Table of Contents

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

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

4. - Discovering Cells Sequencing • 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. - Discovering Cells Links on Cell Theory • Click the SciLinks button for links on the cell theory.

6. End of Section:Discovering Cells

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

8. - Looking Inside Cells Mitochondrion • 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.

9. - 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.

10. - Looking Inside Cells Plant and Animal Cells

11. - Looking Inside Cells Golgi Body • 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.

12. - 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.

13. - Looking Inside Cells Previewing Visuals • 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.

14. - Looking Inside Cells The Cytoplasm and Organelles • Click the Video button to watch a movie about cytoplasm and organelles.

15. - Looking Inside Cells Specialized Cells • Click the Video button to watch a movie about specialized cells.

16. End of Section:Looking Inside Cells

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

18. - 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.

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

20. About 70%; the percentages are the same. 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? - Chemical Compounds in Cells Compounds in Bacteria and Mammals

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

22. 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. Drawing Conclusions: In general, how do a bacterial cell and mammalian cell compare in their chemical composition? - Chemical Compounds in Cells Compounds in Bacteria and Mammals

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

24. - 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 Carbon, hydrogen, oxygen Carbohydrate Make up much of the structure of cells and speed up chemical reactions Carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur Protein Carbon, hydrogen, oxygen Lipid Store energy

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

26. End of Section:Chemical Compounds in Cells

27. 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 as5 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 - The Cell in Its Environment Ratios

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

29. - The Cell in Its Environment Diffusion • In diffusion, molecules move from an area of higher concentration to an area of lower concentration.

30. - The Cell in Its Environment Osmosis • In osmosis, water diffuses through a selectively permeable membrane.

31. - 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.

32. Key Terms: Examples: passive transport active transport - The Cell in Its Environment Building Vocabulary • 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: Examples: selectively permeable The cell membrane is selectively permeable, which means that some substances can pass through the membrane while others cannot. The movement of dissolved materials through a cell membrane without using cellular energy is called passive transport. 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.

33. - The Cell in Its Environment More on Cellular Transport • Click the PHSchool.com button for an activityabout cellular transport.

34. End of Section:The Cell in Its Environment

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

36. End of Section:Graphic Organizer