Unit 3 Flashcards
(31 cards)
Like other catalysts, enzymes…
- increase the rate of reactions without being consumed in reactions
- do not alter the chemical equilibrium between reactants and products
Enzymes act by…
decreasing the activation energy
A reaction in which the substrate glucose binds to the enzyme hexokinase and the configuration of both molecules changes is an example of…
an induced-fit mechanism
Because of the central role that one amino acid plays in the mechanism by which proteins are cleaved by the enzymes trypsin and chymotrypsin, these enzymes are called ………… proteases
Serine
The trypsin substrate binding site contains an aspartate residue, which is able to form an ionic bond with which amino acids in its polypeptide substrates?
Lysine or arginine
Coenzymes are…
small molecules that work with an enzyme to enhance reaction rate
Which statement below best describes the usual relationship of the inhibitor molecule to the allosteric enzyme in feedback inhibition of enzyme activity?
the inhibitor is the final product of the metabolic pathway
In allosteric regulation, binding of a small regulatory molecule to an enzyme …………. the enzyme activity
either stimulates or inhibits
Proteins can be covalently modified by the addition of a phosphate groups to all but which of the following amino acids?
Arginine
The free-energy change of a reaction is determined by…
- instrinic properties of the reactants and products
- concentration of the reactants and products
- temperature of the reactants and products
The Delta G for hydrolysis of ATP to ADP and Pi, is ………….kcal/mole
-7.3
The hydrolysis of ATP to ADP and phosphate allows glucose-6-phosphate to be synthesized from glucose and phosphate because the…
Enzyme coupling of these two reactions allows the energy of ATP hydrolysis to drive the synthesis of glucose-6-phosphate
Glycolysis yields a net gain of …….ATP molecules per molecule of glucose
2
Under aerobic conditions, the end product of glycolysis is…
pyruvate
Glycolysis produces four molecules of ATP from each molecule of fructose-I,6-bisphosphate because…
- two molecules of ATP are required to convert glucose to fructose-1,6-bisphosphate
- fructose 1,6-bisphosphate is converted into two molecules of 1,3-bisphospholglycerate, each of which produces two ATPS when metabolized to pyruvate
In glycolysis, the key control enzyme that is inhibited by excess ATP is…
phosphofructokinase
Under aerobic conditions, the end product of glycolysis is…
pyruvate
Under anaerobic conditions, the NADH produced by glycolysis is recycled by a reactions that produces NAD+ and…
ethanol or lactate
In eukaryotic cells, glycolysis takes places in the…
cytosol
In eukaryotic cells, the citric acid cycle occurs in the…
Mitochondria
As compared on a per gram basis to carbohydrates, fatty acids produces approximately …………. energy through the oxidation process.
2.5 times more
Fatty acids are broken down in a stepwise process…….. carbon(s) at a time
two
In the light reactions of photosynthesis…
H2O is converted to O2 and NAD is reduced to NADPH
The Calvin cycle can occur…
in the absence of light
