BIO14- Chapter 5 Microbial Metabolism

5-16 Describe the chemical reactions of, and list some products of, fermentation.

-Any spoilage of food by microorganisms -Any process that produces alcoholic beverages or acidic dairy products -Any large-scale microbial process occuring with or without air *Alcohol fermentation: produces ethanol + CO2 *Lactic acid fermentation: produces lactic acid

What happens to an enzyme below itsoptimal temperature? Above its optimal temperature?

-OPtimimal TEMP: 35-40C.-rate of reactions declines and DENATURES (looses its charecterisics) above. when its below rate of reactins DECREASES until it reaches its optimal temperature

5-4 Describe the mechanism of enzymatic action.

1) the substrate contacts the active site on the enzyme to form 2)an enzyme-substrate complex 3)the substrate is then transformed into products 4)the products are released 5) the enzyme is recovered unchanged and is now free to react with other substrate molecules

List four compounds that can be made from pyruvic acid by an organism that uses fermentation.

1) water 2) CO2 3) ethanol 4) lactic acid

5-11 Describe the chemical reactions of glycolysis.

1.The most common pathway for the oxidation of glucose is glycolysis. Pyruvic acid is the end-product. 2.Two ATP and two NADH molecules are produced from one glucose molecule

5-15 Compare and contrast aerobic and anaerobic respiration.

AEROBIC: the final electron acceptor is O2 ANAEROBIC: the final electron acceptor is an inorganic molecule other than O2, or rarely an organic molecule, yields less energy than aerobic because only part of the KREBS cycle operates under anaerobic conditions

5-6 Distinguish competitive and noncompetitive inhibition.

COMPETITIVE INHIBITOR: fill the active site of an enzyme and compete with normal substrate for the active site -they can do this because its shape and chem structure are similar to normal substrate ex: sulfanilamide (potent antibacterial drug) inhibits the enzyme whose normal substrate is para-aminobenzoic acid (PABA)= an essential nutrient used by many bactera in the synthesis of folic acid, a vitamin that functions as a coenzyme NON-COMPETITIVE INHIBITOR: do not compete with the substrate for the enzyme's active site, interacts with another part of the enzyme ex: allosteric site is the site where the inhibitor binds outside the active site and causes change of shape and becomes nonfunctional =as a result enzyme's activity is REDUCED!

Why is glucose such an importantmolecule for organisms?

Glucose is important nutrient for organisms. they have many hydrogen atoms are highly reduced compoundes so have LOTS of stored energy Cells take nutrients, some of which serve as energy sources and degrade them from highly reduced compounds when a cell oxidizes a molecule of glucose (C6H12O6) to CO2 and H2O, the energy in the glucose molecule is removed in a stepwise manner and ultimately is trapped by ATP, which can then serve as an energy source for energy-requiring reactions.`

electron transport chain

NADH and FADH are oxidized, contributing the electrons they have carried from the substrates to a "cascade" of oxidation-reduction reactions involving a series of additional electron carriers. Energy from these reactions is used to generate a considerable amount of ATP. In respiration, most of the ATP is generated in the third step.

Why is feedback inhibition noncompetitive inhibition?

Noncompetitive, or allosteric, inhibitors play a role in a type of biochemical control called feedback inhibition, or end-product inhibition. -This control mechanism stops the cell from making more of a substance than it needs and thereby wasting chemical resources. In some metabolic reactions, several steps are required for the synthesis of a particular chemical compound, called the end-product. The process is similar to an assembly line, with each step catalyzed by a separate enzyme (Figure 5.8). In many metabolic pathways, the end-product can allosterically inhibit the activity of one of the enzymes earlier in the pathway

5-8 Explain the term oxidation-reduction.

Oxidation is the removal of e- from an atom or molecule, a reaction that often produces energy. Reduction means that it has gained one or more e-. An e- is transferred from molecule A to molecule B. In the process, molecule A is oxidized and molecule B is reduced.

What happens during the preparatory and energy-conserving stages of glycolysis?

PREPATORY STAGE: uses 2 molecules of ATP SPENT to phosphorylate glucose, making it easier to break it apart in two 3-carbon molecules energy is invested in the form of ATP to prepare glucose for utilzstion by the cell ENERGY-CONSERVING STAGE: 4 ATP and 2 NADH molecules are ACQUIRED produced along with 2 pyruvic acid molecules. At the end of GLYCOLYSIS: the energy found in glucose has been converted to a net of 2 ATP molecules and 2 NADH molecules.

5-10 Explain the overall function of metabolic pathways.

Sequence of enzymatically catalyzed chemical reactions occurying in a cell. Organisms release and store energy from organic molecule by a series of controlled reactions rather than in a single burst. If the energy were released all at once, as a large amount of heat, it could not be readily used to drive chemical reactions and would in fact damage the cell.

5-5 List the factors that influence enzymatic activity.

TPSPAI 1) temperature -increased rate of reactions = increased temperatures vice versa for decreasing -optimal temp for most disease producing bacter is 35-40C. -denaturation of enzyme changes arrangement/shape 2) pH -enzymes have optimum pH which they are most active; above or below this pH value, enzyme activity and reaction rate decline -change in pH can cause denaturation 3) substrate concentration -with increasing concentration of substrate molecules, the rate of reaction increases until the active sites on all the enzyme molecules are filled, at which point the maximum rate of reaction is reached 4) presence or absence of inhibitors -classified as either CI or NCI

Why is enzyme specificity important?

The 3-D structure enables it to "find" the correct substrate from among the diverse molecules in a cell; the 3-D of specific amino acids of the active site fits the substrate somewhat as a lock fits with its key ex: a specific enzyme might hydrolyze a peptide bond only between two specific amino acids

Compare the energy yield (ATP) of aerobic and anaerobic respiration.

The total ATP yield is less than in aerobic respiration because only part of the Krebs cycle operates under anaerobic conditions. AEROBIC requires O2 therefor requiring more ATP and more energy then anaerobic respiration which does NOT require O2.

respiration of glucose

To produce energy from glucose, microorganisms use two general processes: cellular respiration and fermentation. occurs in 3 principal stages: 1)glycolysis 2) Krebs Cycle 3) ETC

cellular respiration

after glucose has been broken down to pyruic acid, the pyruvic acid can be channeled into the next step of either fermentation or cellular respiration. definition: ATP-generating process in which molecules are oxidized and the final electron acceptor comes from outside the cell and is almost always an inorganic molecule. -an essential feature of respiration is the operation of an ETC. ***there are two types of respiration, depending on whether an organism is an aerobe, which uses O2 or an anaerobe, which doesn't use O2.

What is a coenzyme?

an organic nonprotein helper for catalytic reactions.

5-3 Identify the components of an enzyme.

apoenzyme (protein portion inactive) + cofactor (nonprotein activator) --> substrate (holoenzyme active)

Distinguish catabolism from anabolism.

catabolism: includes the processes that break down complex molecules (carbohydrates, lipids, proteins, dna, rna) into simpler molecules (fatty acids, amino acids, sugars, nucleotides) while harvesting their energy and storing it usually in the form of ATP anabolism: includes the process that build more complex molecules from simpler molecules; the energy acquired through catabolic processes is used to drive anabolic processes neither is completely efficient; so some of the energy is lost into the environment as heat coupled reactions: This coupling of energy-requiring and energyreleasing reactions is made possible through the molecule adenosine triphosphate (ATP).

Krebs Cycle

the oxidation of acetyl CoA (a derivative of pyruvic acid) to carbon dioxide, with the production of some ATP, energy-containing NADH, and another reduced electron carrier, FADH2 (the reduced form of flavin adenine dinucleotide). -Krebs Cycle *A series of reactions that release a large amount of potential energy to be transferred to the ETC End products: *2 ATP *NADH *FADH By products: *Carbon dioxide

glycolysis

the oxidation of glucose to pyruvic acid with the production of some ATP and energy-containing NADH. -Glycolysis *The converstion of glucose into pyruvic acid End products: *Pyruvic avid *NADH *Net gain of 2 ATP what is produced in glycolysis? 2 net ATPs and 2 NADH.

5-1 Define metabolism, and describe thefundamental differences between anabolism and catabolism.

the sum of all chemical reactions that take place in an organism; includes catabolism and anabolism; defined as energy balancing act

What is the purpose of metabolic pathways?

to release and store energy from organic molecules by a series of controlled reactions rather than a single burst.