Unit 1 Lesson 2 Chemistry of Life Copyright © Houghton Mifflin Harcourt Publishing Company

It’s Elementary What are atoms and molecules? Unit 1 Lesson 2 Chemistry of Life It’s Elementary What are atoms and molecules? All cells (and all matter) are made up of atoms and molecules. An element is a substance that cannot be broken down into a simpler substance. The smallest unit of an element that maintains the properties of that element is called an atom. Copyright © Houghton Mifflin Harcourt Publishing Company 2

What are atoms and molecules? Unit 1 Lesson 2 Chemistry of Life What are atoms and molecules? What are the six main elements that make up the human body? Copyright © Houghton Mifflin Harcourt Publishing Company 3

What are atoms and molecules? Unit 1 Lesson 2 Chemistry of Life What are atoms and molecules? A molecule is a group of atoms held together by chemical bonds. Some molecules are made up of only one type of atom. Most molecules are made up of two or more types of atoms. Copyright © Houghton Mifflin Harcourt Publishing Company 4

What are atoms and molecules? Unit 1 Lesson 2 Chemistry of Life What are atoms and molecules? A compound is a substance made up of atoms of two or more elements joined by chemical bonds. Most molecules found in cells are compounds. Compounds have different properties than the elements that make them. Copyright © Houghton Mifflin Harcourt Publishing Company 5

Cell Fuel What are some important types of molecules in cells? Unit 1 Lesson 2 Chemistry of Life Cell Fuel What are some important types of molecules in cells? Organisms use nutrients for energy and as building materials. A lipid is a fat molecule or a molecule that has similar properties. Lipids have many jobs in cells, such as storing energy. Your cells get lipids from foods such as olive oil and fish. Copyright © Houghton Mifflin Harcourt Publishing Company 6

What are some important types of molecules in cells? Unit 1 Lesson 2 Chemistry of Life What are some important types of molecules in cells? A protein is a molecule made up of smaller molecules called amino acids. Protein-rich foods are broken down into amino acids, which make new proteins to build and repair body structures. Proteins called enzymes help chemical processes happen in cells. Copyright © Houghton Mifflin Harcourt Publishing Company 7

What are some important types of molecules in cells? Unit 1 Lesson 2 Chemistry of Life What are some important types of molecules in cells? Carbohydrates are molecules that include sugars, starches, and fiber. Cells use carbohydrates for energy and energy storage. Simple carbohydrates are made of one or a few sugars linked together. Complex carbohydrates contain many sugar molecules linked together. Copyright © Houghton Mifflin Harcourt Publishing Company 8

What are some important types of molecules in cells? Unit 1 Lesson 2 Chemistry of Life What are some important types of molecules in cells? Nucleic acids are molecules that carry information in cells. Nucleotides are the smaller molecules that make up nucleic acids. DNA is a nucleic acid that carries information that cells need to make other molecules. Copyright © Houghton Mifflin Harcourt Publishing Company 9

Waterworks What are phospholipids? Unit 1 Lesson 2 Chemistry of Life Waterworks What are phospholipids? A lipid that contains phosphorus is called a phospholipid. The head of a phospholipid molecule is attracted to water. The tail repels water. Much of a cell’s membrane is made of a double-layer of phospholipids, which regulates molecules entering and leaving the cell. Copyright © Houghton Mifflin Harcourt Publishing Company 10

What are phospholipids? Unit 1 Lesson 2 Chemistry of Life What are phospholipids? What causes a cell membrane to have a double-layer structure? Copyright © Houghton Mifflin Harcourt Publishing Company 11

Unit 1 Lesson 2 Chemistry of Life Why is water important? Water moves through a cell membrane by a process called osmosis. Water moves into and out of a cell, from areas of higher concentration to areas of lower concentration. Too little water in a cell causes it to shrink. Too much water in a cell causes it to burst. Copyright © Houghton Mifflin Harcourt Publishing Company 12