MODEL SUBJECTIVE AND OBJECTIVE QUESTION FOR ENZYMES

MODEL SUBJECTIVE QUESTION*

  1. What are enzymes? Discuss their nature.
  2. Write note on cofactors and coenzymes.
  3. Give classification and nomenclature of enzymes.
  4. Describe properties of enzymes.SHORT QUESTIONS
    1. Define enzymes.

    Ans:     An enzy me is a biological catalyst that can accelerate a specific

    chemical reaction by lo xering the activation energy but remain unaltered in the process.

    1. What is the chemical nature of enzyme?

    Ans:     Most enzyimes are proteins. Some are nucleic acids (RNA) like

    1. What is active site of enzyme? Give its function.

    Ans:    The globular structure of encsule has at least one surface region.This region has a croice or pocket. Ibis crevice occupies only a small portion of the surface of enzymes. It is known as the enzyme’s active site. Active site has a specific shape. Therefore, a substrate molecule fifs into it in a very specific way.

    1. What are the components of active site?

    Ans: The active site has two components: Binding site: It recognizes the specific substrate and forms enzyme substrate complex. This reaction activates the catalytic site. Catalytic site: The activated catalytic site changes the substrate into products.

    1. What is key and lock model?

    Ans: Emil Fischer proposed the lock and key model in 1890. According to this model a specific enzyme can transform only specific substrate into products. According to this model, the active site is a rigid structure. It cannot be changed during any step of the reaction.

    1. What is induced fit Model? Give its significance.

    Ans: This model was proposed by Koshland in 1959. He proposed this model on the basis of new evidences, lie describes that when a substrate combines with an enzyme, it induces changes in the active site. These chanties enable the enzyme to perform its catalytic activity. ‘

    1. What are cofactors? Give examples.

    Ans: The metal ions which are loosely attachedwith,the enzymes are called cofactors. These metal ions are Ca, Mg. Mii2, Cu”, and Zn.

    1. Differentiate between coenzyme anti prosthetic groups.

    A ns:     Coenzymes are non protein, organic molecules that participate in enzyme-catalyzed reactions. The covalent’s bonded non-protein part cofactors are called prosthetic group.


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    1. What is allosteric site? Give its function.

    Ans: Some enzymes have special allosteric site. Some specific effectors can bind with this allosteric site A I losterie enzymes change their structure in response to binding of eflectors.

    1. Differentiate between apoenzyme and holoenzyme.

    Ans: Some enzymes require prosthetic group for their normal activities. Prosthetic group is firmly bound to the enzy me. It activates the enzy me. Hie inactive enzy me ss ithout prosthetic group is called apoenzyme. The actise cut) me ss ith attached prosthetic group is called holoenzy me.

    1. What are Oxidoreductases? Give examples.

    Ans:      These enzymes caulk ie biological oxidations and reductions.They are further subdivided into oxidases, peroxidases, catalases, dehydrogenases and reductase.

    1. What are Hydrolases? Give two examples.

    Ans: These enzymes catalyses the hydrolysis of the molecules of organic foods, polysaccharides, fats and proteins. In the process the large food molecules are split into smaller fragments by the addition of water. Thus these enzymes are also called digestive or hydrolytic enzymes. Examples: Maltase, pepsin

    1. What is activation energy? How is it lowered?

    Ans: Activation energy is the minimum energy that is required to start a reaction. Enzyme lowers the activation of energy. The reaction can take place in the absence of enzyme. But it needs higher amount of activation energy.

    1. What are ligases? Give their function?

    Ans: These enzymes link two molecules along with the breakdown of a pyrophosphate bond (PP). of ATP. They are also called synthetases.

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