| A | B |
|---|
| Big Bang | hypothesis that proposes that the universe began as a huge explosion |
| light year | unit is used to describe distances in space |
| Alpha Centauri | closest star to Earth other than the sun |
| Radiometric Dating | technique used to measure the age of old fossils and rocks that is based on the decay of radioactive elements |
| early earth atmosphere | contained the gases ammonia methane and water vapor |
| stratosphere | region of the atmosphere which contains the ozone layer |
| troposphere | region of the atmosphere that ranges from sea level up to seventeen kilometers above the Earth surface |
| ozone layer | region of the atmosphere that prevents most of the dangerous UV light from the sun from reaching the Earth surface |
| chemical evolution | random generation of the organic building blocks of life that is thought to have occurred under the conditions present on primitive Earth |
| Oparin | Russian scientist who proposed the hypothesis explaining how life may have originated |
| Haldane | English scientist who proposed the hypothesis explaining how life may have originated |
| heterotroph hypothesis | hypothesis that proposes that the first precells lived off of randomly formed organic molecules in the Earth primitive oceans |
| Urey and Miller | simulated the conditions thought to exist on primitive Earth verifying the Hot Thin and Hot Thick Soup |
| carbon dioxide | What gas did the primitive heterotroph cells add to Earth atmosphere |
| oxygen | What gas did the first autotrophs add to Earth’s atmosphere |
| Halley Comet discovery | discovery lends credence to the possibility that organic molecules could have form in the hostile environment of space |
| biological evolution | organisms have changed over time |
| coacervates | protein lipid aggregates that were thought to be the precursors of the first cells |
| Woese | proposed that the first precells formed on dust particles in the atmosphere |
| Greenhouse Effect | carbon dioxide in the atmosphere traps certain forms of radiant energy causing the temperature on Earth to increase |
| Cech | discovered that RNA can code hereditary instructions and catalyze chemical reactions |
| Cairns Smith | proposed that the first life forms were actually self replicating organic molecules or inorganic crystals |
| virus | obligate parasites composed of a protein coat containing a strand of either DNA or RNA |
| Schopf | found the oldest microfossils or fossil microorganisms |
| microfossils | fossils of single celled organisms that formed minute wormlike filaments |
| stromatolites | domelike rock layers in which the Australian microfossils were found |
| cyanobacteria | simple prokaryotic bacteria that are capable of carrying out the process of photosynthesis |
| prokaryotes | small primitive cells that lack internal membrane bound organelles |
| anaerobes | organisms that can survive in environments that contain no oxygen |
| methanogens | anaerobic bacteria that obtain energy by combining carbon dioxide and hydrogen to produce methane gas |
| eukaryotes | cells that contain numerous membrane bound compartments that carry out specific functions |
| organelle | membrane bound compartment that has a particular function in a cell |
| mitochondrion | organelle that use oxygen to synthesize ATP during the process of cellular respiration |
| plastid | organelle that use light to synthesize ATP during the process of photosynthesis |
| Margulis | hypothesized that both the mitochondria and the plastids originated as free-living prokaryotes |
| Cell Symbiosis Hypothesis | hypothesis that both the mitochondria and the plastids originated as free-living prokaryotes |
| retrovirus | viruses whose genetic information is stored in RNA molecules rather than DNA molecules |
| scrapie | fatal degenerative disease affecting the central nervous system of sheep and goats |
| kuru | fatal neurodegenerative disease transmitted by cannibalism and thought to be caused by prions |
| Creutzfeldt Jakob disease | fatal neurodegenerative disease in humans that is similar to Mad Cow disease |
