Microbio CH 6

Enzymes function as biological catalysts, accelerating the conversion of one substance, the , into another, the

substrate or reactant, product

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

synthase

All of the following are essential for an electron transport chain to function EXCEPT ______.

ATP

The main energy currency of cells is the molecule called

ATP

The enzymes of the tricarboxylic acid cycle are found in the _ matrix in eukaryotes and in the _ in prokaryotes.

mitochondrial or mitochondrion Blank 2: cytoplasm or cytosol

The TCA cycle completes the ______ of glucose.

oxidation

In addition to yielding energy, catabolic pathways generate carbon intermediates that can be used in anabolic pathways for the biosynthesis of macromolecules. These carbon skeletons are called

precursor metabolites

Consider the three key central metabolic pathways (glycolysis, pentose phosphate pathway, and the TCA cycle). What three beneficial products of these pathways?

precursor metabolites ATP reducing power

The form of energy that results from the electrochemical gradient established by the electron transport chain is the ______. Multiple choice question.

proton motive force

For each six-carbon molecule of glucose that enters glycolysis, how many molecules of pyruvate are made, and how many carbon atoms does each pyruvate have?

Two molecules of pyruvate, each with three carbon atoms.

The energy released by ______ is captured by cells to make ATP; this ATP can then be used for biosynthesis, or ______.

catabolism; anabolism

Some enzymes act with the assistance of a non-protein component. This component is called a _ if that component is an organic molecule it can be called a_

cofactor : coenzyme

Consider the effect of temperature on enzyme activity. If the temperature is too high, proteins will _ and no longer function

denature

In addition to four protein complexes, the mitochondrial electron transport chain has two freely-moving ______, ubiquinone and cytochrome c, that serve to ______.

electron carriers; shuttle electrons between the complexes

The function of NAD+/NADH, NADP+/NADPH, and FAD/FADH2 in a cell is to carry

electrons

Hydrogen sulfide is produced as a result of certain types of anaerobic respiration. Some chemolithotrophs can then use this as a/an ______.

energy source

Consider how cells obtain energy to make ATP. The chemical that serves as the electron donor is the_ source, and the one that ultimately accepts those electrons is the _ electron acceptor.

energy, terminal

The central metabolic pathway that generates reducing power in the form of NADPH is the __ pathway.

pentose phosphate

The three main types of electron carriers in a typical electron transport chain are , , and flavoproteins.

quinones Blank 2: cytochromes

Competitive inhibition Non-competitive inhibition by regulatory molecules Non-competitive inhibition by enzyme poisons

1. Inhibitor binds to the active site of the enzyme, blocking access of the substrate 2. Inhibitor reversibly changes the shape of the enzyme so that the substrate can no longer bind to the active site 3. Inhibitor permanently changes the shape of the enzyme, making the enzyme non-functional

When a cell processes glucose or other organic molecules through its central metabolic pathways, it does so to generate what three critical things? Multiple choice question.

ATP, reducing power, precursor metabolites

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.

The series of sequential chemical reactions in a cell that converts a starting compound to an end product is called a pathway.

Metabolic

The electron transport chain is a cluster of membrane-embedded electron carriers that accept electrons from the coenzymes _ and _ and then pass these electrons along the chain.

NADH FADH2

Which of the following are important electron carriers for a cell?

NADP+/NADPH FAD/FADH2 NAD+/NADH

In photosynthesis, what do the light reactions, or light-dependent reactions, accomplish?

They capture radiant energy and convert it to chemical energy in the form of ATP.

Cells can quickly alter the activity of certain key enzymes, using other molecules that bind reversibly and distort them. This control of enzymes is called regulation.

allosteric

An atom that has a lower affinity (attraction) for electrons than another is described as ______ than the other. Multiple choice question.

less electronegative

Proteins that function as biological catalysts are called

enzymes

Proton motive force is ______.

the form of energy that results from the electrochemical gradient established by the electron transport chain

The central metabolic pathways together produce ______. Multiple choice question.

water and carbon dioxide

In oxidation-reduction reactions, or redox reactions, the substance that loses electrons is _, and the substance that gains those electrons is

oxidized, reduced

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

Which of the following correctly describe cytochromes found in an electron transport chain?

Cytochromes are proteins that contain heme, a molecule that holds an iron atom in its center. Several different cytochromes exist.

Which of the following are true statements about what happens to glucose inside a cell?

Glucose can be used in catabolism to yield energy, or the precursor metabolites generated from its breakdown can be used in anabolism. Some glucose might be oxidized to CO2, generating the maximum amount of ATP. Some glucose might enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis.

What are the two main forms of energy?

Kinetic Potential

In order for cells to obtain energy, they remove electrons from an energy source and ultimately donate them to the terminal electron acceptor. What does this tell us about the electron affinity of the energy source and the terminal electron acceptor?

The energy source has a lower affinity for electrons, and the terminal electron acceptor has a higher affinity for electrons.

The _ energy is the energy it takes to start a reaction.

activation

Although the pentose phosphate pathway is used by cells to break down glucose, it is particularly important because of its contribution to ______. Multiple choice question.

biosynthesis

Glucose catabolism encompasses two key processes: (1) oxidizing glucose molecules to generate ATP, reducing power, and precursor metabolites; and (2) transferring the electrons carried by NADH and FADH2 to the terminal electron acceptor. The second process, transfer of electrons, is accomplished as part of which of the following?

cellular respiration fermentation

In oxidative phosphorylation, quinones, cytochromes, and flavoproteins are all carriers.

electron

The electron transport chain of mitochondria has ______ different protein complexes.

four

The primary pathway used by many organisms to convert glucose to pyruvate is

glycolysis

Enzymes are biological ______ that are typically _______.

catalysts; protein

Atoms that are more electronegative than others ______.

have a higher affinity for electrons

What is the active site of an enzyme?

The critical site to which a substrate binds by weak forces.

Consider the following linear metabolic pathway of a bacterial cell: Starting compound → Intermediate-a → Intermediate-b → End Product. The first two reactions are catalyzed by enzymes A and B, respectively. If a mutant cell arose that was unable to produce enzyme B, what would be the impact on the other components of the pathway?

The cell could still produce intermediate-a but would be unable to produce intermediate-b or the end product.

Oxidative phosphorylation, the mechanism by which cellular respiration uses the NADH and FADH2 generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP, involves what two steps?

The electron transport chain generates a proton motive force. ATP synthase uses the energy of the proton motive force to drive the synthesis of ATP.

Which of the following is an example of activation energy?

The energy of a small flame used to light the natural gas of a Bunsen burner.

The light-independent reactions of photosynthesis occur _______ the light-dependent reactions, and function to _______. Multiple choice question.

after; synthesize organic compounds from CO2

The reactions that capture radiant energy and convert it into chemical energy in the form of ATP are called the - reactions.

light dependent

In addition to glucose, which of the following organic compounds can serve as energy sources for microbes?

lipids disaccharides polysaccharides fatty acids monosaccharides proteins

The sum total of all chemical reactions in a cell is called

metabolism

The mechanism by which cellular respiration uses reducing power generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP is , phosphorylation.

oxidative

Cells use three key metabolic pathways referred to as the central metabolic pathways. These collectively ______.

oxidize glucose to CO2

If the theoretical maximum ATP yield in prokaryotes from oxidative phosphorylation is 34 ATP for a single glucose molecule, what is the total ATP gain when substrate-level phosphorylation is included? Multiple choice question.

38 ATP