CH 21 (chem final)
Which of the following are electron carriers in the electron transport chain
A) Fe-S clusters B) Coenzyme Q C) Cytochrome C D) Iron(II) ions E) all of these Answer: E
Glycolysis occurs mainly in the
cytosol of all cells
Every turn of the citric acid cycle directly produces ________ high energy molecule(s).
1
How many ATP molecules are formed for each NADH molecule brought into complex I?
2
The net number of ATP formed when one molecule of glucose is converted to pyruvate is
2
Which of the following reactions of the citric acid cycle is a decarboxylation occurring?
A) conversion of succinyl CoA to sucicinyl B) conversion of isocitrate to α-ketoglutarate C) α-ketoglutarate to succinyl CoA D) All three reactions are decarboxylations. E) only B and C Answer: E
Which reaction(s) of glycolysis is(are) key regulation step(s) in the process?
A) formation of fructose-6-phosphate from glucose-6-phosphate B) formation of glucose-6-phosphate from glucose C) cleave of fructose-1,6-bisphosphate D) formation of fructose-1,6-bisphosphate from fructose-6-phosphate E) Both B and D. Answer: E
Which of the following is common to the structures of NAD+, and FAD?
ADP
Which group of compounds includes only low-energy molecules?
ADP, CO2, NAD+, FAD
Which of the following reactions is the least energetic?
AMP + H2O → Adenosine + Pi
Which of the following does not undergo oxidation-reduction reactions?
ATP
Which group of compounds includes only high-energy molecules?
ATP, acetyl-SCoA, NADH, FADH2
Classify each pathway of carbohydrate metabolism as anabolic or catabolic. Justify your choice in each case.
Answer: Glycolysis is catabolic, because a large molecule is broken into smaller ones, with a net production of high-energy molecules. Gluconeogenesis is anabolic because it is a synthesis reaction. It consumes energy as ATP and GTP. Glycogenolysis is catabolic because it involves breaking larger molecules into smaller ones. Glycogenesis is anabolic because it consumes energy in the form of UTP in order to build a larger molecule from smaller ones.
Which of the following statements about free radicals is incorrect?
B vitamins provide protection from their harmful effects.
The hydrolysis of creatine phosphate is coupled with the synthesis of ATP. The equations for the reactions are given below. Would this coupling be favored?
Creatine phosphate + H2O → Creatine + HOPO3-2 ΔG = -10.3 kcal/mol ADP + HOPO3-2 + H+ → ATP + H2O ΔG = +7.3 kcal/mol Answer: Add the two equations to get: Creatine phosphate + ADP + H+ → Creatine + ATP ΔG = -10.3 kcal/mol + 7.3 kcal/mol = -3.0 kcal/mol. Therefore, the reaction is favored.
All of the following statements concerning digestion are correct except
Digestion begins in the stomach and is completed in the large intestine
Which statement concerning coenzymes and redox reactions is incorrect
FAD is the reduced form of FADH2.
Which statement is true concerning the relationship between FAD and FADH2?
FADH2 is the reduced form of FAD
Which of the following are produced as a net result of glycolysis? I. NADH II. NAD+ III. ADP IV. ATP
I and IV
Which statement is true concerning the relationship between NAD+ and NADH?
NAD+ is the oxidized form of NADH
Which of the following cofactors is used in fatty acid synthesis?
NADPH
The major function of the pentose phosphate pathway when nucleic acid synthesis is a priority is
Producing ribose
Which of the following is not true of NAD+ and FAD?
They donate electrons to the electron transport system.
a cyclic metabolic sequence can best be described as 1 in which
a series of reactions regenerates the initial reactant
In many catabolic processes the principal product is ________ to be processed in the ________.
acetyl coenzyme A, citric acid cycle
When energy is needed and adequate oxygen is available, pyruvate is converted to
acetyl-CoA
Which chemical is produced from pyruvate when it is metabolized in muscle cells under aerobic conditions?
acetyl-CoA
the common molecule produced from all foods at the second stage of catabolism is
acetyl-CoA
All of the following molecules are directly involved in the electron transport chain except
acetyl-SCoA
ATP stands for
adenosine triphosphate
All of these enzymes used in glycolysis involve the transfer of a phosphate group except
aldolase
The enzyme that catalyzes cleavage of fructose 1,6-bisphosphate to dihydroxyacetone phosphate and D-glyceraldehyde-3-phosphate is
aldolase
the biochemical process in which simple molecules are combined to make larger ones and energy is consumed is referred to as
anabolism
metabolism is composed of which process(es)
anabolism and catabolism
All of the following chemicals are involved in the citric acid cycle except
ascorbate
the biochemical process in which complex molecules are broken down into simpler ones and energy is released is referred to as
catabolism
Which polysaccharide is not broken down by α-amylase?
cellulose
all of the following are energy strategies used in biochemical reactions except
chemica reactions occur in pairs in order to change the value of ΔG for one of the reactions
the mitochondria are the organelles where _____ takes place and most ____ is produced
citric acid cycle; ATP
The electrons brought into the electron transport chain are transferred in the following order of
complex I; CoQ; complex III; cytochrome c; complex IV.
The driving force which provides the energy for synthesis of ATP in the fourth stage of metabolism is the
concentration gradient of hydrogen ions between the two sides of the inner mitochondrial membrane.
The synthesis of ATP from ADP and monohydrogen phosphate ________ 7 kcal/mol of energy and is an ________ reaction.
consumes; endergonic
Entry of monosaccharides other than glucose into the glycolysis pathway initially involves
conversion into phosphates.
Which reaction of the citric acid cycle involves the addition of water across the double bond?
conversion of fumarate to malate
the enzymes of the oxidative phosphorylation system are located in the
cristae of the mitochondria
a metabolic pathway in which a series of steps, each using different enzymes, regenerates 1 of the early reactants, is a(an) _____ pathway
cyclic
the regions of a cell found between the nuclear membrane and the cell membrane is called the
cytoplasm
The fourth stage of metabolism, in which the high energy molecules from stage three are oxidized to produce ATP is referred to as
electron transport chain
photosynthesis is an _____ process bcs the free energy of the products is ______ the free energy of the reactants
endergonic; greater than
all of the following are specific requirements for energy in biochemical processes except
energy needed for unfavorable reactions must be available in the form of heat
The dehydration of 2-phosphoglycerate to phosphoenolpyruvate uses the enzyme
enolase
The formation of acetyl coenzyme A is an example of a(an) ________ reaction.
esterification
Which of the following monosaccharides is generated during digestion of milk?
galactose
Which of the following carbohydrates can also be used as fuel in glycolysis?
galactose, fructose, and mannose
The most important monosaccharide for energy production is
glucose
Which conversion is accomplished during glycolysis?
glucose to pyruvate
The synthesis of glycogen from excess glucose is
glycogenesis
All of the following are reactions in the oxidation of glucose which produce energy except
glycogenolysis
The pathway followed by glucose when energy is needed is
glycolysis
which of the following organelles is involved in the synthesis is macromolecules
golgi apparatus
All of the following chemicals except ________ provide protection against potentially harmful oxygen species.
hydrogen peroxide
the reaction in which ATP is converted to ADP with release of 7.3kcal is a(an)
hydrolysis
The proton-translocating ATP synthase complex is located in the
inner membrane of mitochondria
The metal that acts as an electron carrier in the cytochromes in the electron transport chain is
iron
Conversion of dihydroxyacetone phosphate to D-glyceraldehyde 3-phosphate is a(an)
isomerization
The conversion of glucose 6-phosphate to fructose 6-phosphate in the second step of glycolysis is a(an) ________ reaction.
isomerization
ATP is the molecule most often used for energy transport because
it's hydrolysis releases an intermediate amount of energy and is relatively slow except in the presence of the appropriate enzymes
a metabolic pathway that can be illustrated as A -> B -> C -> D is said to be a(an) _____ pathway
linear
which of the following organelles is involved in breakdown of unwanted molecules and cellular components
lysosome
the sum of all the biochemical reactions occurring in an organism is
metabolism
the cellular organelle associated with energy production is the
mitochondrion
the cellular organelle that is responsible for most cellular catabolic redox reactions is the
mitochondrion
The major products of carbohydrate digestion are
monosaccharides
exergonic reactions are those that have a _____ value of ΔG and ______ spontaneous
negative; are
Endergonic reactions are that are ______ and that _____ liberate free energy
nonspontaneous ; do not
The process of converting ADP to ATP in the mitochondrion takes place by a process known as
oxidative phosphorylation
the process by which cell produces ATP in the mitochondria is called
oxidative phosphorylation
In the first step of glycolysis, the conversion of glucose to glucose 6-phosphate is known as
phosphorylation
endergonic reactions are those that have a ______ value of ΔG and ______ spontaneous
positive; are not
The major function of the pentose phosphate pathway when energy for anabolic reactions is a priority is
producing NADPH
The most important goal of glucose metabolism is
production of ATP as an energy source for all cells
All of the chemicals below are associated with the pentose phosphate pathway except
pyruvate
Which of the following is not a product of digestion?
pyruvate
The products of glycolysis important in metabolism are
pyruvate, ATP, and NADH
In addition to producing ATP, the citric acid cycle produces ________ as high energy molecules and ________ as its major chemical waste product.
reduced coenzymes; CO2
In a pair of coupled reactions, if the favorable reaction releases more energy than the amount required by the unfavorable reaction, the excess energy is
released as heat and used to maintain body temperature
The hydrolysis of ATP to ADP ________ 7 kcal/mol of energy and is an ________ reaction.
releases; exergonic
which of the following organelles is involved in protein synthesis and transport
rough endoplasmic reticulum
a metabolic pathway in which a molecule is progressively built up by repeated interaction with the same set of enzymes is a(an) ______ pathway
spiral
Exergonic reactions are those that are ______ and that _____ liberate free energy
spontaneous; do
The target molecule(s) for α-amylase is(are)
starch and glycogen.
When ATP is produced by direct transfer of a phosphate group instead of from reactions coupled to electron transport, the process is referred to as ________ phosphorylation.
substrate level
Which reaction of the citric acid cycle generates the high energy molecule GTP?
succinyl-CoA to succinate
Harmful byproducts of biochemical oxidation include
superoxide ions and hydroxyl free radicals.
When a cell's need for NADPH or ribose-6-phosphate exceeds its need for ATP, glucose-6-phosphate is metabolized by
the pentose phosphate pathway.
All of the following statements concerning digestion are correct except
the same enzymes are used in the digestion of carbohydrates, lipids, and proteins.
a spiral metabolic sequence can best be described as 1 in which
the same set of enzymes progressively builds up or breaks down a molecule
the ultimate source of energy for all but very few bichemical reactions is
the sun
The purpose of coupling two biochemical reactions is to
the use of an exergonic reaction to drive an endergonic reaction
After O2 has been reduced in the electron transport chain, the oxygen atoms are part of what molecules?
water