1. Cells  All cells have two characteristics in common Surrounded by a cell membrane Surrounded by a cell membrane At some point contain DNA At some point contain DNA  Two Types Prokaryotic and Eukaryotic Prokaryotic and Eukaryotic

2. Prokaryotes  Generally smaller and simpler  Genetic material is not contained in a nucleus  Grow, reproduce, respond to the environment  Example: Bacteria

3. Eukaryotes  Generally larger and more complex  Contain dozens of structures and internal membranes  Highly specialized cells  Genetic material is contained in a nucleus  May be single celled organisms, or part of a large multi-cellular organism

4. Diversity of Cellular Life  Unicellular Organisms Made of a single cell Made of a single cell Majority of life on Earth Majority of life on Earth  Multi-cellular Organisms Made of many cells Made of many cells Depend on cooperation and communication among specialized cells Depend on cooperation and communication among specialized cells

5.  Cell specialization: cells develop in different ways to perform different tasks Animal cells: red blood cells (transport oxygen), pancreas (protein production), muscle cells (movement) Animal cells: red blood cells (transport oxygen), pancreas (protein production), muscle cells (movement) Plant cells: guard cells (regulate exchange in leaves) Plant cells: guard cells (regulate exchange in leaves)

6. Levels of Organization  Individual Cells  Tissues Cells grouped together Cells grouped together A group of similar cells that perform a particular function A group of similar cells that perform a particular function  Organs Tissues work together Tissues work together  Organ Systems Group of organs that work together to perform a specific function Group of organs that work together to perform a specific function

7. Osmosis and Diffusion Chapter 7.3

8. Cell Boundaries  Cell Membrane Thin flexible barrier that surrounds a cell Thin flexible barrier that surrounds a cell Regulates what enters and leaves the cell, provides protection and support Regulates what enters and leaves the cell, provides protection and support  Cell Wall Strong supporting layer around the cell membrane Strong supporting layer around the cell membrane Gives protection and support to a plant cell Gives protection and support to a plant cell

9. Cell Membrane Structure  Made of two layers (lipid bilayer) Gives cell membranes a flexible structure that forms a strong barrier Gives cell membranes a flexible structure that forms a strong barrier  Contains protein and carbohydrate molecules Helps materials cross the membrane Helps materials cross the membrane

10. Cell Wall Structure  Found outside the cell membrane (plants) Main function to provide support and protection Main function to provide support and protection  Allows water, oxygen, carbon dioxide to pass through  Made from carbohydrates and protein

11. Diffusion  Movement of dissolved molecules from one side of cell membrane to another  Particles move from an area where they are more concentrated to an area where they are less concentrated  Substances diffuse across a membrane without the cell using any energy

13. Osmosis  Diffusion of water across a selectively permeable membrane Most membranes selectively permeable Most membranes selectively permeable some substances can pass through and others cannot some substances can pass through and others cannot Water passes easily across most membranesWater passes easily across most membranes

14. Osmosis  How Osmosis works… Water will move across the membrane until equilibrium is reached Water will move across the membrane until equilibrium is reached Moves from high to low concentrationMoves from high to low concentration Osmotic pressure: pressure on the hypertonic side of a selectively permeable membrane Osmotic pressure: pressure on the hypertonic side of a selectively permeable membrane

15. Solutions  Hypertonic: side of the membrane with more molecules; “above strength”  Hypotonic: the side of the membrane with less molecules; “below strength”  Isotonic: concentrations the same on both sides of the membrane; “same strength”

17. Facilitated Diffusion  Cell membrane has certain channels (proteins) that make it easy for certain molecules to cross the membrane Will only occur if there is a higher concentration on one side of the membrane Will only occur if there is a higher concentration on one side of the membrane

18. Active Transport  Small molecules and ions are carried across membranes by proteins Requires energy, cells use majority of their energy for transport Requires energy, cells use majority of their energy for transport  Endocytosis Process of taking material into the cell by folding of cell membrane Process of taking material into the cell by folding of cell membrane  Exocytosis Membrane of vacuole fuses with cell membrane forcing contents out of cell Membrane of vacuole fuses with cell membrane forcing contents out of cell