- Question 1 of 7
1. In proteins, amino acid residues whose side chains contain hydroxyl groups can undergo phosphorylation, a process that plays a major role in regulating protein function. Which of these mutations would be expected to disrupt a phosphorylation site?
Replacement of a tyrosine residue with a phenylalanine.
Uhh no. The correct answer is:
Replacement of a tyrosine residue with a phenylalanine.
- Question 2 of 7
2. As protein-coding genes evolve, 'conservative' mutations – ones that replace an amino acid with one of similar size, polarity, and charge – often have little effect on protein function. This bit of evolutionary biology becomes clinically useful when genomic sequencing of your patient uncovers variant forms of protein-coding genes and you are asked for advice on the health implications of this finding. Which of the mutations listed here best fits the definition of 'conservative'?
Replacement of an isoleucine residue with a valine.
Uhh no. The correct answer is:
Replacement of an isoleucine residue with a valine.
- Question 3 of 7
3. Two proteins are found to have the same mass and the same numbers of copies of each kind of amino acid residue.
None of these statements is true.
Uhh no. The correct answer is:
None of these statements is true.
- Question 4 of 7
4. If a mixture of proteins is subjected to electrophoresis in the absence of any denaturing agent like SDS, each protein will migrate at a rate that is a complicated function of its mass, charge, and shape (conformation). In the presence of SDS, however, each protein will migrate at a rate that is a function of:
Its mass only.
Uhh no. The correct answer is:
Its mass only.
- Question 5 of 7
5. You are investigating a tumor found in workers exposed to asbestos and have just isolated a protein secreted in large amounts by tumor cells but not by normal ones. A colleague in the bioinformatics lab says that if you could tell her the sequence of the first 10 amino acid residues in the protein, she could probably do a computer analysis to identify the gene that encodes your protein. A good technique to get this information would be to:
Subject the protein to Edman degradation.
Uhh no. The correct answer is:
Subject the protein to Edman degradation.
- Question 6 of 7
6. A common structural feature of proteins folded in their native conformations involves segments of polypeptide chain from several different parts of the protein’s primary sequence. Successive segments in this structure are oriented in opposing amino-to-carboxyterminal senses, and all atoms in the peptide backbone capable of forming hydrogen bonds have done so. This structural feature is:
An anti-parallel beta-pleated sheet.
Uhh no. The correct answer is:
An anti-parallel beta-pleated sheet.
- Question 7 of 7
7. Two different drugs inhibit a viral enzyme that follows Michaelis-Menten kinetics. One drug acts as a competitive inhibitor, while the other acts as a non-competitive inhibitor. Which drug will affect the Vmax of the enzyme?
Only the drug that acts as a non-competitive inhibitor will affect it.
Uhh no. The correct answer is:
Only the drug that acts as a non-competitive inhibitor will affect it.