Prentice Hall - Science Explorer - Cells and Heredity
Chapter 1- Cell structure and Function
Section 3- Chemical Compounds in Cells
Questions - Comment - Key Words - ConnectionsElement Compound Carbohydrates Lipids Protein Animo Acids Enzymes Nucleic Acid DNA RNA |
Main Ideas; Visuals + PredictionsElements and Compounds
Elements Element: Any substance that cannot be broken down into simpler substances. * The smallest unit of an element is called an atom. * An element is made up of only one kind of atom. *The elements found in living things include carbon, hydrogen, oxygen, nitrogen, phosphorus, and sulfur. Compounds Compound: Two or more elements that are chemically combined. * smallest unit of many compound is called molecule. ex: A molecule of carbon dioxide consists of one carbon atom and two oxygen atoms. Organic and Inorganic Compounds
* compounds that contain carbon = organic compounds * Some important groups of organic compounds found in living things are carbohydrates, lipids, proteins, and nucleic acids. * Compounds that don't contain carbon = Inorganic compounds ex: Water and sodium chloride, or table salt Carbohydrates Carbohydrates: An Energy-rich organic compound, such as a sugar or a starch, that is made of the elements carbon, hydrogen, and oxygen. * Carbohydrates are important components of some cell parts. ex: the cellulose found in the cell walls of plants is a type of carbohydrate. Carbohydrates are also found in cell membranes. Lipids Lipids: An Energy-rich organic compound, such as a fat, oil, or wax, that is made of carbon, hydrogen, and oxygen. * Cells store energy in lipids for later use. ex: during winter, a dormant bear lives on the energy stored as fat within its cells. * The cell membranes are made mainly of lipids. Proteins Protein: Large organic molecule made of carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur. ex: a bird’s feathers, a spider’s web, and your fingernails Structure of Proteins Animo acids: A small molecule that is linked chemically to other amino acids to form different proteins. ex: Like the alphabet. The 26 letters can make thousands of words by just choosing a letter and the order. Even a change in one letter. ex: from rice to mice, creates a new word. * Similarly, a change in the type or order of amino acids can result in a different protein. Functions of Proteins Enzymes: A type of protein that speeds up a chemical reaction in a living thing. ex: enzymes in your saliva speed up the digestion of food by breaking down starches into sugars in your mouth. Nucleic Acids Nucleic acid: Very large organic molecule made of carbon, oxygen, hydrogen, nitrogen, and phosphorus, that contains the instructions cells need to carry out all the functions of life. *There are two kinds of nucleic acids
Water and Living Things * water makes up about 2/3 of your body. *Water plays many important roles in cells. ex:
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