1. 7th Science Cells and Heredity (Module A)
Unit 1: Cells
Lesson 1: Characteristics of Cells

2. Organism - any living thing that carries out its own life processes.
Unit 1 Lesson 1 The Characteristics of Cells
What is a cell?
A cell is the smallest functional and structural unit of all living organisms.
Organism - any living thing that carries out its own life processes.
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3. Unit 1 Lesson 1 The Characteristics of Cells
Cell size
All cells are small - size is limited by their outer surface area.
If too large, can’t take in enough nutrients or get rid of enough wastes.
The surface area-to-volume ratio: ratio of the outer surface to the cell’s volume.
The smaller the cell, the greater this ratio.
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5. Cell theory 1. All organisms are made up of one or more cells.
Unit 1 Lesson 1 The Characteristics of Cells
Cell theory
Three basic components:
1. All organisms are made up of one or more cells.
2. The cell is the basic unit of all organisms.
3. All cells come from existing cells.
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6. Cell Hall of Fame
Unit 1 Lesson 1 The Characteristics of Cells
Robert Hooke (1665) - first to describe cells. He looked at the bark of a cork tree under a microscope (that he built).
Thought that cork cells looked like cells in monastery
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7. Cell Hall of Fame (con’t) read pg. 8-9
Unit 1 Lesson 1 The Characteristics of Cells
Cell Hall of Fame (con’t) read pg. 8-9
Anton van Leeuwenhoek (1673) made first microscope, described “wee beasties” in pond water.
Matthias Schleiden (1838) said all plants are made of cells.
Theodor Schwann (1839) said all animals tissues are made of cells.
Rudolf Virchow (1858) said cells divide to form new
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8. A few more important cell theory things:
Unit 1 Lesson 1 The Characteristics of Cells
A few more important cell theory things:
Unicellular organisms: Organisms made up of just one cell
One cell has to carry out ALL
life functions.
multicellular organisms: Organisms made up of more than one cell
Cells have specialized functions.
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9. Two types of cells
Unit 1 Lesson 1 The Characteristics of Cells
Prokaryotes - No nucleus or membrane-bound organelles
All are single-celled
DNA is in the cytoplasm
Have ribosomes to make proteins
Some have flagella to help move
Smaller than eukaryotes
Examples: bacteria, archaea
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10. Bacteria Flagella

11. Eukaryotes - have DNA in a nucleus
Unit 1 Lesson 1 The Characteristics of Cells
Eukaryotes - have DNA in a nucleus
Have other membrane-bound organelles
Most are multicellular
Also have ribosomes (not membrane bound)
Examples: animals, plants, protists, fungi
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12. All cells have… cell membrane – protective outer layer
Unit 1 Lesson 1 The Characteristics of Cells
cell membrane – protective outer layer
controls materials moving into and out of the cell.
cytoplasm - region inside the cell that includes the fluid and all the organelles except for the nucleus.
organelle - small body in the cytoplasm
specialized to perform a specific function
DNA (deoxyribonucleic acid)- genetic material that provides instructions for all cell processes
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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?
How many parts of a cell can you name?
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