Chapter 6
Proteins that function as biological catalysts are called_____
enzymes
In the case of plants, algae, and cyanobacteria, the two major products of photosynthesis are ______.
glucose and oxygen
Use the following four words to correctly complete the sentence: endergonic, exergonic, anabolism, catabolism."Cells constantly produce ATP during___reactions of___and then use its power ____reactions of _____
exergonic catabolism endergonic anabolism
Lipid synthesis generally requires the components___and___acids
glycerol;fatty
The primary pathway used by many organisms to convert glucose to pyruvate is
glycolysis
In terms of their metabolism, prokaryotes are _______ with respect to compounds they use for energy and _______ in their biosynthetic processes.
highly diverse; remarkably similar
The form of energy that results from the electrochemical gradient established by the electron transport chain is the ______.
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
The figure depicts oxidation-reduction reactions, which are also known as____reactions
redox
Which of the following combinations of molecules is produced during the light-dependent reactions of photosynthesis and used in the light-independent reactions?
ATP and NAPDH
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 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.
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
In oxidative phosphorylation, quinones, cytochromes, and flavoproteins are all__carriers
electron
The figure illustrates a type of regulation used by cells to rapidly control certain key enzymes. The arrow labeled "1" points to the____site, and the arrow labeled "2" points to the___site
allosteric;active
Examples of electron carriers are proteins that contain heme, a molecule that holds an iron in its center. These are called
cytochromes
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
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
All of the following accurately describe enzymes EXCEPT ______.
enzymes provide energy to help reactions proceed more rapidly
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.
Energy is the ability to do work and can exist as____energy (stored energy) and____energy (energy of motion).
potential;kinetic
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 reducing power ATP
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
The three main types of electron carriers in a typical electron transport chain are____ ,_____ and ___
quinones, cytochromes, flavoproteins
Proteins are composed of various combinations of usually how many different amino acids?
20
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
The electron transport chain of mitochondria has ______ different protein complexes.
4
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.
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
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
Competitive inhibition Non-competitive inhibition by regulatory molecules Non-competitive inhibition by enzyme poisons
Sulfa drugs Allosteric regulators Mercury
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.
The energy is the energy it takes to start a reaction.
activation energy
The critical site of an enzyme to which a substrate binds by weak forces is called the___ __
active site
Cells use ATP as the ready and immediate donor of free energy. ATP stands for_____ _____
adenosine triphosphate
The light-independent reactions of photosynthesis occur _______ the light-dependent reactions, and function to _______.
after; synthesize organic compounds from CO2
Metabolic pathways can be linear,____, or ____
brached; cyclical
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;proteins
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 a____if that component is an organic molecule it can be called a .___
cofactor coenzyme
Identify each of the following by the most precise descriptive term as either a cofactor or coenzyme: magnesium:____; NADP+:______zinc___
cofactor coenzyme cofactor
The diagram shows a type of metabolic pathway known as a(n)____pathway
cycle
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?
it increases their rate
What are the two main forms of energy?
kinetic;potential
An atom that has a lower affinity (attraction) for electrons than another is described as ______ than the other.
less electronegative
The reactions that capture radiant energy and convert it into chemical energy in the form of ATP are called the____ ____ reaction
light dependent
The series of sequential chemical reactions in a cell that converts a starting compound to an end product is called a_____pathway
metabolic
The enzymes of the tricarboxylic acid cycle are found in the___matrix in eukaryotes and in the_____in prokaryotes.
mitochondrial;cytoplasm
The mechanism by which cellular respiration uses reducing power generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP is_____phosphorylation
oxaditive
The TCA cycle completes the ______ of glucose.
oxidation
In oxidation-reduction reactions, or redox reactions, the substance that loses electrons is____Blank 1Blank 1 reduced , Incorrect Unavailable, and the substance that gains those electrons is
oxidized;reduced
The central metabolic pathway that generates reducing power in the form of NADPH is the___ ____pathway
pentose phosphate
Enzymes function as biological catalysts, accelerating the conversion of one substance, the___, into another, the ____
substrate;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
Proton motive force is ______.
the form of energy that results from the electrochemical gradient established by the electron transport chain
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
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
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.
8 ATP 6 ATP 24 ATP 38 ATP
Glycolysis Transition step TCA cycle Total yield of aerobic respiration
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;FADH
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.
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.
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.
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.
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.
Competitive inhibition Non-competitive inhibition by regulatory molecules substrate can no longer bind to the active site Non-competitive inhibition by enzyme poisons
Inhibitor binds to the active site of the enzyme, blocking access of the substrate Inhibitor reversibly changes the shape of the enzyme so that the substrate can no longer bind to the active site Inhibitor permanently changes the shape of the enzyme, making the enzyme non-functional
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.
Oxidative phosphorylation, the mechanism by which cellular respiration uses NADH and FADH2, generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP, involves what 2 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.
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
Although the pentose phosphate pathway is used by cells to break down glucose, it is particularly important because of its contribution to ______.
biosynthesis
Atoms that are more electronegative than others ______.
have a higher affinity for electrons
