AutotrophsandTheirEnergySources: Photoautotrophs- Oxygenic photosynthesis- Anoxygenic photosynthesis Chemoautotrophs (lithoautotrophs) survive totally oninorganic substancesMethanogens, a kind of chemoautotroph, producemethane gas under anaerobic conditionsCopyrightThe11
Autotrophs and Their Energy Sources • Photoautotrophs – Oxygenic photosynthesis – Anoxygenic photosynthesis • Chemoautotrophs (lithoautotrophs) survive totally on inorganic substances • Methanogens, a kind of chemoautotroph, produce methane gas under anaerobic conditions 11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. © Kathy Park Talaro
Heterotrophs andTheirEnergy/SourcesCooiahtBTheDigestion in Bacteria and FungiMajorityare chemoheterotrophs- Aerobic respirationTwo categoriesOrganicdebris(a)Walled cell isa barrier.Enzymes- Saprobes: free-livingmicroorganisms that feed onorganic detritus from dead(b)Enzymes are transported outside the wall.organisms: Opportunistic pathogen·Facultative parasite2-Parasites:derive nutrientsfromEnzymes hydrolyze the bonds on nutrientshost·Pathogens: Some are obligate parasites12(d)Smallermoleculesaretransportedacrossthewallandcelmembraneintothecvtoplasm
Heterotrophs and Their Energy Sources • Majority are chemoheterotrophs – Aerobic respiration • Two categories – Saprobes: free-living microorganisms that feed on organic detritus from dead organisms • Opportunistic pathogen • Facultative parasite – Parasites: derive nutrients from host • Pathogens • Some are obligate parasites 12 (b) (c) (d) Digestion in Bacteria and Fungi (a) Walled cell is a barrier. Enzymes are transported outside the wall. Enzymes hydrolyze the bonds on nutrients. Smaller molecules are transported across the wall and cell membrane into the cytoplasm. Organic debris Enzymes Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display
TheMcGraw-HillCompaniesConcept Check:If an organism is degrading large organic moleculesto get both carbon and energy, it would be bestdescribed as aA.PhotoheterotrophB.PhotoautotrophC.ChemoheterotrophD.Chemoautotroph
Concept Check: If an organism is degrading large organic molecules to get both carbon and energy, it would be best described as a A. Photoheterotroph B. Photoautotroph C. Chemoheterotroph D. Chemoautotroph
Transport:MovementofChemicalsAcrosstheCellMembranePassive transport-does not require energy,substancesexist in agradient and move fromareas of higherconcentration toward areas of lowerconcentration-Diffusion-Osmosis-diffusionofwater- Facilitated diffusion - requires a carrier Active transport - requires energy and carrier proteins;gradient independent- Active transport- Group translocation - transported molecule chemicallyaltered- Bulk transport - endocytosis, exocytosis, pinocytosis14
14 Transport: Movement of Chemicals Across the Cell Membrane • Passive transport – does not require energy; substances exist in a gradient and move from areas of higher concentration toward areas of lower concentration – Diffusion – Osmosis – diffusion of water – Facilitated diffusion – requires a carrier • Active transport – requires energy and carrier proteins; gradient independent – Active transport – Group translocation – transported molecule chemically altered – Bulk transport – endocytosis, exocytosis, pinocytosis
Diffusion-NetMovementofMoleculesDownTheirConcentrationGradient(PassiveTransport)Copyright The McGraw-Hll Companies, Inc. Permis sion required for reproduction or displayHowMoleculesDiffuseinAqueousSolutions15
Diffusion – Net Movement of Molecules Down Their Concentration Gradient (Passive Transport) 15 Copyright © The McGraw -Hill Companies, Inc. Permission required for reproduction or display. How Molecules Diffuse in Aqueous Solutions