Tag: proteins and enzymes

Questions Related to proteins and enzymes

Enzymes, which catalyze biochemical reactions are very complex. They help in the reaction of very specific substances. This suggests that the enzyme and the reacting biochemicals are complementary to one another like a:

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. dog in his kennel

  2. horse and a rider

  3. lock and key

  4. leaf and a bud

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Correct Option: C
Explanation:

Enzymes are very specific in nature. Only those substrates that can fit into the active site of an enzyme can be bound within it. This specific action is similar to a lock and key where a key(reacting biochemicals) can only be used to actuate a specific lock(enzyme) and not all of them. 

Which of the following factors are responsible for the increase in the rate of a surface catalysed reaction?
I. A catalyst provides proper orientation for the reactant molecules to react
II. Heat of adsorption of reactants on a catalyst helps reactant molecules to.overcome activation energy
III. The catalyst increases the activation energy of the reaction 
IV. Adsorption increases the local concentration of reactant molecules on the surface of the catalyst
Select the correct answer using the codes given below:

chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

  1. I and II

  2. I and III

  3. I, II and IV

  4. I, II and III

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Correct Option: A
Explanation:

A catalyst works by providing an alternative reaction pathway to the reaction product. The rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.

Primary structure of a protein is?

bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

  1. sequence in which $\alpha-$ amino acids are linked to one another

  2. sequence in which amino acids of one polypeptide chain are joined to other chains

  3. the folding patterns of polypeptide chains

  4. the pattern in which the polypeptide chain are arranged

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Correct Option: A
Explanation:
The primary structure of a protein refers to the sequence of amino acids in the polypeptide chain. The primary structure is held together by peptide bonds that are made during the process of protein biosynthesis.

Most common types of secondary structures of proteins are?

bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

  1. $\alpha-$ helix and $\beta-$ helix structures

  2. $\alpha-$ helix and $\beta-$ pleated structures

  3. right and left hand twisted structures

  4. globular and fibrous structures

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Correct Option: B
Explanation:
The most common types of secondary structures are the $\alpha$ helix and the $\beta$ pleated sheet. Both structures are held in shape by hydrogen bonds, which form between the carbonyl O of one amino acid and the amino H of another.

Proteins are found to have two different types of secondary structures vix. $\alpha-$ helix and $\beta-$ pleated sheet structure, $\alpha-$ helix structure of a protein is stabilised by:

bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

  1. peptide bonds

  2. van der Waals forces

  3. hydrogen bonds

  4. dipole-dipole interactions

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Correct Option: C
Explanation:

Answer:- (C) hydrogen bonds

Two major factors stabilize the $\alpha$-helix structure are intrachain H-bonding and minimization of steric interference between side chains.

In $\alpha$-helix structure, polypeptide chains are folded in a:

bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

  1. right hand side

  2. left hand side

  3. both way

  4. none of these

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Correct Option: C
Explanation:

In $\alpha -$helix structure, polypeptide chains are folded in a both way (heft hand and write hand).

Cheese is a

bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

  1. Glubular protein

  2. Conjugated protein

  3. Denatured protein

  4. Derived protein

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Correct Option: C
Explanation:

Cheese is a denatured protein. When producing (hard or semi-hard) cheese, the cheese yield can be increased by subjecting part of the cheese milk to a high temperature heat treatment. Thermal denaturation of whey proteins changes the protein structure so that part of the whey remains in the curd during the cheese-making process. 

Denaturation of proteins can be carried out by

bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

  1. heat

  2. mineral acids

  3. bases

  4. all of the above

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Correct Option: D
Explanation:

Denaturation of proteins can be carried out by heat, mineral acids or bases. Denaturation is a process in which proteins lose their quaternary, tertiary and secondary structure which is present in their native state by application of some external stress or compound, such as a strong acid or base, a concentrated inorganic salt, an organic solvent, radiation or heat. If proteins in a living cell are denatured, it results in disruption of cell activity and possibly cell death. Denatured proteins can exhibit a wide range of characteristics from loss of solubility to communal aggregation.

Enzymes are

bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

  1. Carbohydrates

  2. Nucleic acids

  3. Globular proteins

  4. Fibrous proteins

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Correct Option: C
Explanation:

Option (C) is correct.
Enzymes are globular proteins, and catalyze metabolic reactions in living organisms.
They have a specific tertiary structure with an active site complementary to the substrate. They can speed up a reaction but do not get used up. Their activity can be affected by temperature and $pH$.

The type of bond that is most important in maintaining secondary structure of a protein is 

bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

  1. disulphide bridges

  2. hydrogen bonding within the backbones

  3. hydrogen bonding between $R$ group

  4. salt bridges

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Correct Option: B
Explanation:
Secondary structure of a protein is generally maintained y hydrogen bonding between the $-NH$ group of one amide and the $C=O$ group of another amide