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From the membrane in: the bacterial cytoplasm

From the membrane in: the bacterial cytoplasm. Cytoplasm is a gel made of water, salts, LMW molecules, and lots of proteins. DNA = nucleoid, w/ proteins Plasmids = small circular DNA Ribosomes: site of protein synthesis. Cytoplasm may also contain inclusions, gas vacuoles,

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From the membrane in: the bacterial cytoplasm

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  1. From the membrane in: the bacterial cytoplasm • Cytoplasm is a gel made of water, salts, LMW molecules, and lots of proteins. • DNA = nucleoid, w/ proteins • Plasmids = small circular DNA • Ribosomes: site of protein synthesis. Cytoplasm may also contain inclusions, gas vacuoles, extended membrane systems, or magnetosomes. But generally NO membrane-bound organelles.

  2. Inclusions and granules • Storage molecules found as small bodies within cytoplasm. • Can be organic (e.g. PHB or glycogen) or inorganic (Sulfur, polyphosphate. • PHB, a type of PHA, degradable plastic (polyester); glycogen, a polymer of glucose. • Sulfur, a metabolic by-product; polyphosphate, polymer of PO4 www.qub.ac.uk/envres/EarthAirWater/ phosphate_removal.htm

  3. Magnetosomes Membrane coated pieces of magnetite, assist bacteria in moving to microaerophilic environments. An organelle? North is down. Magnetospirillum magnetotacticum www.calpoly.edu/~rfrankel/ mtbphoto.html

  4. Review of eukaryotic cells www.steve.gb.com/ science/cell_biology.html

  5. Eukaryotic cell reminders • Eukaryotic cells have a variety of compartments • Membrane-bound organelles, carry out functions • DNA in nucleus. NO NUCLEUS in Prokaryotes! • Mitochondrion is an enslaved bacterium • Inner and outer membrane like a Gram – bacterium • Mitochondrion has its own DNA and ribosomes • It is the same size as a bacterium. • Lysozome is an organelle • Contains various digestive enzymes • Important part of WBC’s defenses against bacteria

  6. How things get in (and out) of cells • Eukaryotic cells • Have transport proteins in membrane • Have a cytoskeleton made of microtubules • Allows for receptor mediated endocytosis, phagotcytosis, etc. • Cell membrane pinches in, creates vesicle • Prokaryotic cells • Have very little cytoskeleton • Can NOT carry out endocytosis • Entry of materials into cell by diffusion or transport processes ONLY.

  7. Illustrations: entry into cells Both prokaryotes and eukaryotes. Only eukaryotes. http://bio.winona.msus.edu/bates/genbio/images/endocytosis.gif http://www.gla.ac.uk/~jmb17n/Teaching/JHteaching/Endocytosis/figures/howdo.jpg

  8. Type of molecule affects transport • Small molecules can pass through a membrane • Water; otherwise, no osmosis • Gases such as O2 and CO2 • Lipid molecules can • Dissolve in lipid bilayer, pass through membrane • Many antibiotics, drugs are lipid soluble • Larger, hydrophilic molecules cannot • Ions, sugars, amino acids cannot pass through lipids • Transport proteins required

  9. Transport through membranes • Simple diffusion • Molecules travel down concentration gradient • Membrane is not a barrier to their passage • Facilitated diffusion • Molecules travel down concentration gradient • Cannot pass through lipid bilayer; their passage is facilitated by protein transporters • Active transport • Molecules travel against concentration gradient • Requires input of metabolic energy (ATP), transporter

  10. How molecules get through the membrane http://www.rpi.edu/dept/chem-eng/Biotech-Environ/Membranes/bauerp/diff.gif

  11. Group translocation As molecule passes through the membrane, it is chemically changed. This is a type of active transport. Saves energy: 2 tasks for 1 low cost.

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