3/7/12 Ques+ons •  Where does a photoautotroph get its energy? –  The sun •  What name do we give an organism that fixes carbon from the atmosphere? –  Autotroph •  What organisms obtain their energy and their carbon from digested molecules? –  Chemoheterotroph Ques+ons •  Copper, iron, molybdenum, zinc all serve what purpose in an organism’s cellular processes? –  These trace elements serve as enzyme cofactors. •  Nitrogen fixa+on ‘fixes’ nitrogen from what source? –  The atmosphere Eukaryo+c Nutri+on 1 3/7/12 Eukaryote Nutri+on Nutrition Mode
Energy Source Carbon Source
Photoautotroph
Light
CO2
Chemoautotroph
Inorganic chem
CO2
Photoheterotroph
Light
Organic chem
Chemoheterotroph
Organic chem
Organic chem
Eukaryo+c Nutri+on Eukaryotes can obtain nutrients though 1.  Photosynthesis 2.  Absorp+on of nutrients 3.  Direct feeding* *unique to eukaryotes Eukaryo+c Nutri+on Absorp'on of nutrients Absorp+ve Feeding Eukaryotes are not as versa+le as prokaryotes. Eukaryotes cannot use as wide of a variety of electron donors and acceptors. Fig. 28.5 2 3/7/12 Eukaryo+c Nutri+on Absorp'on of nutrients Absorp+ve Feeding •  Most eukaryotes use glucose as an electron donor (energy) and oxygen as the electron acceptor •  What lifestyle strategies allow for absorp+ve feeding? –  Decomposers (Feed on the dead) –  Parasites (Feed on the living) Absorp+ve Feeding Decomposers •  Fungi are the most important decomposers on the planet. •  They obtain all their nutrients from absorbing nutrients from other organisms hWp://en.wikipedia.org/wiki/File:Fungi_3_REFON.JPG Tangent Ancient Fungi 250 MYA Largest ex+nc+on event on Earth (90% loss) Followed by a massive pulse in the abundance of fungi Provided evidence that this ex+nc+on was not limited to marine ecosystems Fig 31.2 3 3/7/12 Absorp+ve Feeding Decomposers •  Along with certain bacteria, the fungi are the only group that can metabolize the lignin and cellulose that make up wood. hWp://www.geograph.org.uk/photo/267054 Absorp+ve Feeding Cellulose and Lignin Fig 30.11 Lignin for biochemists Absorp+ve Feeding •  6-­‐carbon rings make lignin extremely rigid •  Helped plants ‘defy’ gravity and develop a vascular system Bryophytes: no lignin hWp://wdict.net/word/lignin/ hWp://www.wildlandsleague.org/display.aspx?pid=174&cid=222 4 3/7/12 Absorp+ve Feeding Lignin The Reckoning •  Fungi “blast” lignin by removing a single electron from one 6-­‐carbon ring –  This creates a free radical and violent chain reac+on And the fungus doesn’t even eat it! hWp://www.flickr.com/photos/cornellfungi/1490805486/ Absorp+ve Feeding The Real Feast Once the lignin peroxidase sonens the wood, the fungus can begin to decompose the cellulose Trichoderma Uses 7 different kinds of cellulase enzymes hWp://www.sciencephoto.com/media/13515/enlarge Absorp+ve Feeding Glucose What else uses absorp+ve feeding? Cellulose hWps://myorganicchemistry.wikispaces.com/Cellulose hWp://drpinna.com/avoiding-­‐diabetes-­‐8685 5 3/7/12 Absorp+ve Feeding Giardia hWp://www.wormsandgermsblog.com/tags/giardia/ hWp://pethealthlibrary.purinacare.com/ar+cles/understanding-­‐giardia-­‐infec+ons/ Absorp+ve Feeding Giardia hWp://www.drtummy.com/index.php?op+on=com_content&task=view&id=147 hWp://www.sciencephoto.com/media/364925/enlarge Absorp+ve Feeding Giardia hWp://www.rhk9klub.ca/archives/1646 6 3/7/12 Absorp+ve Feeding Diphyllobothrium Absorp+ve Feeding Diphyllobothrium •  No diges+ve tract! –  All absorp+ve feeding •  D. latum outcompetes the body for absorp+on of vitamin B12 –  Causes pernicious anemia in humans hWp://www.stumbleupon.com/stumbler/midnight-­‐creeper/reviews/60/ Absorp+ve Feeding hWp://www.atlas.or.kr/atlas/alphabet_view.php?my_codeName=Spirometra%20erinacei hWp://www.path.cam.ac.uk/~schisto/general_parasitology/parasitology_cestodes_tegument.html Microtriches 7 3/7/12 Plerocercoid Coracidium Procercoid A bear and her tapeworm Direct Feeding by Eukaryotes 8 3/7/12 Direct Feeding Direct Feeding by Eukaryotes •  Bacteria cannot ingest par+cles from the environment. WHY? Large par+cles will not fit through the cell wall! •  Pro+sts have no cell wall, now capable of inges+ng large food par+cles Direct Feeding Feeding in a Ciliate Cytostome Oral groove Gullet ~ Mouth Food vacuole formed at terminus of oral groove Lysosome fuses with food vacuole, material digested hWp://sciences.aum.edu/bi/bi2033/thomson/paramecium.htm Direct Feeding Feeding in a Ciliate hWp://sciences.aum.edu/bi/bi2033/thomson/paramecium.htm 9 3/7/12 Direct Feeding hWp://www.youtube.com/watch?v=a4aZE5FQ284 Direct Feeding Feeding in a Ciliate Pellicle: complex series of membranes that helps maintain rigid structure Food vacuoles first become highly acidic, then basic. Remains are expelled. Pellicle hWp://sciences.aum.edu/bi/bi2033/thomson/paramecium.htm Direct Feeding Stentor Feeding •  Sessile feeder •  Cilia creates current •  Food is funneled into cytostome hWp://www.photomacrography1.net/forum/viewtopic.php?t=1626&sid=dc4669f8aa6721b9bf6c3e12211649t 10 3/7/12 Direct Feeding Stentor Feeding hWp://www.youtube.com/watch?v=trVjBVaY-­‐E8 Ro+fers Feeding Direct Feeding Feeding in Amoeboids •  Pseudopodia used for locomo+on and feeding •  Phagocytosis •  Amoeoboids have flexible membrane, no dis+nct form hWp://www.mindfiesta.com/nutri+on 11 3/7/12 Direct Feeding Amoeba Feeding hWp://www.youtube.com/watch?v=W6rnhiMxtKU Direct Feeding Big step! •  With the development of ac+ve feeding, eukaryotes climbed up the food chain •  Instead of compe+ng with bacteria for food, eukaryotes were beginning to feed on bacteria 12