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Unit 2 Lesson 1 The Characteristics of Cells Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells Florida Benchmarks • SC.6.N.2.2 Explain that scientific knowledge is durable because it is open to change as new evidence or interpretations are encountered. • SC.6.L.14.2 Investigate and explain the components of the scientific theory of cells (cell theory): all organisms are composed of cells (single-celled or multi-cellular), all cells come from pre-existing cells, and cells are the basic unit of life. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells Florida Benchmarks • MA.6.A.3.6 Construct and analyze tables, graphs, and equations to describe linear functions and other simple relations using both common language and algebraic notation. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells Cell-ebrate! What is a cell? • A cell is the smallest functional and structural unit of all living organisms. • An organism is any living thing that carries out its own life processes. • Robert Hooke was the first to describe cells. He looked at the bark of a cork tree under a microscope. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells Why are most cells small? • Cells are small because their size is limited by their outer surface area. • If cells get too large, they cannot take in enough materials or get rid of enough wastes. • The surface area-to-volume ratio of a cell is the ratio of the outer surface to the cell’s volume. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells Cell Hall of Fame What is the cell theory? • The cell theory lists three basic characteristics of all cells and organisms. • All organisms are made up of one or more cells. • The cell is the basic unit of all organisms. • All cells come from existing cells. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells What is the cell theory? • Antoni van Leeuwenhoek was the first to describe living cells. • Matthias Schleiden concluded that all plants are made of cells. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells What is the cell theory? • Theodor Schwann determined that all animal tissue is made of cells. • Rudolf Virchow proposed that cells could only come from the division of other cells. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells What is the cell theory? • Organisms made up of just one cell are called unicellular organisms. • The single cell must carry out all of the organism’s life functions. • Organisms made up of more than one cell are called multicellular organisms. • The cells of multicellular organisms have specialized functions. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells On the Cellular What structures do cells have in common? • All cells have some structures in common. • A cell membrane is a protective layer that covers a cell’s surface and controls materials moving into and out of the cell. • The cytoplasm is the region inside the cell that includes all the organelles except for the nucleus. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells What structures do cells have in common? • An organelle is a small body in the cytoplasm that is specialized to perform a specific function. • The nucleus is a membrane-bound organelle that contains DNA. • DNA, or deoxyribonucleic acid, is genetic material that provides instructions for all cell processes. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells What structures do cells have in common? • How many parts of a cell can you name? Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells What are two types of cells? • Prokaryotes are single-celled organisms that do not have a nucleus or membrane-bound organelles. • Prokaryotes’ DNA is in the cytoplasm. They have organelles without cell membranes called ribosomes. • Some have flagella, or hairlike structures that help them move. Copyright © Houghton Mifflin Harcourt Publishing Company Unit 2 Lesson 1 The Characteristics of Cells What are two types of cells? • Eukaryotes are organisms made up of cells that contain DNA in a nucleus, membrane-bound organelles, and ribosomes. • Animals, plants, protists, and fungi are eukaryotes. Copyright © Houghton Mifflin Harcourt Publishing Company