micro microbial metabolism
Some members of which of the following groups can use inorganic chemicals such as hydrogen sulfide and ammonia for energy?
Prokaryotes only
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?
38
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
8 ATP matches Glycolysis 6 ATP matches Transition step 24 ATP matches TCA cycle 38 ATP matches Total yield of aerobic respiration
Consider the three key central metabolic pathways (glycolysis, pentose phosphate pathway, and the TCA cycle). What three beneficial products of these pathways?
ATP precursor metabolites reducing power
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?
ATP synthase uses the energy of the proton motive force to drive the synthesis of ATP. The electron transport chain generates a proton motive force.
When a cell processes glucose or other organic molecules through its central metabolic pathways, it does so to generate what three critical things?
ATP, reducing power, precursor metabolites
With respect to their synthesis, how are amino acids typically grouped?
By structurally related families that share common biosynthesis pathways
In order to form lipids, how are fatty acids and glycerol synthesized?
Fatty acid chains are assembled from 2-carbon acetyl groups from the transition step; the precursor to glycerol comes from glycolysis.
Which of the following are true statements about what happens to glucose inside a cell?
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. Glucose can be used in catabolism to yield energy, or the precursor metabolites generated from its breakdown can be used in anabolism.
The figure illustrates a type of regulation used by cells to rapidly control certain key enzymes. The arrow labeled "1" points to the
allosteric active - 2
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, noncompetitive
Proteins are hydrolyzed by proteases, enzymes that break the peptide bonds between
amino acid subunits
Nucleotide subunits of DNA and RNA are composed of three units: a 5-carbon sugar, a phosphate group, and a nucleobase. They are initially synthesized ______.
as ribonucleotides that can be converted to deoxyribonucleotides by replacing the 2' hydroxyl group with a hydrogen atom
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
Some enzymes act with the assistance of a non-protein component. This component is called f that component is an organic molecule it can be called a
cofactor coenzyme
In terms of their metabolism, prokaryotes are _______ with respect to compounds they use for energy and _______ in their biosynthetic processes.
highly diverse; remarkably similar
Purines and pyrimidines are synthesized ______.
in distinctly different manners
Until the optimal temperature is reached, raising the temperature has what effect on the speed of enzymatic reactions?
increase
two types of energy
kinetic and potential
The series of sequential chemical reactions in a cell that converts a starting compound to an end product is called a ___ pathway.
metabolic
sum of all chemical reactions in the body
metabolism
Identify each of the following by the most precise descriptive term as either a cofactor or coenzyme: magnesium: ; NADP+: ; zinc:
mg - cofactor nadp - coenzyme zinc - cofactor
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, glycolysis
Fats, the most common simple lipids, are broken down by lipases into their component ______.
glycerol and fatty acids
Lipid synthesis generally requires the components ___ and _____ acids.
glycerol and fatty acids
Microorganisms that can grow on polysaccharides and disaccharides first break these down to glucose or precursor metabolites that can then enter into the pathway of
glycolysis
The primary pathway used by many organisms to convert glucose to pyruvate is
glycolysis
The enzymes of the tricarboxylic acid cycle are found in the____ matrix in eukaryotes and in the in prokaryotes.
mitochondrial cytosol
The electron transport chain is a cluster of membrane-embedded electron carriers that accept electrons from the coenzymes __ and __
nadh fadh2
The TCA cycle completes the ______ of glucose.
oxidation
The mechanism by which cellular respiration uses reducing power generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP is
oxidative phosphorylation
The mechanism by which cellular respiration uses reducing power generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP is ___
oxidative phosphorylation
The central metabolic pathway that generates reducing power in the form of NADPH is the
pentose phosphate pathway
In addition to glucose, which of the following organic compounds can serve as energy sources for microbes?
polysaccharides fatty acids disaccharides monosaccharides lipids proteins
Energy is the ability to do work and can exist as ___ energy (stored energy) and ___ energy (energy of motion).
potential kinetic
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 pathways.
precursor
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
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
enzymes -
the name of an enzyme typically reflects its function and ends in -ase enzymes are very specific, usually acting on only one or a few substrates enzymes are not used up in the process of catalyzing reactions enzymes are biological catalysts
Certain intermediates of catabolic pathways, called precursor metabolites, are important because ______.
they serve as carbon skeletons from which subunits of macromolecules can be made
Proteins are composed of various combinations of usually how many different amino acids?
20
What happens to an organism if it lacks one or more enzymes in a given biosynthetic pathway?
It must have the end product provided from an external source.
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.
What is the active site of an enzyme? Multiple choice question.
The critical site to which a substrate binds by weak forces.
Fats are hydrolyzed by lipases. The glycerol component is then converted to a precursor metabolite, and the fatty acids are degraded using a series of reactions called β-oxidation that remove successive 2-carbon units. Where do these components enter the central metabolic pathways for further oxidation?
The precursor metabolites from glycerol enter glycolysis; the 2-carbon units from fatty acids are added to coenzyme A and enter the TCA cycle.
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?
They will grow aerobically, consume the O2 dissolved in the juice, and then switch to fermenting sugars to yield alcohol.
Microorganisms can grow on a variety of organic compounds other than glucose, including polysaccharides, proteins, and lipids. How do they accomplish this?
They break these macromolecules down into appropriate precursor metabolites that are then introduced into central metabolism or used in biosynthesis.
Which of the following are reasons an organism might use fermentation?
They lack an electron transport chain. A suitable inorganic terminal electron acceptor is not available.
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 critical site of an enzyme to which a substrate binds by weak forces is called the
active site
Although the pentose phosphate pathway is used by cells to break down glucose, it is particularly important because of its contribution to ______.
biosynthesis
Enzymes are biological ______ that are typically _______
catalysts; protein
Consider the effect of temperature on enzyme activity. If the temperature is too high, proteins will
denature
Hydrogen sulfide is produced as a result of certain types of anaerobic respiration. Some chemolithotrophs can then use this as a/an ______.
energy source
All of the following accurately describe enzymes EXCEPT ______.
enzymes provide energy to help reactions proceed more rapidly
