Chapter Intro-page 170

1. Chapter Intro-page 170 What You’ll Learn Cells are the foundation for the development of all life forms. Birth, growth, death, and all life functions begin as cellular functions.

2. Lysosomes Nucleus Plasma Membrane Endoplasmic Reticulum Mitochondrion Chapter Intro-page 174

3. 7.1 Section Objectives – page 171 Section Objectives: • Relate advances in microscope technology to discoveries about cells and cell structure. • Compare the operation of a microscope with that of an electron microscope. • Identify the main ideas of the cell theory.

4. Section 7.1 Summary – pages 171-174 The History of the Cell Theory • Before microscopes were invented, people believed that diseases were caused by curses and supernatural spirits. • As scientists began using microscopes, they quickly realized they were entering a new world–one of microorganisms. • Microscopes enabled scientists to view and study cells, the basic units of living organisms.

5. Section 7.1 Summary – pages 171-174 Development of Light Microscopes • The first person to record looking at water under a microscope was Anton vanLeeuwenhoek. • The microscope van Leeuwenhoek used is considered a simple light microscope because it contained one lens and used natural light to view objects.

6. Section 7.1 Summary – pages 171-174 Development of Light Microscopes Compound light microscopes use a series of lenses to magnify objects in steps. These microscopes can magnify objects up to 1 500 times.

7. Section 7.1 Summary – pages 171-174 The Cell Theory • Robert Hooke was an English scientist who lived at the same time as van Leeuwenhock. • Hooke used a compound light microscope to study cork, the dead cells of oak bark. Cells are the basic building blocks of all living things.

8. Section 7.1 Summary – pages 171-174 The cell theoryis made up of three main ideas: All organisms are composed of one or more cells. The cell is the basic unit of organization of organisms. All cells come from preexisting cells.

9. Section 7.1 Summary – pages 171-174 Development of Electron Microscopes • The electron microscope was invented in the 1940s. • This microscope uses a beam of electrons to magnify structures up to 500 000 times their actual size.

10. Section 7.1 Summary – pages 171-174 Development of Electron Microscopes There are two basic types of electron microscopes. The scanning electron microscope scans the surface of cells to learn their three dimensional shape. • The transmission electron microscope allows scientists to study the structures contained within a cell.

11. Section 7.1 Summary – pages 171-174 Two Basic Cell Types Cells that do not contain internal membrane-bound structures are called prokaryotic cells. Click here • The cells of most unicellular organisms such as bacteria do not have membrane bound structures and are therefore called prokaryotes.

12. 7.1 Section 7.1 Summary – pages 171-174 Two Basic Cell Types Cells containing membrane-bound structures are called eukaryotic cells. Click here • Most of the multi-cellular plants and animals we know are made up of cells containing membrane-bound structures and are therefore called eukaryotes.

13. Section 7.1 Summary – pages 171-174 Two Basic Cell Types The membrane-bound structures within eukaryotic cells are called organelles. • Each organelle has a specific function that contributes to cell survival.

14. Section 7.1 Summary – pages 171-174 Two Basic Cell Types • Separation of organelles into distinct compartments benefits the eukaryotic cells. The nucleus is the central membrane-bound organelle that manages cellular functions.

15. Section 2 Objectives – page 175 Section Objectives • Explain how a cell’s plasma membrane functions. • Relate the function of the plasma membrane to the fluid mosaic model.

16. Summary Section 2 – pages 175-178 All living cells must maintain a balance regardless of internal and external conditions. Survival depends on the cell’s ability to maintain the proper conditions within itself.

17. Summary Section 2 – pages 175-178 Why cells must control materials The plasma membrane is the boundary between the cell and its environment.

18. Summary Section 2 – pages 175-178 It is the plasma membrane’s job to: • allow a steady supply of glucose, amino acids, and lipids to come into the cell no matter what the external conditions are. • remove excess amounts of these nutrients when levels get so high that they are harmful. • allow waste and other products to leave the cell.

19. Summary Section 2 – pages 175-178 This process of maintaining the cell’s environment is called homeostasis. Selective permeabilityis a process used to maintain homeostasis in which the plasma membrane allows some molecules into the cell while keeping others out.

20. Summary Section 2 – pages 175-178 Plasma Membrane Water

21. Summary Section 2 – pages 175-178 Structure of the Plasma Membrane The plasma membrane is composed of two layers of phospholipids back-to-back. Phospholipids are lipids with a phosphate attached to them.

22. Summary Section 2 – pages 175-178 Phosphate Group The lipids in a plasma membrane have a glycerol backbone, two fatty acid chains, and a phosphate group. Glycerol Backbone Two Fatty Acid Chains

23. Summary Section 2 – pages 175-178 Makeup of the phospholipid bilayer The phosphate group is critical for the formation and function of the plasma membrane. Phosphate Group

24. Summary Section 2 – pages 175-178 Makeup of the phospholipid bilayer The fluid mosaic modeldescribes the plasma membrane as a flexible boundary of a cell. The phospholipids move within the membrane.

25. Summary Section 2 – pages 175-178 Other components of the plasma membrane: Cholesterol plays the important role of preventing the fatty acid chains of the phospholipids from sticking together. Cholesterol Molecule

26. Summary Section 2 – pages 175-178 Other components of the plasma membrane: Transport proteins allow needed substances or waste materials to move through the plasma membrane. Click image to view movie.

27. Section 3 Objectives page 179 Section Objectives • Understand the structure and function of the parts of a typical eukaryotic cell. • Explain the advantages of highly folded membranes. • Compare and contrast the structures of plant and animal cells.

28. Section 3 Summary – page 179-187 Cellular Boundaries The plasma membrane acts as a selectively permeable membrane.

29. Section 3 Summary – page 179-187 The cell wall The cell wall is a fairly rigid structure located outside the plasma membrane that provides additional support and protection.

30. Section 3 Summary – page 179-187 Nucleus and cell control Nucleolus Chromatin Nuclear Envelope

31. Section 3 Summary – page 179-187 Assembly, Transport, and Storage The endoplasmic reticulum (ER) is an organelle that is suspended in the cytoplasm and is the site of cellular chemical reactions.

32. Section 3 Summary – page 179-187 Assembly, Transport, and Storage Endoplasmic Reticulum (ER) Ribosomes

33. Section 3 Summary – page 179-187 Assembly, Transport, and Storage Golgi Apparatus

34. Section 3 Summary – page 179-187 Vacuoles and storage Vacuolesare membrane-bound spaces used for temporary storage of materials. Notice the difference between vacuoles in plant and animal cells. Plant Cell Vacuole Animal Cell

35. Section 3 Summary – page 179-187 Lysosomes and recycling Lysosomes are organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria.

36. Section 3 Summary – page 179-187 Energy Transformers: Chloroplasts and energy Chloroplastsare cell organelles that capture light energy and produce food to store for a later time.

37. Section 3 Summary – page 179-187 Chloroplasts and energy The chloroplasts belongs to a group of plant organelles called plastids, which are used for storage. Chloroplasts contain green pigment called chlorophyll. Chlorophyll traps light energy and gives leaves and stems their green color.

38. Section 3 Summary – page 179-187 Mitochondria and energy Mitochondria are membrane-bound organelles in plant and animal cells that transform energy for the cell.

39. Section 3 Summary – page 179-187 Mitochondria and energy A mitochondria, like the endoplasmic reticulum, has a highly folded inner membrane. Energy storing molecules are produced on inner folds.

40. Section 3 Summary – page 179-187 Structures for Support and Locomotion Cells have a support structure called the cytoskeleton within the cytoplasm. The cytoskeleton is composed of microtubules and microfilaments. Microtubules are thin, hollow cylinders made of protein and microfilamentsare thin solid protein fibers.

41. Section 3 Summary – page 179-187 Cilia and flagella Some cell surfaces have cilia and flagella, which are structures that aid in locomotion or feeding. Cilia and flagella can be distinguished by their structure and by the nature of their action.

42. Section 3 Summary – page 179-187 Cilia and flagella Cilia Cilia are short, numerous, hair-like projections that move in a wavelike motion.

43. Section 3 Summary – page 179-187 Cilia and flagella Flagellaare long projections that move in a whip-like motion. Flagella and cilia are the major means of locomotion in unicellular organisms. Flagella

44. Chapter Summary – Section 1 • Main Ideas • Microscopes enabled biologists to see cells and develop the cell theory. • The cell theory states that the cell is the basic unit of organization, all organisms are made up of one or more cells, and all cells come from preexisting cells.

45. Chapter Summary – Section 1 • Main Ideas Continued • Using electron microscopes, scientists can study cell structure in detail. • Cells are classified as prokaryotic and eukaryotic based on whether or not they have membrane-bound organelles.

46. Chapter Summary – Section 2 • Main Ideas • Through selective permeability, the plasma membrane controls what enters and leaves a cell. • The fluid mosaic model describes the plasma membrane as a phospholipid bilayer with embedded proteins.

47. Chapter Summary – Section 2 • Main Ideas • Eukaryotic cells have a nucleus and organelles, are enclosed by a plasma membrane, and some have a cell wall that provides support and protection. • Cells make proteins on ribosomes that are often attached to the highly folded endoplasmic reticulum. Cells store materials in the Golgi apparatus and vacuoles.

48. Chapter Summary – Section 3 • Main Ideas Continued • Mitochondria break down food molecules to release energy. Chloroplasts convert light energy into chemical energy. • The cytoskeleton helps maintain cell shape, is involved in the movement of organelles and cells, and resists stress placed on cells.

49. A prokaryotic cell does not have internal organelles surrounded by a membrane. Most of a prokaryote’s metabolism takes place in the cytoplasm. 3. Plasma membrane 2. DNA 1. Ribosomes 4. Cell wall Click here to return to chapter summary Chapter Assessment

50. This eukaryotic cell from an animal has distinct membrane-bound organelles that allow different parts of the cell to perform different functions. 1. Nucleus 2. Nucleolus 3. Chromosomes 4. Plasma membrane Click here to return to chapter summary 5. Organelles Chapter Assessment