Bacterial Metabolism Sum up all the chemical processes
Bacterial Metabolism – Sum up all the chemical processes that occur within a cell 1. Anabolism: Synthesis of more complex compounds and use of energy 2. Catabolism: Break down a substrate and capture energy
Overview of cell metabolism
Bacterial Metabolism – Autotroph: Photosynthetic bacterial Chemoautotrophic bacteria – Heterotroph: Parasite Saprophyte
Energy Generating Patterns – – After Sugars are made or obtained, they are the energy source of life. Breakdown of sugar(catabolism) different ways: • Aerobic respiration • Anaerobic respiration • Fermentation
Photosynthesis (1) Higher plants – – Light reaction: Photolysis of H 2 O produce ATP and NADPH Two photosystem (I & II) Dark fixation: use the production from light reaction (ATP and NADPH) to fix CO 2 Reaction: 6 CO 2 + 6 H 2 O -----> C 6 H 12 O 6 +6 O 2 (Light and chloroplast)
Bacteria Photosynthesis i. Only one photosystem can not do photolysis of H 2 O ii. H 2 O not the source of electron donor iii. O 2 never formed as a product iv. Bacterial chlorophyll absorb light at longer W. L. v. Similar CO 2 fixation vi. Only has cyclic photophosphorylation
How the Bacteria synthesize NADPH n Grow in the presence of the H 2 gas H 2 + NADP+ ------- NADPH 2 hydrogenase n Reverse the electron flow in the etransport chain H 2 S S S + NADP+---- SO 4 -2 + NADPH 2 Succinate Fumarate n Simple non-cyclic photosynthetic e- flow
Chlorophyll a and bacteriochlophyll a(1)
Chlorophyll a and bacteriochlophyll a(2)
Anoxygenic photosynthesis
Anoxygenic versus oxygenic phototrophs(2)
Anoxygenic versus oxygenic phototrophs(1)
Photosynthetic bacteria (1) Chlorobium-green sulfur bacteria Use green pigment chlorophyll Use H 2 S (hydrogen sulfide), S (sulfur), Na 2 S 2 O 3 (sodium thiosulfate) and H 2 as e- donors. (2) Chromatium-purple sulfur bacteria Use purple carotenoid pigment, same e-donors (3) Rhodospirillum-non sulfur purple bacteria Use H 2 and other organic compounds such as isopropanol etc, as e-donors. Reaction: CO 2 + 2 H 2 A -----> CH 20 +2 A n A is not O
Chemautotroph – – Some bacteria use O 2 in the air to oxidize inorganic compounds and produce ATP (energy). The energy is enough to convert CO 2 into organic material needed for cell growth. Examples: Thiobacillus (sulfur S) Nitorsomonas (ammonia) Nitrobacter (nitrite) – Various genera (hydrogen etc. )
Aerobic respiration Most efficient way to extract energy from glucose. – Process: Glycolysis Kreb Cycle Electron transport chain – Glycolysis: Several glycolytic pathways – The most common one: glucose-----> pyruvic acid + 2 NADH + 2 ATP –
Aerobic respiration – – – Euk. glucose -----> G-6 -P----->F-6 -P-----> …. . . 2 pyruvate +2 ATP + 2 NADH Prok. glucose-----> G-6 -P------>F-6 -P Process take places during transport of the substrate. Phosphate is from phosphoenolpyruvate (PEP). . . -----> 2 pyruvate +2 ATP + 2 NADH
– Kreb cycle: Pyruvate + 4 NAD + FAD -----> 3 CO 2 +4 NADH + FADH GDP + Pi -----> GTP + ADP -----> ATP + GDP – Electron trasnport Chain 4 HADH -----> 12 ATP FADH ------> 2 ATP Glycolysis -----> 8 ATP – Total 15 ATP Total equation: C 6 H 12 O 6 + 6 O 2 ------> 6 CO 2 + 6 H 2 O + 38 ATP
Generation of a proton-motive force(1)
Generation of a proton-motive force(2)
Mechanism of ATPase
Anaerobic respiration 1. Final electron acceptor : never be O 2 2. Sulfate reducer: final electron acceptor is sodium sulfate (Na 2 SO 4) Methane reducer: final electron acceptor is CO 2 Nitrate reducer : final electroon acceptor is sodium nitrate (Na. NO 3) 3. 4. O 2/H 2 O coupling is the most oxidizing, more energy in aerobic respiration.
Fermentation Glycosis: Glucose ----->2 Pyruvate + 2 ATP + 2 NADH § Fermentation pathways a. Homolactic acid F. P. A -----> Lactic Acid eg. Streptococci, Lactobacilli b. Alcoholic F. P. A -----> Ethyl alcohol eg. yeast §
c. Mixed acid fermentation P. A -----> lactic acid acetic acid H 2 + CO 2 succinic acid ethyl alcohol eg. E. coli and some enterbacter d. Butylene-glycol F. P. A -----> 2, 3, butylene glycol eg. Pseudomonas e. Propionic acid F. P. A -----> 2 propionic acid eg. Propionibacterium
Alternative energy generating patterns(1)
Alternative energy generating patterns(2)
Alternative energy generating patterns(3)
Alternative energy generating patterns(4)
Energy/carbon classes of organisms
Chlorophyll a and bacteriochlophyll a(3)
Comparison of reaction centers of anoxyphototrophs
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