AP Biology AP Biology AP Biology AP Biology

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AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

AP Biology

Chapter 7. 3, 7. 4, 7. 5 Movement across the Cell Membrane AP Biology

Chapter 7. 3, 7. 4, 7. 5 Movement across the Cell Membrane AP Biology

Objectives: You should be able to. . § Predict the movement of molecules and

Objectives: You should be able to. . § Predict the movement of molecules and water. § Accurately describe diagrams using § § § hypertonic, hypotonic, and isotonic. Describe how animal and plant cells react in different solutions. Compare passive, active, and bulk transport. Vocabulary: diffusion, osmosis, lyse, turgid, flaccid, plasmolyze, simple diffusion, facilitated diffusion, protein pump, endocytosis, exocytosis AP Biology

Diffusion § 2 nd Law of Thermodynamics governs biological systems u universe tends towards

Diffusion § 2 nd Law of Thermodynamics governs biological systems u universe tends towards disorder (entropy) § Diffusion u AP Biology movement from HIGH LOW concentration

Simple Diffusion § Move from HIGH to LOW concentration “passive transport” u no energy

Simple Diffusion § Move from HIGH to LOW concentration “passive transport” u no energy needed u AP Biology diffusion movement of water osmosis

Diffusion § 2 nd Law of Thermodynamics governs biological systems u universe tends towards

Diffusion § 2 nd Law of Thermodynamics governs biological systems u universe tends towards disorder (entropy) § Diffusion - Move from HIGH to LOW concentration “passive transport” u no energy needed u AP Biology diffusion movement of water osmosis

AP Biology

AP Biology

The Special Case of Water Movement of water across the cell membrane AP Biology

The Special Case of Water Movement of water across the cell membrane AP Biology 2007 -2008

Osmosis is diffusion of water § Diffusion of water from HIGH concentration of water

Osmosis is diffusion of water § Diffusion of water from HIGH concentration of water to LOW concentration of water across a semi-permeable membrane AP Biology

Concentration of water § Direction of osmosis is determined by comparing total solute concentrations

Concentration of water § Direction of osmosis is determined by comparing total solute concentrations u Hypertonic - more solute, less water u Hypotonic - less solute, more water u Isotonic - equal solute, equal water hypotonic AP Biology hypertonic net movement of water

Cell survival depends on balancing water uptake & loss. AP Biology

Cell survival depends on balancing water uptake & loss. AP Biology

1 Managing water balance § Hypotonic u a cell in fresh water u high

1 Managing water balance § Hypotonic u a cell in fresh water u high concentration of water around cell § problem: cell gains water, swells & can burst § example: Paramecium w ex: water continually enters KABOOM! Paramecium cell § solution: contractile vacuole w pumps water out of cell ATP w ATP u plant cells No problem, here § turgid = full § cell wall protects from bursting AP Biology freshwater

Pumping water out § Contractile vacuole in Paramecium ATP AP Biology

Pumping water out § Contractile vacuole in Paramecium ATP AP Biology

2 Managing water balance § Hypertonic I’m shrinking, a cell in salt water I’m

2 Managing water balance § Hypertonic I’m shrinking, a cell in salt water I’m shrinking! u low concentration of water around cell u § problem: cell loses water & can die § example: shellfish § solution: take up water or pump out salt u plant cells § plasmolysis = wilt § can recover AP Biology I will survive! saltwater

3 Managing water balance § Isotonic u u animal cell immersed in mild salt

3 Managing water balance § Isotonic u u animal cell immersed in mild salt solution That’s perfect! no difference in concentration of water between cell & environment § problem: none w no net movement of water flows across membrane equally, in both directions I could w cell in equilibrium be better… n w volume of cell is stable § example: blood cells in blood plasma w slightly salty IV solution in hospital AP Biology balanced

1991 | 2003 Aquaporins § Water moves rapidly into & out of cells u

1991 | 2003 Aquaporins § Water moves rapidly into & out of cells u evidence that there water channels § protein channels allowing flow of water across cell membrane AP Biology Peter Agre Roderick Mac. Kinnon John Hopkins Rockefeller

Do you understand Osmosis… . 05 M . 03 M Cell (compared to beaker)

Do you understand Osmosis… . 05 M . 03 M Cell (compared to beaker) hypertonic or hypotonic Beaker (compared to cell) hypertonic or hypotonic AP Biology Which way does the water flow? in or out of cell

Do you understand Diffusion… Cell (compared to beaker) hypertonic or hypotonic Beaker (compared to

Do you understand Diffusion… Cell (compared to beaker) hypertonic or hypotonic Beaker (compared to cell) hypertonic or hypotonic AP Biology Which way does the _____ flow? in or out of cell

Facilitated Diffusion § Diffusion through protein channels u u channels move specific molecules across

Facilitated Diffusion § Diffusion through protein channels u u channels move specific molecules across cell membrane facilitated = with help no energy needed open channel = fast transport HIGH LOW AP Biology

AP Biology

AP Biology

Active Transport § Cells may need to move molecules against concentration gradient u u

Active Transport § Cells may need to move molecules against concentration gradient u u u conformational shape change transports solute from one side of membrane to other protein “pump” “costs” energy = ATP LOW conformational change ATP HIGH AP Biology

Active transport § Many models & mechanisms ATP AP Biology ATP antiport symport

Active transport § Many models & mechanisms ATP AP Biology ATP antiport symport

Animal Sodium-Potassium Pump AP Biology

Animal Sodium-Potassium Pump AP Biology

Proton pump… Plants and Fungi Electrochemical gradient (+/- charges AND Concentration gradient) coupled with

Proton pump… Plants and Fungi Electrochemical gradient (+/- charges AND Concentration gradient) coupled with a cotransporter AP Biology

Getting through cell membrane § Passive Transport u Simple diffusion § diffusion of nonpolar,

Getting through cell membrane § Passive Transport u Simple diffusion § diffusion of nonpolar, hydrophobic molecules w lipids w HIGH LOW concentration gradient u Facilitated diffusion § diffusion of polar, hydrophilic molecules § through a protein channel w HIGH LOW concentration gradient § Active transport u diffusion against concentration gradient § LOW HIGH u u AP Biology uses a protein pump requires ATP

Transport summary simple diffusion facilitated diffusion active transport AP Biology ATP

Transport summary simple diffusion facilitated diffusion active transport AP Biology ATP

How about large molecules? § Moving large molecules into & out of cell through

How about large molecules? § Moving large molecules into & out of cell through vesicles & vacuoles u endocytosis u § phagocytosis = “cellular eating” § pinocytosis = “cellular drinking” u AP Biology exocytosis

AP Biology

AP Biology

Endocytosis phagocytosis fuse with lysosome for digestion pinocytosis non-specific process receptor-mediated endocytosis triggered by

Endocytosis phagocytosis fuse with lysosome for digestion pinocytosis non-specific process receptor-mediated endocytosis triggered by molecular signal AP Biology

Any Questions? ? AP Biology

Any Questions? ? AP Biology