6.1 All organisms are made of cells

1. 6.1 All organisms are made of cells

2. I. The Cell Theory • In 1655 Robert Hooke observed “compartments” in a thin slice of cork which he named cells • In 1700 Anton van Leeuwenhoek had developed light microscopes to observe tiny living organisms which he named “animalcules”

3. First microscopes

4. The Cell Theory C. Cell theory is the generalization that all living things are composed of cells, and that cells are the basic unit of structure and function in living things

5. II. Microscopes as Windows to Cells • Light microscopes can magnify objects up to about 1,000 X • Electron microscopes can magnify objects up to about 1,000,000 X C. A photograph of the view taken through a microscope is called a micrograph

6. Microscopes

7. Microscopes SEM- scanning electron microscope TEM- transmission Both must use preserved specimens.

8. Microscopes

9. III. An Overview of Animal and Plant Cells • Each part of a cell with a specific job to do is called an organelle B. The plasma membrane defines the boundary of the cell and regulates traffic in and out of the cell

10. Overview of animal and plant • The nucleus stores the genetic material of the cell D. The region of the cell between the nucleus and the plasma membrane is called the cytoplasm

11. Animal Cell

12. Animal Cell

13. Plant cell

14. Plant cell

15. IV. Two Major Classes of Cells • A prokaryotic cell lacks a nucleus and most other organelles B. A eukaryotic cell has a membrane bound nucleus and organelles

16. Animal v. Plants

17. Eukaryotic v. Prokaryotic

18. 6.2 Membranes organize a cell’s activities

19. I. Membrane Structure • Membranes regulate the transport of substances across it • Membranes are composed mostly of proteins and phospholipids

20. Membrane structure • The phospholipids form a two-layer sandwich called a “phospholipid bilayer” which surrounds the organelle or cell D. The membranes are fluid-like rather than sheets of molecules locked rigidly into place

21. Plasma membrane

22. Plasma membrane

23. II. The Many Functions of Membrane Proteins • Many types of proteins are embedded in the membranes phospholipid bilayer B. Some proteins carry out some of the cells important chemical reactions, others helps cell communicate and recognize each other, other proteins move substances like sugar and water across the membrane

24. Functions of Membrane Proteins

25. 6.3 Membranes regulate the traffic of molecules

26. I. Diffusion • Diffusion is the net movement of the particles of a substance from where they are more concentrated to where they are less concentrated B. Equilibrium is reached when the movement of particles in one direction is equal to the number of particles moving in the other

27. Diffusion

28. II. Passive Transport • A selectively permeable membrane allows some substances to cross the membrane more easily than others and blocks the passage of some substances altogether

29. Passive transport • Diffusion across a membrane is called passive transport because no energy is expended by the cell, only the random motion of molecules is required to move them across C. Facilitated diffusion is when transport proteins provide a pathway for certain molecules to pass

30. Passive transport Carbon dioxide, oxygen- nonpolar Water, glucose - polar molecules

31. III. Osmosis • The passive transport of water across a selectively permeable membrane is called osmosis • A solution with a higher concentration of solute is called hypertonic hyper = “above” C. A solution with a lower concentration of solute is called hypotonic hypo = “below”

32. III. Osmosis D. A solution that has an equal concentration of solute is called isotonic iso = “equal” • When an animal cell is placed in a hypotonic solution it swells • - When an animal cell is placed in a hypertonic solution it shrinks

33. Osmosis

34. IV. Active Transport • When a cell expends energy to move molecules or ions across a membrane it is called active transport B. A specific transport protein pumps a solute across a membrane, usually in the opposite direction it travels in diffusion

35. Active Transport Sodium / potassium pump

36. V. Transport of Large Molecules • Large molecules have to be packed into vesicles, which are small membrane sacs that specialize in moving products into, out of and within a cell

37. Transport of large molecules • When a cell exports its protein products, a vesicle fuses with the plasma membrane and spills its contents outside the cell-a process called exocytosis • The reverse process, endocytosis, takes materials into the cell within vesicles that bud inward from the plasma membrane

38. Transport of large molecules

39. 6.4 The cell builds a diversity of products

40. I. Structure and Function of the Nucleus A. The nucleus in a cell contains DNA which controls all of the activities inside the cell B. The nucleus is surrounded by the nuclear envelope which has hole in it which allow substances to pass in and out of the nucleus C. Inside the nucleus is the nucleolus which contains parts necessary to make ribosomes

41. nucleus

42. II. Ribosomes • DNA codes for the production of proteins which are made in the ribosomes B. The ribosomes are either bound to the surface of the endoplasmic reticulum or suspended in the cytoplasm

43. III. The Endoplasmic Reticulum • The endoplasmic reticulum is an extensive network of membranes which functions as the main manufacturing and transportation facility in the cell 1. Rough ER-The rough ER has ribosomes which insert proteins right into or through the ER membrane or packaged in vesicles and transported outside the cell

44. Endoplasmic Reticulum 2. Smooth ER-The smooth ER lacks ribosomes but enzymes in the smooth ER allow it to make lipid molecules

45. IV. The Golgi Apparatus A. The golgi apparatus receives products from the ER and modifies, stores and routes proteins and other products to their final destination B. This organelle is analogous to a processing a shipping center of the cell

46. V. Vacuoles • The cytoplasm has large, membrane bound sacs called vacuoles B. Some vacuoles contain undigested nutrients, some pump out excess water that diffuses into a cell, others store chemicals that contribute to cell growth

47. VI. Lysosomes • Membrane bound sacs called lysosomes contain digestive enzymes that can break down such molecules like proteins, nucleic acids and polysaccharides B. Lysosomes will digest food, destroy bacteria and digest damaged organelles

48. V. Membrane Pathways in a cell • The membranes inside a cell are transferable from one organelle to another B. Products may leave a cell without ever crossing a membrane

49. Membrane pathway in a cell

50. 6.5 Chloroplasts and mitochondria energize cells