Slides 1 to 102 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Cell Membrane Key Note Things tend to even out, unless something—like a cell membrane—prevents this from happening. Across a freely permeable or water permeable membrane, diffusion and osmosis will quickly eliminate concentration gradients. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Cell Membrane Membrane Transport Permeability – property that determines which substances can enter/leave the cytoplasm Freely – any substance crosses Selective – certain substances cross Permeability factors Molecular size/shape Electrical charge Lipid solubility Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Cell Membrane Membrane Transport Processes Passive Transport – no energy expended Diffusion (includes osmosis) Filtration Facilitated Transport (carrier-mediated) Active Transport – energy expended Carrier-Mediated Vesicular Transport Endocytosis Exocytosis Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Cell Membrane Membrane Transport Definitions Diffusion Osmosis Random movement down a concentration gradient (higher to lower [C]) Osmosis Movement of water across a membrane down a gradient in osmotic pressure (lower to higher osmotic pressure) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Cell Membrane Diffusion Figure 3-4

Diffusion Across Cell Membranes The Cell Membrane Diffusion Across Cell Membranes Figure 3-5

The Cell Membrane Osmosis Figure 3-6

The Cell Membrane Osmotic Effects of Solutions on Cells Isotonic—Cells maintain normal size and shape Hypertonic—Cells lose water osmotically and shrink and shrivel Hypotonic—Cells gain water osmotically and swell and may burst. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Cell Membrane Osmotic Flow across a Cell Membrane Figure 3-7

The Cell Membrane Passive Membrane Transport Filtration Hydrostatic pressure pushes on water Water crosses membrane Small solutes follow water through pores Examples: blood pressure and urine formation Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

The Cell Membrane Carrier-Mediated Transport - Passive Membrane proteins as carriers Facilitated Diffusion (no ATP required) Co-transport Counter-transport Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Facilitated Diffusion The Cell Membrane Facilitated Diffusion Figure 3-8

Carrier-Mediated Transport – Active Active transport (ATP consumed) Independent of concentration gradients Ion pumps - Na+/K+ Exchange Pump

The Cell Membrane The Sodium-Potassium Exchange Pump Figure 3-9

The Cell Membrane Vesicular Transport Active Transport Membranous vesicles move material into/out of cell Types: Endocytosis - movement into cell Receptor-Mediated Pinocytosis – cell drinking Phagocytosis – cell eating Exocytosis - Movement out of cell Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

EXTRACELLULAR FLUID Ligands Ligands binding to receptors Exocytosis Receptor-Mediated Endocytosis Ligands binding to receptors Target molecules (ligands) bind to receptors in cell membrane. Exocytosis Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. Coated vesicle CYTOPLASM Vesicles fuse with lysosomes. Ligands are removed and absorbed into the cytoplasm. Fusion Detachment The membrane containing the receptor molecules separates from the lysosome. Lysosome Ligands removed Fused vesicle and lysosome The vesicle returns to the surface. Figure 3-10 1 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Ligands Ligand receptors CYTOPLASM EXTRACELLULAR FLUID Ligands Receptor-Mediated Endocytosis Ligands binding to receptors Target molecules (ligands) bind to receptors in cell membrane. Ligand receptors CYTOPLASM Figure 3-10 2 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Ligands Ligand receptors CYTOPLASM EXTRACELLULAR FLUID Ligands Receptor-Mediated Endocytosis Ligands binding to receptors Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. CYTOPLASM Figure 3-10 3 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Ligands Ligand receptors CYTOPLASM EXTRACELLULAR FLUID Ligands Receptor-Mediated Endocytosis Ligands binding to receptors Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. Coated vesicle CYTOPLASM Figure 3-10 4 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Ligands Ligand receptors CYTOPLASM Fused vesicle and lysosome EXTRACELLULAR FLUID Ligands Receptor-Mediated Endocytosis Ligands binding to receptors Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. Coated vesicle CYTOPLASM Vesicles fuse with lysosomes. Fusion Lysosome Fused vesicle and lysosome Figure 3-10 5 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Ligands Ligand receptors CYTOPLASM Fused vesicle and lysosome EXTRACELLULAR FLUID Ligands Receptor-Mediated Endocytosis Ligands binding to receptors Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. Coated vesicle CYTOPLASM Vesicles fuse with lysosomes. Ligands are removed and absorbed into the cytoplasm. Fusion Lysosome Fused vesicle and lysosome Figure 3-10 6 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

EXTRACELLULAR FLUID Ligands Ligands binding to receptors Endocytosis Receptor-Mediated Endocytosis Ligands binding to receptors Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. Coated vesicle CYTOPLASM Vesicles fuse with lysosomes. Ligands are removed and absorbed into the cytoplasm. Fusion Detachment The membrane containing the receptor molecules separates from the lysosome. Lysosome Ligands removed Fused vesicle and lysosome Figure 3-10 7 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

EXTRACELLULAR FLUID Ligands Ligands binding to receptors Exocytosis Receptor-Mediated Endocytosis Ligands binding to receptors Target molecules (ligands) bind to receptors in cell membrane. Exocytosis Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. Coated vesicle CYTOPLASM Vesicles fuse with lysosomes. Ligands are removed and absorbed into the cytoplasm. Fusion Detachment The membrane containing the receptor molecules separates from the lysosome. Lysosome Ligands removed Fused vesicle and lysosome The vesicle returns to the surface. Figure 3-10 8 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Vesicle Foreign object Undissolved residue Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object This fusion activates digestive enzymes. CYTOPLASM Pseudopodium (cytoplasmic extension) Undissolved residue The enzymes break down the structure of the phagocytized material. EXTRACELLULAR FLUID Residue is then ejected from the cell by exocytosis. Figure 3-11 1 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Phagocytosis Foreign object CYTOPLASM EXTRACELLULAR FLUID Figure 3-11 Cell membrane of phagocytic cell A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. Foreign object CYTOPLASM Pseudopodium (cytoplasmic extension) EXTRACELLULAR FLUID Figure 3-11 2 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Phagocytosis Foreign object CYTOPLASM EXTRACELLULAR FLUID Figure 3-11 Cell membrane of phagocytic cell A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. Foreign object CYTOPLASM Pseudopodium (cytoplasmic extension) EXTRACELLULAR FLUID Figure 3-11 3 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Vesicle Foreign object Phagocytosis Cell membrane of phagocytic cell A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Foreign object CYTOPLASM Pseudopodium (cytoplasmic extension) EXTRACELLULAR FLUID Figure 3-11 4 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Vesicle Foreign object Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object CYTOPLASM Pseudopodium (cytoplasmic extension) EXTRACELLULAR FLUID Figure 3-11 5 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Vesicle Foreign object Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object This fusion activates digestive enzymes. CYTOPLASM Pseudopodium (cytoplasmic extension) EXTRACELLULAR FLUID Figure 3-11 6 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Vesicle Foreign object Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object This fusion activates digestive enzymes. CYTOPLASM Pseudopodium (cytoplasmic extension) The enzymes break down the structure of the phagocytized material. EXTRACELLULAR FLUID Figure 3-11 7 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Vesicle Foreign object Undissolved residue Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object This fusion activates digestive enzymes. CYTOPLASM Pseudopodium (cytoplasmic extension) Undissolved residue The enzymes break down the structure of the phagocytized material. EXTRACELLULAR FLUID Residue is then ejected from the cell by exocytosis. Figure 3-11 8 of 8 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings

Coloring Workbook The packet will be due the day before the test. You can now complete numbers 8, 9, 10 and 11.