EASY
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How does inhibitor affect the reaction rate of enzyme activity?

Important Questions on Biomolecules

HARD
Given below are the four schematics that describe the dependence of the rate of an enzymatic reaction on temperature. Which of the following combination is true for thermophilic and psychrophilic organisms?

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MEDIUM

The graph given below shows the Michaelis-Menten kinetics for two reactions (R1 and R2; represented as solid and dotted lines, respectively). Enzymes E1 and E2 have Vmax values, Vmax1 and Vmax2, respectively. The respective KM values for E1 and E2 are KM1 and KM2. (KM1=KM2).

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The correct statement(s) for reactions R1 and R2 is/are

MEDIUM

Given below are two statements :

Statement I : Low temperature preserves the enzyme in a temporarily inactive state whereas high temperature destroys enzymatic activity because proteins are denatured by heat.

Statement II : When the inhibitor closely resembles the substrate in its molecular structure and inhibits the activity of the enzyme, it is known as competitive inhibitor.

In the light of the above statements, choose the correct answer from the options given below : 

MEDIUM
Match the following lists.
  List-I   List-II   List-III
A Coenzymes are organic compound i No structure similarities I Ribose-5 phosphate isomerase
B Isomerases ii Differ from inorganic catalysis II During catalysis
C Non-competitive enzyme inhibition iii Catalyzing interconversion of optical positional isomers III Operates at high temperatures also
D Enzyme catalysts iv With the apoenzyme only as a transient IV Metal ion of copper

The correct match is:

MEDIUM
Which of the following describes the given graph

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HARD

A scientist performed enzyme kinetics and obtained velocityv as a function of substrate concentration [S] and the values are given in the table below.

S(μMolar)  v (μ/min) S(μMolar)  v (μ/min)
50 10.2 400 62.5
100 19.1 800 75.3
150 31.2 1000 76.2
200 38.1 1300 76.3
300 55.4 1600 77.2

The Km of the substrate could

EASY
The formation of the Enzyme - Substrate complex is essential for
EASY
Co-enzymes are components of an enzyme complex which are necessary for its function. Which of these is a known co-enzyme?
MEDIUM
Solid and dotted lines represent the activities of pepsin and salivary amylase enzymes of the digestive tract, respectively. Which one of the following graphs best represents their activity vs pH?
EASY
Which one of the following statements is correct, with reference to enzymes?
EASY
Which ONE of the following coenzymes is required for the conversion of L-alanine to a racemic mixture of D- and L-alanine?
MEDIUM
Select the option which is not correct with respect to enzyme action:
HARD

Study the following

(I) Km value Affinity of the enzyme Inverse measure enzyme affinity
(II) Hydrolases P-O bonds Linking 2 compounds
(III) Transferases Transfer of a group Inhibitor of reaction
(IV) Emil Fisher Lock and key hypothesis Formation of ES complex

The correct combinations are

HARD

The following graph shows the concentration of substrate on enzyme activity:

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What does the Y-axis represent?

MEDIUM

The graph below depicts the velocity of an enzyme-catalyzed reaction vs. substrate concentration. Identify the alphabets with the correct descriptions.

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I. A= Enzyme activity

II. B= Substrate concentration at maximum velocity

III. A= Substrate concentration at which half of the maximum velocity

IV. B= Half of the maximum velocity