1. Table of Contents Discovering Cells Looking Inside Cells
Chemical Compounds in Cells
The Cell in Its Environment

2. Development of the Cell Theory
- Discovering Cells
Development of the Cell Theory
The cell theory states the following:
All living things are composed of cells.
Cells are the basic units of structure and function in living things.
All cells are produced from other cells.

3. Light Microscopes - Discovering Cells
The lenses in light microscopes magnify an object by bending the light that passes through them.

4. Sequencing - Discovering Cells
Construct a flowchart showing how the work of Hooke, Leeuwenhoek, Schleiden, Schwann, and Virchow contributed to scientific understanding of cells.
Discovering Cells
Hooke sees cells in cork.
Leeuwenhoek sees many one-celled organisms.
Schleiden concludes that all plants are made of cells.
Schwann concludes that all animals (and all living things) are made of cells.
Virchow proposes that new cells form only from cells that already exist.

5. End of Section: Discovering Cells

6. Nucleus - Looking Inside Cells
The nucleus is the cell’s control center, directing all of the cell’s activities.

7. Mitochondrion - Looking Inside Cells
Mitochondria are known as the “powerhouses” of the cell because they convert energy in food molecules to energy the cell can use to carry out its functions.

8. Endoplasmic Reticulum
- Looking Inside Cells
Endoplasmic Reticulum
The endoplasmic reticulum is similar to the system of hallways in a building. Proteins and other materials move throughout the cell by way of the endoplasmic reticulum. The spots on this organelle are ribosomes, which produce proteins.

9. - Looking Inside Cells
Plant and Animal Cells

10. Golgi Body - Looking Inside Cells
The Golgi bodies receive proteins and other newly formed materials from the endoplasmic reticulum, package them, and distribute them to other parts of the cell.

11. Plant and Animal Cells Activity
- Looking Inside Cells
Plant and Animal Cells Activity
Click the Active Art button to open a browser window and access Active Art about plant and animal cells.

12. Previewing Visuals - Looking Inside Cells
Before you read, preview Figure 12. Then write two questions you have about the illustrations in a graphic organizer like the one below. As you read, answer your questions.
Plant and Animal Cells
Q. How are animal cells different from plant cells?
A. Plants cells have a cell wall and chloroplasts, which animal cells to not have.
Q. What do mitochondria do?
A. Mitochondria convert energy in food molecules to energy the cell can use.

13. End of Section: Looking Inside Cells

14. Elements and Compounds
- Chemical Compounds in Cells
Elements and Compounds
Carbon dioxide, which is found in gas bubbles, is a chemical compound. So is water.

15. Compounds in Bacteria and Mammals
- Chemical Compounds in Cells
Compounds in Bacteria and Mammals
All cells contain carbohydrates, lipids, proteins, and nucleic acids, as well as water and other inorganic compounds. But do all cells contain the same percentages of these compounds? The graph compares the percentage of some compounds found in a bacterial cell and a cell from a mammal.

16. Compounds in Bacteria and Mammals
- Chemical Compounds in Cells
Compounds in Bacteria and Mammals
Reading Graphs:
What do the red bars represent? What do the blue bars represent?
Red bars represent percentages of compounds in bacterial cells; blue bars represent percentages of compounds in mammalian cells.

17. Compounds in Bacteria and Mammals
- Chemical Compounds in Cells
Compounds in Bacteria and Mammals
Interpreting Data:
What percentage of a mammalian cell is made up of water? How does this compare to the percentage of water in a bacterial cell?
About 70%; the percentages are the same.

18. Compounds in Bacteria and Mammals
- Chemical Compounds in Cells
Compounds in Bacteria and Mammals
Interpreting Data:
Which kind of compound–proteins or nucleic acids–makes up the larger percentage of a mammalian cell?
Proteins

19. Compounds in Bacteria and Mammals
- Chemical Compounds in Cells
Compounds in Bacteria and Mammals
Drawing Conclusions:
In general, how do a bacterial cell and mammalian cell compare in their chemical composition?
They are similar, though mammalian cells have a lower percentage of nucleic acids, and bacterial cells have a lower percentage of lipids and fewer proteins.

20. Water and Living Things
- Chemical Compounds in Cells
Water and Living Things
About two-thirds of the human body is water.

21. Comparing and Contrasting
- Chemical Compounds in Cells
Comparing and Contrasting
As you read, compare and contrast carbohydrates, proteins, and lipids in a table like the one below.
Type of Compound
Elements
Functions
Store and provide energy and make up cellular parts
Carbohydrate
Carbon, hydrogen, oxygen
Make up much of the structure of cells and speed up chemical reactions
Protein
Carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur
Lipid
Carbon, hydrogen, oxygen
Store energy

22. Click the SciLinks button for links on proteins.
- Chemical Compounds in Cells
Links on Proteins
Click the SciLinks button for links on proteins.

23. End of Section: Chemical Compounds in Cells

24. Ratios - The Cell in Its Environment
The concentration of a solution can be expressed as a ratio. A ratio compares two numbers. It tells you how much you have of one item in comparison to another. For example, suppose you dissolve 5 g of sugar in 1 L of water. You can express the concentration of the solution in ratio form as 5 g:1 L, or 5 g/L.
Practice Problem
Suppose you dissolve 7 g of salt in 1 L of water. Express the concentration of the solution as a ratio.
7 g:1 L or 7 g/L

25. A Selective Barrier - The Cell in Its Environment
The cell membrane protects the contents of the cell and helps control the materials that enter and leave.

26. Diffusion - The Cell in Its Environment
In diffusion, molecules move from an area of higher concentration to an area of lower concentration. Molecules will reach equilibrium. Where their concentration is equal.

27. Osmosis - The Cell in Its Environment
In osmosis, water diffuses through a selectively permeable membrane. (Usually the Cell Membrane)

28. Passive and Active Transport
- The Cell in Its Environment
Passive and Active Transport
Passive and active transport are two processes by which materials pass through the cell membrane. Active transport requires the cell to use its own energy, while passive transport does not.

29. Building Vocabulary - The Cell in Its Environment
A definition states the meaning of a word or phrase. After you read the section, reread the paragraphs that contain definitions of Key Terms. Use all the information you have learned to write a definition of each Key Term in your own words.
Key Terms:
Key Terms:
Examples:
passive transport
active transport
Examples:
selectively permeable
The movement of dissolved materials through a cell membrane without using cellular energy is called passive transport.
The cell membrane is selectively permeable, which means that some substances can pass through the membrane while others cannot.
diffusion
Diffusion is the process by which molecules move from an area of higher concentration to an area of lower concentration.
Active transport is the movement of materials through a cell membrane using cellular energy.
osmosis
Osmosis is the diffusion of water molecules through a selectively permeable membrane.

30. More on Cellular Transport
- The Cell in Its Environment
More on Cellular Transport
Click the PHSchool.com button for an activity about cellular transport.

31. End of Section: The Cell in Its Environment

32. Graphic Organizer Organic Compounds Carbo-hydrates Nucleic acids
types
made of
include
Organic Compounds
Carbo-hydrates
Nucleic acids
Lipids
Proteins
Fats, oils, and waxes
Amino acids
Sugars
Starches
DNA
RNA

33. End of Section: Graphic Organizer