4/19/12 Objective: Understand and explain the field of astrobiology Warm-Up: List three of water’s special properties

Water Water’s high specific heat means that the chemical reactions important to life can be “insulated” by water Another reason water is good for living things is because water can dissolve most substances This means water can hold and transport nutrients for organisms Adhesion and cohesion allow water to move easily through organisms

Organic Molecules In science, the word “organic” means anything that is alive or a part of a living thing Every organic molecule contains the elements carbon and hydrogen Other elements that can be found in organic molecules are oxygen, nitrogen, phosphorous, and sulfur There are four important organic molecules

The Four Organic Molecules Proteins Proteins are made of smaller molecules called amino acids Lipids (Fats) Carbohydrates (Sugar & Starch) Nucleic Acids DNA and RNA; these molecules carry your genetic information Made of smaller molecules called nucleotides

Where did these molecules come from? The scientists Miller and Urey demonstrated that the atmosphere of early Earth could have produced some amino acids Other similar experiments have shown that the chemistry of early Earth could also have produced some nucleotides But other scientists think that these organic molecules might have been carried to Earth by comets and/or meteors

Astrobiology Astrobiologists study the possibility that life might exist other places in the universe Astrobiologists have found some organic molecules on meteors that hit Earth’s surface These findings have caused some scientists to hypothesize that these meteors were the source for the first organic compounds on Earth