60 Questions
What type of molecules are enzymes?
Protein molecules
What is the function of enzymes in cellular activity?
Speeding up chemical reactions
What is the main characteristic of enzymes in relation to their substrates?
They have high specificity
Under what conditions do enzymes function?
Aqueous solutions under mild conditions of temperature and pH
What is the main role of an enzyme in a chemical reaction?
To increase the speed of the reaction without suffering changes
What is the specific molecular environment provided by enzymes for chemical reactions?
An energetically favorable environment
What is the main factor that the Gibbs Free Energy (∆Go) depends on?
The final state
In which type of reaction does the free-energy change (∆G) have a negative value?
Exergonic reaction
In which type of reaction do the products contain more free energy than the reactants?
Endergonic reaction
What happens to the reaction when ∆G is large and negative?
The reaction tends to go in the forward direction
In competitive inhibition, how does the intercept on the plot of 1/V versus 1/[S] change in the presence of inhibitor?
It remains the same
What is the energy that cells can and must use, described by the Gibbs free-energy function G?
Free energy
What is the main effect of noncompetitive inhibition on Vmax and the intercept on the vertical axis?
Vmax decreases, intercept increases
What is the main function of the Michaelis-Menten model in enzymatic reactions?
To measure the rate of enzyme activity
Which type of inhibition cannot be overcome by increasing the concentration of substrate?
Reversible noncompetitive inhibition
What does Km represent in the Michaelis-Menten equation?
The enzyme's affinity for the substrate
What is the characteristic feature of irreversible inhibitors?
They chemically modify the enzyme and tightly bind to it
What does Vmax indicate in enzymatic reactions?
The concentration of active sites in fully saturated enzymes
What is the role of modulators in allosteric enzymes?
They regulate enzyme activity by binding to a different site than the active site
What does a large and negative ∆G value indicate for a chemical reaction under standard conditions?
The reaction proceeds spontaneously
What is the effect of competitive inhibitors on Km and Vmax?
$K_m$ increases, $V_{max}$ decreases
What does a large and positive ∆G value indicate for a chemical reaction?
The products contain more free energy than the reactants
Which type of inhibition involves simultaneous binding of inhibitor and substrate to the enzyme?
$Noncompetitive$ inhibition
What is unique for each enzyme and inversely proportional to its affinity for the substrate?
Km value
What is a characteristic feature of reversible competitive inhibitors?
$K_m$ increases, $V_{max}$ does not change
In what conditions does Vmax occur during an enzymatically catalyzed reaction?
When all active sites are occupied by substrate molecules
What distinguishes allosteric enzymes from Michaelis-Menten enzymes?
$Allosteric$ enzymes do not follow Michaelis-Menten kinetics
In noncompetitive inhibition, what happens to Km and Vmax?
Km decreases, Vmax increases
Which type of inhibitors competitively bind to allosteric sites instead of active sites?
Noncompetitive inhibitors
Which type of NSAID inhibits only COX-2?
Celecoxib
What is the function of COX-1 according to the widely held belief?
Produces homeostatic PGs
Which type of pain directly results from a lesion in nerves and the somatosensory system?
Neuropathic pain
What is the primary function of NSAIDs?
Analgesic and anti-inflammatory
Which NSAID is classified as a non-selective inhibitor of COX?
Diclofenac sodium
What is the main effect of selective NSAIDs?
Inhibiting only COX-2
Which type of NSAID is known for its antipyretic action?
Ibuprofen
What is the primary source of belief regarding the production of PGs by COX-1 and COX-2?
"Widely held" belief
Which type of pain affects structures in the mouth, such as gingival and subgingival tissue?
"Somatic" pain
"Arthrotec" is a combination of which two compounds known for inhibiting COX?
"Diclofenac sodium" and "Misoprostol"
Which type of amino acids in the active site directly participate in the chemical reaction?
Catalytic amino acids
What type of molecules are holoenzymes?
Non-protein portion
What is the region in the enzyme molecule where the enzymatic catalysis takes place?
Active site
What do coenzymes provide during the enzymatic process?
Energy and electrons
What is the essence of catalysis in enzymatic reactions?
Decrease in activation energy
What is the energy derived from enzyme-substrate interactions called?
Binding energy
What determines the speed of a chemical reaction according to the text?
$\Delta G^\ddagger$ (Activation energy)
What is the transition state in a chemical reaction?
$S^\ddagger$
What does the ground state represent in a reaction coordination diagram?
$S \rightarrow P$
What is the function of coenzymes in enzymatic reactions?
To facilitate the catalysis by being non-covalently bound to the enzyme
What is the main function of vitamin C (ascorbic acid) in enzymatic reactions?
Avoids oxidation of other vitamins
What do transferases do in enzymatic reactions?
Transfer a chemical group to another molecule
What is the characteristic of hydrolases in enzymatic reactions?
Special type of transferases that transfer a OH from water to another substrate
What is the role of cyclooxigenase (COX) in enzymatic reactions?
Catalyze the first step in the synthesis of prostaglandins (PGs) from arachidonic acid
What is the primary function of COX-1 according to its distribution and expression?
Widely distributed and constitutively expressed in most tissues
What is the effect of pH on enzymes in enzymatic reactions?
Acts as a denaturing agent of proteins and thus to enzymes
What is the role of ligases in enzymatic reactions?
Catalyze the formation of carbon-carbon bonds, requiring ATP energy
What do isomerases catalyze in enzymatic reactions?
(Isomerases) Catalyze the movement of a group or double bond within a molecule producing a new isomer
What do oxidoreductases catalyze in enzymatic reactions?
Catalyze addition or removal of groups to double bonds; formation of double bonds by removal of groups
What is the main function of metal ions as cofactors in enzymatic reactions?
To participate in diverse functions such as oxidation-reduction and promoting hydrolysis
What type of reaction do hydrolases catalyze in enzymatic reactions?
Hydrolysis reactions
Test your knowledge of enzymatic reaction kinetics and regulation with this quiz. Questions cover topics such as Lineweaver-Burk plot, calculation of Km and Vmax, Michaelis-Menten equation, enzyme inhibition, allosterism, and other factors that regulate enzymatic activity.
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