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Chapter 3

Biology Text Book Notes - Chapter 3.docx

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Department
Biology
Course
Biology 1202B
Professor
Richard Gardiner
Semester
Winter

Description
Biology Text Book Notes Lecture 1: Chapter 3 Origin of Life Panspermia:  Asteroids (coming from mars) brining organic matter to earth proving that there could have been life on MARS  ALH84001: found to be 4.5 billion years old o Same age as our solar system (earth was formed 4.6 billion years ago)(universe was formed 15 billion years)  Strong evidence that there was life on mars o ALH84001 had been fractured and subsequently split by liquid H2O o Fossilized prokaryotes found on ALH84001 o Found microscopic minerals “globules’; strong resemblance to mineral alteration caused by primitive prokaryotes on earth o Meteorite contains an abundance of polycyclic aromatic hydrocarbons (PAH)  Formed when microorganisms die What is life  Atoms found in living are no different then atoms in non living things (abiotic)  Follow same fundamental laws of chem. And physics 7 Characteristics of Life: 1. Display order 2. Harness and utilize energy 3. Reproduce respond to stimuli 4. Exhibit homeostasis 5. Growth and development 6. Evolve **Virus is not considered alive  lack the cellular machinery to synthesize their own proteins Spontaneous Generation:  Living matter cannot generate spontaneously from non-living matter o Louis Pasteur  Different in earlier earth; First cell arose where there had been no life  Louis Pasteur proved there is no spontaneous generation but not how the first cell came alive Cell theory 1. All organisms are composed of one or more cells 2. The cell is the smallest unit that has the properties of life 3. Cells arose only from the forth and division of preexisting cells Early Atmosphere  Very different then today o Today is oxidizing atmosphere o Today is colder then the early  The early atmosphere had o No ozone (03) due to lack of O o Abundance of H2O vapor o Large quantizes of H2S, CO2, NH3, CH4 o Reducing atmosphere  No free O2 o Free hydrogen and Hydrides (CH4, NH3, H2O) o Energy-electric discharge in storms or solar energy  No ozone layer Oparin-Haldane Hypothesis - Maximum number of H and electrons fully recued o Rich electrons can be donated to make reaction occur which can lead to the build up of complex organic molecules Miller-Urey Experiment - Oparin and Haldane hypothesized the ultra violet light and abundant of lightening provide energy that combined with reducing condition lead to the accumulation of building blocks required for life. - Later Miller and Urey tested the hypothesis o Recuing components into apparatus and exposed to continous sparks  H2O vapour was added o After a week organic compounds were found  Urea  Amino acids  Lactic  Formic  Acetic acid  Others now also found  Hydrogen cyanide HCN  Formaldehyde CH2O Polymers - Nucleic acid are polymers or nucleotide - Proteins are polymer of simple sugar - Polymers wouldn’t have survived in the aqueous environment or primordial earth as they would have hydrolyzed o Hydrolyzed: break down by adding H2O o Condensation: forming polymers by removing water - However an alternate hypothesis is that solids surfaces: clay would have provided an unique environment for polymerization to occue - Clay can also store potential energy and therefore could have channeled some of the energy into the reaction taking place on them. Protobionts - Protobiont: a group of abiotically (non living) produced organic molecules that are surrounded by a membrane or membrane like structure - Allows for internal environment to develop that is different from the external environment - Could have form spontaneously, given the condit
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