Exam 1 01 16 2013 Mastering Biology MBPOLLOCK01639 not graded Quizzes on Moodle Three Domains of Life Bacteria Archaea Eukaryote o Go back in time no Eukaryotes o Go back further no archaea o 3 8 4 billion years ago nothing chemical traces o No theory to describe how life came about only hypotheses Several possible explanations Octums razar simplest explanation is the most likely Earth is 4 6 billion years old know because of the moon Difference between hypothesis and theory History of Life on Earth The experiment of Miller and Urey look up picture o Wanted to know what Earth looked like before organisms o Put together what they thought was the original compounds in the air but forgot oxygen o Created lightning o Would something living come out of this experiment No it o Ran for a few days and realized the water they were circulating got brown which told them some kind of reaction didn t work was happening o Took a sample of water but still nothing living but some of the molecules that were forming were biological molecules building blocks of life o So if this process happened all over the Earth with millions of years we could possibly create something o Purified water electric spark chamber stimulates a lightning storm gases of primeval atmosphere organic molecules appear after only a few days Theory of evolution by natural selection When life appeared through time it began to change for over 4 billion years 100 billions of species on planet today o All related o Prebiotic soup How did life begin A few centuries ago o People thought that new living things appeared all of the time Didn t have much technology no microscopes Through seasons things tend to appear all the time Spontaneous Generation Refuted o Mid 1800s Louis Pasteur famous for pasteurizing milk o Broth in flask is boiled to kill preexisting microorganisms as broth cools condensing water collects sealing the mouth of the flask no life in flask it wouldn t spoil if neck is later broken off outside air can carry microorganisms into broth Life came from the air outside environment Ex If leave a steak on counter as opposed to putting in a sealed container Contradicts the spontaneousness that life just started somehow 4 billion years ago Conditions on Early Earth Atmosphere o CO2 CH4 NH3 H2 N2 HCl H2S H2O similar to Jupiter o No free oxygen o Frequent storms with lots of lightning massive sources of energy that help catalyze things on Earth o Frequent volcanic eruptions massive sources of energy that help catalyze things on Earth o Frequent meteor impacts massive sources of energy that help catalyze things on Earth o UV light from the sun o No ozone layer Earth before life Arose Earth is about 4 6 billion years old o Radiometric dating of meteorites and moon rocks how we measures this o What can change rate of decay speed of light Life arose about 3 8 billion years ago o Chemical traces in rocks 3 8 billion years ago o Fossil bacteria in rocks 3 5 billion years ago o No spontaneous generation now but must have happened then From that life we have all life on planet today Rate of decay of 40K to 40Ar o Potassium 40 40K naturally decays to argon 40 40 Ar o Half lives o Know this o Look at powerpoint How to Assemble a Living Thing Accumulation of organic molecules o Pre biotic soup Catalyze reactions o Enzymes proteins or peptide bonds some RNAs Reproduce from stored genetic information DNA Separate the living thing from the outside environment o Membranes The Chicken of the Egg Now DNA RNA Protein central dogma of biology o Need proteins to synthesize more DNA o How do you replicate DNA DNA helicase polymerase okasaki fragment DNA ligase Three proteins to make DNA To make proteins you need DNA o RNA to store information and can catalyze certain reactions So how did earliest cells do it o Ribozymes RNA enzymes RNA molecules that can catalyze reactions especially those involved in synthesis and processing of RNA itself Conclusion Earliest cells used RNA to store information Ribozymes to catalyze reactions Separate inside from outside o Microspheres as Proto Cells Just add fat and protein to water then shake Different amino acids hydrophobic hydrophilic disulfide bonds Water elements energy Prebiotic soup Amino acids nucleotides lipids sugars Microspheres like protocels surrounding more complex Organic molecules like RNA carbohydrates proteins lipids First prokaryotes science miracle Drake equation of the probability of this ever happening anywhere else Family Tree of life phylogeny evolutionary tree Look at picture Eucarya third multicellular o Land plants green algae red algae amoebas cellular slime molds animals fungi forams ciliates dinoflagellates diatoms euglena trypanosomes leishmania Archaea second Bacteria first o Sulfolobus thermophiles halophiles methanobacterium o Green nonsulfur bacteria mitochondrion spirochetes chlamydia green sulfur bacteria cyanobacteria plastids including chloroplasts Common ancestor of all life first species o Because of this we have 100 million species o Right off the bacteria branch Homo sapiens 200 000 years Theory of evolution by natural selection Evolved from very simple bacteria Body composed of 50 trillion cells Principles of Evolution Why are there so many species Taxonomic family groups classification Lenais o Predicted evolution from certain things What is science theory hypothesis Look in power point Charles Darwin Theory of Evolution People realized before him that there were family classifications and groups and had a hypothesis that life on the planet changed Didn t know about DNA Mendel Wallace also had similar ideas so they communicated but were also competing Darwin beat him to it Voyage of HMS Beagle o Went around South America Africa Great Britain Galapagos Islands and around Australia o Took samples of fossilized creature and other living samples o As the creatures moved from South America to the Galapagos Islands they started to change o The tortoise shells were different o Swimming iguana for seaweed o Finches Darwin thought they were a bunch of different types of birds modern day DNA has placed them all in the Islands Seed eaters bud eaters insect eaters The Origin of Species by means of natural selection was published in 1859 o At this time it was a hypothesis o Main points of Origin of Species Evolution occurs in populations Population all individuals of one species in one Growth with reproduction inheritance variability a ratio of increase so high as to lead to a
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