The Evolution of Microscopes and Cell Structures

1. Cells

2. Long, Long Ago…. • Before microscope, people thought that diseases were caused by curses and supernatural spirits • Microscopes enabled scientists to view and study cells • Anton VanLeeuwenhoek – developed the 1st light microscope

3. Today’s microscopes • Today we have much more advanced microscopes • Compound light microscope – series of lenses to magnify objects • SEM (Scanning Electron Microscope) – scans the surface of cells • TEM (Transmission Electron Microscope) – see structures inside the cell

4. Cell Theory • All organisms are composed of cells • All cells come from other living cells • Cells are the basic unit of structure and function

5. Homeostasis • All organisms must maintain a balance regardless of internal and external conditions • This task is controlled by the plasma membrane

6. Plasma Membrane • The plasma membrane serves as the boundary between the cell and its environment • Allows specific amount of nutrients to enter and allow waste to exit

7. Characteristics of cell membrane • Selectively permeable – allows some molecules to enter and keeps others out • Like a screen door

8. Plasma Membrane • Made up of two layers of phospholipids • Controls what moves into and out of the cell • Selectively permeable • AKA: Lipid Bilayer, Fluid Mosaic, Cell Membrane

9. Cell Wall • Rigid structure • Located outside of plasma membrane • Found in plant cells, fungi, some bacteria and protists • Provides support and protection • Composed of cellulose (carbohydrate)

10. Two Basic Cell Types • Prokaryote • Eukaryote

11. Nucleus • Control center of the eukaryotic cell • Contains directions to make proteins • Chromatin – strands of genetic material (DNA)

12. Nucleolus • Structure within the nucleus • Produces ribosomes

13. Ribosomes • The site of protein synthesis • Found in the cytoplasm or on the Endoplasmic Reticulum

14. Cytoplasm • Clear, gelatinous fluid inside the cell • Helps suspend organelles

15. Endoplasmic Reticulum • Site of cellular chemical reactions • Series of highly folded membranes • Rough Endoplasmic Reticulum – have ribosomes attached • Smooth Endoplasmic Reticulum – does not have ribosomes attached

16. Golgi Apparatus • AKA: Golgi Body • Flattened system of tubular membranes • Modifies and packages proteins • Sort proteins to be sent to appropriate destination

17. Vacuoles • Temporary storage of materials • Store food, enzymes, other materials needed by the cell, and waste • Plant cells usually have one large vacuole, animal cells usually contain many smaller vacuoles

18. Lysosomes • Contain digestive enzymes that digest excess or worn out organelles, food particles, viruses and bacteria

19. Chloroplasts • Found in the cells of green plants • Organelle that captures light energy and produces food to store for later use • Contains chlorophyll – gives plants their green color

20. Mitochondria • Organelles that transform energy for the cell • Double membrane structure with highly folded inner membrane

21. Cytoskeleton • Support structure for the cell • Composed of microtubules and microfilaments • Helps cell to maintain shape

22. Cilia and Flagella • Aid in locomotion or feeding • May move the entire cell, or aid in movement of substances across the cell surface

23. Identify the Following Cellular Structures

24. Animal Cells - Don’t have a cell wall - Contain centrioles - Contain many small vacuoles Plant Cells - Generally larger than animal cells - Have a cell wall - Contain chloroplasts - Have one large central vacuole Plant and Animal Cells Critical Thinking : Why are plant and animal cells similar?

25. Advantages of highly folded Membranes • Folded membranes are an advantage to a cell because • Cell processes can be more efficient • Membranes provide a larger surface area for cell process to take place • Remember all cell membranes are made up of phospholipids and by controlling what goes in and out of the membrane they help the cell maintain homeostasis