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79 terms

Review 2

Chapters 8-10
STUDY
PLAY
Which of the following represents kinetic energy?
The flow of hydrogen ions (H+) through ATP synthase and the phosphorylation of ADP to form ATP
The sum total of all the anabolic and catabolic reactions in a living cell is called its
metabolism.
What term most precisely describes the cellular process of making higher energy molecules out of lower energy ones?
anabolism
How does the first law of thermodynamics apply to organisms?
As energy transformations occur, free energy is transferred from one form to another, it is neither created nor destroyed.
During photosynthesis, plants capture only about 5% of the energy available in sunlight and convert it into the potential energy found in glucose. This inefficiency in energy transfer is an example of?
the second law of thermodynamics.
In any system, the total energy includes usable energy and unusable energy. The usable energy is referred to as
free energy
If ΔG of a chemical reaction is positive, you can conclude that it...
is endergonic.
The mathematical expression for the free change in free energy of a system is G=H-T S.
S is the change in entropy

T is the temperature
statements about enzymes
An enzyme changes shape when it binds to a substrate; Enzymes lower the activation energy.; An enzyme may orient substrates, induce strain, or temporarily add chemical groups; Most enzymes are much larger than their substrates.
The hydrolysis of sucrose to glucose and fructose is exergonic. However, if sucrose is dissolved in water and the solution is kept overnight at room temperature, there is no detectable conversion to glucose and fructose. Why?
Room temperature does not achieve the necessary energy of activation for the reaction to occur.
In some cases, a substrate-enzyme complex is stabilized by
hydrogen bonds; covalent bonds; ionic attractions; hydrophobic interactions.
could denature an enzyme
high temperature; changes in pH
Why is ATP an important molecule in metabolism?
Its hydrolysis provides an input of free energy for endergonic reactions; Its terminal phosphate groups ionize easily, releasing free energy; It transfers (couples) free energy between exergonic and endergonic reactions.
Many enzymes require NAD+ and NADH for a reaction to occur. They temporarily bind to and then release from the substrate to participate in other reactions. NAD+ and NADH are considered
coenzymes
Four atoms of ferrous Iron (Fe) are required for hemoglobin protein to efficiently carry oxygen in the human bloodstream. The iron most likely functions as a(n)
cofactor necessary for enzyme activity
How do competitive and noncompetitive enzyme inhibitors differ?
Competitive inhibitors bind to the active site, whereas noncompetitive inhibitors change the shape of the active site.
An allosteric inhibitor
changes the shape of an enzyme (the shape of its active site).
The process that involves an end product acting as an inhibitor of an earlier step in a metabolic pathway is called
feedback inhibition.
When organisms move from one environment to another, they sometimes synthesize variations of existing enzymes, which are called
isozymes.
You are studying a new species never before studied. It lives in freshwater hot springs where the water temperature averages 50°C to 60°C. You determine that it has a surface enzyme that catalyzes a reaction leading to its protective coating, and you decide to study this enzyme in the laboratory. Under what conditions would you most likely find optimal activity of this enzyme?
55°C
statements about metabolic
The product of one reaction becomes the reactant for the next reaction; They are a series of enzyme-catalyzed reactions; Many are compartmentalized in eukaryotes; Many are highly conserved even between organisms in different domains of life
When NADH gives two electrons to complex I of the respiratory electron transport system, NADH is
oxidized
When electrons move closer to a more electronegative atom, what happens?
Free energy is released.
In all cells, glucose catabolism begins with
glycolysis.
NAD+
is a key electron carrier in redox reactions.
occurs during aerobic respiration
Pyruvate oxidation to acetyl-CoA; The citric acid cycle
an intermediate of the citric acid cycle
oxaloacetate
Substrate-level phosphorylation is the enzymatic transfer of a phosphate from an organic molecule to?
ADP
The pyruvate dehydrogenase complex (pyruvate oxidation) generates
CO2; NADH + H+ from NAD+.
produced/generated during the citric acid cycle
NADH and FADH2
Animals breathe in air containing oxygen and breathe out air with less oxygen and more carbon dioxide. The carbon dioxide comes from
Chemical energy was converted to heat and then released; Most was converted to muscle and muscle weighs less than fat
During aerobic respiration in the eukaryotic cell, H+ ions accumulate where?
mitochondrial intermembrane space.
statements about the respiratory electron transport chain
Electrons are received from NADH and FADH2; Electrons are passed from donor to recipient carrier molecules in a series of oxidation-reduction reactions; Most of the enzymes are part of the inner mitochondrial membrane; It contains Cytochromes and Ubiquinone (Coenzyme Q).
Human infants and hibernating animals have specialized "brown fat" cells that produce a protein called Thermogenin. This protein releases the H+ ion gradient created by the respiratory electron transfer chain. regarding "brown fat" cells
The cells would generate large amounts of heat.
The component of aerobic respiration that produces the most ATP per mole of glucose is
the electron transport chain and oxidative phosphorylation.
statements regarding the formation of lactate by human
it is an example of fermentation; it recycles NAD+ from NADH
Phosphofructokinase is an allosteric enzyme that catalyzes the conversion of fructose-6-phosphate to fructose-1,6-bisphosphate, an early step of glycolysis. An increased accumulation of citrate (an allosteric regulator of PFK) would be expected to...
inhibit the enzyme and slow the rates of glycolysis and the citric acid cycle.
Plants are green because
chlorophylls absorb blue and orange-red wavelengths of light and reflect green light
The main photosynthetic pigments in plants are _______ and _______.
chlorophyll a; chlorophyll b
Accessory pigments
allow plants to absorb visible light of varying wavelengths.
gives up electrons during noncyclic photophosphorylation (light dependent reactions)?
water (H2O)
The net energy outcome of noncyclic photophosphorylation (light dependent reactions) is
ATP and NADPH
Which of the following occurs during the light-independent (dark or calvin-benson) reactions of photosynthesis?
ATP and NADPH are recycled back to ADP and NADP+; CO2 is converted into organic molecules (glyceraldehydes-3-phosphate).
Where would you find photosytem II in a green plant?
the thylakoid membrane of a chloroplast
If you were to grow a green plant in a lighted chamber in the presence of radioactive carbon dioxide for several minutes only, which of the following types of compounds in the plant would be radioactive?
Calvin cycle intermediates
During sunny dry days, photorespiration may occur in plants. During photorespiration, the enzyme rubisco uses _______ as a substrate.
O2
Glycolysis
is the conversion of glucose to two molecules of pyruvate
The conversion of malate to oxaloacetate in the citric acid cyle takes place with the conversion of NAD+ to NADH. In this reaction, NAD+ is
the oxidizing agent; reduced
In the complete oxidation of glucose, 6 CO2 molecules are formed per glucose molecule. The number of CO2 molecules released by glycolyisis is ___, by oxidation (intermediate step) is______, and by the citric acid cycle is ______.
0;2;4
The role of oxygen gas in our cells is to
accept electrons from the respiratory chain
"Anaerobic conditions" means that there is an abundance of
oxygen
During which process is most ATP generated in the cells?
Electron transport coupled with chemiosmosis
Approximately how many ATP molecules per glucose molecule are produced via glycolysis and cellular respiration in eukaryotes?
36
Statements concerning the synthesis of ATP in cellular respiration
The proton-motive force is the establishment of a charge and concentration gradient across the membrane; " " drives the protons back across the membrane through channels established by the ATP synthase channel protein; The ATP synthase protein is composed of two units
If phosphofructokinase is inhibited by ATP ans/or citrate, what reaction/reactions will be interrupted?
Glycolysis
What would happen if the enzyme phosphofructokinase were not allosterically regulated?
Enzyme activity would be insensitive to citric acid cycle products
What is the metabolic fate of pyruvate in anaerobic muscle?
It is reduced to lactate
Oxygen can cause damage to cellular compnents because
its oxidation leads to incomplete electron transfer, which forms toxic intermediates
The O2 gas prduced during photosynthesis is derived from
water
The wavelength of Xrays is shorter than the wavelength of infrared waves. Based on this information,
Xrays have more energy per photon than infrared waves have.
When white light strikes a blue pigment, blue light is
scattered or transmitted
The main photosynthesis pigments in plants are ______ and ______
Chlorophyll A; Chlorophyll B
Photosystem II
is the first light-absorbing complex in photosynthesis
Cyclic electron transport involves ____ and generates _____
photosystem I; ATP
How many glyceraldehyde-3-phosphate (G3P or PGAL) molecules are produced by the Calvin cycle when 18 CO2 are fixed?
6
The enzyme rubisco is an enzyme that is both a carboxylase and oxygenase. When conditions favor the use of oxygen as a substrate in Calvin cycle, this phenomena is called
photorespiration
The first law of thermodynamics states that the total energy in the universe is
constant
During photosynthesis, plants use light energy to synthesize sugars from carbon dioxide. They do not make new energy in this process; they merely convert it from light energy to chemical energy. Photosynthesis is thus an illustration of
the first law of thermodynamics
The AG of ATP hydrolysis is negative and the change in entropy is positive. The reaction, therefore,
is exergonic
When ADP gains a phosphate to form ATP.
energy is consumed
Phosphorylation of ADP to ATP is endergonic, whereas the hydrolysis of ATP to ADP is exergonic. The two reactions are therefore said to be
coupled
An active site is the
part of the enzyme that binds with a substrate
Enzymes may catalyze a reaction by _____ the substrates
orienting; inducing strain in; adding chemical groups to; adding charges to
In order to determine if a reaction is at "saturation," you would add ____ and determine if the reaction rate ____
more substrate; increases
An allosteric inhibitor (non competitive)
changes the shape of an enzyme
End products of biosynthetic pathways often act to block the initial step in that pathway
negative feedback
If you want to permanently block the function of the enzyme, you could add
a molecule that can covalently bind the active site
Which molecule from glycolysis or the citric acid pathway serves as the building block for lipid synthesis?
Acetyl CoA
In order for a coupled reaction to have a net AG of -3.3 kcal/mol,
the exergonic reaction needs to release more energy than the endergonic reaction requires