CH8: Microbial Metabolism

• Catabolism involves breaking down polymers. This in turn releases energy (or ATP).
• Anabolism involves the building up of monomers. This requires energy.
• ATP consists of 3 phosphates, ribose sugar, and adenine. ATP provides energy for chemical reactions.
• Metabolic pathways are a series of reactions where an output of one reaction serves as an input for another.
• Histidine is an amino acid made from metabolic pathways, which synthesizes proteins.
• Enzymes function to lower the activation energy and speed up reactions as a catalyst.
• Inhibitors can slow enzyme activity either by binding to its active site to prevent substrate binding (competitive) or binding to its allosteric site and changing its shape (noncompetitive).
• A cofactor is an inorganic ion that helps stabilize an enzyme.
• A coenzyme is an organic molecule needed for enzyme function.
• An apoenzyme needs a cofactor or coenzyme to function.
• A holoenzyme forms when its coenzyme or cofactor is bound to it.
• A redox reaction involves the transfer of electrons between reactants.
• Oxidation involves losing electrons, while reduction involves gaining electrons. (OIL RIG)
• Photoautotrophs use light energy and convert it to chemical energy. Their carbon source is inorganic. In eukaryotes (cyanobacteria), this happens in the chloroplasts. For prokaryotes this happens in the internal membrane.
• Light reactions in phototrophs input water, ADP, Pi, and NADP+. They output ATP, oxygen, and NADPH.
• Carbon reactions in photoautotrophs input CO2, ATP, and NADPH2. They output ADP, NADP+, and glucose.
• Glycolysis, the first step of making ATP, converts 1 glucose molecule into 2 pyruvates. Additionally, 2 net ATP and 2 NADH are formed.
• The Entner-Doudoroff pathway is similar to glycolysis, but it makes one net ATP and generates NADPH instead of NADP.
• The pentose phosphate pathway is similar to glycolysis, but it makes one net ATP and generates 2 NADPH instead of NADP.
• Pyruvate oxidation, the second step of making ATP, produces 2 CO2, 2 NADH, and 2 Acetyl-CoA from pyruvate.
• If going from glycolysis to fermentation, then no ATP is generated, and no oxygen is present. NAD+ is used for recycling too.
• The Kreb's cycle, the third step of making ATP, uses 2 Acetyl-CoA to produce 2 ATP, 4 CO2, 2 FADH2 and 6 NADH.
• Oxidative phosphorylation, the fourth/last step of making ATP, uses the FADH2 and NADH from the Kreb's cycle to donate electrons and synthesize ATP.
• Aerobic respiration produces 38 ATP. Anaerobic respiration produces 36 ATP. Fermentation produces 2 ATP.
• Oxidative phosphorylation takes place in the mitochondria of eukaryotes, and cell membrane of prokaryotes.
• Protein Hydrolysis of Protein catabolism is done by proteases and outside of the cell.
• Deamination of protein catabolism involves removing the amine groups by deaminases.
• After proteins undergo deamination, they go to the Kreb's cycle.
• The glycerol during fat catabolism undergoes hydrolysis by lipases. It's then converted into DHAP, where it's sent to glycolysis.
• The fatty acids during fat catabolism undergo beta-oxidation, where they're broken down into two carbon atoms and attached to a CoA, making acetyl-CoA. This is sent to the Kreb's cycle.
• Amphibolic pathways refer to reversible metabolic pathways.
• Carbohydrate anabolism uses glucogenesis, which forms glucose form non-sugar precursors.
• Lipid anabolism is done by reversing the beta-oxidation process.
• Amino acid anabolism is done by using ammonia/amine groups to synthesize new amino acids.
• Nucleotide anabolism is done by getting its sugar from ribose, nitrogenous bases from folic/amino acids, and phosphate from ATP.
• Bioluminescence uses the enzyme luciferase to make energy, where FMNH2, O2, and aldehydes act as substrates.