Tag: biology
Questions Related to biology
The enzymes ribulose biphosphate carboxylase-oxygenase and phosphoenol pyruvate carboxylase are activated by
-
Mg
-
Zn
-
Mo
-
Mn
Both RUBISCO and PEP carboxylase are important enzymes of dark reaction of photosynthesis. RUBISCO catalyzes carboxylation in C3 plants. In the presence of magnesium activated RUBISCO, carbon dioxide combines with ribulose bis phosphate to form phosphoglyceric acid. In C4 plants, mesophyll cells fix carbon dioxide with the help of phospho enol pyruvate in the presence of magnesium activated phospho-enol pyruvate carboxylase.
Haemoglobin is composed of four subunits. When one subunit binds to oxygen, it increases the chances that the other three subunits will also bind to oxygen. What is this type of activity called?
-
Inhibition
-
Cooperativity
-
Enzyme substrate complex
-
Catalysis
-
Activation
Cyanide causes irreversible inhibition of cytochrome oxidase. This is because it
-
Combines with iron.
-
Destroys tertiary structure.
-
Attaches to copper.
-
All the above.
Which statement regarding enzyme inhibition is correct?
-
Competitive inhibition occurs when a substrate competes with enzyme for binding to inhibitor protein
-
Competitive inhibition occurs when the substrate and the inhibitor compete for active site on the enzyme
-
Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate
-
Non-competitive inhibitors often bind to the enzyme irreversibly
An enzyme brings about
-
Decrease in reaction time
-
Increase in reaction time
-
Increase in activation energy
-
Reduction in activation energy
Enzymes are proteins which accelerate the rate of the reaction. The substrate and product have different energy state. The energy gap between the substrate and the product is known as activation energy which is the minimum energy required to initiate a reaction. The enzymes lower the activation energy and lead to the faster conversion of substrate to the product.
Nerve gas (DFP) inhibits neurotransmission as it reacts with
-
Serine of acetylcholine-esterase.
-
Choline of acetylcholine-esterase.
-
Acetylcholine.
-
Noradrenaline.
An enzyme promotes a chemical reaction by
-
lowering the energy of activation
-
changing the free energy difference between substrate and product
-
increasing molecular motion
-
all of these.
Modulators
-
Inhibit enzyme activity
-
Stimulate enzyme activity
-
Function as coenzymes
-
Both A and B
A modulator is a type of molecule which either stimulates or inhibits enzyme activity. Those which stimulate enzyme activity are known as inducers while those which inhibit enzyme activity are known as inhibitors. The inhibitors can be competitive, non-competitive or allosteric inhibitors.
Which of the following inactivates the enzyme by changing its shape?
-
Competitive inhibitor
-
Allosteric inhibitor
-
Coenzyme
-
All of the above
Allosteric means in a different steric conformation or occurrence of more than one shapes. Allosteric modulators bind to a site different from the active site and bring changes in the shape or conformation of the enzyme molecule. The change in shape can activate the enzyme or inhibit the activity of enzyme. An allosteric inhibitor will bind to allosteric site and bring in the conformational changes to reduce the enzyme activity.
Identify the correct statement regarding enzyme inhibition.
-
Non-competitive inhibition of an enzyme can be overcomed by adding large amount of substrate.
-
Competitive inhibition is seen when a substrate competes with an enzyme for binding to an inhibitor protein.
-
Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme.
-
Non-competitive inhibitors often bind to the enzyme irreversibly.
Competitive inhibition is the inhibition of an enzyme by an inhibitor which has structural similarity to the active site and thus competes with the substrate for binding with the active site. Competitive inhibition is a reversible inhibition and depends on the relative concentration of substrate and inhibitor.