Solutions & Cell Transport

Solutions

Review on Cell Membranes All cells have a cell membrane Functions: Controls what enters and exits the cell to maintain an internal balance called homeostasis Provides protection and support for the cell

Review cntd. Structure of cell membrane Lipid Bi-layer – double layers of phospholipids Phosphate head is polar (water loving) Fatty acid tails non- polar (water fearing) Proteins embedded in membrane for the movement of larger molecules.

Solutions Terms to know: Solute a substance dissolved in another substance (ex. Kool-Aid mix) Solvent a substance that does the dissolving (ex. Water) Solution mixture of solutes & solvents (ex. Kool-Aid) There are 3 types of solutions Isotonic Hypertonic Hypotonic

Parts of a Solution SOLUTE – the part of a solution that is being dissolved (usually the lesser amount) SOLVENT – the part of a solution that dissolves the solute (usually the greater amount) Solute + Solvent = Solution Solution Solute Solvent Hot chocolate Orange juice Salt water Chocolate milk

In a salt water solution… Is salt the solute or the solvent? Is water the solute or the solvent? What does the solute do? What does the solvent do?

A Salt Water Solution Animation Solute (salt) Solvent (water)

Isotonic Solutions Solutions that contain the same concentration of solutes inside and outside the cell (or normal saline) solutions. There is no net movement of water either into or out of the cell. Cells maintain their normal shape.

Hypotonic Solutions The solution has a lower concentration of solutes and a higher concentration of water than inside the cell. The water will move into the cells resulting in the swelling and lysis of the cells.  hypO – cell explOdes/grOws Low solute in solution

Hypertonic Solutions The solution has a higher concentration of solutes and a lower concentration of water than inside the cell. Has less water than the cell and water moves out of the cell. So the cell shrinks. hypeR – cell shRinks High solute in solution

Review http://www.tvdsb.on.ca/WESTMIN/science/sbi3a1/cells/Osmosis.htm

Cell Transport

This is gonna be hard work!! Cellular Transport high low Weee!! Passive Transport cell doesn’t use energy Diffusion Facilitated Diffusion Osmosis Active Transport cell does use energy Protein Pumps Endocytosis Exocytosis high low This is gonna be hard work!!

Passive Transport Cell uses no energy Molecules move randomly Molecules spread out from an area of high concentration to an area of low concentration. Until equilibrium is met. 3 types: Osmosis Diffusion Facilitated Diffusion

Diffusion Diffusion Random movement of particles from an area of high concentration to an area of low concentration. Not necessarily across a membrane. Diffusion continues until all molecules are evenly spaced equilibrium is reached High concentration  low concentration.

Facilitated Diffusion diffusion of specific particles through transport proteins found in the membrane Transport Proteins are specific – they “select“ only certain molecules to cross the membrane

Osmosis Osmosis: diffusion of water through a selectively permeable membrane Water moves from high to low concentrations Water moves freely through pores. Solute (green) to large to move across.

Active Transport Cell transport that requires energy.

This is gonna be hard work!! Active Transport Uses energy Transport of molecules from low concentration to high concentration Sends molecules where they are needed Exocytosis Endocytosis Phagocytosis Pinocytosis high low This is gonna be hard work!!

Endocytosis Endocytosis: taking bulky material into a cell Cell membrane in- folds around particle forms food vacuole & digests food This is how white blood cells eat bacteria!

Endocytosis Pinocytosis Phagocytosis Cell drinking Taking in of liquids Phagocytosis Cell eating Taking in of solid particles

Exocytosis Exocytosis: Forces material out of cell in bulk Cell changes shape – requires energy

Review 3 solutions Isotonic No net gain of molecules Cell size doesn’t change Hypotonic Low solute Water moves into the cell The cell swells or explodes Hypertonic High solute Water leaves the cell The cell shrinks There are 2 types of cellular transport Active Transport  low to high Passive Transport  high to low There are 3 types of passive transport Osmosis Diffusion Facilitated Diffusion Osmosis  water across a membrane Solvent, solute, solution 3 types of solutions