1. Unit 1 Lesson 1 The Characteristics of Cells
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2. Cell-ebrate! What is a cell?
Unit 1 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.
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3. Why are most cells small?
Unit 1 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 nutrients 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. The smaller the cell, the greater this ratio.
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4. Cell Hall of Fame What is the cell theory?
Unit 1 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.
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5. Unit 1 Lesson 1 The Characteristics of Cells
What is the cell theory?
Anton van Leeuwenhoek was the first to describe living cells.
Matthias Schleiden concluded that all plants are made of cells.
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6. Unit 1 Lesson 1 The Characteristics of Cells
What is the cell theory?
Theodor Schwann determined that all animal tissues are made of cells.
Rudolf Virchow proposed that cells could form only from the division of other cells.
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7. Unit 1 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.
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8. On the Cellular What parts do all cells have in common?
Unit 1 Lesson 1 The Characteristics of Cells
On the Cellular
What parts do all 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 the fluid and all the organelles except for the nucleus.
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9. What parts do all cells have in common?
Unit 1 Lesson 1 The Characteristics of Cells
What parts do all 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.
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10. What parts do all cells have in common?
Unit 1 Lesson 1 The Characteristics of Cells
What parts do all cells have in common?
How many parts of a cell can you name?
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11. What are the two types of cells?
Unit 1 Lesson 1 The Characteristics of Cells
What are the 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 hairlike structures called flagella that help them move.
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12. What are the two types of cells?
Unit 1 Lesson 1 The Characteristics of Cells
What are the 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.
Most eukaryotes are multicellular but some are unicellular.
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