Download Chimpanzee DNA - AISG SP Moodle

Name ________________
Investigating Common Descent
One of the most common misconceptions about human evolution is seen in the statement “humans came
from apes.” This statement assumes that organisms evolve through a step-by-step progression from lower
forms to higher forms of life and the direct transformation of one species into another. For example, there is
a misconception that given enough time chimpanzees will evolve into humans. Evolution however is not a
progressive ladder. Modern species, such as humans, are derived from, but not the same as, organisms that
lived in the past.
Based on observations that Darwin made during his voyage to the Galapagos Islands, he concluded that
three species of mockingbirds on the Galapagos Islands had some connection to a single species of
mockingbird on the South American mainland.
Today we know that a single species can have multiple descendent species. This idea means that all birds
and all vertebrates share some common ancestors. Evolutionary biologists trying to determine relationships
analyze bones, bone structure, behaviors, and DNA to analyze the relation ships between organisms.
Today you will compare DNA segments from 4 different organisms: gorilla, chimpanzee, human, and a
hypothetical DNA segment from a common ancestor.
Question: What is the evolutionary relationship between gorillas, chimpanzees, humans, and a common
ancestor?
Hypothesis: Circle the hypothesis below that you think best describes the relationship between Gorillas
(G), Chimpanzees (C), and Humans (H) to a common ancestor (A). In the space below, explain WHY you
think the hypothesis you chose is the best description of the relationship.
Hypothesis 1
G C H
A
Hypothesis 2
G C
H
A
Hypothesis 3
G C H
A
EXPLANATION/ REASON your above choice: GIVE A SCIENTIFIC EXPLANATION FOR
YOUR CHOICE
Procedure One:
1.
Working in groups of 4, make 3 strands of DNA according to the following specifications.
Each color of paper clip will represent one of the four base pairs of DNA. Choose a color to
represent each base pair:
Fill in the Table Below
BASE PAIR
COLOR of PAPER CLIP
Adenine (A)
represented by:
Thymine (T)
Cytosine (C)
Guanine (G)
2.
3.
Go get 20 of each color paper clip.
Make your DNA strands by connecting paper clips in the proper sequence

Group Member 1: AGGCATAAACCAACCGATTA (HUMAN)

Group Member 2: AGGCCCCTTCCAACCGATTA (CHIMPANZEE)

Group Member 3: AGGCCCCTTCCAACCAGGCC (GORILLA)
4.
The fourth member of the group should use labeling tape to make a label for each strand.
5.
Lay each strand so that they are all aligned from left to right.
6.
Compare the human DNA to the chimpanzee DNA by matching the strands base by base.
7.
Count and record the number of bases that match. Count and record the number of bases that
are not the same
8.
Repeat steps 5 and 6 with the human DNA and the gorilla DNA
DATA: Fill in the Table Below
Data Table 1: Human DNA vs. Chimpanzee and Gorilla DNA
Human DNA compared
Number of matches
Unmatched bases
to:
Chimpanzee DNA
Gorilla DNA
Questions for Procedure One: ANSWER QUESTIONS BELOW
1.
How do the gorilla DNA and the chimpanzee DNA compare with the human DNA?
2.
What does the data suggest about the relationship between humans, gorillas, and
chimpanzees
3.
Which of the hypotheses is best supported by the data?
Procedure Two:
1.
Make a strand of ancestor DNA according to the sequence below:

AGGCCGGCTCCAACCAGGCC (COMMON ANCESTOR)
2.
Compare the common ancestor DNA to all three samples of DNA. Count and record the
number of matches and the number of bases that are not the same.
3.
Disassemble your DNA models
DATA: Fill in the Table Below
Data Table 2: Common Ancestor DNA vs. Human, Chimpanzee, and Gorilla DNA
Common ancestor DNA
Number or Matches
Unmatched Bases
compared to:
Human DNA
Chimpanzee DNA
Gorilla DNA
Questions for Procedure Two: ANSWER QUESTIONS BELOW
1.
Which DNA is most similar to the common-ancestor DNA?
2.
Which two DNA strands were most similar in the way they compared to the common
ancestor DNA?
3.
Which of the hypotheses in Part 1 does the data best support?
4.
Does your data “prove” the hypothesis? Why or why not?
5.
What other kinds of data might provide additional support of the hypothesis?
6.
Based on the hypothesis that is best supported, circle the statement that is most accurate.
Explain your answer.
a.
Humans and apes have a common ancestor.
b.
Humans evolved from apes.
Explanation
7.
According to all of the data collected, circle the statement that is most accurate. Explain your
answer.
a.
Chimpanzees and humans have a common ancestor.
b.
Chimpanzees are direct descendents of humans.
Explanation
8.
A comparison of many DNA sequences indicates that human DNA and chimpanzee DNA are
98.8 percent identical. What parts of your data support this result?
9.
Evolutionary biologists often disagree about the rate of evolutionary change and about the
exact nature of speciation (new species arising) and divergence (branching). How were the DNA
models useful for testing hypotheses about evolutionary relationships?
10. The table below lists five animals along with four physical characteristics. A plus sign (+)
indicates that the animal has this characteristic while a minus sign (–) indicates that the characteristic is
absent.
Animal
Jaws
Limbs
Hair
Placenta
Salamander
+
+
–
–
Mouse
+
+
+
+
Jellyfish
–
–
–
–
Koala
+
+
+
–
Salmon
+
–
–
–
a. Based on the features above, a student constructed a evolutionary tree. State the names of the
organisms missing in the following tree.
(2
11. The below Evolutionary tree shows the evolutionary history of species A to D. Discuss the
evolutionary relationships between species A to species B, C and D.
12.
Evolutionary Trees show evolutionary relationships among organisms. Comparative
morphology investigates characteristics for similar physical characteristics to determine which
organisms share a recent common ancestor. An evolutionary tree will begin by grouping organisms
based on a characteristics displayed by ALL the members of the group. Subsequently, the larger
group will contain increasingly smaller groups that share the traits of the groups before them.
However, they also exhibit distinct changes as the new species evolve. Further, molecular evidence
from genes which rarely mutate can provide molecular clocks that tell us how long ago organisms
diverged in to different species .
b. Which organisms in the above evolutionary tree in figure 1 have fur and mammary glands?
c. Which organisms in the evolutionary tree in figure 1 have jaws?
d. Based on the evolutionary tree in figure 1, which shared a common ancestor most recently –
a mouse and a lizard or a mouse and a perch?
e. Which two organisms would you expect to have a closer matching DNA sequence for a gene
that is NOT under natural selection pressure in nature – Hagfish and Pigeon or Hagfish and
Salamander?
13.
Part II Molecular Evidence: Cytochrome c is a protein located in the cell and is involved
with cellular respiration.
a. Compare each organism’s DNA sequences for the gene Cytochrome c with the ancestor cell
and each other.
b. Circle or highlight the differences (mutations) present in the cytochrome c DNA sequences from
ancestor cell.
c. Record the differences between the Ancestor DNA and the other organisms
DNA.
d. Based on the number of differences and similarities, which organism is the closest living relative to the
ancestor cell.
e. Based on the number of differences and similarities, which organism has the most
f.
Based on the number of differences and similarities in DNA sequences, which organisms are more closely
related Dolphins and sharks OR dolphins and cats?
14.
Now we will make a phylogenetic tree for eight different species using the differences in
DNA sequence for the Cytochrome c gene
Figure 3: Below shows differences between 8 organism’s gene for Cytochrome C protein.
a. Using the data above, complete your evolutionary tree in the space provided below.
b. Explain why you think more closely related organisms have more similar Cytochrome C gene.