Biology 102 Exam #1 Study guide
Biology 102 Exam #1 Study guide BIOL 102 001
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This 5 page Study Guide was uploaded by Kaeli on Sunday September 4, 2016. The Study Guide belongs to BIOL 102 001 at University of South Carolina taught by Mihaly Czako in Fall 2016. Since its upload, it has received 62 views.
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Date Created: 09/04/16
Biol 102 Exam # 1 Study Guide Evolution Definition Change in the allele frequencies of a population over time Caused by: Genetic drift o Decreasing frequencies of a certain allele Nonrandom mating Gene flow o Migration from one population to another Natural selection o The only one that causes adaptive evolution Requires: Genetic variability Heritable traits Genetic variation caused by: Mutation Duplication Recombination (During meiosis) o Must result in new alleles o Most important for variation Effects of gene changes in position or number: Typically harmful Small duplications can lead to beneficial functions Hardy Weinberg: p + q = 1 p +2pq+q =12 o p = frequency of dominant allele o q = frequency of recessive allele Used to determine if evolution has occurred To be exact: o No genetic drift o No nonrandom mating o No gene flow o No natural selection o Very large populations Example: You know that a lake contains a population of 400 halloween fish. A fish can be either black or orange, and a black fish is the homozygous recessive bb genotype. 152 of the fish in the lake are black. How many of the fish do you expect to be homozygous dominant? How many heterozygous? q2 152/400 = .38 = Because you know that 152 of the 400 are black, you know how many are 2 homozygous recessive. This genotype is expressed in the equation as q . 2 Therefore q =.38 . 38 = q = .616 Take the square root to find q p + .616 = 1 p = .384 Use basic algebra to find p 2 p = .147 2pq = .473 Substitute to find frequencies for the unknowns .147 * 400 = 59 .473 * 400 = 189 Multiply the frequencies by the original population and you’re done! If you were to then find out the real population of homozygous dominant was instead 100, would you expect that evolution had occurred? YES! – because they differed from the expected populations, a mechanism of evolution must have occurred. Founder effect When a few individuals create a new population New allele frequencies will differ Bottleneck effect When the population decreases immensely Gene pool may differ Random process Modes of selection Directional o Favors one extreme end of phenotypic range o Directional shift Disruptive o Favors extreme ends of phenotypic range o Bimodal Stabilizing o Favors intermediate and acts against extreme phenotype o Narrow distribution Sexual selection Intrasexual selection o Direct competition among males for mates Intersexual selection o One sex (usually females) are choosy about mates Balancing selection o When natural selection maintains stable frequencies of alleles o Heterozygote advantage Example: Sickle cell and malaria Frequencydependent selection o One phenotype becomes too prevalent and is eliminated or decreased Speciation General Speciation o The process of forming new species o Consists of Morphology Physiology Behavior Biochemistry DNA Types Allopatric o Distance creates a reproductive barrier Sympatric o Non distance based o Causes: Polyploidy Sexual selection New ecological niches Types of species Biological o Potential to interbreed Produce fertile, surviving offspring o Do not successfully breed with other populations o Gene flow between populations holds them together genetically o Species can have diversity Morphological o Structural features Asexual inclusive o Objective Ecological o Based on niche Phylogenetic o Smallest group on phylogenetic tree o Difficult to determine what degree of difference is required for a different species Reproductive isolation Prezygotic o Temporal o Habitat o Behavioral Postzygotic o Reduced or no fertility o Reduced or no viability o Hybrid breakdown Fossils Form in sedimentary rocks o Layers called strata Prefer species that: o Had hard parts Such as shells o Were very numerous o Existed for a long time Ages found by radiometric dating Protocells May have formed by a vesicle containing selfreplicating RNA o MUST have been replicating to count as a protocell o Also had a lipid bilayer Spontaneously form in water Clay increases chances of forming
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