Chapter 13 - Exam 3 Flashcards
Autotroph
use CO2 from the atmosphere as their sole source of carbon
Heterotroph
cannot use atmospheric CO2 and must obtain carbon from their outside environment
Metabolism
the chemical reactions in the organism
Metabolites
series of intermediates through which precursors are converted to products
Intermediary Metabolism
the combined activities of all the metabolic pathways that interconvert precursors, metabolites, and products of low molecular weight
Catabolism
the degradative phase of metabolism (releases energy)
Anabolism
the building phase of metabolism (requires energy)
What is ΔG?
expresses the amount of energy capable of doing work during a reaction at constant temperature and pressure
What is ΔH?
enthalpy (the heat content of the reacting system)
What is ΔS?
entropy (randomness or disorder in a system)
If ΔG is negative, then the reaction
proceeds foward
If ΔG is positive, then the reaction
proceeds in reverse
Understand how reactions are thermodynamically coupled
thermodynamically unfavorable reactions can be coupled to favorable reactions (often involves coupling to ATP hydrolysis)
Homolytic Cleavage
cleavage of a covalent bond where each atom leaves the bond as a radical, carrying one unpaired electron
Heterolytic Cleavage
cleavage of a covalent bond where one atom retains both bonding electrons (more common)
Nucleophiles
functional groups rich in and capable of donating electrons
Electrophiles
electron-deficient functional groups that seek electrons (carbon can act as either a nucleophile or electrophile)
Carbanion
negatively charged carbon atom
Carbocation
positively charged carbon atom
Rearrangements, isomerization, and eliminations
redistribution of electrons results in alteration without changes in the overall oxidation state of the molecule
Rearrangements can be
substitution, addition, or elimination reactions
Free Radicals
homolytic cleavage of covalent bonds to generate free radicals
Group Transfers
the transfer of acyl, glycosyl, and phosphoryl groups from one nucleophile to another (acyl group transfer involves the addition of a nucleophile to the carbonyl carbon of an acyl group to form tetrahedral intermediate)
Oxidation
loses electrons
Reduction
gains electrons
Standard Reduction Potential (ΔE)
a measure (in volts) of the relative affinity of the electron acceptor of each redox pair for electrons
Positive Standard Reduction Potential (ΔE)
takes electrons
Negative Standard Reduction Potential (ΔE)
donates electrons
Understand the relationship between the standard reduction potential ΔE and ΔG
when ΔE is greater than 0, then ΔG is less than 0 (inverse relationship), and the reaction is thermodynamically favored; vice versa
