1. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cell Theory  The cell is the basic structural and functional unit of life  All cells come from preexisting cells  Organismal activity depends on individual and collective activity of cells  Biochemical activities of cells are dictated by subcellular structure  Continuity of life has a cellular basis (hereditary information within cells)  (there are some variation between sources as for the components of the cell theory)

2. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.2 Secretion being released from cell by exocytosis Peroxisome Ribosomes Rough endoplasmic reticulum Nucleus Nuclear envelope Chromatin Golgi apparatus Nucleolus Smooth endoplasmic reticulum Cytosol Lysosome Mitochondrion Centrioles Centrosome matrix Microtubule Microvilli Microfilament Intermediate filaments Plasma membrane

3. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Plasma Membrane  Separates intracellular fluids from extracellular fluids - Helps in maintaining homeostasis  Plays a dynamic role in cellular activity  Describe the plasma membrane

4. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Fluid Mosaic Model  Double bilayer of lipids with imbedded, dispersed proteins  Bilayer consists of phospholipids, cholesterol, and glycolipids  Glycolipids are lipids with bound carbohydrate  Phospholipids have hydrophobic and hydrophilic bipoles

5. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Phospholipid molecule CH 2 CH 3 CH 2 CH CH 2 CH 3 CH 2 CH 3 N + O O O–O– P O CH 2 CH CH 2 C O C O O O Phosphate group Hydrophilic head Hydrophobic tails

6. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Phospholipid bilayer Water Hydrophilic heads Hydro- Phobic tails Hydrophilic heads Oil in water

7. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings http://ebiomedia.com/prod/LC/LCenvelope.html

8. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Membrane Proteins Figure 3.4.1

9. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Functions of Membrane Proteins Figure 3.4.2

10. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Membrane Tight Junctions: An intercellular junction between cells in which the outer layers of the cell membranes fuse, reducing the ability of larger molecules and water to pass between the cells. Figure 3.5a http://www.answers.com/topic/tight-junction

11. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3.5b Membrane Junctions: Desmosome – anchoring junction scattered along the sides of cells http://www.answers.com/topic/desmosome

12. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Membrane Junctions: Gap junction – An intercellular network of protein channels that facilitates the cell-to-cell passage of ions, hormones, and neurotransmitters Figure 3.5c connexon is an assembly of 6 proteins called connexins that the gap junction between the cytoplasm of two adjacent cells

13. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Cell transport mechanisms

14. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Passive Membrane Transport: Diffusion  Depends on a concentration gradient. (What is a concentration? A concentration gradient?)  Molecules move spontaneously from a place of high concentration to a place of lower concentration to achieve equilibrium  The driving force is kinetic energy and it is influenced by:  Molecule size – the smaller the faster  Temperature – the warmer the faster

15. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Passive Membrane Transport: Diffusion  The plasma membrane is a physical barrier to free diffusion because of the hydrophobic core  Molecules that can pass through are:  Nonpolar / lipid-soluble substances that Diffuse directly through the lipid bilayer – simple diffusion  Gases readily diffuse through lipid bilayer. (Ex. movement of oxygen inside cells and CO 2 outside) – simple diffusion  Small enough to diffuse through channel proteins  Assisted by carrier protein – facilitated diffusion  Material are bound to specific proteins and move through water-filled protein channels

16. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Passive Membrane Transport: Diffusion  Carrier Proteins  Are integral transmembrane proteins  Show specificity for certain polar molecules including sugars and amino acids

17. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Passive Membrane Transport: Osmosis  Osmosis is a simple unassisted diffusion of solvent – usually water.  It occurs through a selectively permeable membrane  Occurs when the concentration of a water/solvent is different on opposite sides of a membrane  Diffusion of water across a semipermeable membrane  Osmolarity – total concentration of solute particles in a solution

18. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Effects of Solutions of Varying Tonicity  Isotonic – solutions with the same solute concentration as that of the cytosol  Hypertonic – solutions having greater solute concentration than that of the cytosol  Hypotonic – solutions having lesser solute concentration than that of the cytosol

19. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Passive Membrane Transport: Filtration  The passage of water and solutes through a membrane by hydrostatic pressure  Pressure gradient pushes solute-containing fluid from a higher-pressure area to a lower-pressure area  Depending on the size of the membrane pores - only solutes of a certain size may pass through it.

20. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings

21. Active Transport  A movement that can be against concentration gradient  Uses ATP to move solutes across a membrane  Two types:  Active transport  Vesicular transport

22. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Active transport  Active transport - Requires carrier proteins  Types of Active Transport  Symport system – two substances are moved across a membrane in the same direction  Antiport system – two substances are moved across a membrane in opposite directions (Na/K)  Primary active transport – hydrolysis of ATP causes phosphorylation of a transport protein that in turn changes its shape. That change “promotes” the passage of materials (ex. Sodium-potassium pump)  Secondary active transports – one ATP-powered pump can drive secondary transport of other solutes.  Sodium-potassium pump moves Na+ against concentration gradient and by that stores energy (creates gradient which is kinetic energy). When sodium moves down it’s gradient it can carry with it (co-transport) other solutes.

23. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Vesicular Transport  Transport of large particles and macromolecules across plasma membranes  Exocytosis – moves substance from the cell interior to the extracellular space  Endocytosis – enables large particles and macromolecules to enter the cell  Phagocytosis – pseudopods engulf solids and bring them into the cell’s interior  Transcytosis – moving substances into, across, and then out of a cell  Vesicular trafficking – moving substances from one area in the cell to another

24. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Passive Membrane Transport – Review ProcessEnergy SourceExample Simple diffusionKinetic energy Movement of O 2 through membrane Facilitated diffusion Kinetic energy Movement of glucose into cells OsmosisKinetic energy Movement of H 2 O in & out of cells Filtration Hydrostatic pressure Formation of kidney filtrate

25. Copyright © 2006 Pearson Education, Inc., publishing as Benjamin Cummings Active Membrane Transport – Review ProcessEnergy SourceExample Active transport of solutesATP Movement of ions across membranes ExocytosisATPNeurotransmitter secretion EndocytosisATP White blood cell phagocytosis