1. Cell Theory All living things are made of cells Cells are the basic unit of life Cells today come only from other living cells Robert Hooke first saw cells in 1665

2. The Structure of a Cell All cells have –Plasma membrane –Cytosol –DNA –Ribosomes

3. Two Major Types of Cells Prokaryotic –No membrane bound organelles –Make up Domains Archaea and Eubacteria Eukaryotic –Membrane-bound organelles –Make up Kingdoms Plantae, Animalia, Protista, and Fungi

4. A prokaryotic cell

5. Overview of an animal cell Cytoplasm: everything inside the cell but the nucleus

6. Overview of a plant cell

7. Cell size The human body has over 5 billion cells. The largest animal is the blue whale, Balaenoptera musculus. It is known to reach lengths over 100 feet (30+ meters) and weigh 120 tons.

8. Cell size So, why aren’t there organisms composed of one really big cell?

9. Surface Area and Volume Surface area of a sphere = 4  r 2 Volume of a sphere = (4/3)  r 3 So as a sphere gets bigger, its volume increases faster than its surface area

10. Figure 7.5 Geometric relationships explain why most cells are microscopic

11. Let’s look at the interior of Eukaryotic cells… Nucleus Ribosomes Endomembrane System –Nuclear envelope –Endoplasmic Reticulum –Golgi Apparatus –Vesicles –Lysosomes –Vacuoles Other organelles: mitochondria, chloroplasts, peroxisomes Cytoskeleton

12. DNA  RNA  protein: a diagrammatic overview of information flow in a cell

13. Figure 7.9 The nucleus and its envelope

14. Figure 7.10 Ribosomes

15. Figure 7.11 Endoplasmic reticulum (ER)

16. Protein Carbohydrate group H2NH2N COOH In the rough ER, proteins are modified by the addition of a carbohydrate group Now = GLYCOPROTEIN

17. Figure 7.12 The Golgi apparatus

18. THE SECRETORY PATHWAY: A MODEL RNA cis face of Golgi apparatus trans face of Golgi apparatus Rough ER Plasma membrane 1. Proteins are synthesized in the RER 2. Protein exits RER in a vesicle. 3. Protein travels through the cisternae of the Golgi apparatus. 4. Protein enters a secretory vesicle that fuses with cell membrane. 5. Protein is secreted from cell.

19. Figure 7.13 Lysosomes

20. Figure 7.14 The formation and functions of lysosomes (Layer 1)

21. Figure 7.14 The formation and functions of lysosomes (Layer 2)

22. Figure 7.14 The formation and functions of lysosomes (Layer 3)

23. Figure 7.15 The plant cell vacuole

24. Figure 7.16 Review: relationships among organelles of the endomembrane system