1.1 Biology is the science of life. Properties of life VITHIN CELLS In its broadest sense, biology is the study of living things-the science of life. Living things come in an astounding variety of shapes and forms, and biologists study life in many differ ent ways. They live with gorillas, collect fossils, and listen to whales. They isolate viruses, grow mushrooms, and ex- amine the structure of fruit flies. They read the messages encoded in the long molecules of heredity and count how many times a hummingbird's wings beat each second What makes something"alive"? Anyone could deduce that a galloping horse is alive and a car is not, but wby? We cannot say, "If it moves, it's alive, "because a car can move, and gelatin can wiggle in a bowl. They certainly are ne alive. What characteristics do define life? All living organ isms share five basic characteristics: 1. Order. All organisms consist of one or more cells with highly ordered structures: atoms make up mole Cell cules, which construct cellular organelles, which are contained within cells. This hierarchical organization continues at higher levels in multicellular organisms and among organisms(figure 1. 2) 2. Sensitivity. All organisms respond to stimuli. Plants grow toward a source of light, and your pupils dilate when you walk into a dark room 3. Growth, development, and reproduction. All or ganisms are capable of growing and reproducing, and they all possess hereditary molecules that are passed to their offspring, ensuring that the offspring are of the same species. Although crystals also"grow, "their growth does not involve hereditary molecules 4. Regulation. All organisms have regulatory mecha nisms that coordinate the organisms internal func- tions. These functions include supplying cells with nu- trients, transporting substances through the organism, ers 5. Homeostasis. All organisms maintain relatively constant internal conditions different from their envi- ronment, a process called homeostasis. All living things share certain key characteristics: order, Macromolecule sensitivity, growth, development and reproduction, egulation, and homeostasis. FIGURE 1.2 Hierarchical organization of living things. Life is highly orga nized-from small and simple to large and complex, within cells, within multicellular organisms, and among organisms Part I The Origin of Living things4 Part I The Origin of Living Things Properties of Life In its broadest sense, biology is the study of living things—the science of life. Living things come in an astounding variety of shapes and forms, and biologists study life in many differ￾ent ways. They live with gorillas, collect fossils, and listen to whales. They isolate viruses, grow mushrooms, and ex￾amine the structure of fruit flies. They read the messages encoded in the long molecules of heredity and count how many times a hummingbird’s wings beat each second. What makes something “alive”? Anyone could deduce that a galloping horse is alive and a car is not, but why? We cannot say, “If it moves, it’s alive,” because a car can move, and gelatin can wiggle in a bowl. They certainly are not alive. What characteristics do define life? All living organ￾isms share five basic characteristics: 1. Order. All organisms consist of one or more cells with highly ordered structures: atoms make up mole￾cules, which construct cellular organelles, which are contained within cells. This hierarchical organization continues at higher levels in multicellular organisms and among organisms (figure 1.2). 2. Sensitivity. All organisms respond to stimuli. Plants grow toward a source of light, and your pupils dilate when you walk into a dark room. 3. Growth, development, and reproduction. All or￾ganisms are capable of growing and reproducing, and they all possess hereditary molecules that are passed to their offspring, ensuring that the offspring are of the same species. Although crystals also “grow,” their growth does not involve hereditary molecules. 4. Regulation. All organisms have regulatory mecha￾nisms that coordinate the organism’s internal func￾tions. These functions include supplying cells with nu￾trients, transporting substances through the organism, and many others. 5. Homeostasis. All organisms maintain relatively constant internal conditions, different from their envi￾ronment, a process called homeostasis. All living things share certain key characteristics: order, sensitivity, growth, development and reproduction, regulation, and homeostasis. 1.1 Biology is the science of life. FIGURE 1.2 Hierarchical organization of living things. Life is highly orga￾nized—from small and simple to large and complex, within cells, within multicellular organisms, and among organisms. Organelle Macromolecule Molecule Cell WITHIN CELLS