What is Life?

1. What is Life? Taken from “Life on Earth… and Elsewhere?”

3. Earth’s life forms all… • are carbon-based. • have a membrane or wall that creates an internal environment. • use energy to maintain an internal state. • require liquid water. • able to extract energy from the environment.

4. Earth’s life forms all… • carry out metabolic processes such as the exchange of gases and solid materials (i.e. consuming raw materials and producing wastes.) • exhibit growth, cell division, reproduction, or replication. • able to have a population evolve and adapt to the environment.

5. In a Nut Shell…. • Things needed to sustain life are: • Food (for energy) • Water • Shelter

6. What does life need to exist? • Liquid water and a method for cycling water (atmospheric, geothermal) so that necessary chemicals can be transported • All known life requires a temp. between [-15°C (5°F) to 115°C (239°F)] liquid water possible in this range. • Energy • Light energy from a star (sun): needs to live at the surface but still be in the correct temperature range and be protected from harmful UV rays and solar wind • Chemical energy -breaking complex compounds into simpler ones (ex. Food energy) • Nutrients – raw materials to construct and maintain bodies

7. Wild, Wacky, Wonderful Water! • Most organisms are 50% to 95% water. • Water’s ability to absorb and retain heat (regulates climate) • Water is polar. (has a negative charge on one end and a positive charge on the other) • Water is the universal solvent. (Lots of substances can dissolve in it.) • Polarity causes surface tension. • only substance that can exist as a solid, liquid, or gas at normal temperatures on Earth. • solid form (ice) is less dense than the liquid form.

8. Carbon is Cool! • Living things are made up mostly of four elements: hydrogen, oxygen, carbon, and nitrogen. When you take away the water, living things are mostly carbon. Graphite (pure carbon) Graphite pencil Sugar cube (C6H12O6)

9. Carbon is Unique. • Its structure is the main reason why life is based on it. • It can form complex molecules. • Carbon is the smallest element that has this ability. Structure of a diamond (all carbon) Amorphous carbon containing molecule

10. Carbon can form 4 bonds (the most possible) because there is room for four more electrons in its outer shell. That Crazy Carbon!!! 4 available bonding locations Carbon bonding with 4 hydrogen atoms

11. Carbon Containing Compounds • Carbon dioxide (reactant in photosynthesis) • Amino acids (building blocks of proteins) • Nucleic acids (like DNA)

12. Carbon Containing Compounds • Carbohydrates (sugars and starches) • Lipids (fats and steroids) • Carbon is also found in rocks like limestone. Starch molecule Steroid molecule

13. Movies about life on other planets.

31. Search for ET • Astrobiology – the study of all living things within the universe, where they might be found and how they were formed. • Astrobiologists look for habitable conditions and direct evidence of life when searching for ETs.

32. Habitable Zone • Distance from a star where water can exist as a liquid, or the distance between the points where there is too much and too little sunlight.

33. Currently, the only life we have found in the universe is located on Earth. What have we found so far?

34. Remember the Inverse Square Law? • Light intensity decreases by the square of the distance.

35. What makes a world habitable? • Besides the basic requirements of life (energy, nutrients and liquid water), a planet or moon also must have: • A temperature range from -15 to 115°C (too high and organic molecules break down; too low and chemicals don’t function properly) • An atmosphere to provide nutrients and protect from ultraviolet radiation and small meteor impacts.

36. Extremophiles! • Organisms that live at the limits of what is acceptable for life. • Most are microorganisms. • They’re found in Antarctica, in hydrothermal vents, and deep in the Earth’s crust.

37. Some love heat…

38. Some love cold…

39. Some love salt… These are solar evaporation ponds near Salt Lake City, Utah. They are shallow ponds that use solar energy to evaporate the water and leave behind salt. As the salinity of the ponds increases, the bacteria species change, creating different colors. These type of bacteria are called Halophiles.

40. Some love acid… These bacteria are acidophiles, or acid loving bacteria. This particular species has been found in environments, such as underground caves, with a pH of 0. And lots of other crazy things!!!

41. What about sending Earth microbes to colonize other worlds? • Pros • help create an atmosphere • add oxygen to the environment • detoxify harmful compounds • establish a food supply • extract useful materials from the planet’s or moon’s crust • Cons • may interfere with learning about extraterrestrial life • Earth life forms may out compete ET life forms, causing them to become extinct • space travel may negatively impact new colony (may pollute the colony planet)

42. 1. All living things are composed of..? • Boron • Carbon • Oxygen • nitrogen

43. 2. Consuming raw materials and producing waste is a living process called: • Eating and then pooping • Mechanisms • photosynthesis • metabolism

44. 3. For life to exist the temperature range needs to be: • -15 oC-115oC • 1oC-100oC • 5oF-215oF • 32oF-106oF

45. 4. Four elements living things are made of: • Helium, oxygen, nitrogen, calcium • Hydrogen, oxygen, nitrogen, carbon • Phosphorus, nitrogen, chloride, oxygen • Sodium, aluminum, hydrogen, carbon

46. 5. How many bonds can carbon form? • 1 • 2 • 3 • 4

47. 6. ____energy needs to be in the right temperature range and UV range for life to exist: • Chemical • Nuclear • Light • electrical

48. 7. Solid water is ____dense than liquid water. • More • Less • Equally • awesomely

49. 8. Scientists who look for habitable conditions and for evidence that life exists: • Biologists • Physicists • Environmentalists • astrobiologists

50. 9. The distance from a star where life and water can exist in liquid form and the distance between where there is too much or too little sun is: • The fun zone • The habitat zone • The habitable zone • The end zone