Continuity

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Continuity

• A Primer on Genetics and Evolution

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The Big Concepts
Heritability of Traits establishes continuity
of life forms Gene Theory - gene is the unit of
inheritance Nucleic Acids Molecular Basis of
Inheritance Central Dogma DNA ? RNA ?
protein Genotypic Variation crossing over,
mutations Phenotypic Variation - traits vary,
result of genotypic variation and environmental
influence Natural Selection differential
reproductive success based on phenotype
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Heritability of Traits
Gregor Mendel principles of heredity Monohybrid
Crosses crossed pure strains of contrasting
traits (phenotype) produced F1 Hybrids (all
same phenotype) eg. Tall vs. dwarf all
tall NOT a simple blending of
traits! self-fertilization of F1 ? 31 ratio in
F2 Conclusion F1 contained both factors
(alleles) one dominant (observed), one
recessive dominant rep. By capital letter
(T) recessive rep. By lower case letter
(t) Law of Segregation 2 factors segregate
independently
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Dominant vs. Recessive Phenotypes Homozygous vs.
Heterozygous Genotypes How to differentiate
between Heterozygote and Homozygous
Dominant?? The test cross Cross with
homozygous recessive Expected Results?? Bio 114
virtual fruit fly lab
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DiHybrid Cross
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Conclusion Law of Independent Assortment
factors on different pairs of homologous
chromosomes sort independently during meiosis.
No linkage, Mendel was very lucky
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Fig. 5.2a
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Fig. 5.2b
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Storage and Transfer of Genetic Information
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Translation
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Translation Animation
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Animal of the Day
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Caenorhabditis elegans (C. elegans) Phylum
Nematoda Class Rhabditea
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Microarray Analysis C. elegans
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Organic Evolution
Living World in perpetual change
Evidence? Fossil Record biased, preservation
selective But, change in animal form and
diversity (species richness) is indisputable
Current History emerging diseases antibiotic
resistant bacteria pesticide resistant
insects documented species extinctions
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Common Descent
All forms of life have descended from ancestral
forms -trace backwards to primordial
species Phylogenetic Tree (Tree of Life)
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Speciation (Multiplication of Species)
Allopatric Speciation-
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Non-allopathic (Sympatric) speciation
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Cichlids of Lake Malawi
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Adaptive Radiation
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Gradualism vs. Punctuated Equilibrium
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Natural Selection
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Microevolution
Genetic Variation and change within a species
change in allelic frequency Allele alternate
character state of a particular gene can be more
than 2, eg. ABO blood types Genetic Equilibrium
how are recessive traits maintained in a
population? Eg. Blond hair, blue eyes, O blood
type Hardy-Weinberg Equilibrium Box on
p.122 no change in allelic frequency unless
disturbed by mutation, migration, natural
selection, nonrandom mating or genetic drift
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Macroevolution
Major Evolutionary Events speciation,
extinction Stephan Jay Gould evolutionary
processes take place over 3 distinct time
scales 1st population genetic processes tens
to thousands of years 2nd speciation and
extinction millions of years 3rd mass
extinctions tens to hundreds of millions of
years
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