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  1. Next time… • Read pp 124-142 – Biological energy and photosynthesis…

  2. Passive Transport • Diffusion • Movement of solutes • Simple vs. facilitated • Osmosis • Movement of water

  3. Active Transport • Can pump molecules AGAINST their concentration gradient • Like H+ in your stomach • Two ways to do this: • Using ATP • Using the power stored in another gradient

  4. Getting big stuff in and out • Endocytosis • Cells taking in material from the outside in vesicles • Can be general or specific (phagocytosis or receptor-mediated) • Exocytosis • Just the opposite, like cells puking

  5. Cell connections • Tight junctions • Cells glued together over entire contact surface • Desmosomes • Like spot-welds (proteins hold cells together) • Gap junctions • Protein pores hold cells together • Plasmodesmata • Like gap junctions in plants (through cell wall)

  6. Parts of the cell • Cytoplasm: • The molecule-rich gel that everything else is floating in

  7. Nucleus • Two double membranes: the nuclear membrane • Nuclear pores: regulate ins and outs • Chromatin: the condensed DNA

  8. Cytoskeleton • Network of fibers • Scaffolding: holds everything in place • Structure and support: keeps the cell solid • Intracellular highway system: moves vesicles around • Cellular movement: cilia, flagella, and pseudopodia

  9. Mitochondria • Two double membranes – inner is folded • Makes two spaces: • Intermembrane space • Matrix • Turns food + O2 into ATP + CO2

  10. Lysosomes • One membrane (two layers of phospholipids) • Garbage disposals of the cell • Very acidic • Enzymes that break molecules apart (hydrolytic enzymes)

  11. Ribosomes • The little machines (made of RNA) that translate copies of DNA into proteins

  12. Rough Endoplasmic Reticulum • Rough ER • One membrane (phospholipid bilayer) • Studded with ribosomes • Protein folding and packaging for export

  13. Smooth ER • No ribosomes • Makes lipids • Breaks down toxic molecules

  14. Golgi apparatus • Processes molecules that are headed out of the cell • Adds carbohydrates and phosphates onto proteins • Adds destination tags

  15. Cell Wall • Mostly in plants • Also some bacteria, protists, and fungi • Adds structure, toughness, and prevents dessication • 100x thicker than plasma membrane • But permeable, and with plasmodesmata

  16. Vacuole • Big (~50-90% of many plant cells) • Stores nutrients • Degrades waste • Holds secondary chemicals • Anti-herbivory • Pigments • Etc. • Physical support and structure

  17. Chloroplast • Double membrane • Thylakoids in the stroma • Photosynthesis! • Sun + CO2 +H2O → glucose + O2 • Found only in plants and protists (algae)