Download Agents of Evolutionary Change

Shape of the Day
• Quiz: Structure of DNA
• Agents of Evolutionary Change Notes
• The Evolution of the Smartie
• **Hand in Yeast Lab Write ups***
Review…
• DNA carries the hereditary information
• Double helix
– Sugar-phosphate backbone
– Nitrogenous bases
• Provides the code to make all of the
proteins that make up the organism
Agents of Evolutionary
Change
Biology 11
• Allele-a different form of a particular
gene
• Example: Genes for flower colour: purple
allele vs white allele
Mutation
• A change in the sequence of DNA
• Mutations can occur when
– There are errors when DNA is copied
– There is exposure to mutagens (chemicals or
radiation)
• Changes to the genetic code lead to
different traits arising
• If the DNA changes the germ line
(gametes), offspring will have same
mutation
• Changes to somatic cells will not pass on
(somatic are all other cells)
• Mutations can lead to…
– No changes in phenotype (physical traits)
– Small changes
– Big changes
• Mutations are random
• Mutations can be beneficial, neutral, or
harmful for the organism
Mechanisms of Change
1. Mutation
–New genes can become more
frequent in population
–Ex. Parents with genes for green
colouration have a offspring with
genes for brown colouration
• Example: Peppered Moth
• Which would be better able to survive
and reproduce in their habitat?
2. Gene Flow (Migration)
• Movement of genes from one population
to another
3. Genetic Drift
• Change in frequency of an allele
• Each generation some individuals leave
behind more offspring than others
4. Non-Random Mating
• Probability that two individuals in a
population will mate is not the same for
all possible pairs of individuals.
• http://www.youtube.com/watch?v=p9zK
d3dfz8I
• http://www.youtube.com/watch?v=U89t
w093s_Y
5. Natural Selection
• the process whereby organisms better
adapted to their environment tend to
survive and produce more offspring