Tag: enzymes

Questions Related to enzymes

Which is not a trait of enzymes?

  1. Proteinaceous nature

  2. Specific in nature

  3. Speed up rate of biochemical reaction

  4. Used up in reaction


Correct Option: D
Explanation:

Enzymes are proteins which help to catalyze the biochemical reaction. The enzyme has a protein part which is not active is known as apoenzyme. It gets activated by the addition of an organic or inorganic cofactor. It is specific in nature as specific substrate bind at the active site of a particular enzyme. It increases the rate of chemical reactions without being used up. The enzymes lower the activation energy and lead to the formation of activated complex, which is also known as transition state and finally changes to the product.

So, the correct answer is option D.

Enzymes exist in the cells as

  1. Solid

  2. Crystals

  3. Solution

  4. Colloid


Correct Option: D
Explanation:

Enzymes are proteins which help to catalyze the biochemical reaction. The enzyme has a protein part which is not active is known as apoenzyme. It gets activated on the addition of an organic or inorganic cofactor. It exists as hydrophilic colloid in the cytoplasm which makes it inert and prevents its dissociation. The hydrophilic part of the colloid is present on the surface which interacts with the water. 

Which is wrong about enzymes?

  1. Enzymes are mostly proteins but some are lipids also

  2. Enzymes are highly specific

  3. Enzymes require optimum pH and temperature for maximum activity

  4. Enzymes are denatured at high temperature


Correct Option: A
Explanation:
Enzymes are made up of proteins which accelerates the rate of the reaction. It lowers the activation energy and converts the reactants into the substrate. The increased temperature increases the kinetic energy of the enzymes which further accelerates the activity of the enzyme but at the higher temperature, it gets denatured as the peptide bonds between the proteins molecules breaks which disrupts the structure of enzymes. 
Enzymatic activity depends on specific pH. pH at which the enzyme has maximum activity is known as optimum pH. The change in pH changes the shape of the enzyme which prevents the attachment of the substrate at the active site and terminates the reaction. 
Enzymes are specific in nature. It forms an enzyme-substrate complex by attaching to the active site of the enzyme which depends specifically on the shape of the active site and the substrate molecules.
So, the correct answer is option A.

Which is true about enzymes?

  1. All enzymes are not proteins

  2. All enzymes are vitamins

  3. All enzymes are proteins

  4. All proteins are enzymes


Correct Option: A
Explanation:

Enzymes are protein in nature. But some enzymes like ribozymes and ribonuclease are RNA based enzymes. It is also known as ribonucleic acid enzymes. These are RNA molecules which helps in the catalysis of a particular reaction. It was discovered in year 1982. The RNA can act as both genetic material and can act as a biocatalyst but different from protein-based enzymes. It acts as a part of ribosome which attaches to the amino acid during protein synthesis. Thomas R. Cech and Sidney Altman discovered catalytic properties of RNA. So, the correct answer is option A.

Enzymes functional in a cell are

  1. Inducible, constitutive and repressible

  2. Inducible and repressible

  3. Inducible only

  4. Repressible only


Correct Option: A
Explanation:

Enzymes are inducible in nature because as the substrate molecules attaches to the active site of the enzyme, it induces a conformational change on the active site to fit in properly.

Constitutive protein are the protein which are constantly active. Enzymes are said to be consitutive in nature as they remain active till the end of the reaction and catalyzes the reaction without being used up.
Enzymes are repressible because their actions can be controlled by addition of an inhibitor or by regulating conditions like temperature, substrate concentration and its pH.
So, the correct answer is option A.

Most of hydrolytic reactions are

  1. Exothermic

  2. Endothermic

  3. Irreversible

  4. Reversible


Correct Option: D
Explanation:

Hydrolytic reactions are the reactions which involves breaking of the bond by the addition of water. It can be reversed by the condensation reaction where the joining of two molecule leads to release of water by formation of bonds. Saccharification is the reaction where the complex sugar molecule is broken into its component sugar molecules by hydrolysis. It can be reversed by condensation reaction.

So, the correct answer is option D.

Enzyme generally have?

  1. Same pH and temperature optima

  2. Same pH but different temperature optima

  3. Different pH but same temperature optima

  4. All wrong


Correct Option: C
Explanation:

The optimum temp of enzymes is 20-35°C. They become inactivated at very low temperature and denatured (destroyed) at very high temp i.e. greater than 45°C. Low molecular weight enzymes are comparatively more heat stable. In archaebacterium Pyrococcus furiosus, the optimum temperature of hydrogenase is greater than 95°C. This heat-stable enzyme enables Pyrococcus to grow at 100°C. The optimum pH of most endoenzyme is pH 7.0 (neutral pH). However, digestive enzymes can function at different pH. For example, salivary amylase act best at pH 6.8, pepsin act best at pH2 etc. Any fluctuation in pH from the optimum causes ionization of R-groups of amino acids which decrease the enzyme activity.

So the correct option is 'different pH but same temperature optima' 

Serine proteases are called so because they

  1. They require serine for their activity

  2. cleave after serine residues in the substate

  3. Are inhibited by the presence of free serine

  4. Have a serine residue at their active sire


Correct Option: A
Explanation:

Serine proteases are enzymes that cleave peptide bonds in proteins, in which serine serves as a nucleophilic amino acid at enzyme's active site. Serine proteases are responsible for coordinating various physiological functions including digestion, immune response, blood coagulation, and reproduction. Hence, serine proteases are called so because they require serine for their activity.

So, the correct answer is 'They require serine for their activity'.

Specific enzymes are needed for the break-down of a particular substance.

  1. True

  2. False

  3. Either

  4. Neither


Correct Option: A
Explanation:
Enzymes are very specific for the substances they act upon and cause their breakdown. For example, cellulase enzyme breakdowns cellulose, protease enzyme breakdowns proteins, pectinase enzyme breakdowns pectin, hemicellulose enzyme breakdowns hemicellulose and many more such enzymes are there. Enzymes are biological catalysts which increase the rate of reaction by lowering the energy of activation. High specificity is a characteristic feature of enzymes.
Hence, the statement given in the question is correct.
So, the correct answer is 'True'

Mark the INCORRECT statement about the enzyme carboxypeptidase.

  1. Zinc is the co-factor for this proteolytic enzyme

  2. It is exopeptidase

  3. It cleaves the peptide bond at N-terminal end of the polypeptide chain

  4. It is an enzyme of pancreatic juice


Correct Option: A