Chapter 7 Cell Structure & Function

1. Chapter 7Cell Structure & Function

2. 7-1: Life is Cellular • OBJECTIVES: • What is the cell theory? • What are the characteristics of prokaryotes and eukaryotes? ********************************** • There is a common structure that makes up every living thing - the cell

3. The Discovery of the Cell • In 1665, Robert Hooke used a microscope and saw chamber in cork that he called cells • Anton van Leeuwenhoek also observed tiny organisms in water • Contributions to the cell theory: • Schleiden - all plants are made of cells • Schwann - all animals are made of cells • Virchow - new cells could only come from the division of existing cells • The Cell Theory: • All living things are composed of cells • Cells are the basic units of structure & function • New cells are produced from existing cells

4. CORK CELLS

5. White Boards • Who was the first scientists to see living cells?

6. White Boards • Which scientist determined that all animals are made of cells?

7. White Boards • The cell theory says: • All living things are composed of cells • New cells are produced from existing cells • Cells are the basic units of _____?_____

8. Exploring the Cell • Light microscopes are limited in detail (resolution) because light is easily scattered as it passes through air • Electron microscopes (TEM’s and SEM’s) can view things 1000x smaller than light microscopes • Scanning probe microscopes can operate in ordinary air and can even show samples in solution (DNA, protein, and other biomolecules)

9. SEM

10. IMAGES

11. Prokaryotes and Eukaryotes • All cells have two things in common • Surrounded by a barrier (membrane) • Contain DNA • The nucleus is a membrane-enclosed structure that contains the cell’s genetic material in the form of DNA • Prokaryotic cells have no nucleus • Eukaryotic cells have a nucleus

12. Prokaryotes and Eukaryotes

13. Prokaryotes and Eukaryotes

14. White Boards • What two features do all cells share?

15. White Boards • Which type of organism has cells that contain a nucleus? PROKARYOTIC or EUKARYOTIC

16. 7-1 Section Assessment • What three statements describe the cell theory? • What are the differences between prokaryotic cells and eukaryotic cells? • Compare the processes used to create a TEM and an SEM. • What structures do all cells have? • How did the invention of the microscope help the cell theory?

17. 7-2: Eukaryotic Cell Structure • What are the functions of the major cell structures? OBJECTIVES

19. Comparing the Cell to a Factory • At first, cells look impossibly complex, but patterns eventually emerge • Many structures are common to eukaryotic cells • These structures act as specialized organs and are called organelles • Eukaryotic cells are divided into two parts: The nucleus and the cytoplasm

20. White Boards • Eukaryotic cells are divided into two parts: the ________ and the ________.

21. Nucleus • The nucleus is the control center • The nucleus contains nearly all the cell’s DNA: Coded instructions for making proteins and other molecules • It is surrounded by a nuclear envelope which has pores to let materials in and out • Chromatin is granular material in the nucleus which is made of DNA bound to protein • Chromatin condenses to form chromosomes when the cell divides • The dark region in the nucleus is the nucleolus: The location of ribosome construction

24. White Boards • ________ is made of DNA bound to protein.

25. White Boards • When a cell divides, chromatin condenses to form ________.

26. Ribosomes • Proteins are assembled on ribosomes • Ribosomes are small particles of RNA and protein and are found throughout the cytoplasm • They produce proteins by following coded instructions that come from the nucleus

28. White Boards • Where do the instructions for making proteins come from?

29. White Boards • Proteins can be found throughout the ________ and are sometimes attached to the ________.

30. Endoplasmic Reticulum • The endoplasmic reticulum (ER) is the site where lipid components of the cell membrane are assembled, along with proteins and other materials that are exported from the cell • Rough ER is covered with ribosomes and is involved in the synthesis of proteins • Smooth ER does not contain ribosomes and contains collections of enzymes that perform specialized tasks (synthesis of lipids, detoxification, etc.)

32. White Boards • Rough ER is involved with the synthesis of ________.

33. Golgi Apparatus • 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 secretion outside the cell • The golgi ships proteins to their final destinations throughout the cell or outside of the cell

35. Lysosomes • Lysosomes are small organelles filled with enzymes • Lysosomes digest (break down) lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell • Lysosomes also break down unuseful organelles and other “junk” in the cell

37. Vacuoles • Vacuoles are saclike structures used for storage of materials such as water, salts, proteins, and carbohydrates • Plant cells have a large central vacuole used for support • Vacuoles can also be found in some single-celled organisms and some animals

39. Mitochondria & Chloroplasts • Mitochondria are organelles that convert the chemical energy stored in food into compounds that are more convenient for the cell to use • Nearly all mitochondria in humans come from the cytoplasm of the mother’s egg cell • Chloroplasts are organelles that capture energy from sunlight and convert it into chemical energy in a process called photosynthesis • Chloroplasts and mitochondria contain their own DNA • Lyn Margulis developed the endosymbiotic theory: Prokaryotic ancestors of mitochondria and chloroplasts developed symbiotic relationships with early eukaryotes

42. White Boards • Organelles that capture energy from sunlight and convert it to chemical energy are called ________.

43. Cytoskeleton • The cytoskeleton is a network of protein filaments that help the cell to maintain its shape • The cytoskeleton is also involved in movement • Microfilaments are threadlike structures made of actin that: • Support the cell • Assist with movement • Microtubules are hollow structures made of proteins called tubulins that: • Maintain shape • Form centrioles during cell division (Animal cells only) • Form cilia and flagella

45. 7-2 Section Assessment • Describe the functions of the endoplasmic reticulum, Golgi apparatus, chloroplast, and mitochondrion. • Describe the role of the nucleus in the cell. • What are two functions of the cytoskeleton? • How is a cell like a factory? • You examine an unknown cell under the microscope and discover the cell contains chloroplasts. What type of organism could you infer that the cell came from?

46. 7-3: Cell Boundaries • Cell membrane: thin, flexible barrier • Cell Wall: Strong supporting layer around the membrane of some cells • What are the main functions of the cell membrane and the cell wall? • What happens during diffusion? • What is osmosis? OBJECTIVES

47. Cell Membrane • The cell membrane regulates what enters and leaves the cell and also provides protection and support • Composed of a lipid bilayer with embedded protein molecules and carbohydrates attached to some of the proteins • Often described as a mosaic • The proteins form channels and pumps to move materials • The carbohydrates act like chemical identification cards

50. White Boards • The cell membrane is composed of a ________ ________ with embedded protein molecules and carbohydrates attached to some of the proteins.