Chapter 7- Cell structure and Function

1. Chapter 7- Cell structure and Function

2. I. Cellular Life A.Life is cellular 1.In 1665 Robert Hooke was the first person to view the cell. 2.Hooke looked at a plant cork and called them “empty chambers.” Later on he called these chambers cells.

4. 3.   Anton van Leeuwenhoek used a microscope to view LIVE cells.

5. B. The cell theory 1. Numerous observations made it clear that cells are the basic unit of life. 2. Many biologists came to form the cell theory. It has three parts

6. a. All living things are composed of cells. b. Cells are the basic unit of structure and function in living thing c. New cells are produced from existing cells.

7. C. Exploring the Cell 1.Scientists and biologists use the microscope to explore the cell. 2.Today researchers have better technique and equipment to study the cell.

9. D.   Prokaryotes and Eukaryotic 1.Cells come in a great a variety of shapes and a range of sizes. 2.Cells fall into two broad categories, depending on whether they contain a nucleus or no.

10. 3. The nucleus is a large membrane- enclosed structure that contains the cell’s genetic material in the form of DNA. 4. Eukaryotes are cells that contain nuclei 5. Prokaryotes are cells that do not contain nuclei.

12. E. Prokaryotes 1.Prokaryote cells are usually smaller and simpler. 2.Prokaryotic cells have genetic material that is NOT contained in a nucleus.

14. F. Eukaryotes 1.Eukaryotic cells are generally larger and more complex than prokaryotic cells. 2.Eukaryotic cells contain a nucleus in which their genetic material is separated from the rest of the cell.

16. II. Eukaryotic cell Structure A. Comparing cell structure 1. The cell acts like a factory with the many different departments that all work together for a unifying result. 2. The specialized organs in the cell are known as organelles.

17. 3. Cell biologists divide the cell into two main parts the nucleus and the cytoplasm. 4. The cytoplasm is the portion of the cell outside the nucleus. 5. The nucleus and cytoplasm work together.

19. B. Nucleus 1. The nucleus contains nearly all the cell’s DNA and with it the coded instructions for making proteins and other important molecules. 2. The nucleus is surrounded by a nuclear envelope composed of two membranes

21. 3. The nuclear envelope allows materials to move into and out of the nucleus. 4. The granular material you can see in the nucleus is called chromatin. 5. Chromatin consists of DNA bound to protein.

23. 6. Most of the time it is condensed to a form called chromosomes

24. 7. Most nuclei also contain a small, dense region known as the nucleolus. The nucleolus is where the assembly of ribosomes begins.

25. C. Ribosomes 1.One of the most important jobs carried out in the cellular factory is making proteins. 2.Proteins are assembled on ribosomes. 3.Ribosomes are small particles of RNA and protein found throughout the cytoplasm.

27. D. Endoplasmic reticulum (ER) 1.The ER is the site where lipid (fats) components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell. 2.The ER can be smooth (lacking ribosomes) or rough (containing ribosomes) 3.The ER acts like a highway transporting the ribosomes to where they need to go.

29. E. Golgi Apparatus 1.The function of the Golgi apparatus is to modify, sort and package proteins and other materials from the ER for storage in the cell or secretions outside of the cell. 2.It acts like the UPS- packages, distributes and ships.

31. F. Lysosomes 1.Lysosomes are small organelles filled with digestive enzymes. 2.Lysosomes go around and eat all the “junk” of the cell.

33. G. Vacuoles 1.Cells contain a saclike structure called a vacuole to store waste- water, salt, protein and carbohydrates.

35. H. Mitochondria and chloroplasts 1.All living things require energy. 2.Nearly all-Eukaryotic cells, including plants contain mitochondria. 3.Mitochondria are organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use.

36. 4. Mitochondria are the powerhouse of the cell, they make ATP- adenoine triphosphate. 5. Chloroplasts are organelles that capture the energy from sunlight and convert it into chemical energy in a process called photosynthesis. 6. Chloroplasts and mitochondria contain their own genetic information of small DNA molecules.

38. I. Cytoskeleton 1.The cytoskeleton helps support the cell. 2.The cytoskeleton is a network of protein filaments that help the cell to maintain its shape. 3.The cytoskeleton is also involved in movement. 4.Microfilaments and microtubules are two of the principal protein filaments that make up the cytoskeleton.

40. III. Cell boundaries A.Cell Membrane 1.The cell membrane regulates what enters and leaves the cell and also provides protection and support. 2.The composition of nearly all cell membranes is a double-layered sheet called the lipid bilayer. 3. In addition to lipids, most cell membranes contain protein molecules that are embedded in the lipid bilayer.

42. B. Cell Walls 1.The main function of the cell wall is to provide support and protection for the cell. 2.Most cell walls are made from fibers of carbohydrate and protein.

44. C. Diffusion through the cell boundaries 1.Every living cell exists in a liquid environment that it needs to survive. 2.One of the most important functions of the cell membrane is to regulate the movement of dissolved molecules from the liquid on one side o the membrane to the liquid on the other side.

45. 3. The cytoplasm of a cell contains a solution of many different substances in water. 4. The concentration of a solution is the mass of solute in a given volume of a solution, or mass/volume.

46. D. Diffusion 1.Diffusion is the movement of a concentration from a low concentration to an area of greater concentration. 2.When the concentration of the solute is the same throughout a system, the system has reached equilibrium. 3.Because diffusion depends upon random particles movements, substances diffuse across membranes without requiring the cell to use energy.

48. E. Osmosis 1.Osmosis is the diffusion of water through a selectively permeable membrane. 2.When two solutions are the same strength they are referred to as isotonic. 3.When there is “above strength” it is referred to as hypertonic.

49. 4. When there is “below strength” it is referred to as hypotonic. 5. For organisms to survive, they must have a way to balance the intake and loss of water. 6. Osmotic pressure could cause great problems for the cell- see figure 7.16 page 186.