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Lecture 2

Biology Lecture 2 Outcomes

5 Pages

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Biology 1002B
Tom Haffie

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Lecture 2 7 Basic Characterists of Life  Display Order o Arranged in a highly ordered manner o Cell: fundamental unit of life  Harness & Utilize Energy o Acquire energy from the environment and use it to maintain state  Reproduce o Have the ability to make more of their own kind  Respond to Stimuli o Can make adjustments to their structure, function and behavior in response to changes to external environment  Exhibit Homeostasis o Regulate internal environment so that conditions stay relatively constant  Growth & Development o Increase their size by increasing the size/number of cells  Evolve o Populations change over generations to become better adapted to the environment Origin of life: *Early forms of life formed in an environment lacking oxygen LUCA  3 main domains of life: Bacteria, Archea, Eukarya  Last Universal Common Ancestor  Evidence of Existence: all forms of life share universal features o All made of cells o Cells made of lipids o Genetic system based on DNA o DNA to RNA to Proteins transfer of information o Common system of protein assembly (ribosomes, mRNA, tRNA) o Proteins (fundamental structural molecule) o Metabolic pathways (ATP & Glucose) Electron Transport Chain o Glucose o Cytoplasm 1 Lecture 2 Life Developed Early  Stromatolites (3.5 bya) structures that are produces by microbial activities (fossils) o Layered rock that is formed when microorganisms bind articles of sediment together, forming thin sheets o Formed by cyanobacteria – modern – posses a sophisticated metabolism Stages of Prebiotic Evolution: what do you need? 1. Abiotic synthesis (where biologically important molecules were made without presence of living things) 2. Heritable information (to continue evolutions) 3. Formation of cells Geophysical Stage  Early (primordial) atmosphere: H2O, H2, CH4, NH3, H2S  Energy sources: UV light, lightning  Reducing atmosphere (atmosphere is filled with electron rich molecules, amino acids, glucose etc are highly reduced so we can get energy from them)have lots of e- Chemical Stage can one make organic molecules from inorganic molecules?  Important Monomers o Amino acids o Sugars o Purines and prymidines  Abiotic synthesis today? (organic from inorganic molecules) o No, O2 is in the air, creates an oxidizing atmosphere and rips off any electrons in its surrounding  Deep Sea Vents: Nutrient rich, teaming with life, lots of sulphur and ammonia, life may have formed there Miller Urey Experiment o Demonstrated that abiotic synthesis of biologically important molecules such as amino acids, sugar, nucleotide bases, lactic, acetic, formic acid, is possible o Reactants  Water vapor  Ammonia  Methane gas  Hydrogen gas o Conditions  Heating by sun  Cooling at night  Radiation from the sun 2 Lecture 2  Energy from electrical storms o Results (after 1 week)  Aldehydes, carboxylic acids formed  Glycine and alanine formed  Amino acids  Sugars  Purines & pyrimidines Chirality  A molecule not superimposable on its mirror image o Two enantomers (optical isomers) o Handedness o Same chemical and physical properties o Different biological properties Thalidomide  Used as a “morning sickness” drug in 1960s o Approved by 20 European countries o Causes birth defects because of the chirality  One form is an antiemetic (stops sickness) and other is teratogen (causes defects, interrupts normal limb development) The chirality problem  Miller Urey exper
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