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Notes mid 1 - BIS 1A Class Notes Characteristics of Life -...

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BIS 1A Class Notes Characteristics of Life - Evolutionary milestones o Planet: 4.5 billion years old o 3.8 bya – 1 st life – prokaryotic “protocell,” probably anaerobic heterotroph o 3.5 bya – 1 st fossils (cyanobacteria_ - photoautotroph o 2.5 bya – oxygen more abundant o 1.5 bya – unicellular Eukaryotes appear (via endosymbiosis) - Cell Theory o What is a cell? Water-based compartment, filled with concentrated chemicals and surrounded by a membrane o 72% of lean tissue in humans is water o 55% of dry weight is protein - Hallmarks of Cell Theory o 1) All life consists of one or more cells o 2) All cells come from preexisting cells o 3) The cell is the smallest unit of life o Theory: using a pattern-based inductive reasoning to predict future results o Spontaneous generation: life arises (full-blown) from non-living materials Mice from rags and grain, flies from meat and air, etc o Pasteur disproved spontaneous generation of microbes Experiment: leave out some growth media, v. boil and seal other media cells can only come from preexisting cells - Levels of Biological Organization o Molecules o Cell/organelles o Tissues o Organs o Organ systems o Organism o Populations o Community o Biosphere - viruses contain hereditary material enclosed in a protein coat (and sometimes a membrane) o not considered alive because they can’t reproduce or metabolize on their own - Biologists study: o Structures – patterns, descriptions of parts of a cell, leaf, animal, etc o Functions – like how plants make sugars
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o Structure is correlated with function - The Scientific Method o 1. Observation o 2. Hypothesis o 3. Experiment o 4. Draw conclusions o 5. Accept or reject hypothesis - How (functional mechanisms) and Why (adaptation and evolution) questions - Hypothesis testing – based on results of experiment - Theory o Hypothesis that has been repeatedly tested and never disproved o Has to have broad predictive power o Has a rigorously tested statement of general principles o Examples: Germ Theory of Medicine, Cell Theory, Atomic Theory, Theory of Relativity, Theory of Evolution Evolution is the Framework of Biology - 1859 – Darwin develops the Theory of Evolution in Origin of the Species - Theorized that natural selection is the mechanism that causes change in populations, leading to adaptation - A.R. Wallace also independently developed the theory of evolution by natural selection, but a little too late - Evolution – in a scientific sense, it doesn’t require progress; is only any process of change - Populations or species can evolve (not individuals) – involves changing gene frequencies - Increased complexity is not an evitable consequence of evolution - Used to think that Man was the ultimate goal of life - Darwin’s Logic o Observation 1: More offspring are produced that are strictly necessary to replace their parents o Observation 2: Nonetheless, population sizes are relatively stable o Observation 3: Resources are limited o Inference 1: There is a struggle for existence, and only a fraction survive
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This note was uploaded on 05/19/2008 for the course BIS 1A taught by Professor Gearhart during the Spring '07 term at UC Davis.

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Notes mid 1 - BIS 1A Class Notes Characteristics of Life -...

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