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.
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Presentation on theme: "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."— Presentation transcript:
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.
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 PO 4 www.qub.ac.uk/envres/EarthAirWater/ phosphate_removal.htm
Magnetosomes www.calpoly.edu/~rfrankel/ mtbphoto.html Membrane coated pieces of magnetite, assist bacteria in moving to microaerophilic environments. An organelle? North is down. Magnetospirillum magnetotacticum
Review of eukaryotic cells www.steve.gb.com/ science/cell_biology.html
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
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.
Illustrations: entry into cells http://bio.winona.msus.edu/bates/genbio/images/endocytosis.gif http://www.gla.ac.uk/~jmb17n/Teaching/JHteaching/Endocytosis/figures/howdo.jpg Both prokaryotes and eukaryotes. Only eukaryotes.
Type of molecule affects transport Small molecules can pass through a membrane –Water; otherwise, no osmosis –Gases such as O 2 and CO 2 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
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
How molecules get through the membrane http://www.rpi.edu/dept/chem-eng/Biotech-Environ/Membranes/bauerp/diff.gif
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.