Ch. 6 Microbiology
Differences between aerobic respiration of glucose and anaerobic respiration of glucose
1. anaerobic harvests less energy than aerobic 2. The composition of ETC is different in anaerobic: carriers may be different 3. the final electron acceptors have lower electron affinities
Fermentation pathway of butyric acid: 1. what microorganisms use this? 2. what are the end products? 3. Consumer products?
1. clostridium 2. butyric acid, butanol, acetone, isopropanol, CO2, and H2 3. biofuels
what are the end products of the transition step of aerobic respiration of glucose?
2 acetyl CoA 2 CO2 (complete oxidation has not occurred yet) 2 NADH
what is the energy yield of fermentation?
2 atp
When a single molecule of glucose is processed by glycolysis in an E. coli cell, which of the following make up the net gain of this process?
2 molecules of NADH, six precursor metabolites, 2 molecules of ATP
The pentose phosphate pathway generates which of the following from each molecule of glucose?
2 precursor molecules, a variable amount of NADPH
Products of TCA cycle in aerobic respiration of glucose
4 CO2, 2 ATP, 6 NADH, 2 FADH2 and 2 precursor metabolites
reduction reactions
A chemical reaction in which a substance gains electrons
oxidation reactions
A chemical reaction in which a substances loses electrons
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
ATP
The main energy currency of cells is ___.
ATP
What is the energy currency for metabolic pathways?
ATP
What is the 4 step process for the formation and breakdown of ATP
ATP, energy released drives anabolic reactions, ADP, energy used comes from catabolic reactions
When a cell processes glucose or other organic molecules through its central metabolic pathways, it does so to generate what three critical items?
ATP, reducing power, precursor metabolites
What occurs during the transition step of central metabolism?
CO2 is removed from pyruvate, electrons are transferred to NAD+ reducing it to NADH and H+ The 2-carbon acetyl group is joined to coenzyme A to form acetyl-CoA
Inhibitor binds to the active site of the enzyme, blocking access of the substrate
Competitive inhibition
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.
In prokaryotes, the electron transport chain is located in the ____ membrane, whereas in eukaryotic cells it is in the ____ membrane of ______.
Cytoplasmic, inner, mitochondria
Why is it difficult, especially in prokaryotes, to calculate an exact ATP yield from oxidative phosphorylation?
Depending on the cell, different carriers are used in the electron transport chain that eject a variable number of protons per pair of electrons Prokaryotes use proton motive force to drive processes other than ATP synthesis
What organism uses fermentation for above reasons?
E. coli
What components are necessary for an electron transport chain?
Electron carriers such as quinones, cytochromes, and flavoproteins A membrane Protein complexes that serve as proton pumps
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
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 two molecules of pyruvate is ___.
Glycolysis
In an electron transport chain, electron carriers are found in what two general locations?
Grouped into large protein complexes that function as proton pumps Freely moving in the membrane where they can shuttle electrons between protein complexes
what is the source of energy for hydrogen bacteria?
H2
When sulfate is used as a final electron acceptor in anaerobic respiration of glucose, what is produced?
H2S
what is the source of energy for sulfur bacteria?
H2S
How does a non-competitive inhibitor work on an enzyme
It binds to a site other than the active site, altering the shape of the enzyme so the substrate can no longer bind
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 are quinones?
Lipid-soluble organic molecules that move freely in the membrane; includes one that serves as a source of vitamin K for humans and other mammals
About how much energy is harvested in the anaerobic respiration of glucose?
More than 2, less than 38 average number=32/34
What is the source of energy for nitrifying bacteria?
NH3, HNO2
Do enzymes provide energy to help reactions proceed more rapidly?
NO
Are there special pathways for these compounds?
No
Inhibitory permanently changes the shape of the enzyme, making the enzyme non-fucntional
Non-competitive inhibition by enzyme poisons
Inhibitor reversibly changes the shape of the enzyme so that the substrate can no longer bind to the active site
Non-competitive inhibition by regulatory molecules
What are some organic compounds microbes can use in respiration other than glucose?
Polysaccharides and disaccharides lipids proteins
Oxidative phosphorylation is the mechanism by which cellular _____ uses the reducing power generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP.
Respiration
Consider the maximum theoretical ATP yield from oxidative phosphorylation of a single molecule of glucose in prokaryotes. Match the relative contributions of the central metabolic pathways and final yield with their approximate contribution in terms of ATP. TCA Cycle, Total max yield, glycolysis
TCA cycle: 22 tap Glycolysis: 6 ATP total max yield: 34 ATP
What occurs during the transition step of central metabolism?
The 2-carbon acetyl group is joined to coenzyme A to form acetyl-CoA. Electrons are transferred to NAD+, reducing it to NADH + H+ CO2 is removed from pyruvate.
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 accurately describe the effect of sulfa drugs on the bacterial pathway for the synthesis of folic acid?
They inhibit an enzyme in the pathway They have structure similar to an intermediate in the pathway the effect is concentration dependent; more sulfa drug relative to substrate increases the likelihood of binding
The critical site of an enzyme to which a substrate binds by weak forces is called the ___ ___.
active site
How do cells produced ATP?
adding Pi to ADP using energy
Cells can quickly alter the activity of certain key enzymes, using other molecules that bind reversible and distort them. This control of enzymes is called ___ regulation
allosteric
non-competitive inhibition by regulatory molecules example
allosteric regulators
what would be the best definition of respiration?
an energy yielding process using ETC or oxidative phosphorylation from a source of energy
Is the fermentation process aerobic or anaerobic?
anaerobic
uses an electron transport chain; does not yield either the most or the least amount of ATP relative to the other two processes
anaerobic respiration
cofactors ___ some enzymes
assist
In response to changing energy needs, cells can regulate allosteric enzymes of catabolic pathways. high levels of which of the following would most likely inhibit such enzymes, thereby slowing down catabolic processes?
atp
the general group of electron carries synthesized from the vitamin riboflavin is called ___
flavoproteins
Enzyme name reflects ____
function
what is an example of lipase breaking down a molecule?
glycerol is converted to dihydroxyacetone phosphate and then enters glycolysis
in fermentation, the ATP-generating reactions are only those of ____
glycolysis
Cytochromes
contain heme, a molecule with an iron atom at the center, there are several types
In prokaryotic cells, all the central metabolic pathways occur in the ___
cytoplasm
Free energy is best definsed as a) the leftover energy that is not used by the cell b) energy of motion c) stored energy present in chemical bonds d) the energy available to do work
d) the energy available to do work
ATP synthase enzyme
harvests the proton motive force to synthesize ATP, uses energy to add phosphate to ADP and 1 ATP is formed per entry of 3 protons
Electrons moving through the ETC supply ____ in order to establish a proton gradient across the membrane
energy
oxidation phosphorylation
energy from exergonic reactions is used to create a proton motive force that drives the addition of Pi, to ADP
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
What are some inorganic compounds used for respiration?
hydrogen sulfide and ammonia (H2S and NH3)
cells constantly produce ATP during ___, reactions of ___ and then use it to power ___ reactions of ___
exergonic, catabolism, endergonic, anabolism
The energy released by an ___ reaction can be used by a cell to drive an ___ reactions.
exergonic; endergonic
When a substrate binds to the active site of an enzyme, what happens to the enzyme?
it slightly changes shape
In photosynthesis, the set of reactions that capture radiant energy and convert it into chemical energy in the form of ATP is called the ___ -___ reactions.
light dependent
What enzyme is used to degrade lipids?
lipases
Athough a modest amount of ATP is generated via substrate level phosphorylation by the central metabolic pathways, these pathways produce a large amount of reducing power that can be used to generate a much larger quantity of ATP via ___ phosphorylation
oxidative
True or false: cells growing in glucose salts medium use glucose exclusively as an energy source
false
although a modest amount of ATP is generated via substrate-level phosphorylation by the central metabolic pathways, these pathways produce a large amount of reducing power that can be used to generate a much larger quantity of ATP via ___ 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
Is substrate level phos. or oxidative phos. used with inorganic compounds are given for respiration
oxidative phosphorlyation
each types of them major electron carries is referred to by two different abbreviations (NAD+/NADH, NADP+/NADPH, and FAD/FADH2.) the first of each pair refers to the ___ form and the second of each pair refers to the ___ form
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
what is the final electron acceptor in the ETC process of aerobic respiration of glucose?
oxygen!
the sun's radiant energy and an electron transport chain create a proton motive force that drives the addition of P to ADP
photophosphorylation
___ organisms harvest the energy of sunlight, using it to power the synthesis of organic compounds from CO2, whereas ___ obtain energy by degrading organic compounds made by others
photosynthetic, chemoorganotrophs
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
propionoic acid, acetic acid, and CO2 are the end products of
propionic acid formation
What are proteins hydrolyzed by?
proteases...the amino groups are deaminated and converted into precursor metabolites
what are flavoproteins?
proteins that are synthesized from the vitamin riboflavin proteins to which a flavin is attached
What are cytochromes?
proteins that contain heme, a molecule that holds an iron atom in its center -There are several different cytochrome types
the chemical structure of the inhibitor is usually ___ to the substrate
similar
enzymes function as biological catalysts, accelerating the conversion of one substance, the ___, into another, the ___.
substrate, product
three processes to generate ATP
substrate-level phosphorylation oxidative phosphorylation photophosphorylation
oxidative phosphorylation
synthesis of ATP using the energy of a proton motive force created by harvesting chemical energy
substrate-level phosphorylation
synthesis of AtP using the energy releases in an exergonic chemical reaction during the breakdown of the energy source
metabolic process unique to prokaryotes
targets of antimicrobial drugs
what are some environmental factors that influence enzyme activity?
temperature, pH, salt concentration
Free energy is best defined as:
the energy available to do work
enzymes are highly ____
specific, one at each step
What organism only has fermentation as an option and why?
streptococcus pneumoniae and because they lack and ETC
competitive inhibition inhibitor example
sulfa drugs
prokaryotes are diverse in using energy sources...name 3 energy sources they an use
sunlight, organic compounds (glucose, polysaccharides, proteins, lipids), inorganic compounds (H2S, NH3)
What is the active site of an enzyme?
the critical site to which a substrate binds by weak forces
Where does the transition step of aerobic respiration of glucose take place in bacterial cells?
the cytoplasm
Role of enzymes
they are biological catalysts that accelerate the conversion of substrate into product by lowering activation energy
why do chemolithotrophs incorporate CO2 into an organic form to fulfill their carbon needs?
they fulfill their energy needs from inorganic compounds such as H2S and NH3 that lack carbon, so they need to obtain their carbon elsewhere
Certain intermediates of catabolic pathways, called precursor metabolites, are important because:
they serve as carbon skeletons from which subunits of macromolecules can be made.
Ethanol can be produced during fermentation by removing CO2 from pyruvate. Humans have taken advantage of microorganisms capable of this process in a number of ways. which of the following are examples of this?
wine and beer making making biofuels bread making making spirits
is the action of allosteric inhibitors reversible?
yes
enzymes are biological ____
catalysts
catabolism
cellular process that harvests the energy released during the breakdown of a compound such as glucose and using it to synthesize ATP
anabolism
cellular processes that synthesize and assemble the subunits of macromolecules, using the energy of ATP; biosynthesis
the process that links the electron transport chain to ATP synthesis is called the ___ theory
chemiosmotic
the competitive inhibitor is ___ dependent
concentration
in prokaryotic cells, all the central metabolic pathways occur in the
cytoplasm
What membrane is the ETC in prokaryotes?
cytoplasmic membrane
The central metabolic pathway that splits glucose and gradually oxidizes it to form two molecules of pyruvate is ___
glycolysis
The primary pathway used by many organisms to convert glucose to pyruvate is _____
glycolysis
lactic acid is a common fermentation product of which of the following types of cells?
gram-positive organisms called lactic acid bacteria, animal muscle cells when O2 is in short supply
products characteristic of specific microbes
identifying markers
All of the following accurately describe enzymes EXCEPT:
enzymes provide energy to help reactions proceed more rapidly.
A group of membrane-embedded electron carriers that pass electrons sequentially from one to another, ejecting protons in the process, is called the
etc
ethanol and CO2 are the end products of
ethanol fermentation
True or false: each individual prokaryote within a species will have an electron transport chain made up of the same components
false
When respiration is taking place with inorganic compounds, are all typical pathways used?
no, only ETC is used because you cannot make pyruvic acid without carbon
Can eukaryotes perform respiration with inorganic compounds?
no, only prokaryotes can
Consider the graph of enzyme activity (y-axis) versus temperature (x-axis). The point indicated by the question mark is the ___ ___
optimum temperature
What are two processes bacteria use to harvest energy from chemicals?
respiration and fermentation
What level is the 2 ATP from fermentation made at
substrate level phosphorylation
energy released in an exergonic reaction is used to power the addition of P to ADP
substrate-level phosphorylation
which of the three central metabolic pathways generate a modest amount of ATP via substrate level phosphorylation? -tricarboxylic acid (TCA) cycle -glycolysis -pentose phospate pathway
-tricarboxylic acid (TCA) cycle -glycolysis
Rank the following energy-generating processes from greatest energy yield to least energy yield.
1. Aerobic respiration 2. Anaerobic respiration 3. Fermentation
Process of electron transport chain
1. An electron carrier donates electrons to a hydrogen carrier 2. The hydrogen carrier must pick up protons from inside the cell 3. The hydrogen carrier passes electrons to a carrier that only accepts electrons 4. Because the electron carrier only accepts electrons, the protons are released to the outside of the cell 5. A proton motive force is set up as protons are moved from inside of the cell to the outside
fermentation pathway of mixed acids: 1. what microorganisms use this? 2. what are the end products?
1. E. coli 2. acetic acid, lactic acid, succinic acid, ethanol, CO2, H2
Fermentation pathway of 2,3-butanediol 1. what microorganisms use this? 2. what are the end products?
1. enterobacter 2. CO2, H2
What are the three steps for aerobic respiration of glucose?
1. glycolysis/pentose phosphate pathway 2A) transition step 2B) TCA or Krebs cycle 3. ETC
4 general groups of chemolithotrophs
1. hydrogen bacteria 2. sulfur bacteria 3. iron bacteria 4. nitrifying bacteria
Fermentation pathway of Propionic acid: 1. what microorganisms use this? 2. what are the end products? 3. Consumer products?
1. propionibacterium 2. propionic acid, acetic acid, CO2 3. Swiss Cheese
2 purposes the the ETC in aerobic respiration of glucose
1. regenerate electron carriers 2. synthesize ATP
Fermentation pathway of ethanol: 1. what microorganisms use this? 2. what are the end products? 3. Consumer products?
1. saccharomyces 2. ethanol, CO2 3. wine and beer
Fermentation pathway of lactic acid: 1. what microorganisms use this? 2. what are the end products? 3. Consumer products?
1. streptococcus/lactobacillus 2. lactic acid 3. yogurt, cheese, pickles
___ ATP made per electron pair from FADH2
2
two 3-carbon molecules enter the pay-off phase of glycolysis for each initial glucose molecule, meaning the steps of this phase occur twice for each glucose. During this pay-off phase of glycolysis, what is the total number of NADH and ATP molecules produced from a single glucose molecule?
2 nadh, 4 atp
what are the end products of glycolysis with aerobic respiration of glucose?
2 pyruvates, 2 atp, and 2 NADH, 6 precursor metabolites
hydrogenation reaction
A reduction reaction in which an electron and an accompanying proton is added to a molecule
Which statement correctly describes how catabolism and anabolism are intimately linked?
ATP made during catabolism is used in anabolism
The membrane-bound enzyme that uses energy from a proton-motive force to add a phosphate group to ADP is called
ATP synthase
The synthesis of ATP is driven by what in the ETC of aerobic respiration of glucose
ATP synthase enzyme
why is mercury an enzyme poison? Describe the steps
mercury oxidizes the S--H groups of amino acid cysteine, coverts it to cystine, cystine cannot form important disulfide bond, enzyme changes shape and becomes nonfunctional
When Nitrate is used as final electron acceptor in anaerobic respiration of glucose, what is produced?
nitrite, ammonia, N2
is the enzyme used up when a substrate binds to the active site?
no
If an inorganic compound is given to a bacteria for respiration, will it undergo glycolysis?
no!
Is there a TCA/krebs or ETC in fermentation?
no!
Will electron carriers accept more electrons if in the reduced form?
no, always need to be in the oxidized form
is glucose fully broken down after glycolysis?
no, its only partially broken down
coenzymes are ___ cofactors
organic
The TCA cycle completes the _____ of glucose.
oxidation
Flavoproteins
proteins to which flavin is attached (flavin type: FAD which is synthesized from riboflavin)
What do these large protein complexes serve as?
proton pumps
Reduced electron carriers represent ____
reducing power
Rank these energy-generating processes from greatest energy yield to least energy yield: -Aerobic respiration -Anaerobic respiration -Fermentation
Aerobic, anaerobic, fermentation
exergonic reaction
Describes a chemical reaction that releases energy because the starting compounds have more free energy than products
Which of the following correctly describes some of the forms of energy represented in this photograph?
Electricity generated by the hydroelectric dam as it captures the energy from moving water. Kinetic energy of the photons that make up the sunlight. Potential energy of the water behind the dam.
Which of the following are true statements regarding energy?
Energy can exist as kinetic energy. Energy cannot be created. Energy is the capacity to do work. Energy can exist as potential energy.
what is an example of non-competitive inhibitors
allosteric inhibitors
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
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 accumulating. this mechanism of control is called
feedback inhibition
What do microbes excrete when organic compounds are given for respiration?
hydrolytic enzymes to degrade the compounds further to appropriate precursor metabolites and transport subunits into the cell
What is the final electron acceptor in the ETC of anaerobic respiration of glucose?
inorganic molecules such as nitrate, sulfate, carbonate (NO3-, SO4, CO3)
precursor metabolites
intermediates of catabolism that can be used in anabolism
Until the optimal temperature is reached, each 10 degree C rise in temperature has what approximate effect on the speed of enzymatic reactions?
it doubles the rate of the reaction
lactic acid is the end product of
lactic acid fermentation
Components of the ETC: most carriers are grouped into...
large protein complexes
An atom that has a lower affinity (attraction) for elections than another is described as ___ than the other.
less electronegative
then why ferment?
maybe there is a lack of oxygen
The ETC is ___-embedded electron carriers
membrane
the series of sequential chemical reaction 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
What membrane is the ETC in eukaryotes?
mitochondrial membrane
acetic acid, lactic acid, succinic acid, ethanol, CO2, and H2 are the end products of
mixed acids fermentation
A cell will usually contain about how many different enzymes?
more than a thousand
enzymes have a ____ range of optimal conditions
narrow
The mechanism by which cellular respiration uses the reducing power generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP is called
oxidative phosphorylation
energy from exergonic reactions is used to create a proton motive force that drives the addition of P to ADP
oxidative phosphorylation
electron carriers can also be considered hydrogen carriers. This is because, along with electrons, they carry ___
protons
What is an example of a precursor metabolite?
pyretic acid (can be converted into amino acids alanine, leucine, or valine)
Three groups of carriers in ETC
quinones, cytochromes, flavoproteins
electrons are removed from energy source through series of ___ reactions
redox
Cellular ___ is the process that transfers electrons extracted from glucose via the central metabolic pathways to the electron transport chain, where they are used to generate a proton motive force that can be harvested to make ATP via oxidative phosphorylation
respiration
Oxidative phosphorylation is the mechanism by which cellular ___ uses the reducing power generated in glycolysis, the transition step, and the TCA cycle to sythesize ATP.
respiration
Menaquinone is a quinone used in the electron transport chain of some prokaryotes. It plays an important role for humans and other mammals because it
serves as a source of vitamin k, providing much of the host's requirement via absorption in the intestinal tract
describe metabolism
the sum total of chemical reactions in a cell
metabolism
the sum total of chemical reactions in a cell
photophosphorylation
the sun's radiant energy and electron transport chain to create a proton motive force that drives the addition of Pi to ADP
Chemiosmotic theory
the theory that a proton gradient is formed by the ETC chain and then used to power ATP synthesis
The metabolic pathway that oxidizes a 2-carbon acetyl group to release two molecules of CO2 and generates the most reducing power of all the central metabolic pathways is called the ___ acid cycle
tricarboxylic (aka citric/Krebs)
True or false: the change in free energy for a given reaction is the same regardless of the number of steps involved
true
anaerobic respiration
uses an electron transport chain; does not yield either the most or the least amount of ATP relative to the other two processes
ETC uses ____generated by glycolysis, Transition step, and TCA cycle to synthesize ATP in aerobic respiration of glucose
reducing powers NADH and FADH2
What is the ecological and environmental significance of nutrient cycling?
there are some many types of bacteria in the soil that a product of respiration for one bacteria cold be the source of energy for one chemolithotroph
What are some advantages and disadvantages of lactic acid production by fermenting microorganisms?
tooth decay creating flair and texture of cheese and yogurt production of pickles and cured sausages
Would reactions occur with enzymes?
yes, but very slowly
example of a competitive inhibitor
sulfa drugs blocking folic acid synthesis
formic acid, ethanol, lactic acid, 2,3-butanediol, CO2, and H2 are the end products of
2-3, butanediol fermentation
All of the following represents two fundamental tasks cells need to accomplish in order to grow EXCEPT:
sexual reproduction
how is the ATP produced in glycolysis of aerobic respiration of glucose?
substrate-level phosphorylation
The ATP generated by fermentation comes from...
substrate-level phosphorylation during glycolysis
Which organism goes with which fermentation pathway? 2,3-butanediol fermentation ethanol fermentation propionic acid fermentation butyric acid fermentation mixed acids fermentation lactic acid fermentation
1. enterobacteria 2. saccharomyces 3. propionibacterium 4. clostridium 5. streptococcus, lactobacillus 6. e. coli
What are the yields of pentose phosphate pathway?
reducing power NADPH, variable amount yields VARY upon the alternative taken 2 precursor metabolites
In aerobic respiration, ___ serves as the terminal electron acceptor
O2
In aerobic respiration, ___ serves as the terminal electron acceptor.
O2
in aerobic respiration, ___ serves as the terminal electron acceptor
O2
Dehydrogenation reaction
Oxidation reaction in which both an electron and an accompanying proton are removed
non-competitive inhibition by enzyme poisons example
mercury
Pentose phosphate pathway
-Also breaks glucose down -Important in the biosynthesis of precursor metabolites (ribose 5-phosphate, and erythrose 4-phosphate)
enzyme name ends in ___
-ase
in contrast to an exergonic reaction, which of the following accurately describe an endergonic reaction? -the reaction requires an input of energy in order to proceed -the reaction releases energy as it proceeds -the products have more free energy than the starting compounds -the starting compounds have more free energy than the products
-the products have more free energy than the starting compounds -the reaction requires an input of energy in order to proceed
If a bacterial cell had no ATP and was given glucose, what would happen with glycolysis?
The cell would be unable to perform glycolysis, since it would lack the initial investment of high-energy phosphate groups
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
ETC and oxidative phosphorylation
The energy produced from the flow of electrons drives oxidative phosphorylation in which ATP is synthesized
what happens to the enzyme when an allosteric inhibitor binds to the allosteric site?
The enzyme shape is distorted and the substrate can no longer bind to the active site
In competitive inhibition, why is the inhibitor successfully able to bind to the active site, thereby blocking access of the substrate?
The inhibitor has a chemical structure similar to the normal substrate
Which of the following best describes the conversion of energy from one form to another illustrated in the picture?
The potential energy of water stored behind the dam is converted to kinetic energy of moving water, which is converted to electrical current.
Anabolism
The set of chemical reactions that synthesize and assemble the sub-units of macromolecules.
Catabolism
The set of chemical that degrade compounds, releasing their energy.
In fermentation, when glucose is oxidized to form pyruvate, and toxic end products are formed, why do the bacteria keep going on?
To consume reducing power and regenerate NAD+ electron carrier
Which of the following correctly describes the transition step and the tricarboxylic acid (TCA) cycle?
Together they generate the most reducing power of all the central metabolic pathways. They produce three metabolities and ATP The transition step converts the pyruvate from glycolysis into acetyl-CoA The TCA cycle oxidizes a 2-carbon acetyle group to release two molecules of CO2.
Which of the three central metabolic pathways generate a modest amount of ATP via substrate level phosphorylation?
Tricarboxylic acid (TCA) cycle Glycolysis
T or F: The change in free energy for a given reaction is the same regardless of the number of steps involved
True
so why not anaerobic?
because you need a final electron acceptor that may not be prsent
What degrades fatty acids?
beta-oxidation to then enter TCA cycle
non-competitive inhibitors
bind to sites other than the active site of an enzyme
competitive inhibitor
binds to the active site of an enzyme
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? a) three molecules of pyruvate, each with two carbon atoms b) two molecules of pyruvate, each with two carbon atoms c) two molecules of pyruvate, each with three carbon atoms d) six molecules of pyruvate, each with one carbon atom e) one molecule of pyruvate with six carbon atoms
c) two molecules of pyruvate, each with three carbon atoms
all of the following are essential form an electron transport chain to function EXCEPT ___: a.) electron carries such as quinones, cytochromes, and flavoproteins b.) protein complexes that function as proton pumps c.) ATP d.) electrons e.) a terminal electron acceptor f.) a membrane
c.) ATP
in oder for the 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? a.) this information doesn't tells us anything about the electron affinities of these molecules b.) the energy source has a higher affinity for electrons, and the terminal electron acceptor has a lower affinity for electrons c.) the energy source and the terminal electron acceptor have equal but opposite electron affinities d.) the energy source has a lower affinity for electrons, and the terminal electron acceptor has a higher affinity for electrons
d.) the energy source has a lower affinity for electrons, and the terminal electron acceptor has a higher affinity for electrons
unlike the electrons carried by NADH and FADH2, the electrons carried by NADPH are ___: a.) used to produce ATP by oxidative phosphorylation b.) transferred to the electron transport chain c.) used to generate proton motive force d.) used to reduce compounds during biosynthetic reactions
d.) used to reduce compounds during biosynthetic reactions
Consider the picture representing metabolism in E. coli growing in a medium that contains only glucose and a few inorganic salts. If the input at the top is glucose and the output at the bottom is CO2 molecules plus energy, this means the four outputs to the sie represent different anabolic pathways. The four groups of molecules that these pathways produce must be ___, ___, ___, and ___
lipid, amino acid, carbohydrate, nucleic acid
Quinones
lipid-soluble molecules that move freely and can transfer electrons between complexes
what is the energy yield when using inorganic compounds for respiration?
low compared to organic
what are the optimal environmental conditions for enzymes in terms of salt and pH
low salt and neutral pH
examples of cofactors
magnesium, zinc, copper, other trace elements
TCA cycle completes... (aerobic respiration of glucose)
the oxidation of glucose
What allows feedback inhibition?
the regulatory molecule being an end product
catabolism
the set of chemical reactions that degrade compounds, releasing their energy
describe catabolism
the set of chemical reactions that degrade compounds, releasing their energy
anabolism
the set of chemical reactions that synthesize and assemble the subunits of macromolecules
describe anabolism
the set of chemical reactions that synthesize and assemble the subunits of macromolecules
What happens at the active site of an enzyme?
the substrate weakly binds
Metabolism is best defined as:
the sum total of all chemicals reactions in a cell
aerobic respriation
uses an electron transport chain; yields more ATP than the other two processes
What type of respiration is used when organic compounds are used for respiration?
aerobic OR anaerobic
uses an electron transport chain; yields more ATP than the other two processes
aerobic respiration
Which of the following are true statements about what happens to glucose inside a cell? -All the glucose molecules are oxidized to CO2, generating ATP and reducing power in the process -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 -Some glucose might enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis
All but number 1
What are the enzymes that break down polysaccharides and disaccharides
Amylases: digest starch Cellulases: digest cellulose
Consider the effect of temperature on enzyme activity. If the temperature is too high, proteins will ____ and no longer function
Denature
Which of the following correctly describe the transition step and the tricarboxylic acid (TCA) cycle? a) they produce three precursor metabolites and ATP b) the TCA cycle generates most of the ATP for the cell c) the TCA cycle reduces a 2-carbon acetyl group to release two molecules of CO2 d) the TCA cycle oxidizes a 2-carbon acetyl group to release two molecules of CO2 e) together they generate the most reducing power of all the central metabolic pathways f) the transition step converts the pyruvate from lycolysis into acetyl CoA
a) they produce three precursor metabolites and ATP d) the TCA cycle oxidizes a 2-carbon acetyl group to release two molecules of CO2 e) together they generate the most reducing power of all the central metabolic pathways f) the transition step converts the pyruvate from lycolysis into acetyl CoA
an atom that has a lower affinity (attraction) for electrons than another is described as ___ than the other a.) less electronegative b.) more electronegative
a.) less electronegative
other than generating some ATP via the substrate-level phosphorylation steps of glycolysis, what critical role do the additional steps of fermentation accomplish? a.) they produce end products, such as ethanol or lactic acid, which are used to inhibit the growth of competitors b.) they consume excess reducing power in order to regenerate NAD+ so that it can accept electrons to keep glycolysis going c.) they use up extra ATP so that glycolysis can continue producing additional reducing power d.) they generate end products such as ethanol, which the cell can then use as an energy source
b.) they consume excess reducing power in order to regenerate NAD+ so that it can accept electrons to keep glycolysis going
microbial breakdown of corn stalks, sugar cane, or wood into ethanol
biofuels
is respiration using inorganic compounds aerobic or anaerobic?
both
Does glycolysis take place aerobically or anaerobically?
both!
metabolic wastes of lactococcus and lactobacillus species contributing to flavor and texture
cheese
endergonic reaction
chemical reaction that requires a net input of energy because the products have more free energy than the starting compounds
the process that links the electron transport chain to ATP synthesis is called the _____ theory
chemiosmotic theory
prokaryotes that extract electrons from inorganic energy sources and pass them to an electron transport chain to generate a proton motive force that is used to make ATP are called
chemolithotrophs
An organic cofactor that functions as a loosely bound carrier of molecules or electrons to assist an enzyme is called a
coenzyme
An organic cofactor that functions as a loosely bound carrier of molecules or electrons to assist an enzyme is called a ___
coenzyme
Some enzymes act with the assistance of a non-protein component. This component is called a ____.
cofactor
The chemiosmotic theory, proposed by Peter Mitchell in 1961, explains: a) how ATP is generated via substrate level phosphorylation b) how reducing power is used to synthesize carbon compounds c) how water moves across a semipermeable membrane but other chemicals do not d) how cells control the diffusion of molecules by using a selectively permeable membrane e) how the electron transport chain is linked to ATP synthesis
e) how the electron transport chain is linked to ATP synthesis
What is the active site of an enzyme? a) the site that breaks off the enzyme as it catalyzes a reaction b) the site at which ATP is generated c) the site characterized by constant motion of molecules d) the site of allosteric regulation of the enzyme e) the critical site to which a substrate binds by weak forces
e) the critical site to which a substrate binds by weak forces
what do reducing powers usually do?
easily transfer electrons to molecules; raise energy level of recipient molecule
examples of coenzymes
electron carriers: FAD, NAD+, NADP+
regulatory molecule is usually the ____ product
end
a cell has only a limited number of electron carrier molecules. During glycolysis, if electrons are not removed from NADH, the cell soon runs out of available NAD+, and the breakdown of glucose ends. This presents a problem for cells that lack a suitable terminal electron acceptor for the electron transport chain or that cannot respire. The solution to this problem is called ___
fermentation
does not use an electron transport chain; yields the least ATP of the three processes
fermentation
Why would bacteria choose the pentose phosphate pathway over glycolysis?
for biosynthetic purposes
The three key metabolic pathways that gradually oxidize ___ to CO2 are collectively referred to as the central metabolic pathways.
glucose
The three key metabolic pathways that gradually oxidize ___ to CO2 are collectively reffered to as the central metabolic pathways.
glucose
the three key metabolic pathways that gradually oxidize ___ to CO2 are collectively referred to as the central metabolic pathways
glucose
Chemolithotrophs
group of bacteria that can use inorganic compounds as a source of energy
The critical site of an enzyme to which a substrate binds by weak forces is called the
active site
consider the three central metabolic pathways that gradually oxidize glucose to CO2. Why are these amphilbotlic pathways. -"amphibolic" is another way for "catabolic," which refers to the set of processes that breaks down molecules and releases energy -although they are catabolic, the precursor metabolites and reducing power they generate can be diverted for biosynthesis (anabolism) -"amphi" means "both kinds," which reflects the dual role of those central metabolic pathways -the term "amphibolic" reflects that these are metabolic pathways that take place in an aqueous environment
-although they are catabolic, the precursor metabolites and reducing power they generate can be diverted for biosynthesis (anabolism) -"amphi" means "both kinds," which reflects the dual role of those central metabolic pathways
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 by which of the following? -the pentose phosphate pathway -glycosis -cellular respiration -the TCA cycle -fermentation
-cellular respiration -fermentation
__ ATP made per electron pair from NADH
3
what are some electron carrier examples?
NAD+/NADH NADP+/NADPH FAD/FADH2
True or False: the change in free energy for a given reaction is the same regardless of the number of steps involved.
True
Which of the following describe enzyme specificity?
With few exceptions, a unique enzyme is required to catalyze each reaction in a cell The substrate must align spatially wit the active site Hydrogen and ionic bonding occur to induce the correct fit between substrate and active site
When a single molecule of glucose is processed by glycolysis in an E. coli cell, which of the following make up the net gain of this process? a) 2 molecules of ATP b) 4 molecules of NADH c) six precursor metabolites d) 4 molecules of ATP e) zero precursor metabolites f) 2 molecules of NADH
a) 2 molecules of ATP c) six precursor metabolites f) 2 molecules of NADH
the main energy currency of cells is ATP, which stands for ___ ___
adenosine triphosphate
An atom that has a lower affinity (attraction) for electrons than another is described as ___ than the other a) more electronegative b) less electronegative
b) less electronegative
in the stair analogy of an electron transport chain, the top of the stairs represents what energy level, and the bottom of the stairs represents what energy level? a.) low; high b.) high; low
b.) high; low
menaquinone is a quinone used in the electron transport chain of some prokaryotes. It plays an important role for humans and other mammals because it ___ a.) provides a major source of energy and carbon b.) inhibits the growth of pathogens, thereby helping the normal microbiota maintain a good microbial community for the host c.) serves as a source of vitamin K, providing much of the host's requirement via absorption in the intestinal tract d.) limits the growth rate of bacteria, keeping them from overpopulating the small intestine
c.) serves as a source of vitamin K, providing much of the host's requirement via absorption in the intestinal tract
Identify each of the following as either a cofactor or coenzyme: magnesium: ___; NADP+:___; zinc: ___.
cofactor; coenzyme; cofactor.
When a compound binds to the active site of the enzyme, blocking access of the substrate to that site, the process is called...
competitive inhibition
in prokaryotes, the electron transport chain is located in the ___ membrane, whereas in eukaryotic cells it is in the ___ membrane of the mitochondria
cytoplasmic, inner
Consider the effect of temperature of enzyme activity. If the temperature is too high, proteins will ___ and no longer function.
denature
proteins ___ at higher temperatures
denature
fermentation
does not use and electron transport chain; yields the least ATP of the three processes
In the figure, compound x donates electrons to compound y. Therefore, compound x is the electron ___ and compound y is the electron ___
donator, acceptor
a 10 degree C increase ____ the speed of enzymatic reaction up until max
doubles
__ is required to establish a gradient
energy
Consider a cell converting glucose into CO2 and water with the release of energy. This is an example of what type of metabolism, and the reactions themselves are considered to be what? a) catabolism; endergonic b) anabolism; exergonic c) catabolism; exergonic d) anabolism; endergonic
c) catabolism; exergonic
What generates the proton motive force?
electron transport chain
Role of electron carriers
electrons that are removed from the energy source are transferred to electron carriers which in turn transfer electrons the the final electron acceptor
what is the source of energy for iron bacteria
reduced iron (Fe2+)
in the electron transport chain, electron carries are found in what two general locations? -tightly bound to lipids of the phospholipid bilayer -grouped into large protein complexes that function as proton pumps -attached to ATP synthase -as part of glucose transporter -freely moving in the membrane where they can shuttle electrons between protein complexes
-grouped into large protein complexes that function as proton pumps -freely moving in the membrane where they can shuttle electrons between protein complexes
which of the following correctly describe cytochromes found in an electron transport chain? -several different cytochromes exist -cytochromes are proteins that contain heme, a molecule that holds an iron atom in its center -cytochromes are always found bound to one of the protein complexes that function proton pumps
-several different cytochromes exist -cytochromes are proteins that contain heme, a molecule that holds an iron atom in its center
which of the following correctly describe respiration? -it is only present in aerobic organisms -all organisms that grow in the presence of O2 must use respiration for their energy needs -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
-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
which of the following are true about glycolysis? -the pathway provides the cell with a large amount of ATP, reducing power, and a number of precursor metabolites -the pathway splits glucose and reduces it to form two molecules of pyruvate -the pathway splits glucose and oxidizes it to form two molecules of pyruvate -the pathway provides the cell with a small amount of ATP, some reducing power, and 6 precursor metabolites
-the pathway splits glucose and oxidizes it to form two molecules of pyruvate -the pathway provides the cell with a small amount of ATP, some reducing power, and 6 precursor metabolites
which of the following correctly describe the transition step and the tricarboxylic acid (TCA) cycle? -together they generate the most reducing power of all the central metabolic pathways -the TCA cycle generates most of the ATP for the cell -the TCA cycle reduces a 2-carbon acetyl group to release two molecules of CO2 -the transition step converts the pyruvate from glycolysis into acetyl-CoA -the TCA cycle oxidizes a 2-carbon acetyl group to release two molecules of CO2
-the transition step converts the pyruvate from glycolysis into aceyl-CoA -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
which of the following are reasons an organism might use fermentation? -they lack the ability to perform glycolysis -a suitable inorganic terminal electron acceptor is not available -they lack an electron transport chain -the energy yield is greater from fermentation than from respiration
-they lack an electron transport chain -a suitable inorganic terminal electron acceptor is not available
For a single molecule of glucose, what is the theoretical maximum of ATP gain from oxidative phosphorylation in prokaryotes growing aerobically?
34 ATP
E. coli will preferentially use ____ respiration, but when O2 is not available, it can switch to _____ respiration if a suitable electron acceptor such as nitrate is present
Aerobic, anaerobic
Oxidative phosphorylation, the mechanism by which respiration uses the NADH and FADH2 generated in glycolysis, the transition step, and the TCA cycle to synthesize ATP, involves what two steps?
The ETC generates a proton motive force ATP synthase uses the energy of the proton motive force to drive the synthesis of ATP
The series of sequential chemical reactions that converts a starting compound to an end product is called a ___ ___
metabolic pathway
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? a) ATP synthesis uses the energy of the protein motive force to drive the synthesis of ATP b) the electron transport chain uses the energy in protons to transfer electrons across the membrane c) electrons flow through ATP synthase to drive the synthesis of ATP d) the electron transport chain is oxidized by the donation of electrons from NADH and FADH2 e) a phosphate group is removed from each NADH and FADH2 f) the electron transport chain generates a proton motive force
a) ATP synthesis uses the energy of the protein motive force to drive the synthesis of ATP f) 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? a) ATP, reducing power, precursor metabolites b) ADP, NADH, glucose c) ADP, reducing power, lactic acid d) ATP, NAD+, pyruvate e) ATP, reducing power, ethanol
a) ATP, reducing power, precursor metabolites
Which of the following are important electron carriers for a cell? a) NAD+/NADH b) ADP/ATP c) FAD/FADH2 d) NADP+/NADPH
a) NAD+/NADH c) FAD/FADH2 d) NADP+/NADPH
Rank the following energy generating processes from greatest energy yield to least energy yield a) aerobic respiration b) fermentation c) anaerobic respiration
a) aerobic respiration c) anaerobic respiration b) fermentation
Which of the following are true statements regarding energy? a) energy is the capacity to do work b) energy can exist as kinetic energy c) energy is destroyed each time it changed from one form to another d) energy can exist as potential energy e) energy cannot be created
a) energy is the capacity to do work b) energy can exist as kinetic energy d) energy can exist as potential energy e) energy cannot be created
Which of the following describe enzyme specificity? a) hydrogen and ionic bonding occur to induce the correct fit between substrate and active site b) enzymes are made from the same type of macromolecule with which they interact c) the substrates must align spatially with the active site d) each enzyme is made by a different organelle e) a particular enzyme will only interact with a single class of molecule. For example, enzyme A might only interact with alcohols f) with few exceptions, a unique enzyme is required to catalyze each reaction in a cell
a) hydrogen and ionic bonding occur to induce the correct fit between substrate and active site c) the substrates must align spatially with the active site f) with few exceptions, a unique enzyme is required to catalyze each reaction in a cell
Unlike human cells, some prokaryotes can use ___ as energy sources a) inorganic chemicals b) organic compounds
a) inorganic chemicals
A cell will usually contain about how many different enzymes? a) more than a thousand b) about fifty c) fewer than a hundred d) ten e) one f) six
a) more than a thousand
Which of the following forms of phosphorylation require an electron transport chain for ATP production? a) photophorphorylation b) substrate level phosphorylation c) oxidative phosphorylation
a) photophorphorylation c) oxidative phosphorylation
Glucose catabolism encompases 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? a) respiration b) fermentation c) glycolysis d) the pentose phosphate pathway e) the TCA cycle
a) respiration b) fermentation
Which of the following are true statements about what happens to glucose inside a cell? a) some glucose might enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis b) glucose can be used in catabolism to yield energy, or the precursor metabolites generated from its breakdown can be used in anabolism c) all the glucose molecules are oxidized to CO2, generating ATP and reducing power in the process d) some glucose might be oxidized to CO2, generating the maximum amount of ATP
a) some glucose might enter glycolysis, only to be siphoned off as a precursor metabolite for biosynthesis b) glucose can be used in catabolism to yield energy, or the precursor metabolites generated from its breakdown can be used in anabolism d) some glucose might be oxidized to CO2, generating the maximum amount of ATP
What occurs during the transition step of central metabolism? a) the 2-carbon acetyl group is joined to coenzyme A to form acetyl CoA b) the 3-carbon pyruvate molecules are joined to form a 6-carbon citrate c) 2 ATP are generated d) CO2 is removed from pyruvate e) CO2 is combined with pyruvate to form the 4-carbon molecule succinate f) electrons are transferred to NAD+, reducing it to NADH + H+
a) the 2-carbon acetyl group is joined to coenzyme A to form acetyl CoA d) CO2 is removed from pyruvate f) electrons are transferred to NAD+, reducing it to NADH + H+
Which of the following explain why a cell might undergo fermentation? a) the cell has a limited number of electron carrier molecules that must be regenerated for glycolysis to continue b) the cell can obtain more ATP from this pathway than via respiration c) this allows the cell to grow in the presence of O2, which otherwise it would be unable to do d) the cell might lack the pathways for respiration, so fermentation might be the only option e) the cell might not have the appropriate terminal electron acceptor available for respiration
a) the cell has a limited number of electron carrier molecules that must be regenerated for glycolysis to continue d) the cell might lack the pathways for respiration, so fermentation might be the only option e) the cell might not have the appropriate terminal electron acceptor available for respiration
Metabolism is best defined as a) the sum total of all chemical reactions in a cell b) digestion of food c) the way in which organisms obtain food d) the manner in which cells grow
a) the sum total of all chemical reactions in a cell
unlike chemoorganotrophs, photosynthetic organisms generate ATP by ___: a.) photophosphorylation b.) oxidative phosphorylation c.) substrate-level phosphorylation
a.) photophosphorylation
metabolic pathways of organisms such as E. coli
model for eukaryotic cells
proton motive force is ___ a.) the form of energy that results from the electrochemical gradient established by the electron transport chain b.) the positive charge that repels protons from the electrons orbiting round them in atoms c.) the attractive force that makes up hydrogen bonds, for example, those holding together water molecules
a.) the form of energy that results from the electrochemical gradient established by the electron transport chain
Considering only the carbon, the TCA cycle incorporates an ___ group from the transition step and releases two molecules of ___ and two molecules of ___.
acetyl, ATP, CO2
Considering only the carbon, the TCA cycle incorporates a(n) ___ group from the transition step and releases two molecules of ___ and two molecules of ___
acetyl, CO2, ATP
Consider the three central metabolic pathways that gradually oxidize glucose to CO2. Why are theme amphibolic pathways? a) "amphibolic" is another word for "catabolic," which refers to the set of processes that breaks down molecules and releases energy b) although they are catabolic, the precursor metabolites and reducing power they generate can be diverted for biosyntheses (anabolism) c) "amphi" means "both kinds," which reflects the dual role of these central metabolic pathways d) the term "amphibolic" reflects that these are metabolic pathways that take place in an aqueous environment
b) although they are catabolic, the precursor metabolites and reducing power they generate can be diverted for biosyntheses (anabolism) c) "amphi" means "both kinds," which reflects the dual role of these central metabolic pathways
All of the following represent the two fundamental tasks cells need to accomplish in order to grow except: a) harvesting energy b) sexual reproduction c) synthesizing cell membranes d) production of ribosomes e) construction of cell walls f) converting energy into a form that can power energy consuming reactions
b) sexual reproduction
In competitive inhibition, why is the inhibitor able to bind to the active site, thereby blocking access of the substrate? a) the inhibitor has a high binding affinity to enzymes b) the inhibitor has a chemical structure similar to the normal substrate c) the inhibitor modifies its shape to fit perfectly with the active site of the enzyme, much like a hand inside a glove
b) the inhibitor has a chemical structure similar to the normal substrate
Which of the following best describes the conversation of energy from one form to another illustrated in the picture? a) the kinetic energy of water stored behind the dam is converted to potential energy of moving water, which is converted to electricity b) the potential energy of water stored behind the dam is converted to kinetic energy of moving water, which is converted to electrical current c) the potential energy in the chemical bonds of the water molecules is converted to electricity d) the potential energy of the water is directly converted into electrical energy, which can be used to charge a battery
b) the potential energy of water stored behind the dam is converted to kinetic energy of moving water, which is converted to electrical current
When a reduced electron carrier (reducing power) transfers its electrons to another molecule, what occurs? a) the energy level of the recipient molecule is lowered b) the recipient molecule is reduced c) the electron carrier is oxidized d) the energy level of the recipient molecule is raised e) the electron carrier is degraded, and the cell must generate a replacement carrier
b) the recipient molecule is reduced c) the electron carrier is oxidized d) the energy level of the recipient molecule is raised
all of the following are true statements regarding energy EXCEPT___: a.) energy is the capacity to do work b.) energy is destroyed each time it is changed from one form to another c.) energy cannot be created d.) energy can exist as potential energy e.) energy can exist as kinetic energy
b.) energy is destroyed each time it is changed from one form to another
when discussing electron carries in the context of biological reactions, why do we often ignore the location of protons? a.) protons, because of their positive charge, are repelled by electron carriers, whose charge distribution only allows them to cary electrons b.) in aqueous solutions, protons do not require carriers c.) in aqueous solutions, electrons do not require carriers d.) electron carriers only carry electrons, not protons, so the protons do not matter
b.) in aqueous solutions, protons do not require carriers
a bacterium that lacks an electron transport chain would be expected to be oxidase ___: a.) positive b.) negative
b.) negative
the ATP generated by fermentation comes from ___ a.) the reducing power obtained from the oxidation of glucose b.) substrate-level phosphorylation during glycolysis c.) the tricarboxylic (TCA) cycle d.) oxidative phosphorylation driven by NADH
b.) substrate-level phosphorylation during glycolysis
free energy is best defined as ___: a.) the leftover energy that is not used by the cell b.) the energy available to do work c.) stored energy present in chemical bonds d.) energy of motion
b.) the energy available to do work
which of the following best describes the conversion of energy from one form to another? a.) the potential energy in the chemical bonds of the water molecules is converted into electricity b.) the potential energy of water stored behind the dam is converted to kinetic energy of moving water, which is converted to electrical current c.) the kinetic energy of water stored behind the dam is converted to potential energy of moving water, which is converted to electricity d.) the potential energy of the water is directly converted into electrical energy, which can be used to charge a battery
b.) the potential energy of water stored behind the dam is converted to kinetic energy of moving water, which is converted to electrical current
Metabolic pathways can be linear, ___, or ___.
brached; cyclical
butyric acid, butanol, acetone, isopropanol, CO2, and H2 are the end products of
butyric acid fermentation
Which statement correctly describes how catabolism and anabolism are intimately linked? a) molecules synthesized by catabolism are broken down by anabolism to release ATP b) ATP made during anabolism is used in catabolism c) ATP made during catabolism is used in anabolism d) both catabolism and anabolism involve the breakdown of molecules to release ATP
c) ATP made during catabolism is used in anabolism
Place the following steps in the correct order to show how the spatial arrangement of electron carriers in a bacterial electron transport chain helps explain how protons are shuttled from one side of the membrane to the other a) because the electron carrier only accepts electrons, the protons are released to the outside of the cell b) a proton motive force is set up as protons are moved from the inside of the cell to the outside c) an electron carrier donates electrons to a hydrogen carrier d) the hydrogen carrier must pick up protons from inside the cell e) the hydrogen carrier passes electrons to a carrier that only accepts electrons
c) an electron carrier donates electrons to a hydrogen carrier d) the hydrogen carrier must pick up protons from inside the cell e) the hydrogen carrier passes electrons to a carrier that only accepts electrons a) because the electron carrier only accepts electrons, the protons are released to the outside of the cell b) a proton motive force is set up as protons are moved from the inside of the cell to the outside
Which of the following accurately describe fermentation? a) it generates more ATP than either glycolysis or respiration b) all cells are able to ferment certain substances c) fermentation does not involve the tricarboxylic acid (TCA) cycle d) glucose is broken down via glycolysis e) NAD+ is regenerated from NADH by the transfer of electrons to pyruvate or a derivative
c) fermentation does not involve the tricarboxylic acid (TCA) cycle d) glucose is broken down via glycolysis e) NAD+ is regenerated from NADH by the transfer of electrons to pyruvate or a derivative
Pass ___ sequentially, eject ____ in the process
electrons, protons
Electrons moving through the electron transport chain supply ___ in order to establish a proton gradient across the membrane (the proton motive force)
energy
The proton motive force results from a gradient: more protons on one side of the membrane relative to the other side. This means that, if protons are allowed to flow back down the gradient, ____ is released that can be harvested to drive ATP synthase.
energy
what are some non-competitive inhibitors that are not reversible
enzyme poisons- mercury
In terms of energy, the series of catabolic reactions by which a cell breaks down glucose are ___. The energy released is then used to drive anabolic reactions in the cell that are ___.
exergonic, endergonic
The graph shows the relative energy as a reaction proceeds. in terms of energy, the reaction catalyzed with an enzyme (red line) is ___, and the reaction that proceeds without that proceeds without an enzyme (blue line) is ___.
exergonic; exergonic
