Section 1 Characteristics of Living Things Bellringer What

Section 1 Characteristics of Living Things Bellringer What are four living and nonliving things that you interact with every day? How do you know whether each is living or nonliving? Do you know what the word inanimate means? If so, write out a definition. Does nonliving mean the same thing as dead? Explain your answer. Write your answers in your science journal. Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Bellringer What do you think your mass would be if there were no water in your body? What else besides water is your body composed of? Where do you think you get the minerals that make up your body mass? Record your answers in your science journal. Copyright © by Holt, Rinehart and Winston. All rights reserved.

The Necessities of Life Objectives • Explain why organisms need food, water, air, and living space. • Describe the chemical building blocks of cells. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Air • Oxygen • Most living things use oxygen in the chemical process that releases energy from food. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Water • Thirsty Cells Your cells and the cells of almost all living organisms are approximately 70% water. • Most of the chemical reactions involved in metabolism require water (from fluids in drinks and foods). • You could survive for only about three days without water. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life A Place to Live/ Shelter (Their Habitat and Ecosystem) • All organisms need a place to live that contains all of the things they need to survive. • Space All organisms need space that contains all of the things they need to survive. Space on Earth is limited, so, organisms often compete with each other food, water, and other necessities. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Food • Making Food Producers (plants) can make their own food. • Taking Food Other organisms are called consumers because they must eat (consume) other organisms to get food. • Energy: All living things need food. • Food gives organisms energy and the raw materials needed to carry on life processes. The nutrients from food replaces cells and End of Slide build body parts. Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Food (Part 2) • Energy Some consumers are decomposers. Decomposers are organisms that get their food by breaking down the nutrients in dead organisms or animal wastes. Ex: mushrooms End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Putting It All Together • Using Nutrients. But all organisms need to break down that food in order to use the nutrients in it. • Putting It All Together Nutrients are made up of molecules. Molecules found in living things are different combinations of six elements: – carbon, – hydrogen, – nitrogen, – oxygen, – Phosphorus – sulfur. • These elements combine to form proteins, carbohydrates, lipids, ATP, and nucleic acids. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Proteins • Making Proteins Organisms break down the proteins in food to supply their cells with amino acids. These amino acids are then linked together to form new proteins. • Proteins in Action • Proteins have many different functions. • Ex: -hemoglobin –binds oxygen in red blood cells. • Ex: enzyme- starts or speeds up chemical reactions in cells. Some proteins protect cells. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Carbohydrates • Simple Carbohydrates Simple carbohydrates are made up of one sugar molecule or a few sugar molecules linked together. • Complex Carbohydrates Complex carbohydrates are made of hundreds of sugar molecules linked together. Functions: Cells use carbohydrates as a source of energy and for energy storage. An organism’s cells break down carbohydrates to release the energy stored in them. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Lipids • Phospholipids are the molecules that form much of the cell membrane. • 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. Most of the lipids stored in plants are oils. Most of the lipids stored in animals are fats. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 Phospholipid Molecules and Cell Membrane All cells are surrounded by a cell membrane (mostly phospholipids). . The cell membrane helps protect the cell and keep the internal conditions of the cell stable. The head of a phospholipid molecule is attracted to water. The tail is not. When phospholipids are in water, the tails come together, and the heads face out into the water. Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life Nucleic Acids (DNA) • What Are Nucleic Acids? Nucleic acids are large molecules made up of molecules called nucleotides. • Nucleic acids are sometimes called the blueprints of life because they have all the information needed for a cell to make proteins. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Section 2 The Necessities of Life • ATP Adenosine triphosphate • ATP is the major energy-carrying molecule in the cell. • The energy in carbohydrates and lipids must be transferred to ATP, which then provides fuel for cellular activities. End of Slide Copyright © by Holt, Rinehart and Winston. All rights reserved.

Chapter 2 It’s Alive!! Or Is It? Concept Map Use the following terms to complete the concept map on the next slide: DNA, sugars, energy, enzymes, living cells proteins, starches, carbohydrates. Copyright © by Holt, Rinehart and Winston. All rights reserved.