Download Activity 100: DNA: The Evidence Within

ACTIVITY 100:
DNA: THE EVIDENCE WITHIN
CHALLENGE HOW DOES DNA
PROVIDE EVIDENCE ABOUT
HOW ANIMALS ARE RELATED?
VOCABULARY:
DNA
CLASSIFICATION
Classification: the process of grouping
similar organisms based on similarities in
form and structure, physiology, and genetic
information.
DNA: Deoxyribonucleic Acid  The
genetic material, located inside the nucleus
of cells, that contains the information for
cell growth, cell division, and cell function.
GETTING STARTED
Read the Intro on Page F-51
Read the Scenario “The Common
Thread” on Page F- 52
Copy the Chart into your Science
Journal on F-52.
NUMBER OF DIFFERENCES
BETWEEN DNA SEQUENCES
Mammal
# 1 (Dog)
Mammal
#2
(Whale)
Mammal
#3
(Horse)
Fish
Mammal
#1
X
Mammal
#2
X
X
Mammal
#3
X
X
X
Reptile
PART B
Does every species within
a class display every
common characteristic
for that class?
Review Act. 76
“People. Bats and Birds”
NUMBER OF DIFFERENCES
BETWEEN DNA SEQUENCES
Fish
Kiwi
Platypus
Armadillo
Fruit
Bat
Mammal
#1
Mammal
#2
Mammal #
3
Reptile
ANALYSIS #1
DNA molecules contain the informational blue
print for the organism, which is inherited
through generations of evolution.
Two species with very similar DNA sequences
are more closely related than two species with
less similar DNA
Therefore, DNA comparisons provide a
major line of evidence for how closely
related any two species are!!
ANALYSIS #2
Because the seahorse is a fish, the
DNA of a seahorse is much more likely
to resemble that of a trout, which is
also a fish, than that of a horse, which
is a mammal.
In this activity, we found sequences
from different mammal species are
much more similar to one another than
they are to sequences from other
species of fish, reptiles, or birds.
ANALYSIS #4
Although humans and lizards share a common
ancestor, humans did not evolve from lizards.
The commonly shared ancestor of both humans and
lizards has been extinct for hundreds of millions of
years.
It was an early reptile, and it may have been lizard-like,
but in the millions of years since it became extinct both
the mammalian and reptilian lineages have undergone
tremendous amounts of diversification.
In fact, no mammalian species alive today, evolved
from another mammalian species alive today, much
less from a reptile species alive today!