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Chapter 6A

Chapter 6A . A Tour of the Cell. Cytology: science/study of cells. Light microscopy Resolving power~ measure of clarity Electron microscopy TEM~ electron beam to study cell ultrastructure SEM~ electron beam to study cell surfaces Cell fractionation~ cell separation; organelle study

dorian-freeman
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Chapter 6A

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  1. Chapter 6A A Tour of the Cell

  2. Cytology: science/study of cells • Light microscopy • Resolving power~ measure of clarity • Electron microscopy • TEM~ electron beam to study cell ultrastructure • SEM~ electron beam to study cell surfaces • Cell fractionation~ cell separation; organelle study • Ultracentrifuges~ cell fractionation; 130,000 rpm

  3. Electron Micrograph

  4. Cell Types: Prokaryotic • Nucleoid: DNA concentration • No organelles with membranes • Ribosomes: protein synthesis • Plasma membrane (all cells); semi-permeable • Cytoplasm/cytosol (all cells)

  5. Cell Size • As cell size increases, the surface area to volume ratio decreases • Rates of chemical exchange may then be inadequate for cell size • Cell size, therefore, remains small

  6. Nucleus • Contains the Genetic material • Chromatin (chromosomes) • Nucleolus: rRNA; ribosome synthesis • Double membrane envelope with pores • Protein synthesis/Transcription (mRNA copies DNA)

  7. Ribosomes • Protein manufacture • Free - cytosol; produce proteins that function in the cell • Bound – roughendoplasmic reticulum; found on surface membranes; manufacture proteins that are exported from the cell • Composed of 2 subunits (rRNA & protein)

  8. Endomembrane System, I • Endoplasmic reticulum (ER) • Continuous with nuclear envelope • Smooth ER - no ribosomes; synthesis of lipids, metabolism of carbohydrates; detoxification of drugs and poisons • Rough ER - with ribosomes; synthesis of secretory proteins (glycoproteins); membrane production

  9. Endomembrane System, II • Golgi apparatus - ER products are modified, stored, and then shipped • Cisternae: flattened membranous sacs making up Golgi • trans face (shipping) & cis face (receiving) • Transport vesicles pinch off of ends of Golgi

  10. Endomembrane System, III • Lysosomes - sac of hydrolytic enzymes; digestion of macromolecules • Phagocytosis • Autophagy: recycle cell’s own organic material • Tay-Sachs disease~ lipid-digestion disorder

  11. Endomembrane system, IV • Vacuoles -membrane-bound sacs (larger than vesicles) • Food Vacuole (phagocytosis) • Contractile (pump excess water) • Central (storage in plants) •tonoplast membrane

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