Tag: enzymes

Questions Related to enzymes

Enzymes that catalyse removal of groups from substrates by mechanisms other than hydrolysis, and addition of groups to double bonds, are called
properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. Ligase

  2. Lyase

  3. Hydrolase

  4. Dehydrogenase

Show answer
Correct Option: B
Explanation:

Lyases enzymes catalyse the breakage of specific covalent bonds and removal of group with out hydrolysis producing double bonds or removal of double bonds by adding group,e.g., histidine decarboxylase that splits $C-C$ bond of histidine,forming $CO _2$ and histamine.

${\overset{X}{\overset{|}C}}-{\overset{Y}{\overset{|}C}} \xrightarrow{lyase}X-Y+C=C$

Relationship between genes and enzymes was discovered by

properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. Waldeyer

  2. W. Johannsen

  3. Bridges

  4. Beadle and tatum

Show answer
Correct Option: D
Explanation:

Sir Archibald Garrod proposed that one enzyme is encoded by one gene. This hypothesis called One gene One enzyme hypothesis, was experimentally proved by Beadle and Tatum by using bread mould Neurospora. Beadle and Tatum showed bread mould mutants that were unable to make specific amino acids. In each one, a mutation had disrupted an enzyme needed to build a certain amino acid. This was caused due to specific gene mutation.

Hence, the correct answer is 'Beadle and Tatum'

The hydrolytic enzymes acting at low pH are

properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. $\alpha$-amylases

  2. Hydrolases

  3. Proteases

  4. Pyrimidases

Show answer
Correct Option: C
Explanation:

A protease (also called peptidase or proteinase) is any enzyme that performs proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein. Proteases may be classified by the optimal pH in which they are active: acid proteases or neutral proteases or basic proteases.

Holoenzyme is the complete enzyme consisting of an apoenzyme and a co-factor. Select the option that correctly identifies the nature of apoenzyme and co-factor.
properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. Apoenzyme - Protein
    Co - factor - Non-Protein

  2. Apoenzyme - Non - Protein
    Co - factor - Protein

  3. Apoenzyme - Protein
    Co - factor - Protein

  4. None of the above

Show answer
Correct Option: A
Explanation:

Conjugated enzymes ( holoenzymes) are formed of two parts a protein part called apoenzyme and a non-protein part named co-factor. The complete conjugated enzyme consisting of an apoenzyme and a co-factor is called holoenzyme. Holoenzyme is the functional unit of enzyme. 

${\underset{(active\,\, enzyme)}{Holoenzyme}}$ $\rightarrow$  ${\underset {(protein\,\, part)}{Apoenzyme}}$ $+ co-factor$
Co-factor may be inorganic or organic in nature. Catalystic activity is lost when co-factor is removed from the enzyme which indicates that it plays a crucial role in catalytic activity of enzymes.
So, the correct answer is 'Apoenzyme - Protein, Co - factor - Non-Protein'.

With reference to enzymes, which one of the following statements is true?

properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. Apoenzyme = Holoenzyme+ Coenzyme

  2. Holoenzyme= Apoenzyme + Coenzyme

  3. Coenzyme= Apoenzyme + Holoenzyme

  4. Holoenzyme= Coenzyme+ Apoenzyme

Show answer
Correct Option: B
Explanation:
Enzymes work efficiently in association with various factors which enhances it's activity. These factors may be;

Coenzymes are organic molecules that are mostly derivatives of vitamins soluble in water by phosphorylation. Example of coenzyme include thiamine pyrophosphate (TPP), flavin adenine dinucleotide (FAD), biotin

Apoenzyme is an inactive form of enzyme lacking the association of coenzyme and/or cofactors. Activation of the enzyme occurs upon binding of an organic or inorganic cofactor.

Holoenzyme is a complete and catalytically active form of enzyme. An apoenzyme together with its cofactor is holoenzyme.  Examples of holoenzymes include DNA polymerase and RNA polymerase which contain multiple protein subunits.

So the correct option is 'Holoenzyme= Apoenzyme + Coenzyme'.

Arrange the steps of catalytic action of an enzyme in order and select the correct option.
I.   The enzyme release the products of the reaction      and the enzyme is free  to bind to another                substrate.
II.  The active site of enzyme is in close proximity of      the substrate and breaks the chemical bonds of     the subtrate.
III. The binding of sustrate induces the enzyme to          alter its shape fitting more tightly around the           sustrate. 
IV.The substrate binds to the active site of the              enzyme.

properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. IV, III, II, I

  2. III, II, I, IV

  3. IV, II, I, III

  4. II, I, IV, III

Show answer
Correct Option: A
Explanation:
Four Steps of Enzyme Action:
1) The enzyme and the substrate are in the same area. Some situations have more than one substrate molecule that the enzyme will change.
2) The enzyme grabs on to the substrate at a special area called the active site. A process called catalysis.
3) The binding of substrate induces the enzymes to alter its shape to fit around the substrate. 
4) The enzyme breaks the chemical bonds of the substrate and releases the product of the reaction and the enzyme is free to bind to another substrate.

So, the correct option is 'IV, III, II, I'.

The inorganic catalyst attached to enzymes is called

properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. Apoenzyme

  2. Lysozyme

  3. Activator

  4. Inhibitor

Show answer
Correct Option: C
Explanation:

An activator is an inorganic catalyst attached to enzymes. The bind to the enzyme and increase its activity. 

So, the correct option is 'Activator'. 

In biochemical reactions, the enzymes act by

properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. By decreasing the energy of the reactants

  2. By increasing the activation energy of the reaction

  3. By decreasing the activation energy of the reaction

  4. By increasing the energy of the products of the reaction

  5. By decreasing the energy of the products of the reaction

Show answer
Correct Option: C
Explanation:

The minimum energy requirement that must be met for a chemical reaction to occur is called the activation energy. The activation energy is the energy difference between the reactants and the activated complex, also known as transition state. In a chemical reaction, the transition state is defined as the highest-energy state of the system. If the molecules in the reactants collide with enough kinetic energy and this energy is higher than the transition state energy, then the reaction occurs and products form. In other words, the higher the activation energy, the harder it is for a reaction to occur and vice versa. However, if a catalyst is added to the reaction, the activation energy is lowered because a lower-energy transition state is formed. Enzymes can be thought of as biological catalysts that lower activation energy. Enzymes are proteins or RNA molecules that provide alternate reaction pathways with lower activation energies than the original pathways. Enzymes affect the rate of the reaction in both the forward and reverse directions; the reaction proceeds faster because less energy is required for molecules to react when they collide. Thus, the rate constant (k) increases.
So, the correct answer is option C.

If an enzyme has been given the EC code 3.2.1.7, it is likely to be involved in

properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. Digestin

  2. Redox reaction

  3. Isomerization

  4. Molecular breakdown

Show answer
Correct Option: A
Explanation:

  • EC number is a numerical classification scheme is based on the chemical reactions which are catalyzed by them. 
  • A system of enzyme nomenclature is associated with a name for the corresponding enzyme. 
  • The number classification can be referred to that enzyme which is involved in digestion.
So, the correct option is 'Digestin'.

Division characteristic of Korpe-Kappe theory are

properties of enzyme enzyme properties enzymes biomolecules: chemical constituents of living cells biology

  1. Anticlinal

  2. T-type

  3. Periclinal

  4. Irregular

Show answer
Correct Option: A
Explanation:
The corner-Kappe theory of root apex is comparable with the tunica-corpus theory of shoot apex. The body-cap concept and tunica-corpus concept both are based solely on the planes of cell division. Anticlinal division is the characteristic of tunica whereas corpus exhibits both anticlinal and periclinal division.
So the correct option is 'Anticlinal'.