Lecture 4 Flashcards
T/F: a spontaneous reaction occurs rapidly
false
T/F: non-spontaneous reactions do not occur
false
H is less than 0
exothermic, release energy
H > 0
endothermic, requires energy
the linked reactions in a pathway and steady states prevent – in cells
accumulation of excess intermediates
pH of interior of cell
7
half of molecule donates protons at
pKa
the charge on amino acid side chains depend on the
pH
spontaneous drives toward
disorder
greater disorder, greater –
entropy
1st law of thermodynamics
energy can be converted from one form to another, but the total energy must always be the same
an enzyme lowers the – and increases –
activation energy, rate of chemical reaction
T/F: enzymes can change equilibrium point for reactions
false
energetically unfavorable reactions can be driven by energetically favorable reactions if the net free-energy change for the pair of coupled reactions is
less than 0
Enzyme catalysis directs substrates through a – reaction pathway
specific
photosynthesis
reduce CO2 and H2O to make carbohydrates
store energy in form of chemical bonds
cellular respiration
oxidize carbohydrates –> release energy as CO2 and H2O = lowest energy state
In the presence of – the most energetically stable form of carbon is CO2 and that of hydrogen is H2O
oxygen
CO2 is restored to the atmosphere when organic molecules are oxidized by cells or burned as fuels
carbon cycle
– store energy in an easily exchangeable form
activated carriers
the useful energy in ATP is contained in
phosphoanhydride bonds
– is the most widely used activated carrier
ATP
dG for hydrolysis of ATP to ADP and Pi is
-46 – -54 kJ/mole
dG for hydrolysis of ATP to AMP and pyrophosphate is
-100 kJ/mole
in addition to ATP, – and – are important activated electron carriers in glycolysis and respiration
NADH and NADPH
NADH is the – form
reduced form that stores high energy
NAD+ is the – form
oxidized form
an important activated carrier that is the intermediate for many biosynthesis pathways
acetyl CoA
the synthesis of RNA or DNA is driven by –
ATP hydrolysis
each monomer carries a high-energy bond that will be used for the addition of the next monomer
head polymerization
each monomer carries a high-energy bond for its own addition
tail polymerization
head polymerization macromolecule
protein
tail polymerization macromolecule
RNA and DNA
cells generate ATP through
controlled stepwise oxidation of sugar in a cell
charge on amino acid side chains depends on the
pH
At a pH below its pka, an acid will be
protonated
– drive the synthesis of the majority of ATP in most cells
oxidative phosphorylation
the complete oxidation of a molecule of glucose to H2O and CO2 producers – molecules of ATP
30
– is where acetyl CoA is produced from food molecules
mitochondria
sugars —> ___ –> acetyl CoA
pyruvate
fat –> __ –> acetyl CoA
fatty acids
