Cell Transport Lecture #11 Ms. Day Honors Biology

REMEMBER: the cell membrane is selectively (semi-) permeable Cell Transport Means moving things INTO and OUT of the cell Cells need to take in Food, gases, water Get rid of waste products Release hormones and enzyme REMEMBER: the cell membrane is selectively (semi-) permeable

REVIEW… Permeability and Cell Transport Hydrophobic (non polar) molecules Can mix with lipids (non polar regions) can pass through membrane easily Ex: CO2, O2, other small nonpolar things Hydrophilic (Polar) molecules Can NOT mix with lipids Lipid INsoluble Do not cross membrane easily Ex: Na+, Cl- , Glucose/other polar or charged things

Types of Cellular Transport high low Weee! Passive Transport cell does NOT use energy Diffusion/Osmosis Facilitated Diffusion Active Transport cell DOES use energy Protein Pumps Endocytosis Exocytosis high low This is going to be hard!

Types of Passive Transport Diffusion= molecules (of ANY type..gas, liquid or solid) move from area of HIGH [ ] to lower [ ] A “net” movement “net” means OVERALL Ex: Perfume, tea, food coloring in water http://www.indiana.edu/~phys215/lecture/lecnotes/lecgraphics/diffusion2.gif http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_diffusion_works.html

DIFFUSION Molecules move DOWN its OWN concentration gradient difference in amount of a substance from one area to another No chemical work (ATP energy) is used

Substances diffuse down their OWN concentration gradient Figure 7.11 B (b) Net diffusion Equilibrium

Effects of Osmosis on Water Balance Diffusion of water across a semipermeable membrane Water molecules move from MORE water to LESS water

Vocabulary Reminder... Solute Solvent Solution “Like mixes with like” A substance that is dissolved Solvent A substance that is doing the dissolving of another substance Solution A uniform mixture of 2+ things “Like mixes with like” Nonpolar things mix w/ other nonpolar things Polar things mix w/ other polar things

Amount of solutes and water is the same on both sides of a membrane 3 Different Types of Solutions ** compare solutions OUTSIDE cell to inside cell 1. Isotonic solution Amount of solutes and water is the same on both sides of a membrane “iso-” means “same” There will be NO net movement of water Cell does not change in size

ISOTONIC SOLUTION Result: Water moves equally in both directions and the cell remains same size! (Cell is in “Dynamic Equilibrium”)

The cell will lose water and shrivel or wilt 2. Hypertonic solution Amount of solutes is greater on one side of a membrane compared to the other side “hyper” means more high [solute] [ ] = concentration of The cell will lose water and shrivel or wilt

HYPERTONIC SOLUTION Result: Water moves from inside the cell into the solution: Cell shrinks!

3. Hypotonic solution Amount of solutes are less on one side of the membrane compared to the other side “hypo” means “less” low [solute] Also, think “hypo” is “low” meaning “low” solutes SURROUNDING cell The cell will gain water and swell (and maybe burst) “Hypo” rhymes with LOW!!!

HYPOTONIC SOLUTION Result: Water moves from the solution to inside the cell): Cell Swells and might burst

Osmosis Animations for isotonic, hypertonic, and hypotonic solutions http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_osmosis_works.html

REVIEW…Types of Passive Transport DOES NOT require ATP energy Moves DOWN (WITH) [ ] gradient Kinetic energy drives movement #2 Active Transport DOES require chemical energy (Ex: ATP) Moves AGAINST its [ ] gradient

2 Types of PASSIVE TRANSPORT GOES DOWN CONCENTRATION GRADIENT (no ATP needed) Molecules move HIGH [ ]low [ ] 1. SIMPLE DIFFUSION **INCLUDES DIFFUSION Uses NO membrane proteins Examples: CO2, O2 2. FACILITATED DIFFUSION needs a little “help” Uses help of channel or carrier proteins Examples: H2O, glucose

2 Types of PASSIVE TRANSPORT 2. FACILITATED DIFFUSION needs a little “help” Uses help of channel or carrier proteins GOES DOWN CONCENTRATION GRADIENT (no ATP needed) Moves POLAR molecules  can NOT easily pass through HYDROPHOBIC region of membrane. Example: ions, smaller polar molecules (ex: sugar)

Aquaporins water is polar but very small It can pass easily through membrane uses aquaporins Oh…now I get it! EXTRACELLULAR FLUID AQUAPORIN Channel protein Water CYTOPLASM

Channel proteins -Provide “tunnels” Channel Proteins animations Channel proteins -Provide “tunnels” Figure 7.15 EXTRACELLULAR FLUID Channel protein Solute CYTOPLASM A channel protein (purple) has a channel through which water molecules or a specific solute can pass. (a)

Carrier proteins -Undergo a subtle change in shape “carry” solute across the membrane

2 Types of Passive Transport

Active transport Uses energy Moves solutes against their [ ] gradients across the cell membrane Energy required  usually ATP Carrier proteins are used…NEVER channel proteins Ex: protein pumps

Passive vs. Active Transport Figure 7.17

Another type of transport = Bulk Transport Occurs by exocytosis and endocytosis BOTH MOVE “BIG” AMOUNTS OF STUFF in OR out OF THE CELL

Exocytosis In exocytosis Transport vesicles move to the plasma membrane, fuse with it, and release their contents “exo-” means “exit” Ex: hormone excretion; nerve cells and transmitters; removal of wastes

Endocytosis In endocytosis Cell takes in molecules by forming new vesicles from the plasma membrane “endo-” means “enter”

2 types of Endocytosis 1. Phagocytosis 2. Pinocytosis “cell eating” Cell engulfs SOLIDS into vesicle & “digests” it 2. Pinocytosis “cell drinking” Cell engulfs LIQUIDS into vesicle & “digests” it

http://highered. mcgraw-hill http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__phagocytosis.html

Endocytosis and Exocytosis Animations http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter6/animations.html#

REVIEW ANIMATIONS http://www.northland.cc.mn.us/biology/Biology1111/animations/passive3.swf Excellent Review all Passive (simple/facilitated diffusion) and Active Transport  No verbal explanation…you have to read the tutorial!