Proteins: peptide bond, structure levels, denaturation

27 questions on Proteins: peptide bond, structure levels, denaturation from the Biomolecules chapter: 5 NEET level, 11 JEE Main, 11 JEE Advanced. Each one opens with its answer and solution.

• The linkage joining two amino acids in a protein is NEET level
• The alpha-helix secondary structure of a protein is stabilised by NEET level
• On denaturation of a protein, which structure remains intact? NEET level
• Which of the following is a fibrous protein? NEET level
• In the dipeptide Gly-Ala (written from N-terminal to C-terminal), the amino acid with the free -NH2 (or -NH3+) group is NEET level
• The number of peptide bonds in a linear octapeptide is JEE Main level
• The peptide bond -CO-NH- has partial double-bond character and the six atoms around it lie in one plane. The cause is JEE Main level
• The number of different tripeptides that can be made by joining three different amino acids, each used exactly once, is JEE Main level
• Which of the following interactions stabilising tertiary structure is a covalent bond? JEE Main level
• Which statement correctly describes the denaturation of a protein by heat? JEE Main level
• Complete hydrolysis of one mole of the pentapeptide Ala-Gly-Ala-Gly-Gly gives JEE Main level
• Assertion (A): Curdling of milk is an example of denaturation of protein. Reason (R): Lactic acid produced by bacteria lowers the pH and unfolds the milk protei... JEE Main level
• In the tripeptide Gly-Ala-Ser (N-terminal to C-terminal), which residue uses both its amino group and its carboxyl group in forming peptide bonds? JEE Main level
• Which statement about the alpha-helix is correct? JEE Main level
• Which statements about the peptide bond in proteins are correct? JEE Main level
• Which of the following proteins are fibrous? JEE Main level
• Using only glycine and alanine, with repetition allowed, the number of different linear tripeptides that contain at least one residue of each of the two amino a... JEE Advanced level
• A polypeptide has molar mass 12000 g/mol and contains 10 cysteine residues, all of which are oxidised pairwise to disulfide bridges (no other change; atomic mas... JEE Advanced level
• Molar masses of the free amino acids: glycine 75, alanine 89, serine 105 g/mol (water 18 g/mol). The molar mass of the tripeptide Gly-Ala-Ser is JEE Advanced level
• The tetrapeptide Ala-Gly-Ser-Val (N-terminal to C-terminal) is partially hydrolysed. Counting every distinct free amino acid, dipeptide and tripeptide that can ... JEE Advanced level
• Which statement about protein structure is INCORRECT? JEE Advanced level
• A cyclic pentapeptide is formed by head-to-tail condensation of five amino acid molecules. The number of water molecules consumed when one molecule of it is com... JEE Advanced level
• The tetrapeptide Gly-Ala-Ser-Val is written from the N-terminal to the C-terminal end. Which statements are correct? JEE Advanced level
• Which of the following pairs of side chains can stabilise tertiary structure through the stated interaction? JEE Advanced level
• Which statements about secondary structures of proteins are correct? JEE Advanced level
• Which statements about the levels of protein structure are correct? JEE Advanced level
• A linear homopolypeptide made only of glycine has molar mass 5718 g/mol. Taking molar masses of glycine = 75 g/mol and water = 18 g/mol, the number of peptide b... JEE Advanced level