BIO 351 FINAL Practice Questions for Chapter 4 (Proteins)

How many amino acids and peptide bonds does a tetrapeptide have?

Which parts of the amino acids AA1 and AA2 are involved in the formation of a peptide bond?

AA1-AA2

Which part of an amino acid gives it its unique identity?

Ovalbumin, the egg white protein is denatured in scrambled egg. Which of the following is not affected?

Which of the following statements about proteins is true?

You have just sequenced a new protein isolated from mice and observe that sulfur-containing cysteine residues occur at regular intervals. "This finding is most consistent with which of the following claims about the protein?

Use the following information to answer the following questions.

"The native structure of hemoglobin (HB) comprises of two a and two ß subunits, each of which carries a heme group. There appear to be no previous studies that report the in-vitro folding and assembly of Hb from highly unfolded a and ß globin in a 'one-pot' reaction. One difficulty that has to be overcome for studies of this kind is the tendency of Hb to aggregate during refolding. This work demonstrates that denaturation of Hb in 40% acetonitrile at pH 10.0 is reversible." (J Am Soc Mass Spectrum 2007, 18, 8-16)

In sickle-cell disease, as a result of a single amino acid change, the mutant hemoglobin tetramers associate with each other and assemble into large fibers. Based on this information alone, what does the sickle-cell hemoglobin exhibit?

Which of the following can be used to predict the 3-D structure of the protein?

Misfolding of polypeptides is a serious problem in cells. Which of the following diseases are associated with an accumulation of misfolded polypeptides?

Use the following figure to answer the question.

Which of the following chemical reactions is represented in the figure?

Which of the following pairs of amino acid residues would you expect to form ionic bonds?

Which of the following stretches of amino acid residues would you expect to find in the interior of protein molecules?

The observation that proteins often renature into their original conformations after they have been unfolded by denaturing solvents implies that ...

Complete the sentence with the best option provided below. The primary structure of a protein is the

To study how proteins fold, scientists must be able to purify the protein of interest, use solvents to denature the folded protein, and observe the process of refolding at successive time points. What is the effect of the solvents used in the denaturation process?

Which of the following statements is TRUE?

Protein folding can be studied using a solution of purified protein and a denaturant (urea), a solvent that interferes with noncovalent interactions.
Which of the following is observed after the denaturant is removed from the protein solution?

The correct folding of proteins is necessary to maintain healthy cells and tissues. The presence of unfolded proteins is associated with some neurodegenerative disorders as Alzheimer's disease. Huntington's disease, and Creutzfeldt-Jakob disease (the specific faulty protein is different for each disease). What happens to these disease-causing, unfolded proteins?

Some proteins have a helices, some have B sheets, and still others have a combination of both. What makes it possible for proteins to have these common structural elements?

Which of the following is NOT a feature commonly observed in B sheets?

Protein structures have several different levels of organization. The primary structure of a protein is its amino acid sequence. The secondary and tertiary structures are more complicated. Consider the definitions below and select the one that best fits the term "protein domain."

Proteins bind selectively to small-molecule targets called ligands. The selection of one ligand out of a mixture of possible ligands depends on the number of weak, noncovalent interactions in the protein's ligand-binding site. Where is the binding site typically located in the protein structure?

Studies conducted with a lysozyme mutant that contains an Asp->Asn change at position 52 and a Glu->Gin change at position 35 exhibited almost a complete loss in enzymatic activity. What is the most likely explanation for the decrease in enzyme activity in the mutant?