Cellular Transport How cells interact with the outside world Chapter 7-3 Pgs

Movement WITH the concentration gradient Stuff moves from high to low concentration

occurs until equilibrium is reached BOOSH! Equilibrium

Getting across a cell membrane Passive transport – Simple diffusion – Osmosis – Facilitated diffusion Active transport Passive transport – Simple diffusion – Osmosis – Facilitated diffusion Active transport

Can Semi Permeable barriers really exist? Can a barrier really be choosy about what it does and doesnt let through? 1.Did the Iodine interact with the Cornstarch? 2.Will the water move in or out of the bag 3.Did the cornstarch move with it? 4.What is this bag permeable to? 5.What does this bag select against?

Simple Diffusion

Simple diffusion Small, non-polar molecules without a charge can squeeze through the cell membrane without the help of protein channels. Flows with the concentration gradient

movement of larger molecules like glucose through the cell membrane – larger molecules must be helped Proteins in the cell membrane form channels for large molecules to pass through Proteins that form channels (pores) are called protein channels outside of cell inside of cell Glucose molecules Facilitated Diffusion

H2OH2O H2OH2O Cell Membrane Protein Channel (aquaporin) Protein Channel (aquaporin)

Osmosis

water Diffuses across a membrane

Osmosis is not simple diffusion H 2 O moves through special protein channels

Na+ Cl-

refers to a solution with a comparatively lower concentration of solutes compared to anothersolutionconcentrationsolutes

Active tranport Using cellular energy in the form of ATP to move particles across the cell membrane Moves against the concentration gradient

ATP Cellular Currency If you want to get something done in the cell you need to spend a little ATP

Active transport

Intake of large molecules or large quantities of molecules by surrounding them with the cell membrane Endocytosis Exocytosis Vesicles

Three types of Endocytosis Cell Eating Cell Drinking Targeted endocytosis Targeted endocytosis

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