Transcript BIO 200 Exam 2 Review

BIO 200 Exam 2 Review
MAY THE CURVE BE EVER IN YOUR FAVOR
Evidence from Genetics – Mendel
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Mendel – pea experiments
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Blending inheritance – NO
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Particulate inheritance – YES
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3:1 phenotype ratio for monohybrid cross
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9:3:3:1 phenotype ratio for dihybrid cross
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Legacy
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Particle Theory of Inheritance
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Law of Segregation
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Law of Independent Assortment
Evidence from Genetics – After
Mendel
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Most traits are polygenic
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Some genes are pleiotropic
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Genes arranged in linear array on chromosomes
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We see chromosomes when stained before cell division
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Polyploidy possible, often in plants
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Genes on same chromosome are linked
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Distribution of chromosomes and crossover between sister chromosomes
during meiosis lead to genetic recombination
Evidence from Biochemistry
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DNA
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Double stranded, Purines – A+G, Pyrimidines – C+T
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Held together by hydrogen bonds
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Know DNA replication concept
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Repairs – proofreading, mismatch repair, excision repair
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Know central dogma
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Hox genes are super important
Mutations/Molecular Clocks
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Types of mutations
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Structural changes – loss/duplication of whole genes, changes in gene arrangement
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Numerical changes in chromosomes
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Point mutations
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Protein chain length modifiers
Homeotic Genes
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Regulate/control clusters of genes
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Similar sequences in all multicellular organisms
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Causes/Effects of Mutation
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When do mutations affect evolution?
Acquired Characteristics/Epigenetics
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Epigenetics
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Changes in expression of genes without changing DNA sequence
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Adding methyl groups to cytosine – inactivates gene, heritable
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Histone modification of chromatin
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Environmentally-induced
Population Genetics
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H-W Equilibrium – p2+2pq+q2=1 and
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No mutation
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No selection
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No gene flow
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Infinite population size
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Random mating
p+q=1
THIS DOESN’T OCCUR IN REAL LIFE – this is just a standard against which we
compare to show that evolution is occurring
Selection
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Stabilizing vs. directional vs. disruptive
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Microevolution – short term changes in allele frequencies within
populations
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Macroevolution – long-term patterns/changes
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Environment chooses whether or not trait is favored
Interspecies Relationships
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Types of interactions – predator/prey, parasite/host, mutualism,
competition, commensalism, ammensalism
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Coevolution – “evolutionary arms race”
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Defense to avoid predation – camouflage, chemical repellants, types of
mimicry
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Competition – intraspecific
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Caused by limited resources, results in reduced growth and reproduction rates
Competition – interspecific
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Usually fighting over some sort of resource – can be alleviated via resource
partitioning
Speciation
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Species definitions – morphological, reproductive (biological), lineage
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Barriers and gene flow
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Allopatric speciation – physical barrier
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Sympatric speciation – no physical isolation, but speciation anyway
Reproductive Isolation
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Prezygotic – mechanical, temporal, behavioral, habitat, gametic
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Postzygotic – low hybrid zygote viability, low hybrid adult viability, hybrid infertility
Adaptive radiation – rapid speciation from a common ancestor; each new
species specialized for different niche (e.g. when dinosaurs became extinct)
The Origin of Life
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Miller-Urey demonstrate that organic molecules can be created in
environment present on early Earth
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First cells – Szostak shows that fatty acids in water form a “huddle,”
creating a lipid bilayer – “Protocells”
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First cells probably used catalytic RNA – “RNA World Hypothesis” – DNA
evolved from RNA
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First organisms – blue-green bacteria
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TIMELINE
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Big Bang (13.8 bya) --- Formation of our solar system (4.6 bya) --- Oldest rocks
(4.4 bya) --- Chemical fossils (3.8 bya) --- Fossils (3.5 bya)
Viruses
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Most abundant “life form” numerically – depend on cellular organisms
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Same form of genetic information storage and transmission as cellular
organisms
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Retroviruses
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Some viral DNA gives us new functions when incorporated into our genome
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Bacteriophage – inserts genetic material into host cell and turns it into a virus
factory; some viruses enter cells intact, shed coat, take over cell machinery
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Lytic vs Lysogenic Life Cycle
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HIV – enveloped retrovirus, rapid emergence of drug-resistant strains