Factors Influencing Diffusion Rates and Directions in Cellular Transport

Outcomes: Identify the factors which influence the rate and direction of diffusion. Identify how osmosis is related to diffusion and the value of osmosis to living organisms. Examine the mechanisms of active transport by identifying and explaining the two processes. Compare the similarities and differences between active and passive transport. **Don t have to write these out** Passive and Active Transport Unit 2- Cell Structure and Function

Cellular Transport Cellular transport moves substances _________the cell and moves substances ________and ________of the cell There are 2 types: _________ Transport _________ Transport 1. 2.

Passive Transport These types of transport do not require energy Diffusion Facilitated Diffusion Osmosis a) b) c)

A) Diffusion Remember from years before that particles in solids, liquids, and gasses are in constant ___________ ___________(Particle Theory of Matter) Substances dissolved in water move constantly in random motion The random _________ of these _________ creates DIFFUSION

The amount of a substance in a certain area is called ___________________ Substances diffuse from an area of _________ concentration to an area of _________ concentration Watch the following video and draw the diagram on the next page: http://www.youtube.com/watch?v=Um6O oN81rb4

Diagram of Diffusion

Diffusion occurs until there is an __________ _______________ of particles in an area/cell The particles continue to move randomly, but there is _____ ____________ ___________ this is called DYNAMIC EQUILIBRIUM

Rate of Diffusion 3 main factors affect the rate that diffusion occurs 1. _______________ When concentration is high, diffusion happens quickly because there are more particles to collide with each other 2. _______________ When temperature increases, the particles collide more quickly 3. _______________ When pressure increases, the particles collide more quickly

B) Facilitated Diffusion While water can diffuse readily across a plasma membrane, most other substances need help Happens through ____________ and _____________ proteins

The CHANNEL PROTEINS in the plasma membrane of the cell are used to diffuse ions and small molecules across the cell membrane (draw the diagram below) http://kentsimmons.uwinnipeg.ca/cm1504/Image132.gif

CARRIER PROTEINS are also used to move substances across a cell membrane by ___________ _________ to help diffusion in a cell (Draw the diagram) http://www.biologyco rner.com/resources/si mpdiff.jpg

C) Osmosis The _________ of water __________ a selectively permeable ____________ is OSMOSIS _____________ the movement of water across the plasma membrane is an important factor in maintaining homeostasis (draw the next diagram)

http://www.biologycorner.com/resources/osmosis.jpg

If the __________________ of solute is higher on one side of the cell membrane, the water will move _____________ the __________ solute __________________ This diffusion happens until dynamic equilibrium occurs

Isotonic Solution When a cell is in a solution that has the same concentration of water and solutes is said to be in an ISOTONIC solution Water moves into and out of the cell at the same rate and cells keep their ______________ ___________

Hypotonic Solution If a cell is in a solution that has a lower concentration of solute, the cell is said to be in a __________________ solution There is more water outside of the cell than inside the cell which causes __________ to move __________ ____ ______ The water moving into the cell creates ___________ ___________

In an ________ cell, the water may enter the cell so much so that it ___________ A plant cell will ________ burst if there is a high osmotic pressure ____________ the cell __________ is very _________

Hypertonic Solution When the ________________ of the solute ____________ of the cell is _______than inside ________ __________ _________ the cell ___________ cells may __________ because of water loss _______ cells ________because the water vacuole is empty

Draw the diagram: http://4.bp.blogspot.com/- yiAZAMJRq4s/Ta79K3vVk8I/AAAAAAAAACE/MhfD0z_ABi8/s1600/ hypo.jpg

Video Explanation http://www.youtube.com/watch?v=AYN wynwaALo

Active Transport This happens when substances have to move from an area of __________ concentration to an area of __________ concentration This process makes sure that cells have the proper ___________ of substances inside of them These forms of cellular transport REQUIRE the use of ______________ by the cell a) Pumps (carrier proteins) b) Endocytosis/Exocytosis

A) Pumps (Carrier Proteins) __________ proteins can move substances against a concentration gradient Some pumps move one type of substance in one direction across the plasma membrane Other pumps move two substances in both directions across the plasma membrane

Sodium Potassium Pump This is a common type of pump moves 3 ___________ ions ______ of the cell moves 2 ___________ ions ______ the cell ATP (a form of energy) _______ _______ into ADP to do this Video demonstration http://www.youtube.com/watch?v=Q73uJ 8WlY_E

http://4.bp.blogspot.com/_207DNIaL- gc/TOaSu8u3q7I/AAAAAAAAAV4/9QLnFO82wQA/s1600/07_16Sodium PotassiumPump.jpg

B) Endocytosis & Exocytosis Particles that are too large to travel through the plasma membrane leave or enter the cell differently

Endocytosis when a cell ______________ something _____________ of the cell The cell membrane __________ ________ and takes the substance inside the cell The substance is now in a __________ to travel throughout the cell

Exocytosis Is when substances ___________ the cell by vesicles ____________ the plasma _______________ to expel (get rid of) the substance

http://www.kscience.co.uk/as/module1/pictures/endoexo.jpg