Biochemistry -At the isoelectric pH of a tetrapeptide: A. only the amino and car
ID: 1003833 • Letter: B
Question
Biochemistry
-At the isoelectric pH of a tetrapeptide:
A. only the amino and carboxyl termini contribute charge.
B. the amino and carboxyl termini are not charged.
C. the total net charge is zero.
D. there are four ionic charges.
E. two internal amino acids of the tetrapeptide cannot have ionizable R groups
-How is trypsinogen converted to trypsin?
A. A protein kinase-catalyzed phosphorylation converts trypsinogen to trypsin.
B. An increase in Ca2+ concentration promotes the conversion.
C. Proteolysis of trypsinogen forms trypsin.
D. Trypsinogen dimers bind an allosteric modulator, cAMP, causing dissociation into active trypsin monomers.
E. Two inactive trypsinogen dimers pair to form an active trypsin tetramer
-Which type of stabilizing sidechain interaction would most likely be interrupted by the presence of
organic solvents like ethanol or isopropanol?
A. Hydrogen bonds
B. Hydrophobic interactions
C. Salt bridges
D. Disulfide bond
E. Allosteric interaction
-Which of the following genetic changes in a peptide sequence would most likely result in a
functional protein?
A. Aspartic acid --> arginine
B. Glutamic acid --> glutamine
C. Glutamine --> asparagine
D. Phenylalanine --> serine
E. Phenylalanine --> tyrosine
Explanation / Answer
Biochemistry
-At the isoelectric pH of a tetrapeptide:
A. only the amino and carboxyl termini contribute charge.
B. the amino and carboxyl termini are not charged.
C. the total net charge is zero.
D. there are four ionic charges.
E. two internal amino acids of the tetrapeptide cannot have ionizable R groups
The correct answer is B. . the amino and carboxyl termini are not charged.
The isoelectric point is the pH at which a particular amino acids carries no net electrical charge.
-How is trypsinogen converted to trypsin?
The correct answer is C) Proteolysis of trypsinogen forms trypsin.
A. A protein kinase-catalyzed phosphorylation converts trypsinogen to trypsin.
B. An increase in Ca2+ concentration promotes the conversion.
C. Proteolysis of trypsinogen forms trypsin.
D. Trypsinogen dimers bind an allosteric modulator, cAMP, causing dissociation into active trypsin monomers.
E. Two inactive trypsinogen dimers pair to form an active trypsin tetramer
-Which type of stabilizing side chain interaction would most likely be interrupted by the presence of
organic solvents like ethanol or isopropanol?
The correct answer is A Hydrogen bonds
.
A. Hydrogen bonds
B. Hydrophobic interactions
C. Salt bridges
D. Disulfide bond
E. Allosteric interaction
-Which of the following genetic changes in a peptide sequence would most likely result in a
functional protein?
The correct answer is C) C. Glutamine --> asparagine
A. Aspartic acid --> arginine
B. Glutamic acid --> glutamine
C. Glutamine --> asparagine
D. Phenylalanine --> serine
E. Phenylalanine --> tyrosine
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