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Studyguide Test 2

by: Anna Proulx

Studyguide Test 2 Biol 151

Anna Proulx
GPA 4.0

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Chapters 20, 25, 26, & 27
General Biology
Professor Felege
Study Guide
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This 5 page Study Guide was uploaded by Anna Proulx on Sunday March 6, 2016. The Study Guide belongs to Biol 151 at University of North Dakota taught by Professor Felege in Spring 2016. Since its upload, it has received 41 views. For similar materials see General Biology in Biology at University of North Dakota.


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Date Created: 03/06/16
STUDYGUIDE TEST 2 Ch 20, 25, 26, 27 CH 20 – ENGINEERING GENES Understand some of the basic techniques used in biotechnology including basic genetic  engineering, polymerase chain reaction (PCR), and DNA sequencing. 1. Explain how gel electrophoresis is used to separate molecules. The DNA is separated by  using an electric field to move DNA from wells at negative end toward the positive end,  which takes place in an agarose gel medium. Short segments travel faster, then results are read on a connected machine. 2. Explain the process of DNA sequencing including the important role of  dideoxynucleotides (contain no 3’ OH so synthesis is terminated when a ddNTP is  added). In dideoxy sequencing, a mix of dNTP + ddNTP + DNA + primers + DNA  polymerase undergoes synthesis. Each new strand built off the template DNA will  contain dNTPs and end with a ddNTP, through electrophoresis the sequence can be read. 3. Explain the process of PCR (polymerase chain reaction) including the important role of  “Taq” polymerase (DNA polymerase from Thermus aquaticus). Mix the gene + dNTPs + primers + Taq polymerase, heat the mix so DNA denatures, cool the mix so primers  anneal, heat the mix and Taq polymerase will synthesize complementary strands.  Denature  Anneal  Extend 4. Explain the steps involved in recombinant DNA technology (e.g., using bacteria to  produce insulin or human growth hormone) including how plasmids (circular piece of  DNA), restriction enzymes (endonuclease, cuts the DNA at its staggered recognition  site), and reverse transcriptase (makes cDNA from RNA) are used during this process.  mRNA from healthy cells is harvested, reverse transcriptase synthesizes cDNA from this  mRNA, restriction endonuclease cuts cDNA at its staggered palindrome sequence,  resulting sticky ends are joined together by DNA ligase, plasmid is formed, cells undergo transformation and uptake plasmids from environment, reproduce and make cDNA  library, marked probe binds to target cDNA sequence to identify recombinant cell 5. Explain how genetically modified crops are made including the role of Agrobacterium  plasmids (allowed vitamin A to by synthesized in rice, carry tumor­inducing plasmids  that contain genes for B­carotene to by made). Made to increase resistance to herbivores,  weeds, and improve food quality. 6. Discuss the ethical concerns associated with genetic engineering. Should people without  diseases be able to utilize this therapy, as a cosmetic? Can we play the role of God? CH 25 – EVOLUTION Understand how natural selection has influenced the diversity of life. 1. Explain the definition of evolution (descent with modification and change in allele  frequencies overtime), fitness (ability to reproduce), and adaptation (trait that increases  an individual’s fitness relative to other individuals). 2. Explain what is meant by a scientific theory. A theory has a pattern component, which  describes the pattern of something in the world, and a process component, a process that  produces the pattern. Widely accepted, supported by evidence, not proven. 3. Explain whether or not individuals can evolve. Individuals do not evolve, populations do. 4. Explain whether or not humans evolved from chimps. Humans did not evolve or descend  from chimps, we shared a common ancestor that evolved into separate species. 5. Explain the evolutionary ideas of Lamarck. Species evolve overtime to become better and more complex, individuals pass on acquired characters. 6. Explain how mockingbirds influenced the ideas of Darwin. Distinct mockingbird species  across the Galápagos Islands descended from common ancestor, then changed overtime. 7. Identify monophyletic groups on phylogenetic trees. Includes ancestor and all its  descendants. 8. Explain the concept of homology. Similarity between species, from a trait held by a  common ancestor long ago. Homologous structures: similar structure, modified functions. 9. Explain the concept of convergent evolution. Similarity between species, for reasons  other than shared ancestry. Analogous structures: different structure, similar functions. 10. Distinguish structural (similarity in adult morphology), developmental (in embryos), and  genetic (similarities in DNA/RNA/amino acid sequence) homologies. 11. Identify some of the evidence for evolution. Extinction proven from fossils, presence of  transitional features between ancestor and descendant, and leftover vestigial traits. 12. Explain the four postulates of natural selection (individual traits in a population vary,  traits are heritable, not all offspring survive, and organisms experience differential  reproductive success), and explain whether evolution will occur if any of the four are not  true. All four criteria must be met for evolution to occur. 13. Identify common misconceptions about evolution, and give examples to illustrate why  they are not true.  ­ Individuals Change: false, populations change not the organisms themselves.  ­ Change is Purposeful: false, mutations occur randomly and happen to be advantageous, not  because of want or need.  ­ Self­Sacrifice: false, organisms do not act for the good of the species, the allele for this trait would become obsolete.  ­ Evolution Perfects Organisms: false, vestigial traits exist unnecessarily, trade­offs must be  made CH 26 – EVOLUTIONARY PROCESSES Understand the Hardy­Weinberg concept’s use in documenting changes in allele frequency. Understand the different modes of natural selection. Understand forces beyond natural selection that can shape the evolution of populations. 1. Explain what the Hardy­Weinberg model of population dynamics is used for. Used to  determine if evolution is occurring in a population.  2. Identify the conditions that must be met to maintain Hardy­Weinberg equilibrium.  Populations must be experiencing all of the following: random mating, no natural  selection, no genetic drift, no gene flow, no mutations. 3. Use the Hardy­Weinberg equations (p + q = 1; and pp + 2pq + qq = 1) to predict allele  and genotype frequencies in a population. Example: In population of 10,000 individuals, 8151 are AA, 1742 are Aa, and 107 are aa Observed genotype frequency:  AA = .8151 Aa = .1742 aa = .0107 Allele frequency: A = .9022 a = .0978 AA + ½ Aa aa + ½ Aa (.8151) + ½ (.1742) (.0107) + ½ (.1742) Expected genotype frequency: AA = .8140 Aa = .1765 aa = .0096         p2 =(.9022)^2        2pq=2(.9022)(.0q07)=(.0107)^2 4. Test whether evolution or nonrandom mating is occurring at a particular gene, using the  Hardy­Weinberg principle. 2 (observed−expected) 2 X  = sum   *use numbers of individuals, not decimal  expected frequencies 2 (8151−8140) 2 (1742−1765) 2 (107−96) 2 X =  +   +   = 1.575 8140 1765 96 Our value of 1.575 < table value of 3.841, meaning with 95% confidence we cannot  reject the null hypothesis and the population is in Hardy­Weinberg equilibrium 5. Distinguish among directional (value of a trait shifts and is more frequent, reduces  genetic diversity of a population), stabilizing (reduces frequencies of extreme traits,  reduces genetic diversity), and disruptive (favors extreme traits, increases genetic  variation) selection. 6. Explain the roles of the following in allele change in populations:  ­genetic drift (due to chance, allele frequencies change due to luck, reduces variation  when alleles are fixed or lost) (including founder effect [individuals establish population  in new geographic area, allele frequencies different than in source population] and  genetic bottleneck [sudden reduction in allele numbers in a population]) ­gene flow (movement of alleles between populations, homogenizes allele frequencies) ­mutation (restores genetic diversity, rare beneficial mutations increase in frequency) ­nonrandom mating (gametes not paired at random, certain ones are more likely to come  together than others, changes genotype frequencies not allele frequencies) (including the  implications of inbreeding: speeds evolutionary change, increases homozygosity and  lowers fitness). 7. Explain the concept of sexual selection (mate choice and competition within gender),  including female fitness (choose mates based on physical characteristics and/or resources  provided males) and male fitness (more intense in males, many die without reproducing  whereas most females obtain a mate, male­male competition). CH 27 – SPECIATION Understand why it is difficult to define a species. Understand ways in which new species can form. *speciation occurs when there is no gene flow.  Genetic drift, natural selection, and mutations may still occur. 1. Distinguish microevolution (small scale, within a population/species, change in allele  frequencies) from macroevolution (major changes overtime, with origin of new species,  such as whales descending from land animals). 2. Explain the  ­biological species concept (identify speciation by reproductive isolation, species do not  interbreed/offspring is not viable or fertile)  ­(including prezygotic (prevents fertilization of zygote) and postzygotic (offspring of matings cannot survive or reproduce) forms of reproductive isolation) ­morphospecies concept (identify speciation by distinctive morphology) ­phylogenetic concept (identify speciation by evolutionary history, smallest monophyletic group on tree of life) of species. 3. Explain the roles that gene flow, selection, genetic drift, and mutation play in the process  of speciation. Gene flow does not occur. The other 3 evolutionary processes continue. 4. Distinguish allopatric (populations experiencing geographic isolation, through dispersal  [individuals colonize new habitat] or vicariance [physical splitting of habitat]) from  sympatric (populations living close enough to interbreed) speciation. 5. Evaluate evidence for the formation of new species in plants through hybridization.  autopolyploidy (doubled chromosome # with parents of the same species, less common,  occurs through nondisjunction, tetraploid offspring mate with each other to form new  species that cannot mate with diploid parental species) and allopolyploidy (parents are  two different species, experience error in mitosis that doubles chromosome number and  allows reproduction). 6. Explain why we need three different sets of criteria to recognize species. ­biological: cannot be used for fossils or asexual species, or if closely related populations  do not interact ­morphological: subjective, cannot be used for cryptic species [differ in traits other than  morphology] ­phylogenetic: only available for a small subset of populations 7. Predict what will happen when two partially divergent populations come into contact  again under various circumstances. ­Populations fuse back together ­Reinforcement: natural selection occurs for traits that reinforce each population’s  differences, prezygotic ­Hybrid zone: hybridization in a particular geographic region ­Extinction: one population dies out, poorer competitor ­New species: hybrid offspring with beneficially adaptive alleles may form new species


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