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RIB OSOMES

RIB OSOMES. STRUCTURE Made of PROTEINS and rRNA FUNCTION (JOB) Make proteins amino acids to make proteins Process called TRANSLATION. . RIBOSOMES (CON’T). Can be attached to Rough ER (proteins made exit cell). OR. Be free (unattached) in the cytoplasm

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RIB OSOMES

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  1. RIBOSOMES STRUCTURE • Made of PROTEINS and rRNA FUNCTION (JOB) • Make proteins • amino acids to make proteins • Process called TRANSLATION 

  2. RIBOSOMES (CON’T) Can be attached to Rough ER (proteins made exit cell) OR Be free (unattached) in the cytoplasm (proteins made stay INSIDE cell)

  3. ROUGH ENDOPLASMIC RETICULUM (RER) STRUCTURE • Has ribosomes on its surface FUNCTION (JOB) • Helps to make proteins for export out of cell

  4. SMOOTH ENDOPLASMIC RETICULUM (SER) STRUCTURE • Has NO ribosomes on its surface • Usually attached to RER FUNCTION (JOB) • Makes lipids (membranes) • Regulates calcium (muscles) • Destroys toxins (Liver)

  5. ENDOMEMBRANE SYSTEM Includes nuclear membrane connected to ER connected to cell membrane (transport)

  6. GOLGI APPARATUS (BODIES) STRUCTURE • Stacks of flat sacs • Looks like pancakes with syrup drips • “Pankcakes” NOT connected FUNCTION (JOB) • Modify • Sort • Package • molecules from ER for storage OR transport in transport vesicles Transport vesicle “syrup bubble”

  7. GOLGI BODIES • flattened sacs • Have a receiving side (cis face) & a shipping or transporting side (trans face) • Receive proteins made by ER • Transport vesicles with modified proteins pinch off CIS TRANS Transport vesicle

  8. 1 Transmembrane glycoproteins Secretory protein Glycolipid 2 Golgi apparatus Vesicle 3 Plasma membrane: Cytoplasmic face 4 Extracellular face Transmembrane glycoprotein Secreted protein Membrane glycolipid Figure 7.10 • Membrane proteins and lipids • Are synthesized in the ER and Golgi apparatus ER

  9. CILIA & FLAGELLA FUNCTION (JOB) of Flagella • Moves WHOLE cells FUNCTION (JOB) of Cilia • Moves fluids or small particles across cell surface

  10. CILIA & FLAGELLA STRUCTURE • Made of protein tubes called microtubules Cilia • Shorter • more numerous Flagella • Longer • fewer (usually 1-3)

  11. CENTRIOLES STRUCTURE • Found only in animal cells inside CENTROSOMES • Paired structures near nucleus (“t” shape” • Made of microtubules FUNCTION (JOB) • Appear during cell division • Help to pull chromosome pairs apart to opposite ends of the cell

  12. CENTRIOLES & THE MITOTIC SPINDLE **Made of MICROTUBULES (Tubulin)

  13. 1 µm Nucleus Lysosome Hydrolytic enzymes digest food particles Food vacuole fuses with lysosome Lysosome contains active hydrolytic enzymes Digestive enzymes Lysosome Plasma membrane Digestion Food vacuole (a) Phagocytosis: lysosome digesting food LYSOSOMES STRUCTURE • They have a low pH • Contain hydrolyticdigestive enzymes FUNCTION (JOB) • Break down food, bacteria &old cell parts • Lyse & release enzymes to break down/recycle cell parts • Programmed for cell death (APOPTOSIS) • Think= “Lysol” cleaner

  14. VACUOLES STRUCTURE • Fluid filled sacks for storage • Small or absent in animal cells • Plant cells have a large Central Vacuole • Surrounded by a membrane called a TONOPLAST • No vacuoles in bacterial cells

  15. VACUOLES (CON’T) FUNCTION (JOB) • In plants, vacuoles store Cell Sap • Includes storage of sugars, proteins, minerals, lipids, wastes, salts, water, and enzymes

  16. CONTRACTILE VACUOLE STRUCTURE • Found in FRESHWATER • unicellular protists like paramecia FUNCTION (JOB) • Regulate water intake by pumping out excess (homeostasis) • Keeps the cell from lysing (bursting)

  17. Chloroplast Peroxisome Mitochondrion 1 µm PEROXISOMES FUNCTION (JOB) • Produce hydrogen peroxide (H2O2) and convert it to water • H2O2 is also toxic to a cell, and an enzyme made by the peroxisome can break down H2O2 Figure 6.19

  18. INTRACELLULAR JUNCTIONS ANIMALS: • Tight junctions:btw neighboring cells; prevents leakage between cells • Desmosomes:riveted, anchoring junction; strong sheets of cells • Gap junctions:cytoplasmic channels; allows passage of materials or current between cells

  19. INTRACELLULAR JUNCTIONS PLANTS: • Plasmodesmata: cell wall “holes”; water and solute passage in plants • Similar to GAP JUNCTIONS in animals

  20. NOW…LET’S PRACTICE 

  21. LIMITS • Diffusionlimits cell size • Movement from higher [ ] to lower [ ] • Larger the distance, slower the diffusion rate • A cell 20 cm would require months for nutrients to get to the center • DNA limits cell size • larger cells need more DNA…Needs more of everything! • Most cells have just one nucleolus

  22. Surface area to volume ratio limits size Volume increase more rapidly than surface area. Cell size doubles, 8x as much volume, but only 4x as much surface area

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