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Biol 1020 midterm 3 review review.docx

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BIOL 1020
Andreas Heyland

Lecture 17 -Natural and artificial selection -Pesticide resistance is an example of natural selection, new pesticide may kill 99% of pests, survivors will carry the allele that allows them to do this -Darwin- descent with modification-adaptations that fit species into new environments -Lamarck= organisms evolve by the use and disuse of body parts, and the acquired characteristics are passed on to offspring -Lyells principles of geology- suggests that natural forces are gradually changing the earth and are still operating today -Darwin took from this that present species arose from ancestral species by natural processes Evolution 1-individuals do not evolve, populations evolve 2-natural selection can amplify or diminish only heritable traits, acqiored characteristics cant be passed on to offspring 3-it is not goal directed and does not lead to perfection, favorable traits vary as environment changes -is contingent on time and place -can occur in a short time -is an editing process more than a creative mechanism -can be seen working in organisms today such as antibiotic resistance -favourable mutations are rare Lecture 18 Populations can be isolated from one another with little interbreeding Individuals within a population may interbreed Evolution is measured as a change in heritable traits in a population over generations Gene pool- total collection of genes at any one time Microevolution- is a change in relative frequencies of alleles in a gene pool over time Mendle – p156 Dominant + recessive genes Genetic variation – independent orientation Crossing over – exchange of genetic material between homologous chromosomes Random fertilization Chromosomal duplication- if the gene is duplicated the new copy can undergo mutation without affecting the function of the original Genetic drift- change in the gene pool of the population by chance ie. Bottleneck effect Gene flow- is the movement of individuals or gametes/spores between populations, can alter allele frequencies in a population, i.e- introducing new member to decreasing populations to introduce new alleles. Speciation – process in which one species splits into two or more species- Allopatric speciation- population of the same species are geographically separated, isolating their gene pool. -isolated pop will no longer share changes in the allele frequency Sympatric- new species arises in the same geographical area as the parent species -gene flow beteween the pops may be reduced by polyploidy Lecture 19 The oldest fossils are prokaryotes and are 3.5 billion years old. -the oldest fossils of eukaryotes are about 2.1 billion years old -the first multicellular plants and fungi began to colonize land about 500 million years ago -evolution of animal phyla occurred about 542 million years ago -human originates about 195 000 years ago Macroevolution - Tectonic plates- the formation and break up panglea affected the distribution and diversification of organisms Lecture 20 Common ancestors of all organisms- bacteria, archaea, eukarya Prokaryotes lack a cell nucleus, mitochondrial or any other membrane bound cell organelle. -not all prokaryotes are bacteria but all bacteria are prokaryptes - almost all have cell wall that can contain large amounts of peptidoglycan gram +, or low gram – Prokaryote cell shapes -cocci- spherical- streptococci -bacilli- rod shaped -spiral Prokaryotes pop growth occurs rapidyly through binary fission- certain types of eukaryotes undergo fission ie. Trichoplax adherens The genome of a pro typically has about one thousandth as much dna as a circular chromosomepacked into a distinct region Nutritional diversity -sources of energy – phototrphs capture enrgy from sunlight -chemotrophs harness the enrgy stored in chemicals Two sources of carbon- autotrophic – CO2 -hetertrophs- organic compounds in other organisms Biofilms -complex associations of one or more several species of prokaryotes and may also include protists and fungi -bio
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