Virtual Labs

Computation of various physical and chemical properties of Proteins and DNA from their primary sequence

1. The isoelectric point of an amino acid is defined as

a: pH where amino acids carboxyl group is uncharged Explanation

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b: pH of maximum electrophoretic mobility Explanation

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c: pH where amino acids amino group is uncharged Explanation

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d: pH where amino acid has a net charge of zero Explanation

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2. Which of the following amino acids has a net negative charge at physiologic pH (~7.4)?

a: Alanine Explanation

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b: Histidine Explanation

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c: Glutamic acid Explanation

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d: Glutamine Explanation

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3. Which of the following properties of a protein is least likely to be affected by changes in pH?

a: Primary structure Explanation

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b: Secondary structure Explanation

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c: Net charge Explanation

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d: Tertiary structure Explanation

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4. If a DNA sample contains 18% C on a molar basis. What will be the molar percentage of A, G, and T respectively?

a: 32,18,32 Explanation

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b: 18,32,32 Explanation

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c: 32,18,18 Explanation

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d: 32,32,18 Explanation

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5. Electrophoretic separation at pH 6 of a sample of protein A (M.W 25 kDa) , protein B (M.W 10 kDa) and protein C 3 (M.W 65 kDa) would result in which of the following? (Note: the isoelectric point of each protein occurs at pH 6)

a: Protein A would move the farthest Explanation

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b: Protein B would move the farthest Explanation

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c: Protein C would move the farthest Explanation

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d: None of the protein would move Explanation

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6. What type of bonds are formed between two amino acids?

a: Glycosidic bond Explanation

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b: Ester linkage Explanation

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c: Phosphodiester bond Explanation

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d: Peptide bond Explanation

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7. Which of the following methods can we use to check molecular weight of our protein?

a: SDS PAGE Explanation

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b: Mass spectrometry Explanation

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c: Analytical SEC Explanation

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d: All of the above Explanation

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8. In terms of DNA and RNA structure, what is a nucleotide?

a: A nucleotide is a heterocyclic base Explanation

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b: A nucleotide is a sugar molecule covalently bonded to a heterocyclic base Explanation

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c: A nucleotide is a sugar molecule bonded to phosphate group/s and a heterocyclic base Explanation

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d: A nucleotide is a heterocyclic base bonded to phosphate group/s Explanation

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9. The melting temperature of a nucleic acid:

a: Is directly proportional to the sum of the percentages of adenine and thymine Explanation

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b: Is directly proportional to the sum of the percentages of adenine and guanine Explanation

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c: Is directly proportional to the sum of the percentages of thymine and cytosine Explanation

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d: Is directly proportional to the sum of the percentages of cytosine and guanine Explanation

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10. Which of the following techniques cannot be used to quantify affinity between an enzyme and its peptide substrate?

a: X-ray crystallography Explanation

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b: Isothermal calorimetry Explanation

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c: Surface plasmon resonance Explanation

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d: Fluorescence anisotropy Explanation

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