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Ch2 Sect1 Characteristics of Living Things (Organisms) 1. Cellular Organization - all organisms are made of cells 2. Chemicals of Life 3. Energy Use - cells use energy to perform jobs, such as repair parts and move chemicals around 4. Response to Surroundings 5. Growth and Development 6. Reproduction - Producing offspring that are similar to the parents 1. Cellular Organization - all organisms are made of cells • A. Unicellular - an organism made up of only 1 cell • B. Multicellular - an organism made up of many specialized cells that do certain tasks 2. The chemicals of life • All living things are composed of four basic elements: • Carbon (C) • Hydrogen (H) • Nitrogen (N) • Oxygen (O) • Other important elements include Iron (Fe), Calcium (Ca), Phosphorous (P), and Sulfur (S). • Together, these elements make up the main compounds of life: carbohydrates, proteins, lipids and nucleic acids. 2. Chemicals of Life • A. All cells contain water • B. Carbohydrates - cells' main energy source • C. Protein - cells' building material • D. Lipids (fats and oils) - energy storage and building material • E. Nucleic Acids - genetic material that direct cellular activities – DNA, RNA 3. Energy Use (metabolism) - Cells use energy to perform jobs, such as repair parts, move chemicals around and make proteins. 4. Response to Surroundings • A. Stimulus - a change in an organism's environment • B. Response - an action or change in behavior caused by a stimulus 5. Growth and Development • A. Growth - become larger • B. Development - process of change to become more complex 6. Reproduction - Producing offspring that are similar to the parents • Asexual - one parent and offspring is identical to that parent. • Sexual – Usually 2 parents and offspring is a genetic combination of yet different from both parents. What gives the property of life? • Life is more than adding up the elements. • These elements interact with each other to cause chemical reactions that are characteristic of life. Life comes from life • Living things arise from living things through reproduction. • The old, mistaken idea, spontaneous generation, was that living things could arise from non-living things = FALSE! Spontaneous Generation Theory • Untill 1600s, most people believed that life came from nonliving matter. • 1668 – Francesco Redi – Italian doctor and poet who helped disproved this theory. (p. 36) • One of the first scientists to run a controlled study. Independent variable? • Whether or not the jar was covered. Francesco Redi’s Conclusion: • He demonstrated that the presence of maggots in decaying meat does not result from spontaneous generation but from eggs laid on the meat by flies. THEREFORE…. • Rotting meat does not produce flies! Louis Pasteur further disproves spontaneous generation. • Pasteur, in the 1800s, conducted more controlled experiments. (p.37) • He added broth to two flasks, but only sterilized one of them by boiling it. He added curved necks to the flasks so air could get in, but not bacteria. • The one not boiled grew cloudy. • He then broke the neck off the boiled broth and it finally turned cloudy too. Pasteur’s conclusion: • New bacteria arise only from existing bacteria. • The experiment of Redi and Pasteur helped to convince people that living things do not arise from nonliving things. The Needs of Living Things Water • Most organisms can live only for a few days without water. • Needed for chemical reactions and… • • • • • Obtaining chemicals from surroundings Breaking down food Growing Moving substances around Reproduction The Needs of Living Things Food • Provides the source of energy to live • Autotrophs – make their own food ex. plant using sun’s energy. • Heterotrophs – obtain food by feeding on others. (A heterotroph’s energy source is also the sun, but indirectly, how?) The Needs of Living Things Living Space • All organisms need a space in which to live that provides shelter, food and water. • Space on Earth is limited, so organisms often must compete for space. • How does a tree do this? The Needs of Living Things • • • • Stable Internal Conditions Organisms must keep internal conditions stable. Homeostasis - maintenance of stable internal conditions. Keeps things just right for cells to function. Why do you get thirsty? How do barnacles keep water in their cells at low tide?