1. How do materials move into and out of cells? Unit 4 Campbell Sec 5.10-5.21 Pgs 79-86

2. Random water movements

3. Molecules move randomly!

4. Solutes also move randomly!  This is due to kinetic molecular motion

5. Diffusion: passive spreading from higher [ ] to lower [ ]  Concentration – amount of solute per unit volume  Moving down concentration gradient  Ex: Sugar in KoolAid Sugar in KoolAid Evaporation of water Evaporation of water Apple pie scent Apple pie scent Fire smoke Fire smoke Osmosis: H 2 O molecule movement Osmosis: H 2 O molecule movement

6. A “Fluid System”  All molecules randomly move until… They hit a barrier that they cannot cross They hit a barrier that they cannot crossor They collide with a molecule that they can react with They collide with a molecule that they can react with Review: What are the 4 indicators of a chemical reaction?Review: What are the 4 indicators of a chemical reaction?

7. How does this affect cells?  Need… Food, water, hormones, gases, vitamins Food, water, hormones, gases, vitamins  Want to get rid of… Toxins, food waste, secretions, gases, & invaders Toxins, food waste, secretions, gases, & invaders  Can cells CHOOSE what goes in or out? Yes and no… Yes and no… Membranes are….. Membranes are….. selectively permeable - It allows some things to cross more easily, while others it blocks altogetherselectively permeable - It allows some things to cross more easily, while others it blocks altogether

8. The Cell Membrane  The cell membrane is the gatekeeper of the cell – it decides what moves in and out!  The plasma membrane forms a boundary between cells and its surroundings  It is selectively permeable!!!

9. What are plasma membranes made of?

10. Membrane Structure Phosphate group Polar Hydrophilic Head Fatty Acid Non-polar Hydrophobic Tails  Made mostly of phospholipids  These form a phospholipid bilayer

11. More diagrams

12. Selective Permeability  Because the interior of the membrane is hydrophobic (non-polar)…….

13. Selective Permeability  But… if a molecule is small enough it will pass through freely also!  Therefore, small, polar molecules pass through: Ex. Water, ions, Ex. Water, ions,

14. How fast do things pass through membranes?

15. Osmosis  Water moves feely through cell membranes  The diffusion of water molecules across a membrane is called osmosis  Water movement depends on solute concentration (tonicity) Isotonic – equal solute concentration in and out Isotonic – equal solute concentration in and out Hypertonic – higher solute concentration Hypertonic – higher solute concentration Hypotonic – lower solute concentration Hypotonic – lower solute concentration

16. How does tonicity affect animals? shriveled happy lysed When put in… Hypertonic Isotonic Hypotonic

17. How does tonicity affect plants? Shriveled Wilted Happy

18. Practice Iso, Hypo, or Hyper? Which way will water move? Solute?  1. A plant cell with 10% intracellular salt concentration is placed in a solution with 15% salt concentration  2. An animal cell with 80% intracellular salt concentration is placed in a solution with 15% salt concentration  3. An animal cell with 19% intracellular salt concentration is placed in a solution with 15% salt concentration  4. A plant cell with 36% intracellular salt concentration is placed in a solution with 47% salt concentration  5. A bacterial cell with 29% intracellular salt concentration is placed in a solution with 29% salt concentration  6. An animal cell with 88% intracellular salt concentration is placed in a solution with 65% salt concentration

19. Osmoregulation  Animals must have a way to prevent excessive uptake or excess loss of water.  This is called osmoregulation  Ex. A freshwater fish, which lives in a hypotonic environment  Have kidneys and gills that work constantly to prevent an excessive buildup of water in the body!!

20. Why give patients IVs with saline instead of purified H 2 O?  Their cells would explode!  application #1

21. Salt is spread on roads to thaw ice. It runs off into the soil as snow melts. Why are nearby plants harmed?  application #2

22. Why does lactose intolerance cause diarrhea? Eat dairy… Eat dairy… No lactase enzyme = no hydrolysis… No lactase enzyme = no hydrolysis… Lactose ends up in large intestine because molecule was too big to be absorbed into blood stream… Lactose ends up in large intestine because molecule was too big to be absorbed into blood stream… Large intestine space is now hypertonic to your body tissues, so water is pulled into intestine tube Large intestine space is now hypertonic to your body tissues, so water is pulled into intestine tube Watery poo = DIARRHEA  Watery poo = DIARRHEA   application #3

23. Why do humans and plants store sugars as glycogen and starch? Glucose can easily enter/exit cells since our membranes have pores for it. Glucose can easily enter/exit cells since our membranes have pores for it. Performing dehydration synthesis on the monosaccharides makes a polymer… your food supply can’t escape! Performing dehydration synthesis on the monosaccharides makes a polymer… your food supply can’t escape! Hormones will tell the storage organs when to release sugar. Hormones will tell the storage organs when to release sugar.  application #4

24. Why is there so much sugar in “preserves” and “jam”?  application #5

25. Why does gargling warm salt water make my sore throat feel better?  application #6

26. Review Qs  Why is kinetic E. important to balance?  You smell smoke from a campfire across the street. Why is this diffusion but NOT osmosis?  What kinds of molecules cross the membrane most easily?  Given: 30% sucrose outside cell, 10% sucrose inside. Which is hypertonic? Which way does water move?  How does swelling affect plants and animals differently?

27. Membrane Reading Quiz  Explain the arrangement/structure of the phospholipids.  What is the difference between peripheral and integral proteins?  What 2 roles does cholesterol play?  List 3+ roles proteins play?