Assignment Background Information: Scientists have found that almost all living organisms have a gene that codes for a protein called Cytochrome C. This protein is important in releasing energy from food. Scientists study similarities such as the gene that codes for Cytochrome C in hopes to learn more about the universal genetic code and the relationship between living organisms on Earth. Procedure: The charts below lists a portion of the amino acids found in the Cytochrome C protein of several different organisms. Use the chart to compare the amino acid sequence in humans to the sequences of the other organisms listed. For each organism, identify any amino acid that is different or missing when compared to the amino acids in the human sequence. Click on the following link to open the activity chart: Amino Acid Sequences in Cytochome-C Proteins. Compare the human/chimpanzee to each other organism, entering the number of differences in the chart (Tip: the next comparison is human/chimpanzee vs. horse). Note that a minus sign (-) indicates that an amino acid is missing in that sequence.
When comparing two sequences, an amino acid in one sequence and a (–) in another would count as a difference. You will submit the completed chart and the reflection to your instructor. Human vs.________ # of differences in the amino acid sequence Rhesus monkey Horse Donkey Common zebra Pig, cow, sheep Dog Gray whale Rabbit Kangaroo Chicken, turkey Penguin Pekin duck Snapping turtle Rattlesnake Bullfrog Tuna Screwfly fly Silkworm moth Tomato horn worm Wheat Rice Baker’s Yeast Candida Yeast Neurospora Reflection Questions: Summarize your amino acid comparison in paragraph form. To guide your summary, reflect on the following questions. What does it mean when scientists say that living organisms share a universal genetic code?
How does a universal genetic code relate to the hypotheses about the origin of life on Earth? How are self-replicating molecules, such as RNA molecules in the “RNA World” hypothesis, essential to the most popular hypotheses about the origin of life on Earth? How might similarities and differences in genetic codes, or the proteins built as a result of these codes, be used to determine how closely related different species are? Based on the amino acid sequence data for the Cytochome-C protein, chimpanzees and humans share an identical coding sequence. What other species identified on the chart has a coding sequence that is most closely related to the humans and chimpanzees and most distantly related? Explain your answer.