Journey of Cell Theory: From Spontaneous Generation to Modern Cell Biology

1. On a notecard write your answerBellringer:In one or two complete sentences describe what the following quote tells us about the origin of new life. Quote: “Fireflies rise from the morning dew, fish and frogs from a muddy stew, maggot worms from rotting meat and mice shall come from sweat and wheat.”

2. Cell Theory and the Scientists Who Helped Shape It

3. What is Spontaneous Generation? • the belief that living things can come from non-living things. • Was once thought to be true, but is now known to be false! How was it disproved? • the following scientists with their combined experiments proved the theory of spontaneous generation to be false & helped develop the Cell Theory.

4. Scientists and the Cell Theory

5. Who was… Francesco Redi? (1668) • scientist whose experiments proved maggots did not come from rotting meat.

6. Who was…Robert Hooke? (1665) • used a compound microscope to look at cork (from bark of a tree) & he saw empty boxlike structures that he named “cells”.

7. Who was…Antonie van Leewenhooke? (mid 1600’s) • used a simple microscope to look at pond water. • was the first to observe microorganisms in pond water.

8. Who was…Matthias Schleiden? (1830’s) • studied numerous plant parts under the microscope and declared “ALL PLANTS ARE MADE OF CELLS!”

9. Who was… Theodor Scwhann? (mid 1830’s) • Used a microscope to observe numerous animal tissues and declared “ALL ANIMALS ARE MADE OF CELLS!”

10. Who was… Rudolf Virchow? (Mid 1830’s) • observed living cells dividing and declared “ALL CELLS COME FROM OTHER LIVING CELLS!”

11. The Cell Theory • Major Contributors: • Matthias Schleiden • Theodor Schwann • Rudolph Virchow

12. The Cell Theory • All living things are made of cells. • Cells are the basic units of structure and function in living things. • Living cells come only from other living cells.

13. Characteristics of All Cells • A surrounding membrane • Cytoplasm – cell contents in thick fluid • Organelles – structures for cell function • Control center with DNA

14. Cell Types • Prokaryotic • Eukaryotic

15. Prokaryotic Cells • First cell type on earth • Cell type of Bacteria and Archaea • No membrane bound nucleus • Nucleoid = region of DNA concentration • Organelles not bound by membranes

16. Eukaryotic Cells • Nucleus bound by membrane • Include fungi, protists, plant, and animal cells • Possess many organelles

19. Plasma (Cell) Membrane

20. Plasma Membrane • Contains cell contents • Double layer of phospholipids & proteins

21. Phospholipids • Polar • Hydrophylic head • Hydrophobic tail • Interacts with water

22. Movement Across the Plasma Membrane • A few molecules move freely • Water, Carbon dioxide, Ammonia, Oxygen • Carrier proteins transport some molecules • Proteins embedded in lipid bilayer • Fluid mosaic model – describes fluid nature of a lipid bilayer with proteins

24. Membrane Proteins 3. Glycoproteins • Identify cell type 4. Enzymes • Catalyze production of substances 1. Channels or transporters • Move molecules in one direction 2. Receptors • Recognize certain chemicals

25. Molecule Movement & Cells • Passive Transport • Active Transport • Endocytosis (phagocytosis & pinocytosis) • Exocytosis

26. Passive Transport • No energy required • Move due to gradient • differences in concentration, pressure, charge • Move to equalize gradient • High moves toward low Types of Passive Transport 1. Diffusion 2. Osmosis 3. Facilitated diffusion

27. Diffusion Molecules move to equalize concentration

28. Osmosis • Special form of diffusion • Fluid flows from lower solute concentration • Often involves movement of water • Into cell • Out of cell

29. Solution Differences & Cells • Isotonic • Solutes equal inside & out of cell • Hypertonic • Solutes greater outside cell • Fluid will flow out of cell solvent + solute = solution • Hypotonic • Solutes in cell more than outside • Outside solvent will flow into cell

30. Facilitated Diffusion • Differentially permeable membrane • Channels (are specific) help molecule or ions enter or leave the cell • Channels usually are transport proteins • (aquaporins facilitate the movement of water) • No energy is used

31. Process of Facilitated Transport • Protein binds with molecule • Shape of protein changes • Molecule moves across membrane

32. Active Transport • Molecular movement • Requires energy (against gradient) • Example is sodium-potassium pump

33. Endocytosis • Movement of large material • Particles • Organisms • Large molecules • Movement is into cells • Types of endocytosis • bulk-phase (nonspecific) • receptor-mediated (specific)

34. Process of Endocytosis • Plasma membrane surrounds material • Edges of membrane meet • Membranes fuse to form vesicle Forms of Endocytosis • Phagocytosis – cell eating • Pinocytosis – cell drinking

35. Exocytosis • Reverse of endocytosis • Cell discharges material • Vesicle moves to cell surface • Membrane of vesicle fuses • Materials expelled