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

http://www.youtube.com/watch?v=mtDm2OKIK1k&NR=1&feature=endscreen

Polar??

• Polar Molecule: a molecule withan 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)

• http://www.youtube.com/watch?v=DVsmtCgXtU0

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

http://www.youtube.com/watch?v=4gLtk8Yc1Zc