UNE Biochemistry Unit 2 And Unit 3
Exam Test Questions All Solved
Correct.
Fuel Oxidation and the Generation of Adenosine Triphosphate - Answer This energy
transformations can be divided into three principal phases: (1) oxidation of fuels (fat,
carbohydrate, and protein), (2) conversion of energy from fuel oxidation into the high-energy
phosphate bonds of adenosine triphosphate (ATP), and (3) use of ATP phosphate bond energy
to drive energy-requiring processes.
Energy transformations in fuel metabolism. - Answer When ATP energy is transformed into
cellular responses, such as muscle contraction, ATP is cleaved to ADP and Pi. In cellular
respiration, O2 is used for regenerating ATP from oxidation of fuels to CO2.
Cellular respiration - Answer The first two phases of energy transformation are part of
cellular respiration, the overall process of using O2 and energy derived from oxidizing fuels to
generate ATP. We need to breathe principally because our cells require O2 to generate adequate
amounts of ATP from the oxidation of fuels to CO2. Cellular respiration uses >90% of the O2 we
inhale.
Phase 1 of respiration - Answer In phase 1 of respiration, energy is conserved from fuel
oxidation by enzymes that transfer electrons from the fuels to the electron-accepting
coenzymes nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD),
which are reduced to NADH and FAD(2H), respectively (Fig. IV.2). The pathways for the oxidation
of most fuels (glucose, fatty acids, ketone bodies, and many amino acids) converge in the
generation of the activated 2-carbon acetyl group in acetyl coenzyme A (acetyl-CoA). The
complete oxidation of the acetyl group to CO2 occurs in the tricarboxylic acid (TCA) cycle, which
collects the energy mostly as NADH and FAD(2H).
Phase 2 of cellular respiration - Answer In phase 2 of cellular respiration, the energy derived
from fuel oxidation is converted to the high-energy phosphate bonds of ATP by the process of
oxidative phosphorylation (see Fig. IV.2). Electrons are transferred from NADH and FAD(2H) to
O2 by the electron-transport chain, a series of electron-transfer proteins that are located in the
inner mitochondrial membrane. Oxidation of NADH and FAD(2H) by O2 generates an
electrochemical potential across the inner mitochondrial membrane in the form of a
transmembrane proton gradient (Δp). This electrochemical potential drives the synthesis of ATP
from adenosine diphosphate (ADP) and inorganic phosphate (Pi) by a transmembrane enzyme
called ATP synthase (or F0F1ATPase).
Phase 3 of cellular respiration - Answer In phase 3 of cellular respiration, the high-energy
phosphate bonds of ATP are used for processes such as muscle contraction (mechanical work),
maintaining low intracellular Na+ concentrations (transport work), synthesis of larger molecules
such as DNA in anabolic pathways (biosynthetic work), or detoxification (biochemical work). As
, a consequence of these processes, ATP is either directly or indirectly hydrolyzed to ADP and Pi
or to adenosine monophosphate (AMP) and pyrophosphate (PPi).
Cellular respiration occurs in the mitochondria - Answer Cellular respiration occurs in
mitochondria (Fig. IV.3). The mitochondrial matrix, which is the compartment enclosed by the
inner mitochondrial membrane, contains almost all of the enzymes for the TCA cycle and
oxidation of fatty acids, ketone bodies, and most amino acids. The inner mitochondrial
membrane contains the protein complexes of the electron-transport chain and ATP synthase,
the enzyme complex that generates ATP from ADP and Pi. Some of the subunits of these
complexes are encoded by mitochondrial DNA, which resides in the matrix. ATP is generated in
the matrix, but most of the energy-using processes in the cell occur outside of the
mitochondrion. As a consequence, newly generated ATP must be continuously transported to
the cytosol by protein transporters in the impermeable inner mitochondrial membrane and by
diffusion through pores in the more permeable outer mitochondrial membrane.
Oxidative metabolism in mitochondria. - Answer The inner mitochondrial membrane forms
infoldings, called cristae, which enclose the mitochondrial matrix. Most of the enzymes for the
TCA cycle, the β-oxidation of fatty acids, and for mitochondrial DNA synthesis are found in the
matrix. ATP synthase and the protein complexes of the electron-transport chain are embedded
in the inner mitochondrial membrane. The outer mitochondrial membrane is permeable to
small ions, but the inner mitochondrial membrane is impermeable.
The rates of fuel oxidation and ATP use are tightly coordinated through feedback regulation of
the electron-transport chain and the pathways of fuel oxidation. - Answer Thus, if less
energy is required for work, more fuel is stored as glycogen or fat in adipose tissue. The basal
metabolic rate (BMR), caloric balance, and ΔG (the change in Gibbs free energy, which is the
amount of energy available to do useful work) are quantitative ways of describing energy
requirements and the energy that can be derived from fuel oxidation. The various types of
enzyme regulation described in Chapter 9 are all used to regulate the rate of oxidation of
different fuels to meet energy requirements.
Fatty acids are a major fuel in the body. - Answer After eating, we store excess fatty acids and
carbohydrates that are not oxidized as fat (triacylglycerols) in adipose tissue. Between meals,
these fatty acids are released and circulate in blood bound to albumin. In muscle, liver, and
other tissues, fatty acids are oxidized to acetyl-CoA in the pathway of β-oxidation. NADH and
FAD(2H) generated from β-oxidation are reoxidized by O2 in the electron-transport chain,
thereby generating ATP (see Fig. IV.2). Small amounts of certain fatty acids are oxidized through
other pathways that convert them to either oxidizable fuels or urinary excretion products (e.g.,
peroxisomal β-oxidation).
Not all acetyl-CoA generated from β-oxidation enters the TCA cycle. - Answer In the liver,
acetyl-CoA generated from β-oxidation of fatty acids can also be converted to the ketone bodies
acetoacetate and β-hydroxybutyrate. Ketone bodies are taken up by muscle and other tissues,
which convert them back to acetyl-CoA for oxidation in the TCA cycle. They become a major fuel
for the brain during prolonged fasting.
Exam Test Questions All Solved
Correct.
Fuel Oxidation and the Generation of Adenosine Triphosphate - Answer This energy
transformations can be divided into three principal phases: (1) oxidation of fuels (fat,
carbohydrate, and protein), (2) conversion of energy from fuel oxidation into the high-energy
phosphate bonds of adenosine triphosphate (ATP), and (3) use of ATP phosphate bond energy
to drive energy-requiring processes.
Energy transformations in fuel metabolism. - Answer When ATP energy is transformed into
cellular responses, such as muscle contraction, ATP is cleaved to ADP and Pi. In cellular
respiration, O2 is used for regenerating ATP from oxidation of fuels to CO2.
Cellular respiration - Answer The first two phases of energy transformation are part of
cellular respiration, the overall process of using O2 and energy derived from oxidizing fuels to
generate ATP. We need to breathe principally because our cells require O2 to generate adequate
amounts of ATP from the oxidation of fuels to CO2. Cellular respiration uses >90% of the O2 we
inhale.
Phase 1 of respiration - Answer In phase 1 of respiration, energy is conserved from fuel
oxidation by enzymes that transfer electrons from the fuels to the electron-accepting
coenzymes nicotinamide adenine dinucleotide (NAD+) and flavin adenine dinucleotide (FAD),
which are reduced to NADH and FAD(2H), respectively (Fig. IV.2). The pathways for the oxidation
of most fuels (glucose, fatty acids, ketone bodies, and many amino acids) converge in the
generation of the activated 2-carbon acetyl group in acetyl coenzyme A (acetyl-CoA). The
complete oxidation of the acetyl group to CO2 occurs in the tricarboxylic acid (TCA) cycle, which
collects the energy mostly as NADH and FAD(2H).
Phase 2 of cellular respiration - Answer In phase 2 of cellular respiration, the energy derived
from fuel oxidation is converted to the high-energy phosphate bonds of ATP by the process of
oxidative phosphorylation (see Fig. IV.2). Electrons are transferred from NADH and FAD(2H) to
O2 by the electron-transport chain, a series of electron-transfer proteins that are located in the
inner mitochondrial membrane. Oxidation of NADH and FAD(2H) by O2 generates an
electrochemical potential across the inner mitochondrial membrane in the form of a
transmembrane proton gradient (Δp). This electrochemical potential drives the synthesis of ATP
from adenosine diphosphate (ADP) and inorganic phosphate (Pi) by a transmembrane enzyme
called ATP synthase (or F0F1ATPase).
Phase 3 of cellular respiration - Answer In phase 3 of cellular respiration, the high-energy
phosphate bonds of ATP are used for processes such as muscle contraction (mechanical work),
maintaining low intracellular Na+ concentrations (transport work), synthesis of larger molecules
such as DNA in anabolic pathways (biosynthetic work), or detoxification (biochemical work). As
, a consequence of these processes, ATP is either directly or indirectly hydrolyzed to ADP and Pi
or to adenosine monophosphate (AMP) and pyrophosphate (PPi).
Cellular respiration occurs in the mitochondria - Answer Cellular respiration occurs in
mitochondria (Fig. IV.3). The mitochondrial matrix, which is the compartment enclosed by the
inner mitochondrial membrane, contains almost all of the enzymes for the TCA cycle and
oxidation of fatty acids, ketone bodies, and most amino acids. The inner mitochondrial
membrane contains the protein complexes of the electron-transport chain and ATP synthase,
the enzyme complex that generates ATP from ADP and Pi. Some of the subunits of these
complexes are encoded by mitochondrial DNA, which resides in the matrix. ATP is generated in
the matrix, but most of the energy-using processes in the cell occur outside of the
mitochondrion. As a consequence, newly generated ATP must be continuously transported to
the cytosol by protein transporters in the impermeable inner mitochondrial membrane and by
diffusion through pores in the more permeable outer mitochondrial membrane.
Oxidative metabolism in mitochondria. - Answer The inner mitochondrial membrane forms
infoldings, called cristae, which enclose the mitochondrial matrix. Most of the enzymes for the
TCA cycle, the β-oxidation of fatty acids, and for mitochondrial DNA synthesis are found in the
matrix. ATP synthase and the protein complexes of the electron-transport chain are embedded
in the inner mitochondrial membrane. The outer mitochondrial membrane is permeable to
small ions, but the inner mitochondrial membrane is impermeable.
The rates of fuel oxidation and ATP use are tightly coordinated through feedback regulation of
the electron-transport chain and the pathways of fuel oxidation. - Answer Thus, if less
energy is required for work, more fuel is stored as glycogen or fat in adipose tissue. The basal
metabolic rate (BMR), caloric balance, and ΔG (the change in Gibbs free energy, which is the
amount of energy available to do useful work) are quantitative ways of describing energy
requirements and the energy that can be derived from fuel oxidation. The various types of
enzyme regulation described in Chapter 9 are all used to regulate the rate of oxidation of
different fuels to meet energy requirements.
Fatty acids are a major fuel in the body. - Answer After eating, we store excess fatty acids and
carbohydrates that are not oxidized as fat (triacylglycerols) in adipose tissue. Between meals,
these fatty acids are released and circulate in blood bound to albumin. In muscle, liver, and
other tissues, fatty acids are oxidized to acetyl-CoA in the pathway of β-oxidation. NADH and
FAD(2H) generated from β-oxidation are reoxidized by O2 in the electron-transport chain,
thereby generating ATP (see Fig. IV.2). Small amounts of certain fatty acids are oxidized through
other pathways that convert them to either oxidizable fuels or urinary excretion products (e.g.,
peroxisomal β-oxidation).
Not all acetyl-CoA generated from β-oxidation enters the TCA cycle. - Answer In the liver,
acetyl-CoA generated from β-oxidation of fatty acids can also be converted to the ketone bodies
acetoacetate and β-hydroxybutyrate. Ketone bodies are taken up by muscle and other tissues,
which convert them back to acetyl-CoA for oxidation in the TCA cycle. They become a major fuel
for the brain during prolonged fasting.
