Astronomy Ch 20
Terms
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- amino acid
- Carbon-chain molecule that is the building block of protein. (p. 476)
- Cambrian period
- A geological period 0.6 to 0.5 billion years ago during which life on Earth became diverse and complex. Cambrian rocks contain the oldest easily identifiable fossils. (p. 478)
- chemical evolution
- The chemical process that led to the growth of complex molecules on primitive Earth. This did not involve the reproduction of molecules. (p. 480)
- chromosome
- A body within a living cell that contains genetic information responsible for the determination and transmission of hereditary traits. (p. 477)
- deoxyribonucleic acid
- The long carbon-chain molecule that records information to govern the biological activity of the organism. DNA carries the genetic data passed to offspring. (p. 476)
- DNA
- See deoxyribonucleic acid.
- Drake equation
- The equation that estimates the total number of communicative civilizations in our galaxy. (p. 490)
- enzyme
- Special protein that controls processes in an organism. (p. 476)
- gene
- A unit of DNA - or sometimes RNA - information responsible for controlling an inherited physiological trait. (p. 477)
- life zone
- A region around a star within which a planet can have temperatures that permit the existence of liquid water. (p. 486)
- Miller experiment
- An experiment that reproduced the conditions under which life began on Earth and manufactured amino acids and other organic compounds. (p. 478)
- mutant
- Offspring born with altered DNA. (p. 475)
- natural selection
- The process by which the best traits are passed on, allowing the most able to survive. (p. 475)
- primordial soup
- The rich solution of organic molecules in Earth's first oceans. (p. 480)
- protein
- Complex molecule composed of amino acid units. (p. 476)
- ribonucleic acid
- Long carbon-chain molecules that use the information stored in DNA to manufacture complex molecules necessary to the organism. (p. 477)
- RNA
- See ribonucleic acid.
- SETI
- The Search for Extra-Terrestrial Intelligence. (p. 489)
- stromatolite
- A layered fossil formation caused by ancient mats of algae or bacteria, which build up mineral deposits season after season. (p. 481)
- water hole
- The interval of the radio spectrum between the 21-cm hydrogen radiation and the 18-cm OH radiation. Likely wavelengths to use in the search for extraterrestrial life. (p. 489)