BIO 240 Week 4 Notes
BIO 240 Week 4 Notes BIO 240
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This 3 page Class Notes was uploaded by Miriam Valenzuela on Friday February 20, 2015. The Class Notes belongs to BIO 240 at San Francisco State University taught by Dr. Andrew Swei and Dr. Dennis Desjardin in Spring2015. Since its upload, it has received 33 views. For similar materials see Second Semester Biology in Biology at San Francisco State University.
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Date Created: 02/20/15
Biology 240 Week 4 Notes Origin of Life The diversification of life on Earth began over 38 billion years ago What Geologic events alter the environment Breaking up of Pangea evolution of photosynthetic organisms releasing oxygen Homo Sapiens Early Years Earth s organisms were microscopic unicellular and aquatic Earliest organisms were prokaryotes Bacteria and Archaea present today in hydrothermal vents in ocean floor Prokaryote Fossils stromatolites microbial mats How was the earth back then very hot excessive volcanic activity numerous meteor impacts radiation little oxygen no ozone high UV radiation reducing atmosphere Hypothesis for early Life life developed from nonliving material that gained the ability to replicate and develop a metabolism spontaneous generation Louis Pasteur 1862 rejected idea of spontaneous generation because broth would only spoil if microorganisms could get in Now we adopt the biogenesis hypothesis in which that life can only come from preexisting life Chemical Processes on Earth developed simple cells which then reproduced 1 the abiotic synthesis of small organic molecules 2 joining of molecules into polymers 3 beginning of selfreplicating molecules 4 packaging molecules into protobionts Stanley Miller and Harold Urey 1953 Tested Oparin Haldane hypothesis by making laboratory conditions similar to the environment of the Earth in early years produced variety of amino acids proved that monomers link to polymers Sidney Fox made small polypeptides by dripping amino acids into hot sand RNA World Hypothesis suggests that the first genes were strands for DNA code for proteins RNA molecules might have been able to selfreplicate RNA sequences have both a genotype and a phenotype Genotype what proteins they code for Phenotype How they fold protobionts abiotically produced molecules which can isolate themselves in an internal environment different from the environment they live in which makes it easier to live in harsh environments Early years of the Earth RNA beginnings of biotic diversity Prokaryotes chemoheterotrophs Problem loss of ATP Solution GLYCOLYSIS No Oxygen necessary Increase in Glycolysis meant that you had a decrease in compounds used in glycolysis Natural selection would favor those organisms able to make their own food autotrophs End Result Aerobic Respiration Eukaryotes Evolved from anaerobic heterotrophic prokaryotes Proberties of Eukaryotes membrane enclosed nucleus endomembrane mitochondria and chloroplasts cytoskeleton multiple chromosomes life cycles Trends colonial prokaryotes organisms organized themselves into sheets and layers communities of prokaryotes benefit from each other specially when metabolic processes are concerned compartamentilization of prokaryotes assigning different functions to different parts Autogenic Origin Making of specialized organelles or structures Endosymbiotic Theory Endocytosis of prokaryotes one cell engulfed another cell and used it for energy symbiotic relationship Mitochondria and Chloroplasts evolved from endosymbiotic bacteria They were thought to be organisms themselves but were engulfed by a bigger organism and were used for their energy and their resources Serial Endosymbiosis mitochondria and chloroplasts were prokaryotes living in larger cells Ancestor for Mitochondria aerobic heterotrophic prokaryotes Ancestor for Chloroplasts photoautotrophic prokaryotes Chicken or the egg Chloroplasts are said to have developed AFTER the mitochondria Mitochondria evolved before chloroplasts Evidence for endosymbiotic theory close in size enzymes transport things in and out of their membranes binary fission circular DNA Both have tRNA DNA ribosomes and other transcription and translation factors
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