Test 1 - Test 1 World made 4.5 billion years ago +/- 5...

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Test 1 World made 4.5 billion years ago +/- 5 million years 3.5 bya prokaryotic heterotrophic life (using organic molecules made by non-living sources) autotrophic prokaryotes (more chemoautotrophs – SH2, H2) photosynthetic autotrophs (using light as energy source 6CO2 + 6HS C6H12O6 + S) oxygenic photoautotroph (using H2O and releasing O2; 6CO2 + 6H2O C6H12O6 + O2) aerobic respiration (kreb’s cycle) eukaryotic life 1.5 bya Two billion years before eukaryotic life Endosymbiosis must have occurred, prokaryotic life joining and living together i.e. mitochondria and chloroplasts anaerobic respiration limited to proarkaryotes Cell and Molecular Biology only 50 years old 1956 – DNA discovered 1962 – Nobel prize for DNA Most biology started in the mid 1800s Genetics, cytology, and biochemistry all come together and intertwine Full understanding of how life started and 3 major topics of biology merged together Cell History Early 17 th century Galileo – put lens together to see insect eye (first microscope) Mid 17 th century Robert Hooke – actually saw cells in pieces of cork Van Leeuvenhook – was able to see bacteria None of these men were biologists! 200 years later Robert Brown – 1820 discovered nucleus in cells Schwann – 1839 discovered cells in animal tissue Cell theory initiated! Cell Theory All organisms are composed of cells Cells are the smallest/most basic unit of life All cells exist from other cells Why are cells so small? Because they need a surface to volume ratio to not burst Cell size varies… membrane exchanges food and O2 Microscopes Light – living tissue (resolution – 0.2 micrometers) Phase contrast Simple Electron – dead tissue (resolution 0.2 nanometers – 1000x better resolution) Mid 20 th century Transmission Scanning Molecules may be observed with electron microscopy may get up to 300,000x enlargement Resolving power of the naked eye = 0.2 mm Resolving power of the light microscope = 0.2 micrometers (1000x better) Resolving power of the electron microscope = 0.2 nanometers (1000x better) Average bacteria are 1 micrometer Average animal cell is 10 micrometers (vol. 1000x>bacteria) Average plant cell is 20 micrometers EVERYTHING STARTED MID 19 th CENTURY Louis Pasteur Discovered bacteria and infection. Started immunization (microbes)
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Population of the world jumped up at the end of his life Prokaryotes vs. Eukaryotes True nucleus vs. nucleoide High and low DNA: an organism dichotomy Eukaryotes separate functions with internal membranes (compartmentalization, prokaryotes do not) Prokaryotes have cytoplasm and ribosomes only Eukaryotes have cytoskeletons (prokaryotes do not) Eukaryotes carry out (endocytosis and exocytosis) Prokaryotes cannot due to rigid cell walls
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This note was uploaded on 04/02/2008 for the course BIOL 2104 taught by Professor Dcimini during the Spring '08 term at Virginia Tech.

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Test 1 - Test 1 World made 4.5 billion years ago +/- 5...

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