Passive Transport Chapter 5 Sec. 1

Passive Transport Cells must maintain Homeostasis Passive Transport allows materials to cross the cell membrane without require energy

Diffusion Moving from a high to a low concentration

Diffusion Concentration gradient – difference between high and low areas

Diffusion Driven by kinetic energy and kinetic theory

Diffusion Equilibrium – concentration is the same throughout

Diffusion across cell membrane Phospholipid bilayer – some materials will dissolve, some will enter through proteins

Osmosis Osmosis – process of water going from an area of high to low concentration

Osmosis Solute – being dissolved Solvent – doing the dissolving (water)

Osmosis Hypotonic – more water outside of the cell Water diffuses into the cell so it will swell Ex. Freshwater fish

Osmosis Hypertonic – more water inside the cell Looses water (water diffuses into environment) Ex. Saltwater fish

Osmosis Isotonic – solute concentration is equal inside and out

Passive transport

Plant Cells Hypotonic – plant swells as it takes on water from roots Hypertonic – plant shrivels as it looses water

Plant Cells Osmotic pressure – pressure that builds inside cell due to osmosis

Plant Cells Plasmolysis – cells shrink away from cell wall and begin to wilt

Animal Cells Lack cell wall or vacuoles Basically will loose shape or burst Cytolysis – bursting of a cell

Facilitated Diffusion When molecules cannot diffuse across membrane easily May not be soluble or may be too large

Facilitated Diffusion Carrier proteins – specific proteins that allow these molecules to pass through cell membrane

Facilitated Diffusion Move from high to low Does not require energy

Facilitated Diffusion Carrier protein binds to molecule Protein changes shape

Facilitated Diffusion Glucose is transported into cell this way. Can move from outside in or inside out

Ion Channels Ion – contains a charge Na+, K+, Ca+2, Cl-

Ion Channels Specific channels for specific ions to cross membrane Some are always open and some have “gates” Chemicals and charges open gates