Change Over Time (Packet #1)
State Standard: H.2L.5 - Explain how multiple lines of scientific
First Name
Last Name
evidence support biological evolution (change)
Examples: Fossils pg. 1-4, Biochemical pg. 5-6, Embryological and
Anatomical pg. 7-10
Response
Scoring Rubric
10 Exceeds
Evaluate the impact of the interactions of genetic variation, reproduction and inheritance, natural
(excellent)
selection and time on biological evolution (change)
8
Meets
Explain how biological evolution is the consequence of the interactions of genetic variation,
(proficient)
reproduction and inheritance, natural selection, and time, using multiple lines of scientific evidence.
6
Nearly Meets
Describe the process of biological evolution through natural selection
Does Not Meet
4
Recognize that species have changed over time
1
Incomplete
Did not participate
Score
How Do Species Compare?
Most classification systems focus on anatomical structures to determine taxonomic levels.
Phylogeny is a kind of family tree for organisms. Figure 1 shows a phylogenetic tree (an organizational
chart) showing the relationships of major groups of animals.
Some scientists who have studied protein sequences have used it to support the idea of a common
ancestor. These scientists theorize that when two species share a similar sequence of protein chains
(DNA), the species may have shared a common ancestor. The closer the sequences are to each other, the
more recently the two species shared an ancestor. Numerous differences in the sequences indicate the two
species are not as closely related.
Fig. 1
For example, the amino
acid sequence in the protein
cytochrome c of humans exactly
matches the sequence in
chimpanzees. The human sequence
differs only by one position when
compared to that of a rhesus
monkey. But for animals that are
clearly not closely related, the
sequence shows an even greater
variance. The amino acid sequence
of humans differs from that of a
chicken by 18 positions and from a
turtle’s by 19 positions.
In this investigation, you
will look at the amino acid
sequence from a variety of
organisms and discuss how closely
related they are.
Part A
1. You will be using Table 1 to examine amino acid sequences from the following animals: Horses,
Donkeys, Rabbits, Snakes, Turtles, and whales.
2. Table 1 shows only a small segment of the sequence of amino acids within the cytochrome c protein.
There are 104 amino acids in this protein. The amino acids function like letters in the alphabet arranged
perfectly to spell a word. If the amino acid sequence changes, the word changes or in this case the protein
changes to fit the needs for the organism. Table 1 shows the sequence between positions 39 and 53.
3. Use the characteristics of the animals, such as appearance, habitat, or diet, for example, to make a
prediction as to which of them are most closely related. Fill out the table 2 in the Data and observations
4. Indicate which animals you think are the least closely related.
Part B
1.Compare the amino acid sequence of the horse to the rest of the animals. How many amino acids differ
between the species? Record your results in Table 2.
2.Study the relationship between the species indicated in the first column of Table 2. What species share
the most similar sequence with a horse? __________________________________________________
3. Which species have sequences that are dissimilar?_______________________________________
Table 1
Position of the
amino acid
Horse
39
Position of the Amino Acids in Cytochrome c
40 41 42 43 44 45 46 47 48 49
A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
Whale
A
B
C
D
E
Y
G
H
Z
J
K
L
M
N
O
Turtle
A
B
C
D
E
V
G
H
Z
J
K
U
M
N
O
Rabbit
A
B
C
D
E
Y
G
H
Z
J
K
L
M
N
O
Donkey
A
B
C
D
E
F
G
H
Z
J
K
L
M
N
O
Snake
A
B
C
D
E
V
G
H
Z
J
K
W
M
N
O
Position of the
amino acid
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
50
51
52
53
Data and Observations
1. Fill out table 2
Animal Appearance
(describe feet)
Table 2
Habitat
(biome)
Diet
Number of Amino
Acid positions
different from horse
Skin covering
Horse
Whale
Turtle
Rabbit
Donkey
Snake
2. In the space below, construct cladogram (a branching tree) using the information you’ve gathered.
Your cladogram should include the animals in the study and how closely related they are to the horse.
horse
Analyze and Conclude
1. Which species are closest to a horse as indicated by the particular sequences of amino acids?
2. Which species are more distantly related to a horse as indicated by the sequence of amino acids in
Table 1?
3. Based on the evidence in table 2, how would you describe species with similar amino acid sequences
in terms of their shape and structure?
4. Based on table 2, make a general statement about whether any of the species other than horses are
more or less similar to each other.
5. Currently, scientists are moving away from the traditional method of grouping organisms based on
comparative anatomy. What methods are they using today to classify organisms (Hint: what evidence
did you use biotechnology to attain?).
6. Cytochrome c is just one strand of amino acids. Your body is programmed with thousands (about
60,000) of these genes. What life molecule is the “program for life”? ____________ What is it’s code?
______-________ and ______-________