heterotrophy: respiration electron path (oxidation) The ETC process The ETC overview Factors affecting the ETC Switching to fermentation
heterotrophy: respiration & fermentation C 6 H 12 O 6 CO 2 NAD + NADH ETC ADP + Plots of ATP 2 H + reduced e- acceptor inorganic e- acceptor C 6 H 12 O 6 pyruvate NAD + NADH substrate Pfew ATP lactic acid ethanol & CO 2 mixed acids butanediol organic pyruvate ferm
respiration inorganic e - acceptor does NOT mean O 2 organic mole. CO 2 fermentation organic e - acceptor organic organic mole. incomplete H stripping, lower ATP yield heterotrophy: respiration & fermentation The Kreb’s Cycle The Kreb’s Cycle in detail
metabolism & media
Chapter Five Learning Objectives 1.Discuss redox reactions in biological systems. 2.Identify the redox partners in aerobic and anaerobic respiration and oxygenic and anoxygenic photosynthesis. 3.Correctly identify the carbon, energy and electron source for an organism when given its nutritional classification (e.g., chemoorganoheterotroph). 4.How is ATP generated in both substrate level and oxidative phosphorylation? 5.Why is it so important that the electron transport chain is housed in a lipid bilayer membrane? Why is a terminal electron acceptor so important? 6.What happens in a microorganism if the terminal electron acceptor of the ETC is not available? What molecules build up? What is done with these molecules? 7.Discuss the major differences between respiration and fermentation. What are the four basic kinds of fermentation?
chemo-: conversion of chemical E ATP iron oxidation sulfur oxidation -synthesis: carbon fixation (CO 2 organic molecule) autotrophy: chemosynthesis 2 H + ADP + P ETC ATP NAD + NADH carbon fixation H2SH2S SO H + ADP + P ETC ATP NAD + NADH carbon fixation 2Fe 3+ 2Fe 2+ heterotrophy
chemosynthesis: iron oxidation Thiobacillus ferrooxidans chemolithoautotrophy energy = Fe 2+ Fe 3+ electron = same carbon = CO 2 CH 2 O
chemosynthesis: sulfur oxidation Sulfolobus acidocaldarius chemolithoautotrophy energy = S 2- (sulfide) / S 2 O 3 2- (thiosulfate) SO 3 2- (sulfite) electron = same carbon = CO 2 CH 2 O
autotrophy: photosynthesisphotosynthesis photo: light E chemical E – light-dependent (light) reactions – ATP & NAD(P)H “reducing power” synthesis: – light-independent (dark) reactions – carbon fixation: piling e - onto CO 2 H 2 S/H 2 O ADP + P chlorophyll ETC ATP NAD(P) NAD(P)H carbon fixation oxidized chlorophyll heterotrophy
non-cyclic photosynthesis in the cyanobacteria cyclic photosynthesis in the purple sulfur bacteria photosynthetic electron photosynthetic electron flow & chemiosmosis Comparing Eukaryotic & Prokaryotic photosynthesis
microbial CO 2 fixation
photosynthesis compared EukaryotesProkaryotes Algae, PlantsCyanobacteriaGreen BacteriaPurple Bacteria electron donorH2OH2OH 2 O or H 2 Ssulfur compounds O 2 productionoxygenic oxygenic anoxygenic anoxygenic environmentaerobic aerobic anaerobic anaerobic CO 2 fixationCalvin-Benson Reverse Citric Acid (Reverse Kreb’s) Calvin-Benson
amphibolism & ATP
chemoheterotrophic growth – aerobic respiration – fermentation photoautotrophic growth – anaerobic, anoxygenic photosynthesis H 2 for e - & CO 2 for C photoheterotrophic growth – anaerobic, anoxygenic photosynthesis C 6 H 6 O 4 (succinate) for both metabolic diversity: the non-sulfur purple bacteria
chapter 5 learning objectives 1.How is ATP generated in chemosynthesis, photosynthesis and respiration? How is the process different for each and how is it the same? 2.Discuss the redox partners of sulfur and iron oxidizing bacteria. 3.How do non-cyclic and cyclic photosynthesis differ? How does each produce ATP and NADPH/NADH? What is each used for? 4.How is carbon fixed during chemosynthesis and photosynthesis? How is the process similar and how is it different? 5.How do amphibolism, catabolism and anabolism relate to growth and repair in cells?