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