Chapter 11 BIOENERGETICS: The role of ATP Flashcards
is the study of the energy changes accompanying biochemical reactions
Bioenergetics or biochemical thermodynamics
Biologic systems are essentially ____ and use chemical energy to power living processes
isothermic
is that portion of the total energy change in a system that is available for doing work—that is, the useful energy, also known as the chemical potential
Gibbs change in free energy (ΔG)
- states that the total energy of a system, including its surroundings, remains constant
-It implies that within the total system, energy is neither lost
nor gained during any change
first law of thermodynamics
- states that the total entropy of a system must increase if a process is to occur spontaneously
second law of thermodynamics
is the extent of disorder or randomness of the system and becomes maximum as equilibrium is approached
Entropy
Under conditions of constant temperature and pressure, the relationship between the free-energy change (ΔG) of a reacting system and the change in entropy (ΔS) is expressed by the following equation
ΔG = ΔH−TΔS
If ΔG is negative, the reaction proceeds spontaneously with loss of free energy
Exergonic
if ΔG is positive, the reaction proceeds only if free energy can be gained
Endergonic
The vital processes—for example, synthetic reactions, muscular contraction, nerve impulse conduction, and active transport—obtain energy by chemical linkage, or ____
coupling
The exergonic reactions are termed ___
catabolism
synthetic reactions that build up substances are termed ____
anabolism
The combined catabolic and anabolic processes constitute ____
metabolism
the principal high-energy intermediate or carrier compound is
adenosine triphosphate (ATP)
___ utilize simple exergonic processes; eg, the energy of sunlight (green plants)
Autotrophic organisms
___ organisms obtain free energy by coupling their metabolism to the breakdown of complex organic molecules in their environment
heterotrophic
- plays a central role in the transference of free energy
from the exergonic to the endergonic processes - nucleotide consisting of the nucleoside adenosine
(adenine linked to ribose), and three phosphate groups
adenosine triphosphate (ATP)
connects those processes that generate
~(P) to those processes that utilize ~ (P)
ATP/ADP cycle
True or False
ATP is able to act as a donor of high-energy phosphate to form those compounds below it. Likewise, with the necessary enzymes, ADP can accept high-energy phosphate to form ATP from those compounds above ATP in the table.
True
There are three major sources of ~(P) taking part in energy
conservation or energy capture
- Oxidative Phosphorylation
- Glycolysis
- The citric acid cycle
is the greatest quantitative source of ~(P) in aerobic organisms. ATP is generated in the mitochondrial matrix as O2 is reduced to H2O by electrons passing down the respiratory chain
Oxidative Phosphorylation
A net formation of two ~(P) results from the formation of lactate from one molecule of glucose, generated in two reactions catalyzed by phosphoglycerate
kinase and pyruvate kinase, respectively
Glycolysis
One ~(P) is generated directly in the cycle at the succinate thiokinase step
The citric acid cycle
act as storage forms of high-energy phosphate and include creatine phosphate, which occurs in vertebrate skeletal muscle, heart, spermatozoa, and brain, and arginine phosphate, which occurs in invertebrate muscle
Phosphagens
important for the maintenance of energy homeostasis in cells
Adenylate kinase
UTP, GTP, and CTP can be synthesized from their diphosphates
nucleoside diphosphate (NDP) kinases
catalyze the formation of nucleoside diphosphates
from the corresponding monophosphates
nucleoside monophosphate (NMP)
