Homologous structures common ancestry o Structures or other attributes in different species that resemble each other because of o Ex mammalian forlimbs vertebrate embryos o All vertbrates share similar developmental genes o Differences arise by genes being switched on or off at varying times during development With in a few weeks of treatment with the drug 3TC a patient HIV population consists almost entirely of 3TC resistant viruses How can this be explained o A few drug resistant viruses were present at the start of treatment and through natural selection increased their frequency Artificial selection o Selective breed of organisims to encourage the occurrence of desirable traits o Analogous to natural selection o The unequal survival and reproduction of organisms due to environmental forces Mechanism Behind Natural selection o Variability o Heritability o Differential reproductive success Natural Selection resulting in the preservation of favorable adaptations o Process selects from what is available in the gene pool o New characteristics are not created on demand Evolution by natural selection o Darwin and Wallace develop thr theory indpendantly Darwin voyage of the beagle Wallace Naturalist in Indonesia Pre Darwinian theory of evolution o Lamark o Use and disuse bodies of living organisms are modified through the use or disuse of parts o Inheritance of acquired characteristics These modifications are inherited by offspring o These ideas turned out to be wrong Evolutionary adaptation o Accumulation of inherited characteristics that enhances organisms ability to survive in specific environment Evolution Dating of fossils o Change overtime of the genetic composition of a population o Decent of modern organisms with modification from pre existing organisms o Order of fossils in rock strata tell us the sequence in which they laid down o This provides relative ages not absolute dates o Radiometric dating can determine absolute ages of fossils Radioactive isotopes decay into daughter isotopes at fixated rate life the amount of time it takes for 50 of an isotope to decay Fossils document the history of life o Sedimentary strata reveal the relative age of fossils Fossils near surface more recent Fossils deeper more ancient Origin of self replicating molecules o Now DNA RNA Proteins Needs proteins to synthsize more DNA o Then earliest cells used RNA to store info o Ribosomes to catalyze reactions Oxygen has a influence of the formation of complex organic molecules because o Negative its highly reactive Alternate Hypothesis o First organic compounds may have been synthesized near hydrothermal vents o Extraterrestrial origin Protobionts o Aggregates of abiotically produced molecules surrounded by a membrane o Liposomes can form when lipids or other organic molecules are added to water Joining molecules into polymers o Small organic molecules polymerize when they are concentrated on hot sand or clay lava or hot rocks in early earth o Lab expieriments support this occurrence Testable hypothesis explaining the origin of life o 1 abiotic synthesis of small organic molecules Miller Urey Expieriment o Joining these molecules to protobionts o The origin of self replicating molecules Conditions on early earth o Atmosphere made up of CO2 CH4 NH3 H2S H2O o No free oxygen o Abundant energy to drive reactions From storms with lighting and volcanic eruptions Early earth o About 4 6 billion years old radiometric dating of meterorites and moon rocks o Life arose about 3 8 billion years ago Chemical traces in rocks 3 8 billion years Fossil bacteria in rocks 3 5 billion years o There is No spontaneous generation now but it must have happened then What evidence suggests that eukaryiotic cells formed symbionic relationships with bacteria o Both chloroplasts and mitochondria contain DNA that is distinct from the nucleus of eukayotic cells o Similarities in inner membrane structures and functions o Both chloroplasts and mitochondria have their own ribosomes and make proteins independent from the cell may have evolved from aerobic bacteria and may have evolved fromphotosynthetic cyanobacteria engulfed by heterothopic cells then kept alive with in the host o Mitochondria chloroplasts What were the earliest organisms like o Prokaryotes Bacteria and archea Fed on accumulated organic molecules heterotrophic some were likelyautotrophic The radioactive isotope 40K decays into 40Ar and has a half life of 1 25 billion years If a newly formed rock contains 100 units of 40K how many units of 40K would it contain after 1 25 billion years How many units of 40Ar would the rock contain when newly formed after 1 25 billion years After 2 5 billion years what would the ratio of 40K to 40Ar be in the rock o 50 o 50 o 25 40K 75 40Ar Radiometric dating o Can determine absolute ages of fossils o Radioactive isotopes decay into daughter isotopes at a fixed rate o life is the amount of time it takes 50 of an isotope to decay Which of the following statements about the origin of genetic material is most probably correct The first genes were o Self replicating catalytic RNA molecules A factor that contributed greatly to the prolonged existaances of simple organic molecules in earths prebiotic oceans was o The virtual absence of atmospheric oxygen The miller urey experiment is significant because it produced evidence that o Conditions on earth 4 billion years ago could in principle produce amino acid o Structures that are similar in function but not in structure and developmental and What doesn t promote sympatric speciation o Gene flow Analogous Structures evolutionary origin Biochemistry and molecular biology o DNA is universal genetic material o All life use approx the same 20 amino acids to make proteins o All use ATP as the primary form of cellular energy o All use RNA and ribosomes to make protein Convergent evolution o Similarity between 2 organisims structure or molecules due to independent evolution along similar lines rather than decent from a common ancestor Which of the following pairs of structures is least likely to represent homology o The legs of a bird and those of an insect The evolution of populations o The smallest unit of evolution One common misconception about evolution is that individual organisms evolve during their lifetime Evolutionary processes eg Natural selection acts on individuals but populatons evolve Mutations o Changes in nucleotide sequence of DNA Source of new alleles and genes o Chromosomal
View Full Document
Unlocking...