Cell Transport

Homeostasis Maintaining internal equilibrium by adjusting physiological processes How do you maintain homeostasis???

Plasma Membrane Regulates what enters/ leaves cell Helps maintain homeostasis Made of phospholipids with embedded proteins. SEMI-PERMEABLE!!!! – Lets some but not all things enter and leave the cell feature=endscreen

Polar?? Polar Molecule: a molecule with an unequal distribution of charge – Each molecule has a positive and negative end – Attract other ions and polar molecules – This is why water can dissolve ionic compounds like salt & polar compounds like sugar

Diffusion Form of passive transport (NO ENERGY NEEDED) Solutes move from HIGH concentration to LOW concentration Go with concentration gradient

Diffusion Results because of random movement of particles Three keys: – Concentration More concentration, more rapidly diffusion occurs due to more collisions between particles – Temperature Increase in temp, will increase energy, and cause more rapid particle movement- Increase rate of diffusion – Pressure Increase pressure will accelerate particle motion

Osmosis Diffusion/movement of water from HIGH to LOW across a membrane (also passive transport)

tU0 tU0

Isotonic Solution The concentration of dissolved substances in the solution is the same as the concentration of dissolved substances inside cell. Keep Shape!!!

Hypotonic Solution The concentration of dissolved substances is lower in the solution outside the cell than the solution inside the cell.

So What?! Since solution inside the cell is more concentrated, water floods in the cell. Animal Cells: cells swell and can swell until they bust Plant Cells: Cells swell, BUT they won’t bust due to the cell wall – Cell becomes more firm

Hypertonic Solution The concentration of dissolved substances outside the cell is higher than the concentration inside the cell.

And? Since solute concentration is higher outside the cell, free water exits the cell. Water flows out of cell. Animal Cells: Shrivel because of decreased pressure Plant Cells: Plasma membrane pulls away from cell wall – Why plants wilt.

All Together Now!

Two Types of Transport Passive Transport – NO Energy – Uses transport proteins Active transport – Requires Energy – Can go against the concentration gradient – Uses transport proteins

Transport Proteins – Move needed substances or waste materials – Facilitated Diffusion = uses transport proteins

Endocytosis Process by which a cell surrounds and takes in material from its environment – Substance engulfed by membrane, not pass through

Exocytosis Expulsion or secretion of materials from a cell – Use to expel wastes; secrete substance like Hormones