Biology ยท 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

Each antibody is a four polypeptide chain with

  1. three light chains and one heavy chain

  2. one light chain and three heavy chains

  3. two light chains and two heavy chains

  4. four light chains and no heavy chain
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Each antibody is a four polypeptide chain with two light chains and two heavy chains.

Multiple choice

Which among the following is a nonessential amino acid?

  1. Isoleucine

  2. Leucine

  3. Lysine

  4. Asparagine
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Asparagine is one of the 20 most common natural amino acids on Earth. It has carboxamide as the side-chain's functional group. It is a nonessential amino acid. Its codons are AAU and AAC.

Multiple choice

Which of the following amino acids plays its role in the urea cycle?

  1. Methionine

  2. Taurine

  3. Ornithine

  4. Histidine

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Ornithine is an amino acid that plays a role in the urea cycle. L-Ornithine is one of the products of the action of the enzyme arginase on L-arginine, creating urea. Therefore, ornithine is a central part of the urea cycle, which allows for the disposal of excess nitrogen.

Multiple choice

The carboxylate anions of ________ amino acids are important neurotransmitters.

  1. Proline

  2. Glutamine

  3. Glutamic acid

  4. Cysteine
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Glutamic acid is one of the 20 proteinogenic amino acids, and its codons are GAA and GAG. It is a non-essential amino acid. The carboxylate anions and salts of glutamic acid are known as glutamates. In neuroscience, glutamate is an important neurotransmitter that plays a key role in long-term potentiation and is important for learning and memory.

Multiple choice

Egg ovalbumin and milk casein are the examples of _______ proteins.

  1. Structural proteins

  2. Motor proteins

  3. Signalling proteins

  4. Storage proteins
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

These proteins contain energy, which can be released during metabolism processes in the organism. Egg ovalbumin and milk casein are such proteins. Almost all proteins can be digested and used as a source of energy and building material by other organisms.

Multiple choice

The protein structure defining the protein molecule in 3d is

  1. Quaternary structure

  2. Ternary structure

  3. Secondary structure

  4. Primary structure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

One of the main conformational parameter of the amino acid structure is the value of the PHI and PSI angles. These angles completely define the conformation of the polypeptide chain. With some special values for these angles the main chain can adopt specially classified conformations, like alpha-helix or beta-strand. The other main feature of the protein secondary structure is the local stabilisation by hydrogen bonds. These conformations are classified as a protein secondary structure.

Multiple choice

The phosphodiester linkages are present in

  1. Proteins

  2. Polysaccharides

  3. Lipids

  4. Nucleic acids

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Nucleic acids are linear polymers (chains) of nucleotides. Each nucleotide consists of three components: a purine or pyrimidine nucleobase (sometimes termed nitrogenous base or simply base), a pentose sugar; and a phosphate group. The sugars and phosphates in nucleic acids are connected to each other in an alternating chain (sugar-phosphate backbone) through phosphodiester linkages.

Multiple choice

The patterns of hydrogen bonds between backbone amide and carboxyl groups are observed in

  1. Primary structures of proteins

  2. Secondary structures of proteins

  3. Tertiary structure of protein

  4. Quaternary structure of protein

Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In proteins, the secondary structure is defined by the patterns of hydrogen bonds between backbone amide and carboxyl groups. The hydrogen bonding patterns may be significantly distorted, which makes an automatic determination of secondary structure difficult.