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8.E: Microbial Metabolism (Exercises)

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    144168
    • Ying Liu, Serena Chang, Grace Murphy, Esther Ajayi-Akinsulire, Isobel Ardren, Izabella Guy, Kai Johnston, Saskia Lee, and Lauren Russell
    • City College of San Francisco

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    8.1: Energy, Matter, and Enzymes

    Cellular processes such as the building or breaking down of complex molecules occur through series of stepwise, interconnected chemical reactions called metabolic pathways. The term anabolism refers to those endergonic metabolic pathways involved in biosynthesis, converting simple molecular building blocks into more complex molecules, and fueled by the use of cellular energy.

    Multiple Choice

    Which of the following is an organism that obtains its energy from the transfer of electrons originating from chemical compounds and its carbon from an inorganic source?

    1. chemoautotroph
    2. chemoheterotroph
    3. photoheterotroph
    4. photoautotroph
    Answer

    A

    Which of the following molecules is reduced?

    1. NAD+
    2. FAD
    3. O2
    4. NADPH
    Answer

    D

    Enzymes work by which of the following?

    1. increasing the activation energy
    2. reducing the activation energy
    3. making exergonic reactions endergonic
    4. making endergonic reactions exergonic
    Answer

    B

    To which of the following does a competitive inhibitor most structurally resemble?

    1. the active site
    2. the allosteric site
    3. the substrate
    4. a coenzyme
    Answer

    C

    Which of the following are organic molecules that help enzymes work correctly?

    1. cofactors
    2. coenzymes
    3. holoenzymes
    4. apoenzymes
    Answer

    B

    Fill in the Blank

    Processes in which cellular energy is used to make complex molecules from simpler ones are described as ________.

    Answer

    anabolic

    The loss of an electron from a molecule is called ________.

    Answer

    oxidation

    The part of an enzyme to which a substrate binds is called the ________.

    Answer

    active site

    True/False

    Competitive inhibitors bind to allosteric sites.

    Answer

    False

    Short Answer

    In cells, can an oxidation reaction happen in the absence of a reduction reaction? Explain.

    What is the function of molecules like NAD+/NADH and FAD/FADH2 in cells?

    8.2: Catabolism of Carbohydrates

    Glycolysis is the first step in the breakdown of glucose, resulting in the formation of ATP, which is produced by substrate-level phosphorylation; NADH; and two pyruvate molecules. Glycolysis does not use oxygen and is not oxygen dependent. After glycolysis, a three-carbon pyruvate is decarboxylated to form a two-carbon acetyl group, coupled with the formation of NADH. The acetyl group is attached to a large carrier compound called coenzyme A.

    Multiple Choice

    During which of the following is ATP not made by substrate-level phosphorylation?

    1. Embden-Meyerhof pathway
    2. Transition reaction
    3. Krebs cycle
    4. Entner-Doudoroff pathway
    Answer

    B

    Which of the following products is made during Embden-Meyerhof glycolysis?

    1. NAD+
    2. pyruvate
    3. CO2
    4. two-carbon acetyl
    Answer

    B

    During the catabolism of glucose, which of the following is produced only in the Krebs cycle?

    1. ATP
    2. NADH
    3. NADPH
    4. FADH2
    Answer

    D

    Which of the following is not a name for the cycle resulting in the conversion of a two-carbon acetyl to one ATP, two CO2, one FADH2, and three NADH molecules?

    1. Krebs cycle
    2. tricarboxylic acid cycle
    3. Calvin cycle
    4. citric acid cycle
    Answer

    C

    True/False

    Glycolysis requires oxygen or another inorganic final electron acceptor to proceed.

    Answer

    False

    Fill in the Blank

    Per turn of the Krebs cycle, one acetyl is oxidized, forming ____ CO2, ____ ATP, ____ NADH, and ____ FADH2molecules.

    Answer

    2; 1; 3; 1

    Most commonly, glycolysis occurs by the ________ pathway.

    Answer

    Embden-Meyerhof

    Short Answer

    What is substrate-level phosphorylation? When does it occur during the breakdown of glucose to CO2?

    Why is the Krebs cycle important in both catabolism and anabolism?

    Critical Thinking

    What would be the consequences to a cell of having a mutation that knocks out coenzyme A synthesis?

    This page titled 8.E: Microbial Metabolism (Exercises) is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Ying Liu, Serena Chang, Grace Murphy, Esther Ajayi-Akinsulire, Isobel Ardren, Izabella Guy, Kai Johnston, Saskia Lee, and Lauren Russell via source content that was edited to the style and standards of the LibreTexts platform.