1. Unit 1 Lesson 1 The Characteristics of Cells
Big Idea: All organisms are made up of one or more cells
Essential Question: What are living things made of?
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2. Cell-ebrate! What is a cell?
Unit 1 Lesson 1  The Characteristics of Cells                               P6
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. 2

3. Unit 1 Lesson 1  The Characteristics of Cells                               P6
All of these cells are microscopic, membranes surrounding the cell, and organelles inside the cell 3

4. Why are most cells small?
Unit 1 Lesson 1  The Characteristics of Cells                                     P7
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. 4

5. Why are most cells small?
Unit 1 Lesson 1  The Characteristics of Cells                                     P7
Why are most cells small?
A. Calculate the surface area
Surface area = # of faces x area of one face
# of faces = 6
Area = 3cm x 3cm
Equation: SA = 6(3cm x 3cm)
Answer: Surface area = 54cm^2
B. Calculate the volume
Volume = side x side x side or Volume = length x width x height
Equation: Volume = 3cm x 3cm x 3cm
Answer: Volume = 27cm^3
C. Calculate the surface-to-volume ratio
Surface Area : Volume
54cm ^2 : 27cm^3
2cm^2 : 1cm^3 5

6. Cell Hall of Fame What is the cell theory?
Unit 1 Lesson 1  The Characteristics of Cells                                   P8-9
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. 6

7. Unit 1 Lesson 1  The Characteristics of Cells                               P8-9
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. 7

8. Unit 1 Lesson 1  The Characteristics of Cells                                  P8-9
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. 8

9. Unit 1 Lesson 1  The Characteristics of Cells                                   P8-9
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. 9

10. What is the cell theory? Cells come from existing cells
Unit 1 Lesson 1  The Characteristics of Cells                                   P8-9
What is the cell theory?
Animal tissues are made of cells, organisms are made up of multiple cells, cells are the basic unit of life
Cells come from existing cells
Plants are made of cells 10

11. Unit 1 Lesson 1  The Characteristics of Cells                                   P8-9
What is the cell theory?
All organisms are made up of one or more cells, the cell is the basic unit of all living things, and all cells come from existing cells 11

12. On the Cellular What parts do all cells have in common?
Unit 1 Lesson 1  The Characteristics of Cells                                  P10
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. 12

13. 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. 13

14. 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. 14

15. 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. 15

16. What are the two types of cells?
Unit 1 Lesson 1 The Characteristics of Cells
What are the two types of cells?
Cell Membrane
Cell Membrane
DNA in cytoplasm
Cytoplasm
Cytoplasm
Organelles
Organelles 16