4 3 glucose i metabolic energy envelope so 4 2

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Unformatted text preview: saccharide, capsule, and murein occur outside the cell membrane o o o o Amino acid ⇒ polypeptides Nucleotides ⇒ nucleic acids (RNA or DNA) Monosaccharides ⇒ polysaccharides Fatty Acids + Glycerol + Phosphate ⇒ phospholipids Polymerization Reactionsnew • Amino Acid1 + Amino Acid2 Dipeptide – Not thermodynamically spontaneous in direction written; violates 2nd law – Spontaneous for Dipeptide breakdown • Activated Building Blocks – Amino acid + ATP Aminoacyl῀AMP + PPi – Aminoacyl῀AMP + tRNA Aminoacyl῀tRNA + AMP IV Assembly Reactions IV o Assembly Reactions involve the chemical modification of macromolecules, their transport to prespecified locations in the cell, and their association to form cellular structures: o o Envelope, appendages, nucleoid, polysomes, inclusions, and enzyme complexes. In some cases, other macromolecules must aid in the process­Directed Assembly High­Energy Compounds and Energy High­Energy Compounds and Energy Storage o o Energy released as a result of oxidation­reduction reactions must be conserved for cell functions In living organisms, chemical energy released in redox reactions is usually conserved in the form of high­energy phosphate bonds o o These compounds function as the energy source to drive energy­requiring reactions in the cell Phosphate groups are attached via oxygen atoms by ester or anhydride bonds o Note: Not all phosphate bonds are high­energy bonds High Energy Bonds High Energy Bonds Two Mechanisms of ATP Synthesis Two Mechanisms of ATP Synthesis Substrate Level Phosphorylation (SLP): 1. • Direct synthesis of ATP or other high energy phosphate in a direct chemical (metabolic) reaction: next slide Oxidative Phosphorylation (OP) 1. • Electron transport mediated synthesis of ATP. Mechanism involves Mitchell’s chemiosmosis and generation of proton motive force Substrate Level Phosphorylation Substrate Level Phosphorylation SLP: Phosphate must be transferred to an appropriate acceptor molecule O O O O Ex: CH C­OH + HO­P­OH CH C­O­P­OH 3 3 OH If an alcohol instead of an acid, you get an ester which is not high energy. O O CH CH OH+ OH­P­OH CH CH O­P­OH (ester) 3 2 3 2 OH OH Electron Transport Chain Electron Transport Chain The presence of a series of membrane associated electron carriers arranged in order of increasingly more positive E0’ Recall: Substrate with ­Eo’ (­.40 range) donates through series to final electron acceptor O2 with +0.82 Eo’. ∆ Eo’ is very large. Electron Transport Chain Electron Transport Chain Common Features of Electron Transport Chains Common Features of Electron Transport Chains The presence of a series of membrane associated electron carriers arranged in order of increasingly more positive E0’ An alternation in the chain of electron only and electron plus proton carriers Cytochromes & iron sulfur proteins (Fe2S2 & Fe4S4 centers) carry e­ only; Like flavoproteins, quinones accept 2 e­ & 2 H+ but transfer only 2 e­ to next carrier The generation of a proton motive force as a result of charge separation across the membrane, acidic out & alkalinein (H+; OH­) Fermentation Fermentation • • • • • ...
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