DNA to Dinosaurs

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DNA to Dinosaurs!
California Standards 4.d., 6.c., 7.d., 8.a. b.
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Or how is it that a change in the nucleotide
sequence of DNA can result in a change in the
population of any species so it is better adapted
to its environment?
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Nucleotides are made up of a phosphate molecule,
a sugar and a nitrogen base.
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A change in a nucleotide can result in a change
in gene expression
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Therefore anything that can change a nucleotide
will result in a mutation.

• 1. Ultraviolet radiation due to ozone break down.
• 2. Chemicals in the environment.
• 3. Changes in the animals habitat such as
• Food source
• Temperature
• Population density, etc.

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This mutation therefore changes the gene
expression or phenotype of the organism.
Darwin observed a change in beak type of
Galapagos finches.
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Factors that affect gene expression

• 1. Density dependent factors
• ? food
• ? water
• ? available nesting areas
• 2. Density independent factors
• ? Change in temperature
• ? light intensity

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These factors can change nucleotide sequence at a
number of stages of gene expression

• 1. During DNA replication.
• 2. During transcription of DNA to mRNA within the
  nucleus.

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• 3. During translation when mRNA translates
  information in mRNA into protein in the cytoplasm.

• 4. During protein synthesis when the amino acid
  sequence changes in the ribosome.

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Cell Cycle
DNA Replication
Gene Expression
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All of this molecular genetics gave rise to

• Charles Darwins Theory of Evolution
• This theory stated that organisms change (mutate)
  in response to their environment.
• Organism adapt to their environment and those
  that adapt the best produce more offspring.

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• Those that produce more offspring will have more
  of their genes in the environment
• Therefore, more of these offspring will be better
  able to adapt or survive and produce even more
  offspring with the same genes.

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• Organisms either adapt or change or they will
  become extinct.
• Species can become isolated due to water
  barriers, desert barriers, mountain barriers to
  evolve into different species.

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Evidence to Support Darwins Theory?

• Homologous structures
• Vestigial structures
• DNA evidence

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Homologous Structures
Vestigial Structures
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Forces of Nature Resulted in

• Divergence in populations which resulted in new
  species.
• Formation of new species is called speciation.
• Creates ecological races which are species that
  have adapted to new environmental pressures.

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Population Dynamics

• The change in populations due to a change in
  their environment.
• Population size number of individuals in a
  population
• Population density number of individuals per
  unit area, (birds per meter squared).

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Changes in Population Genetics

• Genetic Drift random change in gene or allele
  frequency, occurs with small populations
• Gene flow movement of individuals into or out
  of a population
• Nonrandom mating mating with relatives
  (inbreeding)

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Dispersion Models

• Random location of each individual
  self-determined.
• Clumped location of individuals bunched
  together in clusters.
• Evenly located at regular intervals

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These Models result in
Stabilizing selection
No. of birds
Beak Size
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Divergent populations
Directional Selection
No. of Birds
Beak Size
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Hardy-Weinberg principle

• No nonrandom mating
• No genetic drift
• No Natural selection
• No gene flow

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However,

• Environments change
• Mutations occur
• Populations migrate into and out of areas
• There is selective mating going on all the time

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Now you can Connect the Dots