Chapter 6- Microbial Metabolism

Recall that E. coli can grow in glucose-salts medium, which contains only glucose and a few inorganic salts. This means the glucose is serving what two purposes in the cell?

-energy source -Starting point from which all cell components are made

In contrast to an endergonic reaction, which of the following accurately describe an Exergonic reaction

-The reaction releases energy as it proceeds -The starting compounds have more free energy than the products

The pentose phosphate pathway generates which of the following from each molecule of glucose

A variable amount of NADPH, two precursor metabolites

For each glucose molecule, the pentose phosphate pathway yields _____

A variable amount of reducing power in the form of NADPH and two precursor metabolites

The main energy currency of cells is

ATP

The TCA cycle incorporates an acetyl group from the transition step and releases two precursor metabolites, two molecules of ___, and two molecules of ___.

ATP and CO2

The critical site of an enzyme to watch a substrate binds by weak forces is called the

Active site

Rank the following energy generating processes from greatest energy yield at the top to least energy yield at the bottom

Aerobic respiration, anaerobic respiration, fermentation

The chemical structures show the production of ethanol from pyruvate via fermentation. What best explains the events in this diagram

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

Which of the following accurately describe fermentation

Glucose is broken down via glycolysis. Fermentation does not involve the tricarboxylic acid(TCA) cycle. NAD+ is regenerated from NADH by the transfer of electrons to pyruvate or derivative.

The central metabolic pathway that splits glucose and gradually oxidizes it to form to molecules of pyruvate is _______

Glycolysis

In a biosynthetic pathway, The end product generally acts as the allosteric inhibitor, allowing the cell to shut down the pathway when the product begins accumulated. This mechanism of control is called feedback _______

Inhibition

Which of the following accurately describe the pentose phosphate pathway

It breaks down glucose, yield reducing power in the form of NADPH, it's primary role is the production of compounds used in biosynthesis

Most chemoorganoheterotroph's, like the one shown in the figure, depend on the metabolic activities of photosynthetic organisms. Consider the forms of energy represented in the figure, and match each type of energy with the correct description

Kinetic energy- Photons of sunlight Chemical energy- organic compounds

Consider the chemical structure showing the formation of lactate from Pyruvate by fermentation. Which statement best explains what is happening in the diagram

NADH + H Are donating two electrons and two protons to pyruvate, an organic terminal electron acceptor, reducing it to lactate

When and inhibitor binds to a site other than the active site of an enzyme, thereby interfering with its activity this is called ________ inhibition

Non-competitive

Following represent two fundamental tasks cells need to accomplish in order to grow except

Sexual reproduction

Consider the figure of a linear metabolic pathway of a bacterial cell. If a mutant cell 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

Which of the following correctly describe respiration

The electron transport chain uses the electrons to generate a proton motive force that can be used to generate ATP. Electrons extracted from glucose are transferred to the electron transport chain

Why do reduced electron carriers such as NADH, NADHP, and FADH to represent reducing power

They can easily transfer their electrons to another chemical that has a higher affinity for electrons

Other than generating some ATP via the substrate level phosphorylation steps of glycolysis, what critical role do the additional steps of fermentation accomplish

They consume excess reducing power in order to regenerate NAD So that it can except electrons to keep glycolysis going

When photosynthetic organisms convert the energy of sunlight to the energy of chemical bonds, and when chemoorganotrophs convert The energy of one type of chemical bond to that of another, they are _____

Transforming energy

True or false: The change in free energy for a given reaction is the same regardless of the number of steps involved

True

In prokaryotic cells, all the central metabolic pathways occur in the _____

cytoplasm

Free energy is best defined as

energy available to do work

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

glycolysis

Until the optimal temperature is reached, raising the temperature has what effect on the speed of enzymatic reactions?

it increases their rate

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

metabolic

Energy is the potential to do work and can exist as _______ energy (stored energy) and _______ energy (energy of motion)

potential and kinetic

Metabolism is best defined as

sum total of all chemical reactions in a cell

When a single molecule of glucose is processed by glycolysis in an E. coli cell, which of the following make up with the net gain of this process

- two molecules of ATP - six precursor metabolites - two molecules of NADH

Autotrophs use carbon dioxide to synthesize organic compounds. Which of the following descriptions of this process are true

-Photo synthetic organisms, the process is called the light independent reactions -it often involves the Calvin cycle -it is called carbon fixation

Which of the following correctly describe the transition step and the tricarboxylic acid (TCA) cycle

-The TCA cycle oxidizes a 2 carbon acetyl group to release two molecules of CO2 -together they generate the most reducing power of all the central metabolic pathways -The transition stuff converts the pyruvate from glycolysis into acetyl-CoA

The three metabolic pathways that gradually oxidize ______ to CO2 are collectively referred to as the central metabolic pathways

Glucose

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

-sounds glucose might be oxidized to CO2, generating the maximum amount of ATP -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 enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis

Comparing the two drawings showing an interaction between a substrate and an enzyme, identify the substrate, the enzyme substrate complex, the enzyme, and the active site of the enzyme

1-enzyme 2-substrate 3-active site 4-enzyme substrate complex

Consider the illustration of a metabolic pathway. Match the labels with their appropriate locations. Assume a sequential order of letters

1-starting compound 2-enzyme a 3-intermediate a 4-enzyme b 5-intermediate b 6-enzyme c 7-end product

Consider the figure showing the formation and breakdown of ATP. Fill in the labels of the figure by matching the terms with their correct number

1. ATP 2. Energy released drives anabolic reactions 3. ADP 4. Energy used comes from catabolic reactions

During the transition step of central metabolism, all of the following occur except

2 ATP are generated

The TCA cycle turns twice for each molecule of glucose that enters glycolysis. Together, these 2 turns generate

2 ATP, 6 NADH, 2 FADH2, 2 precursor metabolites

When referring to the chemical pyruvic acid, biologist often ignore the effect of pH on the molecule and Call it

Pyruvate

An organic cofactor that functions as a loosely bound carrier of molecules or electrons to assist an enzyme is called a _____

Coenzyme

All of the following processes commonly rely on microbial metabolism to produce items for human use except

Conversion of crude oil to gasoline at a coastal refinery.

The biosynthetic pathways shown, which compound is most likely to serve as the allosteric inhibitor

End product

The statement "the substrate fits into the active side of an enzyme like a hand into a glove" refers to what important property of enzymes

Enzyme specificity

Consider the pathway that converts the amino acid threonine to the amino acid isoleucine. Isoleucine is an allosteric Inhibitor of the first enzyme of the pathway. This is an example of the mechanism called

Feedback inhibition

Glucose cannibalism 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 by which of the following

Fermentation and cellular respiration

Which of the following are produced by the transition step for each molecule of glucose that enters glycolysis

One precursor metabolite, 2 NADH

Consider the graph of enzyme activity versus pH. The point indicated by the question mark Is the

Optimum pH

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

Oxidized, reduced

In aerobic respiration, ________ serves as the terminal electron acceptor

Oxygen

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

Pentose phosphate

Plants, algae, and several groups of bacteria harvest the radiant energy of sunlight and then use it to power the synthesis of organic compounds from CO2 in a process called

Photosynthesis

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

Polysaccharides, monosaccharides, proteins, fatty acids, lipids, disaccharides

When cells use glucose to make amino acids and other subunits for biosynthesis, certain intermediate of catabolism called _______ metabolites exit the " deconstruction line" of the breakdown process

Precursor

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

Proton motive force

one type of metabolism, ________ involves the breakdown of compounds to release energy, whereas another type of metabolism,___________ involves the biosynthesis of macromolecules , using ATP for energy.

catabolism and anabolism

The step that links glycolysis to the TCA is called the_____step

transition

Most coenzymes are derived from

vitamins