Notes on Chapter 6.2 & 6.3 Movement through the Membrane

Homeostasis Examples:Examples: Body temperatureBody temperature SweatingSweating ShiveringShivering DehydrationDehydration Over-hydrationOver-hydration Definition: Process by which organisms maintain a relatively stable internal environment

III. Passive Transport A. Definition: Movement of molecules into and out of cell Movement of molecules into and out of cell that requires no energy that requires no energy B. Why?: Molecules are always in random motion! Molecules are always in random motion! Will always move from area of high Will always move from area of high concentration to low concentration to low

C. Types of passive transport: And OSMOSIS!

1. Diffusion a. Movement of ANYTHING from high concentration to low concentration »Does not require energy! Examples:Examples: Food coloringFood coloring Tea bagTea bag PopcornPopcorn PerfumePerfume

Osmosis _DIFFUSION_ ONLY! -Diffusion of water from _HIGH_ to _LOW_ concentration Solute: Substance in solution that is dissolved (ex. _SALT or SUGAR__) Solvent: Substance in solution that does the dissolving ( ex. _WATER_)

Solute & Solvent

Hypotonic Environment Hypertonic Environment Isotonic Environment TONICITY

Isotonic 97% H 2 O Diagram Where is the most water? Which way does water go? Result? Big words Examples 97% H 2 O Same Inside and outside Even, same concentration overall “equilibrium”: evenly spread “homeostasis: stable internal state contact lens solution, Gatorade

Hypotonic Diagram Where is the most water? Which way does water go? Result? Big words Examples 92% H 2 O 97% H 2 O Outside Inside Burst, get bigger; firm “plasmoptysis”- to burst; “turgid”- get firm Distilled water; Contractile Vacuoles- organelle that soaks up and pumps out water

Paramecium

Hypertonic Diagram Where is the most water? Which way does water go? Result? Big words Examples 97% H 2 O 80% H 2 O Inside Outside Smaller, shrink, go limp “plasmolysis”- to wilt, shrivel, loss of pressure; “flaccid”- go limp Candy, sugar, salt on bushes/grass, gargle with salt water

Hypertonic

3. Facilitated Diffusion a. Definition: uses transport proteins to help certain molecules pass through membrane uses transport proteins to help certain molecules pass through membrane b. Ex: Alcohol, H 2 O, small lipids Alcohol, H 2 O, small lipids Allows in bigger molecules Allows in bigger molecules No energy required! No energy required! Fast & specific, high to low concentrations

IV. Active transport A. Definition: movement of molecules across a movement of molecules across a membrane requiring energy; from low to membrane requiring energy; from low to high concentration! high concentration! B. Why?: to maintain a certain internal to maintain a certain internal environment; environment; transport large molecules transport large molecules in or out of cell in or out of cell

In active transport, materials move against concentration gradientIn active transport, materials move against concentration gradient C. Types of active transport: “ endocytosis ” & “ exocytosis ” “ endocytosis ” & “ exocytosis ” 1. “ Exocytosis ” a.Definition: Large amounts of materials/products fuse with membrane and leave cell

2. Endocytosis a. Definition: process of taking in a. Definition: process of taking in materials by materials by infoldings of cell membranes infoldings of cell membranes Pocket breaks and forms vesicle in cellPocket breaks and forms vesicle in cell Large food & moleculesLarge food & molecules

V. Concentration Gradient A. Explanation: measurement of how the concentration of measurement of how the concentration of something changes from one place to another something changes from one place to another B.In passive transport, molecules go DOWN THE CONCENTRATION GRADIENT. This means they go from HIGH to LOW concentration C.In active transport, molecules go UP THE CONCENTRATION GRADIENT. This means they go from LOW to HIGH concentration