Which of the following best describes a protein domain?Question 19Select one:a.The β-pleated sheet portion of a protein.b.A discrete region of polypeptide chain that has folded into a self-contained three-dimensional structure.c.The α-helical portion of a protein.

What does the quaternary structure of a protein involve?Question 21Select one:a. partial denaturation.b.random coil alternating with α-helixc.the complete three-dimensional conformation.d.The arrangement of two or more polypeptide subunits into a single functional complex.

How does a SH2 domain-containing protein confer specificity to binding to a receptor tyrosine kinase?Group of answer choicesThrough non-covalent binding.With a domain showing high affinity for the neighboring amino acid sequence that neighbors a specific tyrosine.With a domain binding to tyrosine in its non-phosphorylated state.Answers a. and b. are correct.Answers a., b., and c. are correct.

Which of the following help maintain the three-dimensional structure of a typical protein?   1. Attractions between residues with opposite charges  2. Interconversions between alpha helices and beta sheets  3. Disulfide bonds between cysteine residues  4. Hydrogen bonding between different amino acids in a polypeptide chainGroup of answer choices1, 3, 41 and 22, 3, 42 and 4All of 1-4

Which of the following is not a domain in the three-domain system?

Section A Multiple choice (3 marks)1. Which statement best explains why proteins are polymers that can have such a large rangeof structures?A. Each individual cell has a unique proteome.B. Each protein can be folded into many different three-dimensional shapes.C. All proteins are polymers of an amino acid.D. There are twenty kinds of amino acids that can be used as monomers for polypeptides.2. Which of the following contribute to the almost infinite variety of peptide chains?I. The sequence of amino acids in the peptide chain.II. The peptide bonds in the polypeptide chain.III. The types of carbohydrate monomers in the peptide chain.IV. Mutations in protein structure.A. All of the above.B. I, II and III only.C. I only.D. I and IV only3. Which is the most accurate description of, “denaturation”?A. The effect of temperature on proteins.B. The change in properties of peptides.C. The change in structure of a peptide.D. The effect of pH on protein structure