Micobiology 205 chapter 6

Humans have taken advantage of microorganisms capable of this process in a number of ways. Which of the following are examples of this?

bread making, wine and beer making , making biofuels

The process by which chemolithoautotrophs and photoautotrophs incorporate CO2 into organic compounds is called

carbon fixation

Starch and cellulose are both polymers made up of the monosaccharide ________, which means that hydrolysis of the polymers releases subunits that can enter directly into the central metabolic pathway of______+ to be oxidized.

glucose Blank 2: glycolysis

After a deamination reaction removes the amino group from amino acids, the remaining carbon skeletons are converted into the appropriate _______ , metabolites for entry into central metabolic

precursor

As part of cellular respiration, a membrane-bound __________ called ATP uses energy from a proton-motive force to add a phosphate group to ADP.

synthase

The enzyme ATP synthase uses the energy of the proton motive force to ________ ATP.

synthesize

protease

the amino group of the resulting amino acid is removed by reaction called a deamination.

The electrons lost from photosystem II are replaced by electrons derived from a molecule of_____.

water

Lactic acid fermentation Ethanol fermentation Butyric acid fermentation Propionic acid fermentation Mixed acids fermentation 2,3-Butanediol fermentation

Lactic acid fermentation -Lactic acid Ethanol fermentation -Ethanol, CO2 Butyric acid fermentation -Butyric acid, butanol, acetone, isopropanol, CO2, H2 Propionic acid fermentation -Propionic acid, acetic acid, CO2 Mixed acids fermentation -Acetic acid, lactic acid, succinic acid, ethanol, CO2, H2 2,3-Butanediol fermentation -Formic acid, ethanol, lactic acid, 2,3-butanediol, CO2, H2

The lactic acid fermentation pathway is shown here. What statement best explains what is happening in the diagram? Multiple choice question. a. Pyruvate is reducing NADH to NAD+. b. NADH + H+ are donating a pair of electrons and protons to pyruvate, an organic terminal electron acceptor, oxidizing it to lactate. b. NADH + H+ are removing 2 electrons and 2 protons from pyruvate and donating them to lactate. c. NADH + H+ are donating 2 electrons and 2 protons to pyruvate, an organic terminal electron acceptor, reducing it to lactate.

NADH + H+ are donating 2 electrons and 2 protons to pyruvate, an organic terminal electron acceptor, reducing it to lactate.

In photosynthesis by cyanobacteria and chloroplasts, why is O2 generated? Multiple choice question.

The process strips electrons from H2O, generating O2.

Select all that apply Lactic acid production by fermenting microorganisms has many benefits for humans, but also can cause some problems. Which of the following are examples of these advantages and disadvantages? Multiple select question. a.Production of pickles and cured sausages. b. Commonly used in wine making. c. Results in food spoilage. d. Contributes to tooth decay. e. Creating flavor and texture of yogurt and certain cheeses. f. Giving flavor to and making holes in Swiss cheese.

a,c,d and e incorrect: Commonly used in wine making. Reason: Recall that wine (and most beer) making relies on ethanol production, which is typically accomplished by Saccharomyces species (yeast) and others.

Other than generating some ATP via the substrate-level phosphorylation steps of glycolysis, what critical role do the additional steps of fermentation accomplish? Multiple choice question. a. They consume excess reducing power in order to regenerate NAD+ so that it can accept electrons to keep glycolysis going. b. They produce end products, such as ethanol or lactic acid, which are used to inhibit the growth of competitors. c. They use up extra ATP so that glycolysis can continue producing additional reducing power. d. They generate end products such as ethanol, which the cell can then use as an energy source.

a. They consume excess reducing power in order to regenerate NAD+ so that it can accept electrons to keep glycolysis going.

The light-independent reactions of photosynthesis occur _______ the light-dependent reactions, and function to _______. Multiple choice question. a. before; generate ATP and reducing power b. before; synthesize organic compounds from CO2 c. after; generate ATP and reducing power d. after; synthesize organic compounds from CO2 e. before; breakdown glucose to CO2 and H2O

after; synthesize organic compounds from CO2

Consider the theoretical maximum ATP yield from the complete oxidation of glucose via aerobic respiration in prokaryotes. Match the relative contribution in terms of ATP (substrate-level phosphorylation plus oxidative phosphorylation) with the correct metabolic component. Instructions yields 8 ATP = glycolysis 6 ATP __________ 24 ATP________ 38 ATP__________

glycolysis yields 8 ATP transition step yields 6 ATP TCA cycle Yields 24 ATP total yield of aerobic respiration 38

Lactic acid is a common fermentation product of which of the following types of cells?

Gram-positive lactic acid bacteria

In respiring bacteria, how does ATP synthase generate ATP?

It uses the energy released from allowing protons to flow back into the cell to add a phosphate group to ADP.

Which of the following combinations of molecules is produced during the light-dependent reactions of photosynthesis and used in the light-independent reactions?

NADPH and ATP

What microorganisms use a fermentation pathway that results in CO2 and ethanol production? Multiple choice question. a. Saccharomyces species (yeast) and Zymomonas species (bacteria) b. Clostridium species c.Propionibacterium species d.The group of Gram-positive lactic acid bacteria

Saccharomyces species (yeast) and Zymomonas species (bacteria)

This diagram depicts the production of ethanol from pyruvate via fermentation. What best explains the mechanism? Multiple choice question. a. Acetaldehyde is made by removing CO2 from pyruvate, allowing it to combine with NADH + H+ to form ethanol. b.Pyruvate is converted to acetaldehyde, which then donates two electrons and protons to NAD+, yielding ethanol. c.CO2 removal converts pyruvate to the terminal electron acceptor acetaldehyde, which receives 2 electrons and protons from NADH + H+, making ethanol. d. Removal of CO2 converts pyruvate to acetaldehyde, which is oxidized by the donation of 2 electrons and protons from NADH + H+, forming ethanol.

a. CO2 removal converts pyruvate to the terminal electron acceptor acetaldehyde, which receives 2 electrons and protons from NADH + H+, making ethanol.

Which of the following are reasons an organism might use fermentation? Multiple select question. a. They lack an electron transport chain. b. A suitable inorganic terminal electron acceptor is not available. c. The energy yield is greater from fermentation than from respiration. d. They lack the ability to perform glycolysis.

A and B incorrect answer explanation. c. The energy yield is greater from fermentation than from respiration. Reason: The ATP yield from fermentation is much lower than if glucose is oxidized all the way to CO2. The pyruvate (or derivative) used as a terminal electron acceptor in fermentation still contains a great deal of energy. d. They lack the ability to perform glycolysis. Reason: Remember, fermentation relies upon glycolysis to split glucose and generate 2 ATP via substrate-level phosphorylation.

Match the organism(s) with the correct fermentation pathway. a. lactic acid fermentation b.Ethanol fermentation c.Ethanol fermentation d.Ethanol fermentation e.Mixed acids fermentation f.2,3-Butanediol fermentation

Lactic acid fermentation = Streptococcus, Lactobacillus Ethanol fermentation =Saccharomyces Butyric acid fermentation =Clostridium Propionic acid fermentation = Propionibacterium Mixed acids fermentation = E. coli 2,3-Butanediol fermentation = Enterobacter

Although the actual procedure is much more involved, the basic metabolism of wine-making involves inoculating grape juice with a special strain of the yeast Saccharomyces cerevisiae. S. cerevisiae will preferentially perform aerobic respiration on sugars in the juice but can also ferment those sugars to yield CO2 and alcohol, an important component of wine. Assume you inoculate a completely full container of juice and then close the lid. What will the yeast do? Multiple choice question. a. They will grow aerobically on the sugars, producing O2 in the process. b. They will grow aerobically until all the O2 is gone and then stop, because aerobic respiration yields the greatest energy. c. They will grow aerobically, consume the O2 dissolved in the juice, and then switch to fermenting sugars to yield alcohol. d. They will only ferment the sugars to yield alcohol. e. They will grow aerobically, then switch to anaerobic respiration as the O2 level drops.

c. They will grow aerobically, consume the O2 dissolved in the juice, and then switch to fermenting sugars to yield alcohol.

Electron carriers of the electron transport chain are able to move protons across a membrane. They are able to do so because ______. Multiple choice question. a. their protein structure includes a mobile component that physically ratchets to pump the protons across the membranes. B. some accept only hydrogen atoms (proton-electron pairs), whereas others accept only electrons. C. they supply ATP, which is used in a phosphorylation reaction to move protons

B. some accept only hydrogen atoms (proton-electron pairs), whereas others accept only electrons why this is incorrect. a. their protein structure includes a mobile component that physically ratchets to pump the protons across the membranes Reason: Electron carriers do not have a mobile component. Protons are shuttled across the membrane as the carriers accept and release electrons.

The ATP generated by fermentation comes from ______. Multiple choice question. a. the tricarboxylic acid (TCA) cycle Reason: b. oxidative phosphorylation driven by NADH c. substrate-level phosphorylation during glycolysis d. the reducing power obtained from the oxidation of glucose

answer : D. substrate-level phosphorylation during glycolysis the tricarboxylic acid (TCA) cycle Reason: During fermentation, the TCA cycle is either not functioning due to the lack of an appropriate terminal electron acceptor in respiration or because the organism lacks an electron transport chain. oxidative phosphorylation driven by NADH Reason: Oxidative phosphorylation refers to the reducing power generated by the central metabolic pathways being donated to an electron transport chain to create a proton motive force that is used to generate ATP via ATP synthase. substrate-level phosphorylation during glycolysis the reducing power obtained from the oxidation of glucose Reason: In fermentation, the electrons removed from glucose are donated to pyruvate or another organic derivative in order to regenerate NAD+ so that glycolysis can continue.

a. A series of enzymatic reactions convert the proteins, lipids, and polysaccharides into glucose that can then be broken down via glycolysis b. They extract the glucose structures from these macromolecules and excrete the rest as waste products into the surrounding environment. c. They break these macromolecules down into appropriate precursor metabolites that are then introduced into central metabolism or used in biosynthesis. d. They have separate metabolic pathways for these three classes of macromolecules that oxidize the compounds to CO2.

answer c. They break these macromolecules down into appropriate precursor metabolites that are then introduced into central metabolism or used in biosynthesis. Wrong answers: a. A series of enzymatic reactions convert the proteins, lipids, and polysaccharides into glucose that can then be broken down via glycolysis Reason: Rather than convert all the macromolecules into glucose, they are broken down to component parts that can then be introduced into central metabolic pathways at different points, depending on structure, or used in biosynthesis. incorrect ans: b. They extract the glucose structures from these macromolecules and excrete the rest as waste products into the surrounding environment. Reason: Most macromolecules do not directly have a glucose structure. Instead, they are broken apart into precursor metabolites, which can then be introduced into the appropriate central metabolic pathways of the cell, or used in biosynthesis. d. They have separate metabolic pathways for these three classes of macromolecules that oxidize the compounds to CO2. Reason: Remember, cells process the macromolecules down to appropriate precursor metabolites that can then be introduced into the correct central metabolic pathways.