Cell Transport Cell Membrane n n Selectively permeable

Cell Transport Cell Membrane n n Selectively permeable: some things can pass through others can not Usually permeable to: w Oxygen w Water w Carbon dioxide

Large molecules usually can not cross the cell membrane An examples would be “salts”

3 ways substances can move in and out of the cell: Diffusion Osmosis Active transport

Diffusion Main method by which substances move in and out of the cell Process by which molecules move from an area of HIGH concentration to an area of LOW concentration n Concentration: the amount of substance in a given volume

Diffusion is caused by molecules moving and colliding Does NOT require energy A form of PASSIVE transport n Passive transport: movement of materials through a membrane without the use of energy

Diffusion

Osmosis Another form of PASSIVE TRANSPORT Does NOT require energy Diffusion of WATER molecules through a selectively permeable membrane

Important to cells because cells cannot function properly without adequate water WATER moves from an area of HIGH water concentration to an area of LOW water concentration Osmosis Link

Osmosis 100% 95% Distilled Water 95% 90% Salt Water

Definitions for Lab Report Hypothesis: a prediction about the relationship between the variables that can be tested Independent Variable: the variable that is purposefully changed by the experimenter

Dependent Variable: the variable that responds to the independent variable Control: the standard for comparing experimental effects

Active Transport Movement from an area of low concentration to an area of high concentration Requires energy Methods include: n Transport (Carrier) Proteins w Move glucose, sodium, calcium, potassium, etc. n Engulfing (Phagocytosis) w surrounding the material to be taken in