The Path to the Cell Theory

1. The Path to the Cell Theory

2. Click on Leeuwenhoek

3. Advancements in Cell Biology and Imaging Quality

4. Cofounders of the Cell Theory 1858 Rudolf Vichow – Cells come from pre-existing cells.

5. The Cell Theory • All living things are composed of cells. • Cells are the basic units of structure and function in living things. • New cells are produced from existing cells.

6. Modern Cell Theory • With advancements and more studies in science the following additions have been added onto the Cell Theory: • Energy Flow occurs within cells. • Metabolism • Cells contain hereditary information that is passed on from cell to cell during cell division • DNA • All cells are basically the same in chemical composition in organisms of similar species.

7. Cell Types • Cells • Basic units that make up organisms • Can only be observed under a microscope • Three Basic Types: Bacterial Cell Animal Cell Plant Cell

8. Cell Sizes _________ > _____________ > ___________ Plant cell Animal cell bacteria

9. CELL SIZE Typical cells range from 5 – 50 micrometers (microns) in diameter

10. How Big is a Micron ( µ ) ? 1 cm = 10,000 microns 1” = 25,000 microns

11. Number of Cells Although ALL living things are made of cells, organisms may be: • Unicellular–composed of one cell • Multicellular- composed of many cells that may organize into tissues, etc.

12. Multicellular Organisms • Cells in multicellular organisms often specialize (take on different shapes & functions)

13. Cell Specialization • Cells in a multi-cellular organism become specialized by turning different genes on and off • This is known as DIFFERENTIATION

14. Specialized Animal Cells Red blood cells Muscle cells Cheek cells

15. Specialized Plant cells Guard Cells Pollen Xylem cells

16. Biologists divide cells into two main categories: Prokaryotes Eukaryotes

17. Prokaryotes • Simplest type of cell • Cells • Lack a nucleus or membrane bound organelles • Have single, circular chromosomes • Bacteria • Still carry out all life processes – grow, reproduce, move, respond to changes in their environments

18. Prokaryotes • Cell surrounded by cell membrane & cell wall • Nucleoid region (center) contains the DNA • Contain ribosomes (no membrane) in their cytoplasm to make proteins • Flagella – long tail like structure that aids in movement

19. Eukaryotes • More complex type of cells • Cells • Have a nucleus and membrane-bound organelles • Includes single cell and multi cellular organisms like protists, fungi, plants, and animals

20. Contain 3 basic cell structures: Nucleus Cell Membrane Cytoplasm with organelles Eukaryotic Cell

21. Two Main Types of Eukaryotic Cells Animal Cell Plant Cell

22. Cell Organelles (Cell Structures) • Parts and Structures inside of the cell • Very small (microscopic) • Perform various and sometimes specialized functions for the cell • Found in the cytoplasm • May or may not be membrane bound

23. Ribosome (attached) Nucleolus Ribosome (free) Animal Cell Organelles Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus

24. Plant Cell Organelles

25. Ribosome (attached) Nucleolus Ribosome (free) Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus

26. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Cell Membrane • Plasma Membrane • Function: • Surrounds the outside of all cells • Controls what enters and leaves the cell • Takes in food and water • Eliminates wastes • Protects and supports the cell

27. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Cell Membrane • Made up of a phospholipid bilayer • Double layered sheet • Tough, flexible structure that forms a strong barrier between the cell and its surroundings

28. Outside of cell Carbohydrate chains Proteins Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Cell Membrane • Heads(Made of gylcerol and phosphate) • Hydrophilic • Attract water • Point outward • Tails (Made of fatty acids) • Hydrophobic • Repel water • Point inward

29. The Cell Membrane is Fluid Molecules in cell membranes are constantly moving and changing

30. Cytoplasm Ribosome (attached) Nucleolus Ribosome (free) Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus Cytoplasm

31. Nucleus Ribosome (attached) Nucleolus Ribosome (free) Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus

32. Nucleus • Usually the largest organelle • Function: • Controls the normal activities of the cell

33. Nucleus • Function: • Contains DNA in chromosomes • Each cell has a fixed number of chromosomes that carry genes • Genes control the cell’s characteristics

34. DNA is the hereditary material of the cell. DNA contains the code and instructions to make different proteins. *Nucleus is found in eukaryotic cells. (All cells except bacteria).

35. Nuclear Envelope • aka Nuclear Membrane • A double membrane that surrounds the nucleus • Connected to the rough ER • Function: • Has pores that allow materials to enter and leave the nucleus Nuclear membrane or envelope is found in eukaryotic cells. (All cell except bacteria)

36. Nucleolus • Dense, round structure found inside nucleus -There may be more than one (plural -nucleoli) -Disappears when cell divides • Function: -Makes building materials for ribosomes Found in eukaryotic cells. (All cell except bacteria)

37. Cytoskeleton Cell Membrane MICROTUBULES Endoplasmic Reticulum MICROFILAMENTS Ribosomes Mitochondrion

38. Types of Protein Fibers in Cytoskeleton • Microfilaments Made of actin protein found just inside C.M. to help to maintain cell cell shape and also to help cell to move. • Microtubules: Straight, hollow tubes made of globular protein, tubulin. Provide “tracks” for motor proteins to “walk” organelles. • Intermediate Filaments Reinforce cell shape and anchor organelles such as nucleus.

39. Cilia and Flagella • Made of protein tubes called microtubules • Function: • Move cells • Cilia – shorter and more of them on the cell • Flagella – longer and fewer of them on the cell • Found in various cells – (both prokaryotic & eukaryotic)

40. Cilia and Flagella Draw these pictures and label in your notes

41. Centrioles Ribosome (attached) Nucleolus Ribosome (free) Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus

42. Centrioles (animal cells only) • Found only in animal cells • Made of bundles of microtubules • Appear during cell division and form the mitotic spindle • Function: Help to pull chromosome pairs apart to opposite ends of the cell

43. click image

44. Mitochondrion(found in eukaryotics cells) Ribosome (attached) Nucleolus Ribosome (free) Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus

45. Mitochondria • Function: • Powerhouse of the cell • Cellular Respiration (burning of glucose) • Generates ATP (cellular energy) • In both plant and animal cells • The more active the cell (muscle cells) the more mitochondria they have

46. Mitochondria • Surrounded by a double membrane • Has its own DNA • Cristae - folded inner membrane (increases surface area for chemical reactions)

47. Endoplasmic Reticulum (found in eukaryotic cells) Ribosome (attached) Nucleolus Ribosome (free) Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth Endoplasmic Reticulum Rough Endoplasmic Reticulum Centrioles Golgi apparatus

48. Endomembrane System Includes nuclear membrane connected to ER connected to cell membrane (transport)

49. Endoplasmic Reticulum (ER) • Network of hollow membrane tubules • Connects to nuclear envelope and cell membrane • Functions in synthesis of cell products and transport

50. Smooth Endoplasmic Reticulum • Does not have ribosomes on its surface • Attached to the end of the Rough ER • Function: • Makes cell products that are used inside of the cell • Membrane lipids (steriods) • Regulates calcium (muscle cells) • Destroys toxic substances (liver cells)