Transcript Chapter 2
Chapter 2 It’s Alive!! Or Is It? Preview Section 1 Characteristics of Living Things Section 2 The Necessities of Life Concept Mapping < Back Next > Preview Main Chapter 2 Section 1 Characteristics of Living Things Objectives • Describe the six characteristics of of living things. • Describe how organisms maintain stable internal conditions. • Explain how asexual reproduction differs from sexual reproduction. < Back Next > Preview Main Key Vocabulary cell unicellular multicellular stimulus response homeostasis sexual reproduction asexual reproduction heredity DNA metabolism growth development < Back Next > Preview Main Chapter 2 Section 1 Characteristics of Living Things Living Things Have Cells • All living things are composed of one or more cells. • A cell is a membrane-covered structure that contains all of the materials necessary for life. • Some organisms are made up of only one cell (unicellular) and some are made up of trillions of cells (multicellular). In an organism with many cells, different kinds of cells perform specialized functions. ex. - nerve cells, muscle cells < Back Next > Preview Main Chapter 2 Section 1 Characteristics of Living Things Living Things Sense and Respond to Change • A stimulus is anything that causes a reaction or change in an organism or any part of an organism. •A response is the action or behavior change in the organism What are some examples in our lives?? • Homeostasis is the maintenance of a stable internal environment. • Responding to External Change Organisms must respond to change in the external environment in order to maintain their homeostasis. < Back Next > Preview Main Homeostasis • An example we can relate to: Body temperature• When we are cold- shivering, contraction of blood vessels • When we are hot- sweating, dilation of blood vessels < Back Next > Preview Main Chapter 2 Section 1 Characteristics of Living Things Living Things Reproduce • Organisms make other organisms similar to themselves – “copying” • In sexual reproduction, two parents produce offspring that will share characteristics of both parents- provides for more diversity • In asexual reproduction, a single parent produces offspring that are identical to the parent. < Back Next > Preview Main Chapter 2 Section 1 Characteristics of Living Things Living Things Have DNA • The cells of all living things contain the molecule deoxyribonucleic acid, or DNA. •DNA controls the structure and function of cells. •The passing of traits through DNA is called heredity. Parents pass copies of their DNA to their offspring < Back Next > Preview Main Chapter 2 Section 1 Characteristics of Living Things Living Things Use Energy • Organisms use energy to carry out the activities of life. • An organism’s metabolism is the total of all of the chemical activities that the organism performs. ex. Making food (producers), breaking down food, transporting materials, build/repair cell parts < Back Next > Preview Main Chapter 2 Section 1 Characteristics of Living Things Living Things Grow and Develop • All living things, whether they are made of one cell or many cells, grow during periods of their lives. • Living things may develop and change as they grow. < Back Next > Preview Main • Growing is the process of getting bigger. complex organisms grow by making more cells • Development- an organism changes as it grows and becomes more complex < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life Objectives - Section 2 The Necessities of Life • Explain why organisms need food, water, air, and living space. • Describe the chemical building blocks of cells. < Back Next > Preview Main Key Vocabulary producer consumer autotroph heterotroph decomposer carbohydrate lipid protein nucleic acid enzyme ATP < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life Water • Your cells and the cells of almost all living organisms are approximately 70% water. Why is it so important?? •Most of the chemical reactions involved in metabolism require water. • Most substances must be dissolved in water to be useful to the cell •Water helps the cell maintain its size and shape •Water helps the organism maintain a proper temperature < Back Next > Preview Main Air • Air is a mixture of several different gases, including oxygen and carbon dioxide. • Most living things use oxygen in the chemical process that releases energy from food. (aerobic organisms) • Anaerobic organisms do not require oxygen. < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life A Place to Live • All organisms need a place to live that contains all of the things they need to survive. Space on Earth is limited, so organisms are often in competition with each other. Food • All living things need food. Food gives organism energy and the raw material needed to carry on life processes. < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life Food, continued • Making Food Some organisms, such as plants, are called producers. Producers or autotrophs can make their own food by using energy from their surroundings. • Taking Food Other organisms are called consumers or heterotrophs because they must eat (consume) other organisms to get food. Decomposers are consumers that get their food by breaking down the nutrients in dead organisms or animal wastes. < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life Putting It All Together • All organisms need to break down that food in order to use the nutrients in it. • Nutrients are made up of molecules. • Molecules found in living things are usually made up of six elements: carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life Proteins • Proteins are large molecules made up of amino acids. •Making Proteins Organisms break down the proteins in food to supply their cells with amino acids that are then linked together to form new proteins. • Proteins in Action Some proteins form structures that are easy to see. Other proteins help cells do their jobs. Proteins called enzymes start or speed up chemical reactions in cells. ex. saliva < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life Carbohydrates • Molecules made of sugars are called carbohydrates. •Simple Carbohydrates Simple carbohydrates are made up of one sugar molecule or a few sugar molecules linked together. Ex. candy • Complex Carbohydrates Complex carbohydrates are made of hundreds of sugar molecules linked together. Organisms store extra sugar as complex carbohydrates. Ex. potatoes < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life Lipids • Lipids are compounds that cannot mix with water. •Phospholipids are the molecules that form much of the cell membrane. • Fats and Oils Fats and oils are lipids that store energy. When an organism has used up most of its carbohydrates, it can get energy from these lipids. < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life ATP • Adenosine triphosphate, or ATP, is the major energycarrying molecule in cells. • The energy in carbohydrates and lipids must first be transferred to ATP, which then provides fuel for cellular activities. < Back Next > Preview Main Chapter 2 Section 2 The Necessities of Life Nucleic Acids • Nucleic acids are large molecules made up of subunits called nucleotides. • Nucleic acids are sometimes called the blueprints of life because they have all the information needed for a cell to make proteins. • DNA and RNA are nucleic acids. < Back Next > Preview Main Chapter 2 It’s Alive!! Or Is It? Concept Mapping Use the terms below to complete the concept map on the next slide. DNA sugars energy enzymes living cells proteins starches carbohydrates < Back Next > Preview Main Chapter 2 It’s Alive!! Or Is It? < Back Next > Preview Main Chapter 2 It’s Alive!! Or Is It? < Back Next > Preview Main