Chapter 5 Transfer of Materials Across Cell Boundaries To remain alive and function optimally, cells must maintain a biological balance with their immediate environment. They must remain stable. This biological balance is called __________. Cell membranes help organisms maintain homeostasis by controlling what substances may enter or leave the cell. Membrane- Covers and Protects the inside from the outside! And, what is this term?? ______-___________ Homeostasis Equilibrium semi-permeable

The Cell Membrane - Gateway to the Cell Integral or Channel The Plasma Membrane 5/29/2018 The Cell Membrane - Peripheral Proteins Integral or Channel Hydrophobic hydrophilic Gateway to the Cell G. Podgorski, Biol. 1010 2

The Plasma Membrane 5/29/2018 FLUID MOSAIC MODEL FLUID- because individual phospholipids and proteins can move side-to-side within the layer, like it’s a liquid. MOSAIC- because of the pattern produced by the scattered protein molecules when the membrane is viewed from above G. Podgorski, Biol. 1010 3

Cell Membrane Polar heads are hydrophilic “water loving” The Plasma Membrane Cell Membrane 5/29/2018 Polar heads are hydrophilic “water loving” Nonpolar tails are hydrophobic “water fearing” Makes membrane “Selective” in what crosses G. Podgorski, Biol. 1010 4

The Plasma Membrane 5/29/2018 Types of Transport Across Cell Membranes 1) Passive no NRG 2) Active  with NRG G. Podgorski, Biol. 1010 5

Passive Transport : Energy=ATP the movement of substances from across a membrane without the use of chemical Will go from High to a low concentration From where there is a lot to a little Energy=ATP 4 types: Diffusion & Facilitated Diffusion, osmosis (water), ion channels

concentration gradient Difference in concentration of molecules….goes from there is a lot to where there is none Diffusion The movement of a substance from an area of _______ concentration to an area of _____ concentration (down a ) without a membrane Caused by the random movement of particles They have a natural Kinetic NRG A. ____________ HIGH LOW concentration gradient

Fig. 5.8, p. 80

smaller 3. diffusion of substance across the membrane depends on Temperature: __________ temperature = __________ diffusion b. Size: _______ molecules diffuse faster c. Type of molecule: lipids diffuse through easily; electrically charged ions or large particles will not smaller

4. ___________ is reached when the concentration in the cell is equal to the concentration outside the cell; All Passive transport will eventually end here…(keep on moving till all spread out) at that point molecules will diffuse at the same rate they diffuse out Equilibrium

OSMOSIS water = solution osmosis = diffusion of ________ across a semi-permeable membrane; occurs in response to concentration of solutes dissolved in water Goes From High Water Potential (low Solute) to Low Water Potential (High Solute)….from where there is a lot of water to where there is little amount of water water SOLUTE SOLVENT = solution

Diffusion of H2O Across A Membrane The Plasma Membrane 5/29/2018 Diffusion of H2O Across A Membrane Solute High H2O potential Low solute concentration Low H2O potential High solute concentration G. Podgorski, Biol. 1010 13

O E HYPOTONIC (low solute concentration, a lot of water) Hypertonic (high solute concentration, little water) O E If one side is hypotonic the other has to be the opposite (hypertonic)….will keep moving water until EQUILIBRIUM is reached……..At which point inside and outside are both ISOTONIC toward each other!!!! (water still moving but at same rate in and out)

Diffusion of H2O Across A Membrane The Plasma Membrane 5/29/2018 Diffusion of H2O Across A Membrane Hypertonic Hypotonic E High H2O potential Low solute concentration Low H2O potential High solute concentration G. Podgorski, Biol. 1010 15

Cell shrivels and shrinks Conditions Environment is Inside Cell is Water will move Results If solute conc. in the environment is lower than in cell Cell swells, may burst Animal = Cytolysis Plant = Turgor Pressure If solute conc. in the env. is higher than in the cell If solute conc in the env is equal to that of the cell Into and out of cell at equal rates No net movement Hypertonic into cell Hypotonic Cell shrivels and shrinks Animal = Crenation Plant = Plasmolysis Hypertonic (hyper = high) Out of cell Hypotonic Isotonic (iso =) Isotonic

turgor pressure plasmolysis Fig. 5.24, p. 89

A Paramecium lives in a freshwater environment Water is always diffusing into these organisms They need a low water concentration So they are always pumping water out of themselves with a contractile vacuole

Why do we salt our foods to preserve them? Why do we gargle with salt water for soar throats? Salted foods – kill bacteria on it because their water component is removed from them due to osmosis Kills bacteria on contact (like salted food example) Some of pain is due to swelling of tissue which is accumulation of fluids so adding salt will remove from fluid The salt water is what to these cells? ANS: Hypertonic - (salt water has a higher solute concentration)

Cell in Hypotonic Solution The Plasma Membrane 5/29/2018 Cell in Hypotonic Solution 10% NaCL 90% H2O CELL 20% NaCL 80% H2O What is the direction of water movement? 21 G. Podgorski, Biol. 1010 21

Cell in Isotonic Solution The Plasma Membrane 5/29/2018 Cell in Isotonic Solution 10% NaCL 90% H2O ENVIRONMENT CELL NO NET MOVEMENT 10% NaCL 90% H2O What is the direction of water movement? equilibrium The cell is at _______________. 22 G. Podgorski, Biol. 1010 22

Cell in Hypertonic Solution The Plasma Membrane 5/29/2018 Cell in Hypertonic Solution 15% NaCL 85% H2O ENVIRONMENT CELL 5% NaCL 95% H2O What is the direction of water movement? 23 G. Podgorski, Biol. 1010 23

NO NET MOVEMENT OF H2O (equal amounts entering & leaving) The Plasma Membrane 5/29/2018 Isotonic Solution Hypotonic Solution Hypertonic Solution NO NET MOVEMENT OF H2O (equal amounts entering & leaving) Crenate CYTOLYSIS Turgor pressure PLASMOLYSIS G. Podgorski, Biol. 1010 24

Facilitated B.___________ Diffusion used for molecules that can’t diffuse rapidly through cell membrane; ex: glucose….need helpers (too large or not soluble in lipid layer) Still will go from ………

Types of Transport Proteins The Plasma Membrane 5/29/2018 Types of Transport Proteins Channel proteins are embedded in the cell membrane & have a pore for materials to cross…open through middle Carrier proteins can change shape to move material from one side of the membrane to the other 26 G. Podgorski, Biol. 1010 26

Releases into/out of cell Binds to molecule Changes shape shields molecule from interior of membrane Releases into/out of cell

Ion allow passage of important ions (Na+, K+, Cl-, Ca2+); C. _____ channels: allow passage of important ions (Na+, K+, Cl-, Ca2+); some are always open, specific to ion some have “gates” that open and close in response to: stretching of membrane, electrical signals, or chemicals Ion

Active energy from LOW to HIGH II. Transport- the use of (ATP) to transport materials through the cell membrane against the concentration gradient energy from LOW to HIGH

A. Cell Membrane Protein Pumps - proteins embedded in cell membrane; use energy to move ions and large molecules across the membrane against the gradient…low to high…little to a lot

Ca++ Ca++ Ca++ Ca++ Ca++ Ca++ Ca++ Ca++ Ca++ Ca++ P Ca++ P ADP ATP ENERGY INPUT Fig. 5.6c, p. 79

B. Sodium-Potassium Pump – Important in muscle contraction and nerve impulses 3 Na+ (sodium) OUT 2 K+ (potassium) IN Y2K Im sodium, can I come in?

C. Proton Pump - chemiosmosis Transports protons (Hydrogen +) across the membranes of mostly in mitochondria and chloroplasts Use to make ATP = chemiosmosis

low conc. H H+ H+ H+ H+ H+ H+ H+ H+ high conc. H Proton Pump will Pump H+’s against flow low conc. H H+ Lipid bilayer H+ Outside mito Inside mito H+ H+ H+ H+ H+ H+ high conc. H So that they can flow easy “down” their gradient

This protein CAPTURES THIS KINETIC ENERGY to make ATP Outside cell Inside cell H+ H+ H+ H+ H+ H+

D. Endocytosis  EN Enter Cell folding in of membrane to form vesicles Two types Phagocytosis Pinocytosis

Endocytosis – Phagocytosis The Plasma Membrane 5/29/2018 Endocytosis – Phagocytosis Used to engulf large particles such as food, bacteria (whole organisms), etc. into vesicles Called “Cell Eating” 39 G. Podgorski, Biol. 1010 39

Pinocytosis Most common form of endocytosis. The Plasma Membrane Pinocytosis 5/29/2018 Most common form of endocytosis. Takes in dissolved (solutes or fluids) molecules as a vesicle. 40 G. Podgorski, Biol. 1010 40

E. ExocytosisEXEXIT removes wastes and cell products packaged by Golgi vesicles

Exocytosis- moving things out. The Plasma Membrane Moving the “Big Stuff” 5/29/2018 Exocytosis- moving things out. Molecules are moved out of the cell by vesicles that fuse with the plasma membrane. This is how many hormones are secreted and how nerve cells communicate with one another. 42 G. Podgorski, Biol. 1010 42

endocytic vesicle forming plasma membrane exocytic vesicle leaving cytoplasm endocytic vesicle forming Fig. 5.20, p. 87

The Plasma Membrane 5/29/2018 Exocytosis The opposite of endocytosis is exocytosis. Large molecules that are manufactured in the cell are released through the cell membrane. Inside Cell Cell environment 44 G. Podgorski, Biol. 1010 44