Cell Structure & Function

1. Cell Structure & Function Chapter 7

2. The Discovery of the Cell • Without a tool to make them visible cells were until the invention of the microscope • 1665 - Robert Hooke used an early microscope to look at cork cells. • About the same time Anton van Leeuwenhoek observed tiny organisms in pond water. http://www.youtube.com/watch?v=wzI2RrBYZ5U

3. Early Discoveries • 1838 - Matthias Schleiden a German botanist concluded that all plants are made of cells. • 1839 - Theodor Schwann a German biologist stated that all animals are made of cells. • 1855 - Rudolf Virchow a German physician concluded that new cells can only be produced by division of existing cells

4. Cell Theory • All living things are made up of cells. • Cells are the basic units of structure and function in all living things. • New cells are produced from existing cells through cell division.

5. How do microscopes work? • Most use lenses to magnify the image of an object by focusing light or electrons. • Types of microscopes: • Light microscopes – images 1 millionth of m • Electron microscopes – images 1billionth of m • TEM – transmission – thin samples, can see cell structures & molecules • SEM – scanning – 3-D surface images

6. Light Microscope image

7. SEM Images

8. TEM Images

9. Examples of Cells Amoeba Proteus Plant Stem Bacteria Red Blood Cell Nerve Cell

10. As you can seecellscome in many sizes and shapes

11. All cells have some similarities: • At some point they contain DNA • All cells are surrounded by a thin flexible barrier called a cell membrane or plasma membrane. But they also have differences and so are seperated into 2 broad groups: Eukaryotes and Prokaryotes

12. Prokaryotic • Do not have structures surrounded by membranes • Do not separate DNA within a nucleus • One-celled organisms, Bacteria

14. Eukaryotic • Contain organelles, specialized structures that perform specific functions; surrounded by membranes • Nucleus separates DNA from the rest of the cell • Most living organisms, great variety Plant Animal http://library.thinkquest.org/C004535/eukaryotic_cells.html

15. What do these cells have In common?

16. “Typical” Animal Cell http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif

17. “Typical” Plant Cell http://waynesword.palomar.edu/images/plant3.gif

18. Cell Parts Organelles

19. Inside the CellTwo major parts

20. Cytoplasm • Gel-like mixture also called cytosol • Portion outside the nucleus • Surrounded by cell membrane • Contains organelles of eukaryotes – specialized structures that perform specific tasks

21. Nucleus • Directs cell activities • Separated from cytoplasm by nuclear membrane • Contains genetic material – DNA – which contains coded information to make proteins • Prokaryote cells lack a nucleus but they do contain DNA

22. Nuclear Membrane • Surrounds nucleus • Made of two layers • Openings called nuclear pores allow material to enter and leave nucleus • Also called the nuclear envelope http://library.thinkquest.org/12413/structures.html

23. Chromosomes • In nucleus • Made of DNA • Contain instructions for traits & characteristics • Usually in the form of long thin threads called chromatin http://library.thinkquest.org/12413/structures.html

24. Nucleolus • Small dense region inside nucleus • Involved in the assembly of organelles called ribosomes http://library.thinkquest.org/12413/structures.html

25. Vacuoles • Membrane-bound sacs for storage of water, salts, proteins, and carbohydrates • Plants usually have a large vacuole that helps maintain shape • Paramecium – contractile vacuole http://library.thinkquest.org/12413/structures.html

26. Lysosome • Small organelles filled with enzymes to digest waste • Transports digested material to cell membrane for removal • Also breaks down old organelles no longer needed http://library.thinkquest.org/12413/structures.html

27. Cytoskeleton • Helps maintain cell shape and also in movement. • Internal network of protein fibers: • Microfilaments • Microtubules

28. Ribosomes • Each cell contains thousands • Make proteins using instructions from DNA http://library.thinkquest.org/12413/structures.html

29. Endoplasmic Reticulum • Internal membrane system where compounds are assembled and transported • Smooth ER: lacks ribosomes; makes lipids • Rough ER(pictured): ribosomes embedded in surface; modify proteins made by ribosomes

30. Golgi Apparatus • Modifies, sorts, and packages proteins and other materials from the ER for storage in the cell or released outside the cell. • Bundles proteins in tiny vesicles. http://library.thinkquest.org/12413/structures.html

31. Mitochondria • Convert chemical energy stored in food (glucose) into compounds that are able to be used by cells –ATP • In humans most all of our mitochondria come from the cytoplasm of the egg cell – so you got yours from your mother. • They also contain their own DNA! http://library.thinkquest.org/12413/structures.html

32. Chloroplast • Capture energy from sunlight and convert it into food – sugars – that contain chemical energy in a process called photosynthesis. • Surrounded by two membranes • Contain pigment called chlorophyll http://library.thinkquest.org/12413/structures.html

33. Surrounding the Cell

34. Cell Membrane • Outer membrane of cell that controls movement in and out of the cell • Double layer • Also known as the plasma membrane http://library.thinkquest.org/12413/structures.html

35. Cell Wall • Most commonly found in plant cells & bacteria • Supports & protects cells http://library.thinkquest.org/12413/structures.html