microbio chapter 6
The _________________energy is the energy it takes to start a reaction.
activation
Non-competitive inhibition by regulatory molecules
allosteric regulators
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
Use the following four words to correctly complete the sentence: endergonic, exergonic, anabolism, catabolism."Cells constantly produce ATP during_____________ reactions of _______________and then use it to power _________________reactions of__________________ ."
exergonic, catabolism ; endergonic, anabolism
In the case of plants, algae, and cyanobacteria, the two major products of photosynthesis are ______.
glucose and oxygen
Purines and pyrimidines are synthesized ______.
in distinctly different manners
________________ energy (energy of motion)
kinetic
The reactions that capture radiant energy and convert it into chemical energy in the form of ATP are called the ________________-_________________ reactions.
light-dependent
The reactions that capture radiant energy and convert it into chemical energy in the form of ATP are called the__________________ _________________ reactions
light-dependent
In oxidation-reduction reactions, or redox reactions, the substance that loses electrons is_________________ , and the substance that gains those electrons is______________________
oxidized, reduced
In oxidation-reduction reactions, or redox reactions, the substance that loses electrons is___________________ , and the substance that gains those electrons is_____________________
oxidized; reduced
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 ATP
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.
8 ATP---glycolisis 6 ATP -transition step 24 ATP ---- TCA cycle 38 ATP ---- total yield of aerobic respiration
All of the following are essential for an electron transport chain to function EXCEPT ______.
ATP
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
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.
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.
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 combinations of molecules is produced during the light-dependent reactions of photosynthesis and used in the light-independent reactions?
NADPH and ATP
What are the two main forms of energy?
Potential Kinetic
Which of the following are true statements about what happens to glucose inside a cell?
Some glucose might enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis. Some 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.
The primary pathway used by many organisms to convert glucose to pyruvate is
glycolysis
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 ___________________ phosphorylation.
oxidative
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
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
Competitive inhibition
sulfa drugs
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
Which of the following are reasons an organism might use fermentation?
A suitable inorganic terminal electron acceptor is not available. They lack an electron transport chain.
The main energy currency of cells is the molecule called
ATP
With respect to their synthesis, how are amino acids typically grouped?
By structurally related families that share common biosynthesis pathways
Considering the general equation that describes photosynthesis, the rate of the process would be most influenced by the availability of _______ in the atmosphere.
CO2
Although the pentose phosphate pathway is used by cells to break down glucose, it is particularly important because of its contribution to ______.
biosynthesis
The light-independent reactions of photosynthesis occur _______ the light-dependent reactions, and function to _______.
after; synthesize organic compounds from CO2
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
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
Metabolic pathways can be linear, ______________ or, __________________-
branched cyclical
The diagram shows a type of metabolic pathway known as a(n) _____________________ pathway
cyclical
Examples of electron carriers are proteins that contain heme, a molecule that holds an iron in its center. These are called
cytochromes
In prokaryotes, the electron transport chain is located in the_______________membrane, whereas in eukaryotic cells it is in the__________________membrane of mitochondria.
cytoplasmic, plasma, cell; inner
Atoms that are more electronegative than others ______.
have a higher affinity for electrons
In terms of their metabolism, prokaryotes are _______ with respect to compounds they use for energy and _______ in their biosynthetic processes.
highly diverse; remarkably similar
Until the optimal temperature is reached, raising the temperature has what effect on the speed of enzymatic reactions?
it increases their rate
An atom that has a lower affinity (attraction) for electrons than another is described as ______ than the other.
less electronegative
The series of sequential chemical reactions in a cell that converts a starting compound to an end product is called a ____________________pathway.
metabolic
The sum total of all chemical reactions in a cell is called
metabolism
Lipid synthesis generally requires the components
glycerol and fatty acids
The enzymes of the tricarboxylic acid cycle are found in the ______________matrix in eukaryotes and in the _______________in prokaryotes.
mitochondrial; cytoplasm
The central metabolic pathway that generates reducing power in the form of NADPH is the __________--______________ pathway
pentose phosphate
The central metabolic pathway that generates reducing power in the form of NADPH is the _____________ ________________ pathway.
pentose phosphate
Energy is the ability to do work and can exist as ___________ energy (stored energy)
potential
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
Consider the three key central metabolic pathways (glycolysis, pentose phosphate pathway, and the TCA cycle). What three beneficial products of these pathways?
precursor metabolites reducing power ATP
The form of energy that results from the electrochemical gradient established by the electron transport chain is the ______. Multiple choice question.
proton motive force
the electron transport chain consists of large protein-complexes embedded in a membrane. These pass electrons from one to the next, while simultaneously pumping________________ across the membrane,
protons, H+, H ions
Enzymes function as biological catalysts, accelerating the conversion of one substance, the_________ , into another, the __________________ .
substrate, product
Proton motive force is ______.
the form of energy that results from the electrochemical gradient established by the electron transport chain
True or false: With respect to the location of the electron transport chain, the inner membrane of mitochondria is analogous to the cytoplasmic membrane of bacterial cells.
true- The electron transport chain of eukaryotic cells is in the inner membrane of mitochondria, and in bacterial cells it is in the cytoplasmic membrane. This observation is consistent with the Endosymbiotic Theory, which states that mitochondria evolved from a bacterium living within a host cell.
The three main types of electron carriers in a typical electron transport chain are
quinones, cytochromes, flavoproteins
The critical site of an enzyme to which a substrate binds by weak forces is called the
active site
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.
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.
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.
Consider the effect of temperature on enzyme activity. If the temperature is too high, proteins will ______________ and no longer function.
denature
Identify each of the following by the most precise descriptive term as either a cofactor or coenzyme: magnesium:____________ ; NADP+:_____________ ; zinc: ____________.
magnesium=cofactor nadp+ = coenzyme zinc=cofactor
Non-competitive inhibition by enzyme poisons
mercury
Metabolism is best defined as ______.
the sum total of all chemical reactions in a cell
Certain intermediates of catabolic pathways, called precursor metabolites, are important because ______.
they serve as carbon skeletons from which subunits of macromolecules can be made
Competitive inhibition
Inhibitor binds to the active site of the enzyme, blocking access of the substrate Inhibitor binds to the active site of the enzyme, blocking access of the substrate
Non-competitive inhibition by enzyme poisons
Inhibitor permanently changes the shape of the enzyme, making the enzyme non-functional
Non-competitive inhibition by regulatory molecules
Inhibitor reversibly changes the shape of the enzyme so that the substrate can no longer bind to the active site Inhibitor reversibly changes the shape of the enzyme so that the substrate can no longer bind to the active site
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?
The critical site to which a substrate binds by weak forces.
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.
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.
Consider the figure showing the relationship between catabolism and anabolism. Which side shows catabolism, and which side shows anabolism?
The left side shows catabolism, and the right side shows anabolism. anabolism deals with nutrients(source of nitrogen and sulfur) and catabolism deals with waste products (acids, and carbon dioxide)
Cells use ATP as the ready and immediate donor of free energy. ATP stands for ___________________ _____________________
adenosine triphosphate
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.
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.
The energy released by ______ is captured by cells to make ATP; this ATP can then be used for biosynthesis, or ______.
catabolism; anabolism
Enzymes are biological ______ that are typically _______.
catalysts; protein
In oxidative phosphorylation, quinones, cytochromes, and flavoproteins are all __________________carriers.
electron
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
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/electron ; terminal/final
Proteins that function as biological catalysts are called
enzymes
All of the following accurately describe enzymes EXCEPT ______.
enzymes provide energy to help reactions proceed more rapidly
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?
fermentation cellular respiration
The electron transport chain of mitochondria has ______ different protein complexes.
four