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