CHAPTER 12 GLOSSARY-LEHNINGER PRINCIPLES OF BIOCHEMESTRY / BEST FOR YOU/WELL
EXPLAINED AND NEW VERSION PLUS+/100%ERABORATED.
signal transduction - ANSWER The process by which an extracellular signal (chemical,
mechanical, or electrical) is amplified and converted to a cellular response.
specificity - ANSWER The ability of an enzyme or receptor to discriminate among competing
substrates or ligands.
cooperativity - ANSWER The characteristic of an enzyme or other protein in which binding
of the first molecule of a ligand changes the affinity for the second molecule. In positive
cooperativity, the affinity for the second ligand molecule increases; in negative cooperativity, it
decreases.
amplification - ANSWER The action of making something more marked or intense.
enzyme cascade - ANSWER A series of reactions, often involved in regulatory events, in
which one enzyme activates another (often by phosphorylation), which activates a third, and so
on. The effect of a catalyst activating a catalyst is a large amplification of the signal that initiated
the cascade.
modularity - ANSWER The degree to which a system's components may be separated and
recombined, often with the benefit of flexibility and variety in use.
scaffold proteins - ANSWER Noncatalytic proteins that nucleate formation of multienzyme
complexes by providing two or more specific binding sites for those proteins.
desensitization - ANSWER A universal process by which sensory mechanisms cease to
respond after prolonged exposure to the specific stimulus they detect.
,autotroph - ANSWER An organism that can synthesize its own complex molecules from very
simple carbon and nitrogen sources, such as carbon dioxide and ammonia.
heterotroph - ANSWER An organism that requires complex nutrient molecules, such as
glucose, as a source of energy and carbon.
metabolism - ANSWER The entire set of enzyme-catalyzed transformations of organic
molecule in living cells; the sum of anabolism and catabolism.
metabolic pathways - ANSWER Linked series of chemical reactions occurring within a cell.
The reactants, products, and intermediates of an enzymatic reaction are known as metabolites,
which are modified by a sequence of chemical reactions catalyzed by enzymes.
metabolite - ANSWER A chemical intermediate in the enzyme-catalyzed reactions of
metabolism.
intermediary metabolism - ANSWER In cells, the enzyme-catalyzed reactions that extract
chemical energy from nutrient molecules and use it to synthesize and assemble cell
components.
catabolism - ANSWER The phase of intermediary metabolism concerned with the energy-
yielding degradation of nutrient molecules.
anabolism - ANSWER The phase of intermediary metabolism that is concerned with the
energy-requiring biosynthesis of cell components from smaller precursors.
, standard transformed constants - ANSWER Used to calculate standard transformed Gibbs
energies of formation and standard transformed enthalpies of formation of 53 reactants (sums
of species) at 298.15 K, pH 7, and ionic strengths of 0, 0.1, and 0.25 ᴍ.
homolytic cleavage - ANSWER The breaking of a covalent bond in such a way that each
fragment gets one of the shared electrons.
radical - ANSWER An atom or group of atoms possessing an unpaired electron; also called a
free radical.
heterolytic cleavage - ANSWER The process of cleaving a covalent bond where one
previously bonded species takes both original bonding electrons from the other species.
nucleophile - ANSWER an electron-rich group with a strong tendency to donate electrons to
an electron-deficient nucleus (electrophile); the entering reactant in a bimolecular substitution
reaction.
electrophile - ANSWER An electron-deficient group with a strong tendency to accept
electrons from an electron-rich group (nucleophile).
carbanion - ANSWER A negatively charged carbon atom.
alpha amino acid - ANSWER an organic compound that contains both an amino group and a
carboxylic acid group in the form of a carboxylate
- make up proteins
amino acid structure - ANSWER
, alpha carbon - ANSWER carbon in the center of an amino acid
L- amino acid - ANSWER when the amino group is on the left side
- predominates in natural system (more common)
D-amino acid - ANSWER when the amino group is on the right side
glycine exception - ANSWER alpha carbon is not chiral so does not have L and D
stereoisomers
neutral and nonpolar amino acids - ANSWER all R groups are a form of hydrocarbon which
are nonpolar because of C-H bonds.
- Methionine is only one with a non C or H (has S)
thiol ether side chain - ANSWER S in between 2 carbon chains
-present in methionine
neutral polar amino acids - ANSWER amino acids that contain -OH groups, heterocyclic
amine, thiol group, or an amide groups with no charge present in the R groups
basic and polar amino acids - ANSWER amino acids that contain positively charged amino
groups in their R groups (can accept protons)
- His, Lys, Arg
guanidinium group - ANSWER carbon double bonded to nitrogen (positively charged) and
single bonded to nitrogen on each side
EXPLAINED AND NEW VERSION PLUS+/100%ERABORATED.
signal transduction - ANSWER The process by which an extracellular signal (chemical,
mechanical, or electrical) is amplified and converted to a cellular response.
specificity - ANSWER The ability of an enzyme or receptor to discriminate among competing
substrates or ligands.
cooperativity - ANSWER The characteristic of an enzyme or other protein in which binding
of the first molecule of a ligand changes the affinity for the second molecule. In positive
cooperativity, the affinity for the second ligand molecule increases; in negative cooperativity, it
decreases.
amplification - ANSWER The action of making something more marked or intense.
enzyme cascade - ANSWER A series of reactions, often involved in regulatory events, in
which one enzyme activates another (often by phosphorylation), which activates a third, and so
on. The effect of a catalyst activating a catalyst is a large amplification of the signal that initiated
the cascade.
modularity - ANSWER The degree to which a system's components may be separated and
recombined, often with the benefit of flexibility and variety in use.
scaffold proteins - ANSWER Noncatalytic proteins that nucleate formation of multienzyme
complexes by providing two or more specific binding sites for those proteins.
desensitization - ANSWER A universal process by which sensory mechanisms cease to
respond after prolonged exposure to the specific stimulus they detect.
,autotroph - ANSWER An organism that can synthesize its own complex molecules from very
simple carbon and nitrogen sources, such as carbon dioxide and ammonia.
heterotroph - ANSWER An organism that requires complex nutrient molecules, such as
glucose, as a source of energy and carbon.
metabolism - ANSWER The entire set of enzyme-catalyzed transformations of organic
molecule in living cells; the sum of anabolism and catabolism.
metabolic pathways - ANSWER Linked series of chemical reactions occurring within a cell.
The reactants, products, and intermediates of an enzymatic reaction are known as metabolites,
which are modified by a sequence of chemical reactions catalyzed by enzymes.
metabolite - ANSWER A chemical intermediate in the enzyme-catalyzed reactions of
metabolism.
intermediary metabolism - ANSWER In cells, the enzyme-catalyzed reactions that extract
chemical energy from nutrient molecules and use it to synthesize and assemble cell
components.
catabolism - ANSWER The phase of intermediary metabolism concerned with the energy-
yielding degradation of nutrient molecules.
anabolism - ANSWER The phase of intermediary metabolism that is concerned with the
energy-requiring biosynthesis of cell components from smaller precursors.
, standard transformed constants - ANSWER Used to calculate standard transformed Gibbs
energies of formation and standard transformed enthalpies of formation of 53 reactants (sums
of species) at 298.15 K, pH 7, and ionic strengths of 0, 0.1, and 0.25 ᴍ.
homolytic cleavage - ANSWER The breaking of a covalent bond in such a way that each
fragment gets one of the shared electrons.
radical - ANSWER An atom or group of atoms possessing an unpaired electron; also called a
free radical.
heterolytic cleavage - ANSWER The process of cleaving a covalent bond where one
previously bonded species takes both original bonding electrons from the other species.
nucleophile - ANSWER an electron-rich group with a strong tendency to donate electrons to
an electron-deficient nucleus (electrophile); the entering reactant in a bimolecular substitution
reaction.
electrophile - ANSWER An electron-deficient group with a strong tendency to accept
electrons from an electron-rich group (nucleophile).
carbanion - ANSWER A negatively charged carbon atom.
alpha amino acid - ANSWER an organic compound that contains both an amino group and a
carboxylic acid group in the form of a carboxylate
- make up proteins
amino acid structure - ANSWER
, alpha carbon - ANSWER carbon in the center of an amino acid
L- amino acid - ANSWER when the amino group is on the left side
- predominates in natural system (more common)
D-amino acid - ANSWER when the amino group is on the right side
glycine exception - ANSWER alpha carbon is not chiral so does not have L and D
stereoisomers
neutral and nonpolar amino acids - ANSWER all R groups are a form of hydrocarbon which
are nonpolar because of C-H bonds.
- Methionine is only one with a non C or H (has S)
thiol ether side chain - ANSWER S in between 2 carbon chains
-present in methionine
neutral polar amino acids - ANSWER amino acids that contain -OH groups, heterocyclic
amine, thiol group, or an amide groups with no charge present in the R groups
basic and polar amino acids - ANSWER amino acids that contain positively charged amino
groups in their R groups (can accept protons)
- His, Lys, Arg
guanidinium group - ANSWER carbon double bonded to nitrogen (positively charged) and
single bonded to nitrogen on each side
