Cell Transport Lecture #17 Ms. Day Honors Biology

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

REVIEW… Permeability and Cell Transport Hydrophobic (non polar) molecules  Are lipid soluble (can dissolve)  can pass through membrane easily Ex: CO 2, O 2 Hydrophilic (Polar) molecules  Are NOT lipid soluble (can’t dissolve) Lipid INsoluble  Do not cross membrane easily Ex: Na +, Cl -, Glucose/other polar or charged things

Types of Cellular Transport Passive Transport cell do NOT use energy 1.Diffusion/Osmosis 2.Facilitated Diffusion Active Transport cell DOES use energy 1.Protein Pumps 2.Endocytosis 3.Exocytosis high low This is going to be hard! high low Weee!

Types of Passive Transport DiffusionANY Diffusion = molecules (of ANY substance) move from area of HIGH [ ] to lower [ ]  A “net” movement Ex: Perfume, a fart, tea, food coloring in water

DIFFUSION OWN  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 Osmosis water semipermea ble membrane Diffusion of water across a semipermea ble membrane  Water molecules move from MORE water to LESS water

3 Different Types of Solutions ** compare solutions OUTSIDE cell to inside cell 1. Isotonic solution  Amount of solutes and water is the same outside cell as inside the cell “ iso -” means “same” NO  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! (Dynamic Equilibrium)

Hypertonic solution 2. Hypertonic solution  Amount of solutes is greater outside than inside the cell  “hyper” means more  high [solute]  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 3. Hypotonic solution  Amount of solutes is less outside than inside the cell  “ hypo ” means “less” low [solute]  Think: Hypo- sounds like hippo… hippos are big & round; cells in hypotonic solutions get big & round  Also, think “hypo” is “low” meaning “low” solutes SURROUNDING cell  The cell will gain water and swell (and maybe burst) “Hypo” is LOW!!!

HYP0TONIC SOLUTION Result: Water moves from the solution to inside the cell): Cell Swells and might burst

Osmosis Animations for isotonic, hypertonic, and hypotonic solutionsOsmosis

REVIEW…Types of Passive Transport #1 #1 Passive Transport  DOES NOT require ATP energy  Moves DOWN (WITH) [ ] gradient  Kinetic energy drives movement #2 #2 Active Transport  DOES require chemical energy (Ex: A TP)  Moves A GAINST 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: CO 2, O 2. FACILITATED DIFFUSION 2. FACILITATED DIFFUSION needs a little “help” needs a little “help” Uses help of channel or carrier proteins Uses help of channel or carrier proteins Examples: H 2 O, glucose

2 Types of PASSIVE TRANSPORT. FACILITATED DIFFUSION 2. FACILITATED DIFFUSION needs a little “help” needs a little “help” Uses help of channel or carrier proteins 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) 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

Cha nnel proteins -Provide “tu nnel s” 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) Channel Proteins animationsChannel Proteins

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

2 Types of Passive Transport

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

Passive vs. Active Transport Figure 7.17

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

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

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

hill.com/sites/ /student_view0/chapter2/ animation__phagocytosis.html

Endocytosis and Exocytosis Animations hill.com/sites/ /student_view0/ chapter6/animations.html# hill.com/sites/ /student_view0/ chapter6/animations.html#

REVIEW ANIMATIONS ogy1111/animations/passive3.swf ogy1111/animations/passive3.swf  Excellent Review all Passive (simple/facilitated diffusion) and Active Transport No verbal explanation…you have to read the tutorial!