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BIOL 2061 1st Edition Lecture 3Outline of Last Lecture I. How did life begin on EarthII. When did life begin on EarthIII. 4 overlapping stages of lifeIV. Advantages to DNA/RNA/proteins Outline of Current LectureI. Environmental changesII. Origin of EukaryotesIII. Geologic timeIV. Characteristics of lifeLecture:I. Environmental changes- conditions on earth have NOT stayed the same for over4.6 billion yearsa. Changes-i. Climateii. Composition of atmosphereiii. Position of land massesiv. Cataclysmic events- floods, ice ages, volcanic eruptionsb. Planet conditions affect lifei. Ice age= extinctionThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c. Life affect the planet conditionsi. New plants convert CO2 to O2ii. Humans create pollutions causing global warmingd. Heterotrophs or Autotrophs first?i. Scientists believe that heterotrophs came first because there was originally no oxygen in the atmosphere and heterotrophs can do anaerobic cellular respiration.ii. If autotrophs were first then oxygen would’ve been present II. Origin of Eukaryotesa. Endosymbiosis- small organism lives inside a larger organism(picture)b. Origin of Multicellular Eukaryotes (commonalities)i. Single cell divides to produce two daughters cellsii. Daughter cells can follow different paths, producingmulticellular organisms with different cellsiii. Most cells are somatic cells iv. Some cells are specialized for reproductionIII. Geological timea. Epochs Eons Eras Periodsb. There’s been 5 mass extinctions IV. Characteristic of life (in order, 1st to last)a. Prokaryotes arise--- atmosphere had very low oxygenb. Multicellular eukaryotes arise--- oxygen is in atmospherec. Terrestrial plants and arthropods arise--- warm and moist conditionsd. Vertebrate life forms arise--- warm and wet conditions with no ice at polese. Gymnosperms arise, first terrestrial tetrapods arise, fish flourish in the oceans--- dry in the north and ocean in the southf. During the time, the plants that now are source of fossil fuel were growing, amniotic eggs arise, reptiles arise--- cool conditions, and Earth is covered on swampsg. Mammals arise--- volcanos and global warmingh. Birds arise---Hot climate, dry terrestrial with little icei. Humans arise--- tropical conditions with dry


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