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New Core Curriculum
Foundations of Scientific Process
Evolution
Using DNA to our Advantage
Genetic Modification
Introduction of new DNA sequences into an organism to alter
the genetic makeup
– Introduces very specific characteristics
– Use enzymes to manipulate DNA
– Recombinant DNA - new form of DNA that is introduced
– Gene cloning – splicing genes from a variety of species
into a host cell
– Gene therapy – inserting, deleting or manipulating genes
in order to cure or lessen the effects of genetic diseases
Sequencing
• Compare nucleotide sequences from different cells
• Analyze for similarities and differences
– PCR (polymerase chain reaction)  copying selected
segments of DNA
– Genetic fingerprinting
– Cloning
Discussion Activity: GATTACA…our future?
Evolution
Change in frequency of genetically determined
characteristics within a population over time
“Any living cell carries with it the experiences of a billion years
of experimentation by its ancestor.”
- Max Delbruck, 1949
Evolution
Change in frequency of genetically determined
characteristics within a population over time
1. Evolution occurs in populations of organisms of
the same species
2. Genes (specific segments of DNA) determine the
characteristics displayed by organisms
3. The mix of genes within a population can change
Process that chooses/selects from the pool of variable DNA
sequences those that are most adopted for the present
environment and gives organisms possessing such a DNA a
greater chance for survival is Natural Selection
Natural selection encourages passage of beneficial genes to future
generations and discourages harmful or less valuable genes
DNA-based life is the product of
natural selection. So are we.
All species share a common ancestor
and change due to the accumulation of
very slight modifications and their
sorting via Natural selection.
In a population, you will have variation
in the DNA and the fittest members of
the population will survive and pass on
more efficiently their DNA.
There are two primary ways in which
genetic diversity is generated within the
population of a species:
A) mutation (during semiconsdervative
replication of DNA) and
B) genetic recombination (during
reproduction)
A) Semi-conservative Replication
ONE
COPY
C
G
T
A
G
C
A
T
Sequence info is
kept by separated
strand
G
C
A
T
+ mix of four subunit bases
G
A
A
C
T
C
G
T
C
T
A
G
EXACT
COPY
TWO
COPIES
EXACT
COPY
C
G
T
A
G
C
A
T
Provides opportunity for
introduction and
preservation of Novelty
C
G
T
A
G
C
A
T
Mutation = any change in the genetic info (DNA) of an organism
A) Semi-conservative Replication
ONE
COPY
C
G
T
A
G
C
A
T
Sequence info is
kept by separated
strand
G
C
A
T
+ mix of four subunit bases
G
A
A
C
T
C
G
T
C
T
A
G
EXACT
COPY
TWO
COPIES
EXACT
COPY
C
G
T
A
G
C
A
T
To be important in the
Evolution of organisms,
mutations must be in
cells that will become
reproductive cells
C
G
T
A
G
C
A
T
Mutation = any change in the genetic info (DNA) of an organism
B) Genetic Recombination
Reproduction
(non-mutation)
Evolution
Change in frequency of genetically determined
characteristics within a population over time
Genetic Diversity is Important for Natural Selection
How would you represent biological evolution?
How do we know about those links?
A closer look at the skeletal (bone) anatomy
Cranium
Limbs
Different anatomies
Opposum similar
to Echidna :
they are marsupials
DNA sequences
Bear
Opposum
Raccoon
Echidna
Brain
Embryological Development
Species of organisms that are more closely related show greater
similarity in their DNA than those that are distantly related
Human
Sponge
Turnicate
DNA carries hereditary information:
This fact has two main
consequences:
1) one can trace the evolution of
species through their
similarities in DNA
2) the changes that can emerge
along the way are constrained
by the chemistry of DNA.
Natural Selection Acts through DNA: Novel Species have Novel DNA
Species: population of organisms that have the potential to interbreed
naturally to produce fertile offspring , but do not interbreed with other groups
non-fertile
offsprings
The logic behind Evolution…
Individual organisms have traits.
Traits are …
Variable: Different versions found among
different individuals in the population
Heritable : Capable of being passed from one
generation to the next
DNA is the molecular basis for heritability and variability of traits!
Some versions of DNA may prove advantageous for survival
and efficient transfer of hereditary material.
What is considered advantageous depends on ???
ENVIRONMENT
It is decided by ???
NATURAL SELECTION
Evolution: change in frequency of inherited traits of a population from
one generation to another, as governed by Natural Selection