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 Cytochrome-C Proteins.
Compare the human/chimpanzee to each other organism, entering the number of differences in the
chart. 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.________
Rhesus monkey 1
Horse 3
Donkey 3
Common zebra 3
Pig, cow, sheep 3
Dog 3
Gray whale 3
Rabbit 3
Kangaroo 3
# of differences in the amino acid sequence
Chicken, turkey 3
Penguin 3
Pekin duck 2
Snapping turtle 3
Rattlesnake 3
Bullfrog 3
Tuna 6
Screw fly 5
Silkworm moth 12
Tomato horn worm 13
Wheat 18
Rice 17
Candida Yeast 17
Neurospora 18
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? We are
somewhat alike
How does a universal genetic code relate to the hypotheses about the origin of life on Earth? They both
were created
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? The question kind of answered itself but
basically it’s just creating itself
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? They evolve just like humans
Based on the amino acid sequence data for the Cytochrome-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.
The Pekin Duck, and the Rhesus Monkey. Because the numbers are so close