Structural organisation of proteins

Multiple Choice

Which of the following statements about proteins is correct?

• All proteins have the same sequence of amino acids.

• Proteins are made up of only 20 different amino acids.

• The function of a protein does not depend on its structure.

• Proteins do not have a unique 3D structure.

Open Ended

Why is the 3D structure of a protein important for its function?

Multiple Choice

Which of the following best describes the primary structure of a protein?

• The sequence of amino acids in a polypeptide chain

• The folding of the polypeptide chain into alpha helices and beta sheets

• The overall three-dimensional shape of a single polypeptide chain

• The arrangement of multiple polypeptide subunits

Multiple Choice

What is the significance of peptide bonds in the primary structure of proteins?

• They hold amino acids together in a polypeptide chain

• They stabilize the tertiary structure

• They form hydrogen bonds between chains

• They link multiple polypeptide subunits

Multiple Select

Which of the following statements about the primary structure of insulin are correct?

• It consists of two peptides with 21 and 30 amino acids

• It contains two inter-chain disulfide bonds

• It contains one intra-chain disulfide bond

• It is stabilized by hydrogen bonds

Multiple Choice

Which of the following are the two main regular forms of secondary structure in proteins?

• α-helix and β-pleated sheets

• Triple helix and β-bend

• α-helix and triple helix

• β-turn and β-pleated sheets

Multiple Select

Select all the features that correctly describe the α-helix structure of proteins.

• Right-handed spiral

• Stabilized by hydrogen bonds

• Side chains extend inward

• Formed by twisting the polypeptide backbone

Multiple Choice

Which amino acids are known to destabilize the α-helix structure?

• Glycine and proline

• Alanine and leucine

• Serine and threonine

• Valine and isoleucine

Multiple Choice

What is the main difference between parallel and antiparallel β-sheets?

• The direction of the N- and C-terminals in the polypeptide chains

• The number of polypeptide chains involved

• The presence of hydrogen bonds

• The type of amino acids present

Multiple Choice

Which of the following is NOT a force that stabilizes the tertiary structure of a protein?

• Peptide bonds

• Hydrogen bonds

• Disulfide bonds

• Van der Waals forces

Multiple Select

Which of the following statements about quaternary structure of proteins are correct?

• It involves multiple polypeptide chains.

• It is found in all proteins.

• Subunits may be structurally identical or unrelated.

• It is stabilized only by covalent bonds.

Multiple Choice

What type of interaction primarily maintains the association between the four subunits of hemoglobin?

• Ionic interactions

• Peptide bonds

• Phosphodiester bonds

• Glycosidic bonds