Biology · Chemistry

Biomolecules and Enzymes

1,501 Questions

This topic focuses on biomolecules, specifically proteins, enzymes, and amino acids. It includes questions on enzyme structures, protein folding, and catalysis. These concepts are crucial for medical and biology competitive exams.

Enzyme catalysisProtein structuresAmino acid synthesisPolypeptide chainsBiomolecule properties

Biomolecules and Enzymes Questions

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

 Identify the correct statement regarding enzymes:

  1. Enzymes are specific biological catalysts that can normally function at very high temperature

  2. Enzymes are normally heterogeneous catalysts that are very specific in action.

  3. Enzymes are specific biological catalysts that cannot be poisoned

  4. Enzymes are specific biological catalysts that possess well defined active site
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Enzymes are specific biological catalysts that possess well defined active site.
Enzymes function at physiological temperature $ \displaystyle \simeq (37 : ^oC)$


Enzymes can be poisoned using suitable inhibitors.

Hence, the correct option is $\text{D}$

Multiple choice chemistry surface chemistry enzyme catalysis catalysis proteins and enzymes

Which of the following statements regarding enzyme inhibition is correct -

  1. Competitive inhibition is seen when a substrate competes with an enzyme for
    binding to an inhibitor protein

  2. Non-competitive inhibitors often bind to the
    enzyme irreversibly

  3. Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme

  4. Non-competitive inhibition of an enzyme can be overcome by adding large amount of substrate
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
Competitive inhibition is seen when the substrate and the inhibitor compete for the active site on the enzyme because competitive inhibitor has a similar structure as that of a substrate, so it blocks the active site of an enzyme thereby reducing the production formation.
Multiple choice bio-chemistry biological molecule lipids and their function some biomolecules lipids

Identify the incorrectly matched pair.

  1. Ferritin - storage protein

  2. Stearic acid - unsaturated fatty acid

  3. Tyrosine - aromatic amino acid

  4. Vinblastin - alkaloid
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Fatty acids are of two types based on the single and double bonds in their hydrocarbon chain. The saturated fatty acids have only single bonds in their hydrocarbon chain. These are mostly obtained from an animal source. They exist as solids at room temperature. The unsaturated fatty acids have both the single and double bonds in their hydrocarbon chain. These are mostly derived from plant sources. They exist as a liquid at room temperature.

A. Ferritin is iron-storing protein.
B. Stearic acid is a saturated fatty acid made up of 18-carbons.
C. Tyrosine is an aromatic amino acid with a benzene ring.
D. Vinblastin is a vinca alkaloid obtained from the plant Vinca rosea.
Hence, the correct answer is 'Stearic acid- unsaturated fatty acid'

Multiple choice biology simple nutrients into cells blood and its components components of blood composition of blood

Most of the blood proteins are

  1. Acidic

  2. Basic

  3. Neutral

  4. All the above in equal proportions
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Blood proteins are different types of proteins found in blood plasma. These include majorly albumin, globulin, fibrinogen and other regulatory proteins which function as enzymes or hormones. Albumin alone accounts for 55% of the total blood proteins and is acidic in nature. It creates and maintains osmotic pressure of plasma and also helps in the transport of lipids and steroid hormones. Globulin is slightly basic and accounts for 38% of blood proteins. It participates in immune system. Fibrinogen comprises 7% of blood proteins and help in blood clotting.

Thus, the correct answer is option A. 

Multiple choice biology simple nutrients into cells blood and its components components of blood composition of blood

Bilirubin and biliverdin are derived from

  1. Globin

  2. Heme

  3. Iron

  4. Fat
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Bilirubin and biliverdin are derived from heme. The component of haemoglobin responsible for binding oxygen, consists of an iron ion, that binds oxygen and a porphyrin ring, that binds the globin molecules; one molecule binds one molecule of oxygen. Biliverdin results from the breakdown of the heme moiety of hemoglobin in erythrocytes. Bilirubin is the yellow breakdown product of normal heme catabolism, caused by the body's clearance of aged red blood cells which contain hemoglobin.

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

Primary structure of a protein is?

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

Most common types of secondary structures of proteins are?

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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.
Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

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:

  1. peptide bonds

  2. van der Waals forces

  3. hydrogen bonds

  4. dipole-dipole interactions
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

Cheese is a

  1. Glubular protein

  2. Conjugated protein

  3. Denatured protein

  4. Derived protein
Reveal answer Fill a bubble to check yourself
C Correct answer
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. 

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

Denaturation of proteins can be carried out by

  1. heat

  2. mineral acids

  3. bases

  4. all of the above
Reveal answer Fill a bubble to check yourself
D Correct answer
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.

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

Enzymes are

  1. Carbohydrates

  2. Nucleic acids

  3. Globular proteins

  4. Fibrous proteins
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $pH$.

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

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

  1. disulphide bridges

  2. hydrogen bonding within the backbones
  3. hydrogen bonding between $R$ group

  4. salt bridges
Reveal answer Fill a bubble to check yourself
B Correct answer
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
Multiple choice bio-chemistry proteins denaturation of protein proteins and amino acids proteins and enzymes

The sequence in which the $\alpha$-amino acids are linked to one another in a protein molecule is called its:

  1. primary structure

  2. secondary structure

  3. tertiary structure

  4. quaternary structure
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

The primary structure of a protein is defined by the linear sequence of amino acids linked by peptide bonds. Secondary, tertiary, and quaternary structures refer to the folding and spatial arrangement of this chain.