dorsal nerve
cord, but only humans, monkeys and kangaroos have mammary glands.
Record the total number of amino acid differences between humans and each animal shown
above. Write your answer in the box below the arrow pointing to the name of that animal.
1. The COX1 gene codes for a subunit of a protein called cytochrome c oxidase used as an
enzyme in cellular respiration. It is a widely used gene for comparative genomics.
Deduce why this gene may be preferred over other gene sequences.
5. Explain if the results of the genetic comparison oft he COX 1 gene support the evolutionary
reltaionship laid out in the cladogram.
6. Should the cladogram be reworked given the information from the COX 1 gene?