Question 1

________________ gels are often used as the media for electrophoretic techniques such as SDS-PAGE and isoelectric focusing.

Accepted Answer

Polyacrylamide

Question 2

In the Edman procedure for peptide sequence, phenyl isothiocyanate is used to selectively derivitize the __________________ residue, which is then removed as a PTH derivative.

Accepted Answer

N-terminal

Question 3

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-____________: A type of purification that is based on the attraction of the protein for a particular chemical group.

Accepted Answer

Affinity chromatography is the type of purification method that is based on the attraction of the protein for a particular chemical group.

Question 4

The ________________ of a protein is the pH at which its net charge is zero.

Accepted Answer

The answer of The ________________ of a protein is the...

Question 5

Proteins can be separated from small molecules and ions through a semipermeable membrane by __________________.

Accepted Answer

The answer of Proteins can be separated from small molecules...

Question 6

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-____________: A protein purification technique characterized by high resolution and rapid separation.

Accepted Answer

The answer of Use the following to answer questions 1-10:
Choose...

Question 7

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-Sedimentation coefficients are expressed in ____________ units.

Accepted Answer

Sedimentation coefficients are expressed in Svedberg units (symbolized as S or sometimes Sv), which reflects the rate at which a particle of a given size and shape settles in a centrifugal field.

Question 8

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-____________: The separation of proteins based first on charge then size.

Accepted Answer

Two-dimensional electrophoresis involves using both isoelectric focusing and SDS-PAGE to separate proteins first based on charge and then size.

Answer: L
 Affinity chromatography is a technique used to purify proteins based on their specific interactions with ligands (e.g. antibodies) that are immobilized on a solid support.

Answer: H
 The Svedberg (S) unit is used to express the sedimentation rate of particles (e.g. proteins) in centrifugation, taking into account both size and shape.

Answer: J
 Differential centrifugation is a technique used to separate subcellular components based on their densities, by subjecting a homogenized sample to a sequence of centrifugation steps at increasing speeds.

Answer: F
 SDS (sodium dodecyl sulfate) is a detergent that is commonly used in protein electrophoresis to denature and linearize proteins, as well as equalize their charge-to-mass ratios.

Answer: A
 HPLC (high-performance liquid chromatography) is a versatile technique used for separating and analyzing complex mixtures of molecules, including proteins, based on different physicochemical properties.

Answer: C
 MALDI-TOF mass spectrometry is a powerful analytical technique that is commonly used to identify and quantify proteins based on their molecular weights and fragmentation patterns, often after digestion with specific proteases.

Answer: E
 Proteome refers to the complete set of proteins expressed by an organism, tissue, or cell type, including all their post-translational modifications and interactions.

Answer: K
 Overlap peptides are fragments of proteins that are generated during the process of proteolytic digestion, and that can be used for sequencing or identification by mass spectrometry.

Note: B and I were not used.

Question 9

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-Proteins with different sedimentation coefficients can be separated by ____________.

Accepted Answer

Proteins with different sedimentation coefficients can be separated by gradient centrifugation.

Question 10

Molecular exclusion gel or gel-filtration chromatography separates molecules on the basis of __________________.

Accepted Answer

The answer of Molecular exclusion gel or gel-filtration chromatography separates...

Question 11

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-The first step in protein purification from a homogenate is usually ____________.

Accepted Answer

Differential centrifugation is usually the first step in protein purification from a homogenate. This process separates the homogenate into fractions based on size and density.

Question 12

Polypeptides can be fragmented into smaller peptides by cleavage with chymotrypsin, which hydrolyzes the peptide bond at the C-terminal side of ____, ______, and ______ residues.

Accepted Answer

The answer of Polypeptides can be fragmented into smaller peptides...

Question 13

________________ allows the detection of small amounts of target proteins as well as the ability to determine the size of target proteins.

Accepted Answer

The answer of ________________ allows the detection of small amounts...

Question 14

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-The subset of gene products actually expressed by the cell is ____________.

Accepted Answer

"Proteome" refers to the subset of gene products actually expressed by the cell.

Question 15

Using antibodies as reagents to quantify proteins or other antigens is the basis for the technique called ________________.

Accepted Answer

The answer of Using antibodies as reagents to quantify proteins...

Question 16

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-In order to sequence a whole protein, ____________ are used.

Accepted Answer

The answer of Use the following to answer questions 1-10:
Choose...

Question 17

When enzymes are purified, the assay is often based on:

Accepted Answer

Enzymes are known for their catalytic activity, and therefore, the assay for purified enzymes is often based on their ability to catalyze a specific reaction. This is commonly measured using spectrophotometry or other methods to detect the presence or absence of a specific substrate, product, or intermediate in the reaction. Light absorbance, pH, and temperature changes may also be monitored during the assay process, but these are typically secondary measures that help to confirm or optimize the reaction conditions. mRNA levels, on the other hand, are not typically relevant to enzyme assays, as they are a measure of gene expression and not enzyme activity.

Question 18

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-The ratio of enzyme activity relative to total protein is called ____________.

Accepted Answer

The ratio of enzyme activity relative to total protein is called specific activity.

Question 19

In amino acid composition analysis, amino acids are visualized after separation using the chemical reagent _______________.

Accepted Answer

The answer of In amino acid composition analysis, amino acids...

Question 20

Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
-____________ can be added prior to gel electrophoresis to denature the proteins.

Accepted Answer

SDS is commonly used to denature proteins prior to gel electrophoresis.

Quiz 5: Techniques in Protein Biochemistry

________________ gels are often used as the media for electrophoretic techniques such as SDS-PAGE and isoelectric focusing.

In the Edman procedure for peptide sequence, phenyl isothiocyanate is used to selectively derivitize the __________________ residue, which is then removed as a PTH derivative.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -____________: A type of purification that is based on the attraction of the protein for a particular chemical group.

The ________________ of a protein is the pH at which its net charge is zero.

Proteins can be separated from small molecules and ions through a semipermeable membrane by __________________.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -____________: A protein purification technique characterized by high resolution and rapid separation.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -Sedimentation coefficients are expressed in ____________ units.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -____________: The separation of proteins based first on charge then size.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -Proteins with different sedimentation coefficients can be separated by ____________.

Molecular exclusion gel or gel-filtration chromatography separates molecules on the basis of __________________.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -The first step in protein purification from a homogenate is usually ____________.

Polypeptides can be fragmented into smaller peptides by cleavage with chymotrypsin, which hydrolyzes the peptide bond at the C-terminal side of , , and ____ residues.

________________ allows the detection of small amounts of target proteins as well as the ability to determine the size of target proteins.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -The subset of gene products actually expressed by the cell is ____________.

Using antibodies as reagents to quantify proteins or other antigens is the basis for the technique called ________________.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -In order to sequence a whole protein, ____________ are used.

When enzymes are purified, the assay is often based on:

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -The ratio of enzyme activity relative to total protein is called ____________.

In amino acid composition analysis, amino acids are visualized after separation using the chemical reagent _______________.

Use the following to answer questions 1-10: Choose the correct answer from the list below. Not all of the answers will be used. -____________ can be added prior to gel electrophoresis to denature the proteins.