Theodore Schwann and Matthias Schleiden and Virchow composed the cell theory.

1. Theodore Schwann and Matthias Schleiden and Virchow composed the cell theory.

2. Cell Theory • 1. All living organisms are composed of cells and cell products. • 2. The cell is the basic unit of structure and function of all living organisms. • 3. All cells come from pre-existing cells. • 4. An organism as a whole can be understood through the collective activities and interactions of cells.

3. Cytologist-scientist who study cells. • The adult human body has about 75 trillion cells. They are measured in units called micrometers. • Cells vary in shape----their shape is related to their function.

4. ----Nerve cells—long thread-like and transmit impulses from one body part to another. • ----Epithelial cells--line inside of mouth and are flattened, tightly packed and look like floor tiles. (Protect and shield) • ----Muscle cells—slender and rod-like----ends attached to parts they move.

5. Anatomy—The Cell Basic Unit of Life

6. You cannot describe a typical cell due to variations in size, shape, content, and function. The cells we look at are called “composite cells”.

7. Parts of a Cell • Nucleus---innermost part enclosed by a nuclear membrane. • Cytoplasm---mass of fluid that surrounds the nucleus. • Cytosol---fluid portion of cytoplasm—all metabolic reactions occur here. • Cell membrane---(plasma membrane or cytoplasmic membrane) outer most limit of cell.

8. Characteristics of Cell membrane • Thin—visible with a microscope only • Complex surface features outpouchings and infoldings • These provide extra surface area • Seals itself after injury quickly. If too injured, contents of cell escapes and cell dies. • It is selectively permeable and allows some substances to pass through and refuses others.

9. Structure: • Composed of lipids and proteins and some carbohydrates. • Double layer of phospholipid molecules • Contains lots of protein and few lipids. • Framework: double layer of phospholipid molecules.

10. Water soluble heads (hydrophilic) form surface and water insoluble tails (hydrophobic) form interior of membrane.

11. Blood cells are not in direct contact with one another because of fluid-filled spaces(intercellular spaces) separate them.

12. 3 Types of intercellular junctions: • Tight junctions – membranes of adjacent cells converge and becomes fused together. It surrounds the cell like a belt. The cells form sheet-like layers like the digestive tube. • Desmosome – rivets or “spot welds” adjacent cells and forms reinforced structural unit. Skin Cells • Gap junction – tubular channels that link cytoplasm of adjacent cells and allows ions and nutrients to exchange between them. Heart muscle and muscle of digestive tube.

14. Draw the plasma membraneInclude and label the following: • Phospholipid heads • Fatty acid tails • Cholesterol • Channel proteins • Pore proteins • Glycoprotein/Receptor proteins • Fibrous proteins • Identify hydrophobic and hydrophilic regions

15. Other Cell Structures: • Cytoplasm—It contains network of membranes and other organelles suspended in clear liquid cytosol.

16. Nucleoplasm—material inside the nucleus.

17. ER—(Endoplasmic reticulum)- complex organelle composed of membrane-bound flattened sacs, elongated canals and fluid-filled vesicles. • Communication system • Rough ER-ribosomes attached. • Smooth ER-no ribosomes

18. Ribosomes—sites of protein synthesis in the cell.

19. Golgi apparatus—located near the nucleus. It is composed of flattened membrane sacs called cisternae. • Refining, packaging and delivery of protein.

20. Mitochondria—elongated fluid filled—energy producer powerhouse of the cell • Cristae—inner membrane foldings.

21. Lysosomes—shapes vary---contains powerful enzymes to digest many particles. They also function in destruction of worn cell parts.

22. Peroxisome– membranous sacs that resemble lysosomes in size and shape. Found in liver and kidney cells • Break down fatty acids and help Detoxify Alcohol.

23. Centrosome—Central body located in cytoplasm near Golgi apparatus and nucleus consists of hollow cylinders called centrioles which help carry DNA information.

25. Cilia and flagella – motile processes that extend outward from surface of the cell. Cilia – on epithelium; flagella – sperm

27. Vesicles (vacuole) – membranous sacs that vary in size.

29. Microfilaments/microtubules – two types of thin threadlike structures found in cytoplasm to help function to form cellular movements.

30. Nuclear membrane – allows substances to pass between nucleus and cytoplasm.

31. Nucleolus – “little nucleus” small dense body of RNA and protein • Function: production of ribosomes.

32. Chromatin – loosely coiled fibers in nuclear fluid (DNA)

33. Cell Membrane • Substances enter and leave the cell • ---oxygen and food enters • ---carbon dioxide and waste leave

34. The growth of a cell depends on two factors: • A. Increase in volume of individual cell • B. Increase in number of cells • If a cell grows too large it dies. It cannot absorb enough necessary materials to supply its volume or get rid of waste.

35. Cells are limited in size by their surface area-volume relationship.

36. Diffusion • Process in which molecules or ions become scattered or are spread spontaneously from higher to lower concentration. • Particles move and bounce off one another which mixes them. Ex: Sugar cube in water

37. Equilibrium – state of uniform distribution of molecules.

38. Facilitated diffusion • Uses carrier molecule to transport insoluble material across the cell membrane. • Sugar molecules are insoluble in lipids. Sugar glucose may enter by facilitated diffusion. • Glucose molecule combines with special protein carrier molecule at surface of membrane. Union of glucose and carrier molecule forms a compound soluble in liquids that can diffuse to other side. Hormone insulin supports process.

39. Rate is dependent on number of carrier molecules in the cell membrane.

40. Osmosis • Form of diffusion • Water diffuses from a higher to a lower concentration through a selectively permeable membrane. • Osmotic pressure – the amount of pressure needed to stop osmosis • The greater the number of solute particles in solution, the greater the osmotic pressure.

41. Plasmolysis---shrinking of cell contents • Cytolysis---bursting of cell • Hemolysis---red blood cells hemolyze. bursting of red blood cells.

42. 3 types of solutions: • Hypertonic – more water leaves the cell than enters because concentration of solute particles is greater outside the cell.

43. Hypotonic solution– a solution in which more water enters the cell than leaves it. Lesser solute outside the cell.

44. Isotonic solution---solution that contains same concentration of solute particles as a particular cell. Water enters and leaves the cell at the same rate. Cell remains unchanged. • http://www.tvdsb.on.ca/westmin/science/sbi3a1/Cells/Osmosis.htm

45. Active transport • Particles move from regions of lower to higher concentration. • Sodium—higher outside cell than inside cell • 40% of cell’s energy supply may be used for active transport.

46. Filtration – molecules are forced through membrane by hydrostatic pressure usually blood pressure – greater on one side of membrane than the other. • Also takes place in the kidneys when water and various substances are forced out of blood vessels and into kidney tubules by blood pressure ( first step in formation of urine)

47. Dialysis • Dialysis is a method of transport in which diffusible substances are separated from non diffusible substances in a solution – net movement of particles can be controlled by changing concentration gradients of solute and solvent.

48. Endocytosis • Molecules or other particles that are too large to enter cell.

49. 3 types of endocytosis: • Pinocytosis—process in which cells take in tiny drops of liquid from their surroundings. Small portion of cell membrane indents to form sac that enters cytoplasm. Cells take in water and dissolved protein.