History of Life

evidence for the history of life is found in the fossil record

relative dating - comparative dating, uses index fossils, doesn’t give specific age in years. deeper rock = older

radiometric dating - measures radioactive isotopes, dates igneous and metamorphic rocks (fossils are found in sedimentary rock)

half life - the period of time that it takes for 1/2 of the radioactive isotope to decay

radioactive decay - radioactive isotopes change into a more stable form (new element or its product isotope)

4-stage hypothesis for hist. of life - inorganic chemicals form simple organic molecules in primitive ocean, formation of complex organic molecules, formation of self replicating molecules that make inheritance possible, membrane formation

oparin’s primordial soup model - inorganic compounds transformed into organic compounds through sun and lightning in Earth’s oceans

miller urey experiment - replicated primitive atmosphere, amino acids formed

lerman’s bubble model - chemical reactions occurred in bubbles in the ocean, fixed problems with primordial soup model

RNA may have evolved before DNA because - it can act like enzymes, form simple proteins, replicate, store genetic info, found to form as water is frozen and nucleotides are pushed into spaces between water crystals

lipid membrane hypothesis - phospholipids naturally form lipid bilayer called liposomes

endosymbiosis - prokaryote ingested bacteria which later became mitochondria and chloroplasts

autogenous theory - folds in membranes formed eukaryotic organelles

horizontal gene transfer theory - transfer of genetic material between cells led to more complex cell organelles

multicellular - many cells, cell specialization

colonial - many cells, no cell specialization