Cell Boundaries and Movement

Cell Barriers Cell membranes Structure: contain a flexible lipid bilayer with imbedded protein molecules and carbohydrate molecules Function: Substances move across the cell membrane through A.) lipid bilayer B.) protein channels C.) assistance of protein molecules D.) Processes of endocytosis and exocytosis

Cell Barriers Cell Walls Structure: made mostly of tough carbohydrate fiber called cellulose Function: Cell walls support and protect cells; cell walls are porous and allows substances to move through easily

Types of Movement Through Cells A.) Diffusion B.) Osmosis C.) Facilitated Diffusion D.) Active Transport

Diffusion Substances move across the cell membrane from areas of high solute concentration to areas of low solute concentration until equilibrium is reached No energy required Substances continue to move back and forth across the membrane once equilibrium is reached

Osmosis The diffusion of water across a cell membrane Types of osmotic solutions Hypotonic Isotonic Hypertonic

Concentration Concentration of a solution is the mass of solute in a given volume of solution, or mass/volume A Solute is a substance that is dissolved in a solvent to make a solution

Which way will the water move?

Hypotonic Solution Animal Cell the solution has a lower solute concentration than the cell so water moves into the cell causing plant cells to swell and animal cells to swell and burst Lower solute concentration outside cell Lower solute concentration Plant Cell Lower solute concentration outside cell

Isotonic Solution Animal Cell The concentration of solutes is equal inside and outside the cell so water moves across the membrane in both directions maintaining cell size Equal solute concentration inside and outside cell Plant Cell Equal solute concentration inside and outside cell

Hypertonic Solution Animal Cell The solution has a higher solute concentration than the cell so water moves out of the cell and into the solution causing the cell to plasmolyze higher solute concentration outside cell Plant Cell higher solute concentration outside cell

CELL MEMBRANE Lipid layer 1 Proteins Lipid layer 2

Facilitated Diffusion A) Substance specific protein channels allow movement of molecules such as glucose to move across the membrane in either direction B) Substances still move high concentration to low concentration and no energy is required

REMEMBER: Requires ATP Energy! Active Transport Characteristics: Movement of substances is against the concentration gradient Energy is required ! Types of Active Transport Molecular transport Endocytosis Exocytosis REMEMBER: Requires ATP Energy!

Active Transport – Molecular Transport Molecular transport: Protein molecules act like energy requiring pumps to move molecules and ions across membranes

I NEED THOSE GREEN THINGS!

Active Transport – Endocytosis Endocytosis – Materials are taken into the cell by means of forming in the cell membrane. The pocket becomes a vacuole inside the cell.

ENDOCYTOSIS

ENDOCYTOSIS

Cool video showing Endocytosis http://www.youtube.com/watch?v=lgHJUkGPBqs Paramecium EATS 2 amoebas http://www.youtube.com/watch?v=pvOz4V699gk&feature=fvwrel

Exocytosis

Active Transport – Exocytosis Exocytosis – EXPEL WASTES FROM CELL Wastes moved out of the cell when a vacuole fuses with the cell membrane

VIDEO of EXOCYTOSIS http://www.youtube.com/watch?v=U9pvm_4-bHg