1. Homeostasis and Transport
And Cell Structure

2. Types of Transport
Cells move molecules using different types of passive and active transport
These differ from each other by whether or not cells must use energy.
Passive= no energy
Active = use energy

3. Passive Transport
Passive transport —movement of substances through a membrane that requires NO ENERGY
Types:
Diffusion —movement of molecules from high to low concentration
Osmosis —movement of WATER from high to low concentration
Facilitated Diffusion —assisted diffusion of large or insoluble molecules through a cell membrane.
Ion Channel Diffusion —movement of ions from high to low concentration.

4. Diffusion Molecules move from high to low concentration.
Move down their concentration gradient
Molecules can move through semi-permeable membranes
Continues until equilibrium is reached.
Molecules to large to diffuse through the membrane must find a channel pore to travel through

5. Osmosis
Osmosis is the movement of WATER from high to low concentration.
Depends on the concentration of solutes inside and outside of the cell.
Hypotonic Solution—solution outside the cell has a lower concentration of solute molecules than inside. Water moves into the cell. (Oh NO! She’s gonna blow!)
Hypertonic Solution —a solution outside the cell has a higher concentration of solute molecules than inside. Water moves out of the cell. (Cell shrinks!)
Isotonic Solution —a solution in which the concentrations of solute molecules are equal on both sides of the membrane.

6. Control of osmosis
Contractile vacuoles
Solute pumps
Cell Walls

7. Cytolysis —bursting of a cell due to osmosis.
Hypotonic
Isotonic
Hypertonic
Identify the pictures as a cell in an isotonic solution, hypertonic solution and hypotonic solution

8. Facilitated Diffusion
Assisted diffusion of large or insoluble molecules through a cell membrane.
Carrier Proteins help the molecules to move from high to low concentration.
Glucose is transported to cells in this way.

9. Ion Channel Diffusion
Several ions are vital to cells but cannot pass through the cell membrane because they are not soluble in lipids. They are:
Sodium (Na+)
Potassium (K+ )
Calcium (Ca2+ )
Chlorine (Cl-)
They require specific ion channels to pass through membranes

10. Many ion channels have gates that close or open in response
Many ion channels have gates that close or open in response
to three stimuli:
1. stretching of cell membrane
2. electrical signals
3. chemical signals

11. Active Transport
Active Transport —movement of substances through a cell membrane that REQUIRES ENERGY.
Molecules move from low to high concentration ( “up” their concentration gradient).
The Carrier Proteins involved require energy from ATP and are called Cell Membrane Pumps.
Example: Sodium-potassium pump

13. Endocytosis
Movement of VERY LARGE PARTICLES into a cell. The cell membrane pinches off to trap the particle inside a vesicle which can then transport the particle throughout the cell.

14. Two types of endocytosis:
Phagocytosis—movement of large particles
or whole cells
Pinocytosis—movement of fluids

15. Exocytosis
Movement of VERY LARGE PARTICLES out of a cell. Vesicles bring particles to the cell membrane to be released.

16. Cell Theory Cell—smallest unit of life
All living things are made of one or many cells.
Unicellular
Colonies
Multicellular
Cells come only from other cells.
Levels of organization are:
Cells Tissues Organ Organ System Organism

17. Cell Types (two basic types)
Prokaryotes —cells without a nucleus or membrane-bound organelles
Include bacteria and archaebacteria
Eukaryotes —cells with a nucleus and membrane-bound organelles
Include cells from plants, animals, fungi and protists

18. Features common to both prokaryotic and eukaryotic cells include:
DNA —genetic material located in the nucleus of eukaryotic cells and in the nucleoid region of prokaryotic cells
Plasma Membrane —outer boundary of cell
Cytoplasm —all the material inside the plasma membrane, (not including the nucleoid region or nucleus). It includes a fluid part called the cytosol and many organelles and other particules floating in it.
Ribosomes —site of protein synthesis

19. Cell Organelles
Plasma Membrane —Phospholipid bilayer that surrounds a cell. Controls what gets in and out.
Phospholipids have hydrophilic heads and hydrophobic tails

20. Embedded in the phospholipid bilayer are different types of proteins for transport, identification and binding.

21. Cell Organelles
Cytoplasm —gel like substance that fills the cell. Organelles float in cytoplasm.
Nucleus —control center of cell. Contains DNA.
Mitochondria —powerhouse of cell. Site of cellular respiration (where ATP is made). Contains its own DNA.
Ribosomes —protein factories of cell. Can float in cytoplasm or be attached to ER.

22. Cell Organelles
Endoplasmic Reticulum —transport system of cell. Make up a large part of the endomembrane system. Rough (with ribosomes attached) and Smooth (with no ribosomes)
Golgi Apparatus —packaging center. Receives proteins and lipids; modifies and packages them into vesicles.
Vesicles —transport vehicles. Types: Lysosomes, peroxisomes, glyoxysomes, endosomes.

23. Cell Organelles Plant cells have all of the same structures plus:
Cell wall —made of cellulose
Central Vacuole —to store water
Plastids —including chloroplasts (contain their own DNA), chromoplasts and amyloplasts.

24. Compare them all

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