Metabolism of Microbes Study Guide PDF

The Metabolism of Microbes Study Guide 1. All about metabolism. All of the chemical reactions and workings of a cell. Metabolism accomplishes processes through anabolism and catabolism. Metabolism conserves energy in the form of ATP or heat. Electrons are critical to metabolic process...

The Metabolism of Microbes Study Guide 1. All about metabolism. All of the chemical reactions and workings of a cell. Metabolism accomplishes processes through anabolism and catabolism. Metabolism conserves energy in the form of ATP or heat. Electrons are critical to metabolic processes. 2. All about anabolism. Making smaller molecules into larger molecules. Anabolism is also known as biosynthesis which is defined as the synthesis of cell molecules and structures. Anabolism requires the input of energy. 3. All about catabolism. Catabolism is the opposite of anabolism. It is the breaking down of larger molecules to release energy. Catabolism is in relation to exergonic reactions, which release energy. 4. All about enzymes. Enzymes are a type of catalyst that speeds up the rate of a chemical reaction without becoming apart of the products or consumes in the reaction. Reactions are sped up about 1000x million times in comparison to a reaction without enzymes. Enzymes will bind to substrates and participate directly in changes to the substrate. Enzymes do not become apart of the product, is not used up by the reaction, and can function over and over again until it denatures or is shut off. Substrates are the reaction molecules in which the enzymes interact with. o Anabolium 4 Catabolism 60 Go  conjugatedenzyme The structure of Enzymes apoenimd apoenzyme Enzymes are either simple or conjugated. after Simple enzymes consist of the protein alone. fete agookhorated potion Conjugated enzymes, also known as holoenzymes, contain a protein and some other non protein molecule. meteor ◦ The protein portion of the conjugated (holoenzyme) is called the apoenzyme. The apoenzyme is where the substrate binds, also can be called the active site or the catalytic site! ◦ The nonprotein portion of the holoenzymes is called a cofactor ◦ Organic cofactors are called coenzymes; Inorganic cofactors are metallic cofactors. ‣ The organic cofactors (coenzymes) work with the apoenzyme to alter the substrate. They remove a chemical group from one substrate and add it to another substrate. They can carry and transfer hydrogen atoms, electrons, carbon dioxide, and amino groups. ‣ there are also metallic (non organic) cofactors such as iron, copper, magnesium, zinc, cobalt, selenium, etc. These assist with precise functions between enzyme and substrate. They help to bring the substrate and active site to each other and they participate directly in chemical reactions. Enzymes have their own primary structure, variations in folding, and a unique active site specific to the substrate. Enzymes follow a lock & key mechanism. Enzyme processes take place very quickly, up to 1 million times per second! There are SIX classes of Enzymes: 1. Oxidorecutases: transfer electrons from one substance to another OR A. Dehydrogenases: transfer a hydrogen from one compound to another 2. Transferases: transfer functional groups from one substrate to another 3. Hydrolases: cleave bonds on molecules with the addition of water 4. Lyases: add groups or remove groups from double-bonded substrates 5. Isomerases: change a substrate to its isomeric form (same formula, different atomic arrangements) 6. Ligases: catalyze the formation of bonds with the input of ATP and the removal of water Location of Enzymes: Exoenzymes and Endoenzymes Exoenzymes are more harmful to host cells. They are transported extracellularly and break down large food molecules or harmful chemicals. They are made within the cell and transported out of the cell. Endoenzymes are made within the cell and function within the cell. Most enzymes of metabolic pathways are endoenzymes. Enzyme Regularity Enzymes can either be constitutive enzymes or regulated enzymes. Constitutive enzymes are present in relatively consistent amounts, this is regardless of the cell’s environment. An example would be enzymes used for glucose, because glucose is an extremely constant molecule utilized by cells. Regulated enzymes can either be induced or repressed in response to changed in concentration of the SUBSTRATES Enzyme repression stops further synthesis of an enzyme somewhere along its pathway ◦ Types of inhibition/repression of enzymes ‣ Competitive inhibition is when a molecules resembles the substrate and occupies the active site which prevents the substrate from binding; because of this, the enzyme cannot get rid of the inhibitor and shuts down. ‣ Noncompetitive inhibition: an enzyme may have different binding sites, a binding site and a regulatory site. When the regulatory molecule binds to the enzyme, it chemically changes the active site. This process is caused by when a certain concentration of a product is reached and the enzyme is not needed. ◦ Enzyme induction ‣ Enzymes are only induced/appear when a suitable substrate is present; this is the inverse of enzyme repression Energy in Cells Exergonic reactions: release energy as they go forward; energy is available for doing cellular work ty AM 2 energy Endergonic reactions: require the addition of energy to move forward Energy A B M's C Both exergonic and endergonic reactions are coupled together. The released energy from exergonic reactions are immediately used for endergonic reactions. Biological oxidation Reduction Oxidation loss of electrons the compound that loves theelectron is oxidized brokendown Reduction gain of electrons the compound that receives theelectron is reduced Generally a reduced molecule has more energy than the oxidized moletule Phosphorylation: the energy captured in the electrons carrier is used to phosphorylate (add inorganic phosphate) to ADP or another compound ◦Stores energy in a high energy molecule such as ATP There are di erent electron carriers. The most common is NAD (nicotinamide adenine dinucleotide) ◦NAD carries hydrogens and electrons from dehydrogenation reactions ‣ Dehydrogenation reactions occur during a redox reaction when hydrogens are removed from a compound Reduced NAD looks like this: NADH HI OR NADH oxide The NADH can now transfer the Htion to pave a way for metabolic reaction in other words NAD is an eletron carrier ATP: universal currency for energy! ATP is made up of adenine (nitrogenous base) + ribose (5-carbon sugar), and three phosphate groups binded to the ribose ‣ The phosphate group is bulky, with a negative charge. Their repelling electrostatic charges imposes a strain between the last two phosphate groups, and the breaking of the phosphates releases a lot of energy ATP replenishment is an ongoing cycle, when it is used in a chemical reaction, it must be replaced immediately ATP has many metabolic roles such as: ◦Substrate-level phosphorylation: the generation of ATP through a transfer of a phosphate group from a phosphorylated compound directly to ADP ◦Oxidative phosphorlylation: a series of redox reactions occurring during the nal phase of the respiratory pathway ◦Photophosphorylation: ATP formed through a series of sunlight-driven reactions in phototrophs There are Three basic catabolic pathways: 1. Aerobic respiration 2. Anaerobic respiration 3. Fermentation Glycolysis: most commonly used to breakdown glucose! Aerobic respiration: converts glucose to CO2 and allows the cell to recover signi cant amounts of energy Uses: glycolysis, Krebs cycle. And ETC Yields: 36-38 ATPs Aerobic respiration: energy yielding scheme for aerobic heterotrophs  Anaerobic respiration also utilizes glycolysis, Krebs Cycle, and the ETC; however, yields 2-36 ATPS; nal electron acceptor can be NO3-, SO4 2-, CO3 2- or other OXIDIZED compounds Fermentation only uses glycolysis; oxygen is NOT required GLYCOLYSIS Glucose is enzymatically converted to pyruvic acid; synthesizes a small amount of ATP ◦Pyruvic acid allows strict aerobes and some anaerobes to send it to the Krebs cycle for processing and energy release; facultative anaerobes utilize it for acids or other products THE KREBS CYCLE Pyruvic acid is converted to acetyl CoA before entering the cycle, then is converted to citric acid. NADH is formed is moved to the ETC to produce ATP; all reactions in the Krebs Cycle occurs twice The Krebs cycle yields: 4 CO2, 6 NADH, 2 FADH2, and 2 ATP (reduced NADH and FADH2, and 2 ATP through substrate level phosphorylation) THE ELECTRON TRANSPORT SYSTEM Receives the electrons from NADH and FADH2; ATP synthase synthesizes ATP from H+ ions that allow it to go through the cell membrane and bind with ADP to form ATP The proton motive force is the concentration gradient of hydrogen ions through the membrane; in prokaryotic cells, this happens in the cytoplasmic membrane; in eukaryotic cells it occurs in the mitochondrial membranes Yields 34 ATP FERMENTATION The incomplete oxidation of glucose or other carbohydrates in the absence of oxygen Uses organic compounds as the terminal electron acceptors Only yields 2 ATP  End products of alcoholic fermentation are ethanol and CO2; occurs in yeast or bacterial species