Download Amino Acid Sequence-indicators of evolution

Closs
Dote
- $nquiny
Guided
chopter t 6 Lob
Amino Ae id Sequen€es:
Indieqtors of Evolutlon
Frsbiemr
How can you use proteins to determine how closely organisms
are related?
$msroduefimst
Biologists have many ways to study evolution. They can use fossils
to learn about ancient species. They can compare the anatomy of
modern species. They can observe the order in which cells develop
in embryos. All these clues reflect what took place over time at the
molecular level. DNA and proteins, the genes and the products of
genes, provide powerful evidence for descent with modification.
As DNA changes over time, the proteins that are produced
by the DNA change too. The result is that many organisms have
similar, but not identical, versions of a given protein. Differences
among these homologous proteins provide clues to evolution.
In Part A of this lab, you will compare amino acid sequences of
hemoglobin from seven mammals. In Part B, you will analyze data
about sequences in a second protein-cytochrome c. In Part B, the
organisms will be more varied.
Skiiis Foeus
Analyze Data, Graph, Draw Conclusions
Q
m,"er* voemburBmry
Definition
Term
compare
To examine two or more things in order to discover
ways in which they are alike, or comParable, and
ways in which they are different
sequence
The order in which things are arranged, actions are
carried out, or events happen
related
Connected by a common, or shared, origin;
descended from a common ancestor
identical
Exactly the same or alike in every way
Lob Monuol B
.
Copyright @ Peorson Educotion, lnc., or its offilioles. All Righis Reserved.
97
" Skills Lab
&&s*erim$s
. highlighter pen, light_colored
. graph paper
Fre-Lcb &uesfFqms
l.
Predicf Based only on their
anatomy, rank gorillas, bears,
chimpanze"., ,rd mice
recent common ancestor
with humans to least recent .o*iron
ancestor.
frorrr;;
)
Use Anologies you telr a
story
to a third person, and so o".
to a second person who tells
it
is retold, changes are
introduced. Over time, the
oi.rrurrg., increases. How
is this process an analogy f"r
"";t;;
rfr"i frlipens to DNA over time?
h, ,fr. ily
3' lnfer Hemogrobin from two species.is
compared. on the long
protein chains, there
are three rocations where
the amino acids
are different' where wourd
yo" plu." the common ancestor
of
the two species on the
and why?
..tr""tiffi
procedurre
porf A:-comporing
Amino Alid seguences in Hemogrobin
Hemogrobin is the molecure-in
brood that c;rries oxygen.
This
comprex morecure contains
ro* prli"i;;hu;r. Figure 1 shows
the
amino acid sequence for o-ne
of tiror" .t ui*^in eight mammals.
Each retter stands for a differ"",
rocation g1 the protein chain. "r"i"o *r? uu.r, corumn is a
NorE: ro.utior* where the
acids are identicir in a, eight
r""*r"rr-"r.lot shown. amino
Lob Monuol B
r copyright @ peorson Educotion,
rnc., or iis offiriotes
a,
pi^r"+. D^^^-..-
^l
[-loss
Dote
":a@Egf;e.
1. Use the row labeled Human as your control. Compare the
sequence for the bear to the sequence for humans. When you
find a difference in the bear sequence, highlight it.
2. Repeat Step 1 for each of the other mammals. Be sure to
compare each sequence to the sequence for humans.
I
Comporison of qmino ocid sequences
Figure
in-hemoglobin' from eight mommols
4
5
6
9
IO
t2
l3
Humon
T
P
E
S
A
T
Beor
T
(,
E
S
L
Chimponzee
T
P
E
S
Gibbon
T
P
E
S
Gorillo
T
P
E
S
Monkey
T
P
E
N
Mouse
T
D
A
Shrew
S
G
E
A
A
54
56
58
Humon
G
P
Beor
20
25
33
41
43
50
5t
52
A
G
V
F
E
T
P
D
T
G
G
F
D
S
A.
D
A
A
A
T
A
G
F
E
T
P
D
T
A
G
F
E
T
P
D
T
A
G
F
E
T
P
D
A
A
T
T
G
F
E
S
P
D
S
C
S
G
Y
D
S
A
S
C
T
G
E
A
F
D
S
A
S
68
69
7A
71
72
73
75
76
77
BO
87
104
L
\,
A
F
S
D
L
A
H
N
T
R
N
P
L
N
S
F
S
D
L
K
N
N
K
K
Chimponzee
G
P
L
G
F
S
D
L
A
H
N
T
R
Gibbon
G
P
L
G
F
s
D
L
,A
H
N
o
R
Gorillq
G
P
L
G
F
S
D
L
A
H
N
T
K
Monkey
G
P
L
G
A
A
A
A
F
S
D
L
N
H
N
o
K
Mouse
G
A
T
A
F
N
D
L
N
H
S
S
R
Shrew
G
P
H
S
L
G
E
A
N
N
K
R
L
r09
il0
112
V
L
Beor
L
Chimponzee
L
Gibbon
L
I16
117
I18
121
125
126
r30
139
C
I15
A
H
H
F
E
P
V
Y
N
C
A
H
H
F
E
o
Y
N
H
F
E
P
Y
N
H
H
F
E
a
Y
N
Gorillo
L
C
H
H
F
E
P
Y
N
Monkey
L
C
A
A
A
A
H
t
c
c
H
H
F
E
o
Y
N
I
I
G
H
H
L
D
A
F
T
A
S
K
F
E
P
F
N
Humon
Mouse
Shrew
M
L
Lob Monuol B
.
A
Copyright @ Peorson Educotion, lnc., or its offilioles. All Righis Reserved.
99
Closs
Dote
3. Use the data table to record the number
- of differences you
found for each mammal in comparison to humans.
Far* B: Differences in Cytochrome c
Cytochrome c takes part in electron transport during the last
stage of cellular respiration. This erLzyme can be found in yeasts,
bacteria, fungi, plants, and animals. The human cytochrome c
molecule is relatively small. Its single strand of protein has
104 amino acids.
4. In Figure 2, human cytochrome c is the standard. Column 1
lists the species that are being compared to humans. Column 2
lists the number of differences for each pairing. Use the data to
make a bar graph on a separate sheet of graph paper. Select an
order for the bars that will best reveal a pattern in the number
of differences.
Figure 2 How humon cytochrome c differs from
cytochrome c found in other species
Number of Differences
Species
0
Chimponzee
Lob Monrol B
.
Fruit fly
29
Horse
12
Pigeon
12
Rotilesnoke
14
Red breod mold
48
Rhesus monkey
I
Snoppinq turtle
t5
Tuno
21
Wheot
43
Copyrighr @ Peorson Educotion, lnc., or ils offiliotes. All Rights Reserved.
100
AnoEyxe emel fromeBude
l.
2.
Drow eonclusions Based on the hemoglobin data, which mammal listed is
most closely related to humans? What is the evidence for your conclusion?
Anolyze Doto Does the cytochrome
Question
1?
c
data support
your conclusion in
Explain.
3. Evoluote Does the data support the rankings you made in Pre-Lab
Question 1? If not, how would you explain any differences?
4. Design on Experiment The cytochrome c in both horses and pigeons differs
from the human protein at 12locations. Based on this data, you might
infer that horses and pigeons are closely related. What could you do to
support or reject this hyPothesis?
5. Communicote In terms of descent, what does it mean to say that humans
are more closely related to gorillas than to monkeys?
Lob Monuol B
.
Copyright @ Peorson Educoiion, lnc., or its offiliotes. All Rights Reserved
r0r
6. lnierpref Doto A student used the hemoglobin data to conclude that mice
and shrews are more closely related than are mice and humans or shrews
and humans. Was the student correct?
d m*;td $ciernce sl<ilEs
More than l00locations were not listed in Figure 1 because the amino
acid was the same in all eight species. one possible explanation is that no
mutations occurred in the codons for those locations. Suggest another possible
explanation. Hint: Think about why some mutations are hirmful.
Lob Monuol B
r Copyright @ Peorson Educoiion, lnc.,
102
or ifs offiliotes. All Righis Reserved.