Exam 3: Protein Structure and Function

Consider the HIV enzyme called protease.The amino acid residues at the active site are highly hydrophobic.In designing a drug that would bind to the active site and jam it,researchers should use which type of molecule?

Figure 3.3 -In the figure above,which of the following statements is true?

Consider the experiment that Stanley Miller did to simulate chemical evolution.Recall that a glass flask held the reduced gases NH₃,CH₄,and H₂ and that the gases were exposed to electrical sparks.What is the null hypothesis in the experiment?

Which of the following would be an example of a cofactor?

Suppose you discovered a new amino acid.Its R-group contains only hydrogen and carbon atoms.Predict the behavior of this amino acid.

Recent technological advances have made it more feasible than ever to work out the three-dimensional structure of proteins.There is intense interest in this research field,called structural biology.Why?

The aquaporin family of proteins plays a major role in the transport of water all over the body.During the folding process of these proteins,α-helices start forming as

An isomer of a particular molecule is

An enzyme has a total of four active sites.When you denature the molecule and study its composition,you find that each active site occurs on a different polypeptide.Which of the following hypotheses does this observation support?

Which is not a role proteins play in organisms?

Why are polymerization reactions endergonic?

Which of the following best describes the first living entity-the one responsible for the origin of life?

A peptide bond is

What is the process component of the theory of chemical evolution?

Three important functions of proteins are cell

You are studying a protein that is shaped like a doughnut.The shape is a function of which level(s)of protein structure?

What is the pattern component of the theory of chemical evolution?

Which of the following is not true when comparing an uncatalyzed reaction to the same reaction with a catalyst?

You are studying reaction X.Which of the following scenarios would likely NOT help you to increase the rate of this reaction?

Refer to the following paragraph and figure 3.1 to answer the following questions. Figure 3.1 Since structure correlates so well with function, biochemists are constantly looking for new ways to probe the complex structure of proteins in order to understand what they do and how they do it. One of the most powerful techniques in existence today is X-ray crystallography. The main difficulty with this technique is getting the protein to crystallize. Once crystallized, the protein is bombarded with X-rays to create a pattern that can be analyzed mathematically to determine the three-dimensional structure of the protein. This analysis has been performed by Krzysztof Palczewski on the protein rhodopsin, which is a light-sensitive protein found in species ranging from ancient bacteria (archaea)to humans. The structure (schematically shown above, where each letter represents an amino acid)is characterized by a single polypeptide chain with several α-helical segments that loop back and forth across the cell membrane. Another notable feature is the disulfide bond (-S-S-)that can be seen at the bottom of the third transmembrane segment. [Figure adapted from K. Palczewski et al., Science 289 (2000): 739.] -How many times does the protein in Figure 3.1 cross the cell membrane?