30 Questions
What type of inhibition occurs when the inhibitor forms a covalent adduct with the enzyme?
Irreversible inhibition
Which enzyme inhibitor is mentioned in the text as an example of irreversible inhibition?
Penicillin
What happens when the concentration of substrate ([S]) increases concerning the inhibition by an inhibitor ([I])?
Inhibition by [I] increases
Which class of drugs acts on enzymes through simple chemical processes, according to the text?
Basic inorganic compounds
What term describes the gradual decrease in responsiveness to a drug, requiring larger doses to achieve the same effect?
Tachyphylaxis
Which mechanism do osmotic laxatives and diuretics rely on to exert their effects?
Physical action
Which term describes compounds that bind but do NOT activate receptors?
Antagonists
In reversible competitive antagonism, how do antagonists act?
By preventing the attachment of endogenous agonists
Which mechanism of antagonism involves the agonist binding to a site different from the ligand binding site?
Non-competitive antagonism
What happens in irreversible antagonism?
Proteins can only be reactivated by resynthesis
Which type of drug interaction involves passive transport across a cell membrane along its concentration gradient?
Passive transport facilitation
What is the primary effect of drug antagonists on endogenous agonists?
Reduction or blockage
What mechanism typically leads to a gradual decrease in responsiveness to a drug?
Conformational changes in the receptor
Which process can result in the active extrusion of a drug from cells?
Decrease in receptor expression
What type of inhibition involves the competitive binding of a molecule to the active site of an enzyme?
Competitive inhibition
In drug interactions with transporters, what can lead to the active extrusion of the drug?
Conformational changes in the receptor
What is a common outcome of non-competitive enzyme inhibition?
Allosteric regulation
Which of the following can contribute to a decrease in drug efficacy over time?
Exhaustion of mediators
What is the direction of movement of a substance in active transport?
From low to high concentration
What is the result of a drug blocking calcium channels in the heart and smooth muscle?
Reduced contractility
What is the mechanism of action of local anaesthetics on sodium channels?
Blocking of sodium channels
What type of interaction is involved in the blocking of channels by drug molecules?
Physical blocking
What type of transport is involved in the movement of substances against their concentration gradient?
Active transport
What is the target of drugs that act on transporters?
Transport proteins
What is required for the transport of ions and larger molecules across the cell membrane against their concentration gradient?
Active transport
How do antidepressants affect the activity of neurotransmitters?
They inhibit the reuptake of neurotransmitters
What is the mechanism of competitive inhibition?
A drug acts as a substrate analogue to reversibly block the enzyme's active site
What is the effect of increasing the substrate concentration on competitive inhibition?
It overcomes the inhibition
How do non-competitive inhibitors bind to the enzyme?
They bind to a site different from the active site, indirectly blocking the enzyme's function
What is the main difference between competitive and non-competitive inhibition?
The site of inhibition on the enzyme
Learn about enzyme inhibition and irreversible inhibitors through examples like organic phosphates, penicillin, and their effects on enzyme activity. Understand the impact of substrate concentration and inhibitor binding on enzyme kinetics.
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