unit 3 – evolution lesson 1 – mutations and artificial selection
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Unit 3 – Evolution Lesson 1 – Mutations and Artificial Selection. Unit 3 – Evolution. Evolution. What is evolution and why is it important?. Genetic Diversity and Evolution. The mechanism that drives evolution is natural selection. - PowerPoint PPT PresentationTRANSCRIPT
Unit 3 – EvolutionLesson 1 – Mutations and Artificial Selection
Unit 3 – Evolution
Evolution
What is evolution and why is it important?
Genetic Diversity and Evolution The mechanism that drives evolution
is natural selection. Natural Selection: the way in
which nature favours the reproductive success of some individuals within a population over others.
Genetic diversity must be present for nature to favour some individuals over other
Mutations and Genetic Diversity Mutations are the source of genetic
variation What mechanisms have we studied
that increases this genetic diversity?
How Mutations Occur
SubstitutionA substitution is a mutation that exchanges one base for another (i.e., a change in a single "chemical letter" such as switching an A to a G).
-Such a substitution could cause a small change in the protein produced.
For example,sickle cell anemia is caused by a substitution in the beta-hemoglobin gene, which alters a single amino acid in the protein produced.
Sickle Cell Anemia
Heritable disease Codominant Chronic pain
caused by RBCs moving through blood vessels.
Stroke, other cardiovascular complications
How Mutations Occur
InsertionInsertions are mutations in which extra base pairs are inserted into a new place in the DNA.
DeletionDeletions are mutations in which a section of DNA is lost, or deleted.
Types of Mutations Neutral mutation - a mutation that does not
result in any selective advantageor disadvantage.
Harmful mutation - any mutation that reduces the reproductive success of an individual and is therefore selected against; harmful mutations do not accumulate over time
Beneficial mutations - are favoured by
natural selection and accumulate over time
Articifical Selection
Artificial selection - directed breeding in which individuals that exhibit a particular trait are chosen as parents of the next generation; artificial selection is used to produce new breeds or varieties of plants and animals
Guide to Artificial Selection1. Choose a useful species that can be bred in
captivity.2. Breed a large number of individuals.3. Choose a trait that you wish to favour, such
as large size, a particular colour, or sweetness.4. Identify individuals that exhibit the favoured
trait most strongly.5. Breed only these individuals to produce the
next generation of individuals.6. Repeat Steps 4 and 5 over many generations.
Limitations of Artificial Selection Artificial Selection is limited by the
genes that are present in the current population.
Induced Mutations
Thalidomide