MIB3701_ Microbial Physiology_ Portfolio Exams 2020.

MIB3701_ Microbial Physiology_ Portfolio Exams 2020. Substrate level phosphorylation  This process involves the phosphorylation of ADP into ATP from a substrate molecule, and it occurs in the absence of oxygen  And is often a catalyzed by Kinase enzymatic reactions  However this is not high energy yielding reaction, as only two net ATP molecules are produced.  And it occurs by glycolytic pathway. Oxidative Phosphorylation  It’s a high energy yielding reaction that occurs by oxidizing electron carriers such as FADH2 and NADH into FAD+ and NAD+ in the presence of and use Oxygen.  This process occurs by use of the electron transport chain, and is a high energy yielding process.  This process occurs by mechanical reactions. 1.2. Allosteric control  This is an enzyme regulator that binds on the allosteric site of the enzyme and regulate their activity. Reversible covalent modification  This process involves the modification of an enzyme structure either more commonly by adding a phosphoryl group from an ATP molecule to regulate enzyme activity Proteolytic cleavage  Many types of enzymes are produces in an inactive form. Such enzymes are called Zygomens and proenzyme, these enzymes are usually cleaved irreversibly by proteases on specific sites of the polypeptide.  Once attached they can be inactivated by the binding of some irreversible inhibitor  Examples including digestive enzymes and blood clotting cascade of enzymes Enzyme concentration  By regulating our enzyme concentration, we are able to control our affinity (Km and Vmax) for the enzyme catalyzed reaction, therefore as a whole, control the rate of the reaction. Isoenzymes  Are regulatory enzyme that carries out the same catalytic function but differs in terms of their amino acid sequence and regulatory properties.  They exhibited different kinetic parameters and are controlled by different regulatory molecules  Examples include lactate dehydrogenase enzyme. Question 2 Cellular respiration is a process that takes place inside the cells where energy is released from the breakdown of glucose molecules, in order to produce ATP, the cells major energy currency. In microorganisms we have two types of cellular respiratory process, all involving the use or either the cytoplasm or cristae of the mitochondria. We have: 2.1. Aerobic respiration  This process involves the use of Oxygen to oxidize electron carriers NADH and FADH2 to generate ATP.  This process involves the use of the electron transport chain, in the inner mitochondrial membrane.  And occurs by both Substrate level phosphorylation and Oxidative phopsphorylation.  And since Glucose breakdown by Glycolysis pathway involves the use of NAD+ into NADH, oxidative phosphorylation regenerates this NAD+ to drive the reaction forward.  This means that there is no need for fermentation as a process to occur.  And in this process glucose is broken down into water and carbon dioxide.  The net ATP production by this process in 32-38 ATP production. Anaerobic respiration  This process takes place in the absence of oxygen, and can only occurs by means of breaking down Glucose into pyruvate, and from pyruvate into ethanol or lactic acid.  Since organisms that carry out this process have no mitochondria, this process only takes place in the cytoplasm, without the use of the electron transport chain.  And energy production can only take place by substrate level phosphorylation.  NAD+, an important component in ATP production, and glucose breakdown is regenerated by fermentative process that converts pyruvate into Ethanol or lactic acid.  Glucose breaks down into ethyl alcohol, carbon dioxide, and energy.  And the net ATP production by this process is only two ATP molecules 2.2. The electron Transport chain, found in the inner mitochondrial membrane, is responsible for ATP production by use of NADH and FADH2  In the use of this process, Oxygen is needed as the electron acceptor to form water.  It is composed of four complexes, complex 1, 2, 3 and 4.  All responsible for shuffling the electron to Oxygen to form water.  Complex 1 that has a higher affinity for NADH, converting this NADH into NAD+, whiles also taking up the electrons from this molecule.  And the electrons are displaced into complex 1, and given to Flavin mononucleotide that gives up this electrons to co-enzyme Q.  Complex 2 on the other hand has a higher affinity (specific for) FADH2.  It oxidizes FADH2 into FAD+ and those electron are too transferred to Flavin mononucleotide, that in turn itself transfers those electrons to Co-Enzyme Q.  The electrons that were gained by CoQ, are then transferred to complex 3, that contains an ion group, that gets reduced into Fe2+  The electrons gained by Fe3+ are transferred to another ion group in cytochrome C, turning Fe3+ into Fe2+.  Transferring this electrons to the last electron acceptor, complex 4.  The electrons that were gained by Fe3+ in the final electron acceptor into Fe2+ are transferred to 1/2(O2)  Forming water, and hydrolyzing ADP into ATP by ATP synthase.  This resulting in a net formation 34 ATP molecules from this process alone.  This process is a high energy yielding reaction.  And can only occur in the presence of oxygen, without it, it is ineffective. Question 3 3.1. Respiration  Occurs in the presence of Oxygen and in the mitochondria.  NAD+ is regenerated by use of the electron transport chain.  We have Flavin Mononucleotide present in complex 1 that acts as the electron acceptor for NADH into NAD+  We also have Co-enzyme Q acts as the electron acceptor from Flavin Mononucleotide in the second step of cellular respiration by aerobic respiration.  Ferric ion present in complex 3, cytochrome C, and complex 4 acts as an electron acceptor from Co-enzyme Q, and it gets reduced into ferrous ion.  Oxygen is the final electron acceptor, taking up electrons from ferrous ion, forming water. Fermentation  It occurs in the absence of Oxygen and in the cytoplasm.  NAD+ is regenerated either by alcoholic, ethanol or mixed acid fermentation processes.  The electron transport chain is absent, and we therefore do not have FMN, coenzyme Q and Ferric ion as our electron acceptors.  However we have acetaldehyde as our electron acceptor in alcohol fermentation, converting NADH into NAD+, and resulting in the formation of ethanol, an alcohol. This reaction synthesized by alcohol dehydrogenase enzyme  In lactic acid fermentation, pyruvate acts as our electron acceptor for NADH, with the use of the enzyme lactate dehydrogenase. Forming lactate and NAD+.  And since oxygen is absent in this process, it cannot be reduced to water. And therefore water is not a byproduct of this reaction. 3.2. Microorganisms degrade and utilize lipids, carbohydrates, protein and amino acids in three types of cellular works: Chemical work  a process that involves the synthesis of complex biological molecules from much simpler precursors (i.e., anabolism).  This process stores energy for later use, by cellular organism.  Such as triglyceride, glycogenesis and fatty acid synthesis. Transport work  One that requires energy in order to take up nutrients, eliminate wastes, and maintain ion balances.  This process often involves the utilization of ATP.  And there are two main types of transport work that is passive and active.  In Active transport work energy is expended because the cell has to move materials from a region of low concentration, to one of higher concentration.  Whereas passive transport, no energy is required to carry substances throughout cells.  Examples include the transport of amino acids. Mechanical work  The use of Energy for cell motility and to move structures within cells.  All these processes use up energy through the hydrolysis of ATP to drive endergonic reactions.  These process can only occur by use of ATP that can be stored as either carbohydrates, lipids or proteins.  The use of either these product depends on the availability of energy.  And in its absence, either one of the products can be utilized to carry out activity of the cell, and continue with cellular work. 3.3. This process is an energy yielding reaction that occurs without an exogenous electron acceptor.  Its main function is to regenerate NAD+ for ATP production by Glycolysis, in the payoff phase the glycolytic pathway.  Since NAD+ is needed to drive the reaction forward in ATP production pathways, it would need to be regenerated.  And without the exogenous electron acceptors to regenerate NAD+, the process of ATP production would come to a halt, and so to regenerate this intermediate.  A process of fermentation would need to occur, either by lactic acid, mixed acid, or alcohol fermentation.  The by-product of fermentation, that is Ethanol, lactate, succinic and formic acids are useful to agricultural uses, industrial science and medicine. Industrial science uses:  Lactic acid can be used as a humectant, or moisturizer, in the cosmetics industry and as a mordant, a chemical that helps fabrics accept dyes, in textiles industry.  It is also used in making pickles and sauerkraut, foods for which a sour taste is desired.  Lactic acid is used in the dairy industry in making yogurt, cheese and wine making industry. Medical uses:  Products of the fermentative process, have been found to enhance living for human being.  This includes succinic acid, used as supplements to alleviate the symptoms associated with menopause and often used to treat and alleviate pain associated with joint pain, and arthritis. Agricultural uses:  Formic acid a by-product of mixed acid fermentation is used in the agricultural systems to help prevent the growth of bacteria in life stock.  Added to the feed of farm animals. Question 4 Purine and pyrimidine biosynthesis is critical for all cells because these molecules are used in the synthesis of ATP, several co-factor, RNA, DNA and other important cell compounds 4.1. Purine biosynthesis  Begins with ribose-5-phosphate. The first purine product of the pathway is the nucleotide inosinic acid and folic acid  And derivation contribute carbon 2 and 8 to the purine skeleton.  Once inosinic acid has been formed, relative short pathways synthesize Adenosine Monophosphate acid guanosine monophosphate  And produce nucleoside diphosphate and triphosphate by phosphate transfer from ATP Pyrimidine biosynthesis  Pyrimidine biosynthesis begins with aspartic and carbamoyl phosphate  Aspartate carbamoyl transferase catalyzes the condensation of these two substrate to form carbamoyl aspartate  Which is converted to the initial pyrimidine product arotic acid.  The pyrimidine synthesis is completed before ribose is added. 4.2. Bacterial metabolism is classified into three types, phototrophs, Chemoorganotrophs and Chemolithotrophs Chemolithotrophy  This process involves the oxidation of inorganic/organic compounds with the use of reduced inorganic compounds as their electron source.  And is divided into two major category of chemolithautotrophs and chemolithoheterotrophs.