Question 1

What is the basis for separation of proteins by two-dimensional gel electrophoresis? Why is this better for resolving a mixture of proteins?

Accepted Answer

The answer of What is the basis for separation of...

Question 2

In two-dimensional gel electrophoresis,proteins are first resolved by _____ and then by _____.
A)IEF;SDS-PAGE
B)SDS-PAGE;affinity chromatography
C)SDS-PAGE;ion exchange
D)IEF;gel filtration

Accepted Answer

In two-dimensional gel electrophoresis, proteins are first separated by isoelectric focusing (IEF) based on their isoelectric points, and then by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) based on their molecular weights. Therefore, choice A (IEF;SDS-PAGE) is the correct answer.

Question 3

Starting with 1 mCi (milliCurie)of a phosphorus-32-labeled compound,how long would it take until only 0.125 mCi remains?
A)14.3 days
B)28.6 days
C)42.9 days
D)57.2 days

Accepted Answer

Phosphorus-32 has a half-life of 14.3 days. To find out how long it would take until only 0.125 mCi remains, we can use the formula: 
final activity = initial activity x (1/2)^(time/half-life)

0.125 = 1 x (1/2)^(time/14.3)
Taking the logarithm of both sides and solving for time gives us:
time = (log 0.125) x 14.3/log 2 = 42.9 days
Therefore, it would take 42.9 days for only 0.125 mCi to remain.

Question 4

How can gel filtration chromatography separate proteins based on their mass?

Accepted Answer

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Question 5

Gel filtration chromatography separates proteins on the basis of their:
A)charge.
B)mass.
C)affinity for a ligand.
D)mass and charge.

Accepted Answer

Gel filtration chromatography separates proteins based on their size or mass. Larger proteins cannot enter the pores of the gel filtration column and therefore elute first, while smaller proteins are able to enter the pores and therefore elute later. This separation is not based on charge or affinity for a ligand.

Question 6

A chunk of tissue is treated so that each cell's membrane is broken open to release the contents inside,and then subjected to differential centrifugation.Which of the following is true at the end of the centrifugation?
A)Depending on the speed of the centrifugation,the proteasome is more likely to be in the supernatant than a chaperone.
B)Proteins of similar density will be found in the same fraction (either pellet or supernatant).
C)The pellet contains the least dense material.
D)The pellet will contain a purified protein for further analysis.

Accepted Answer

Differential centrifugation separates cellular components based on their densities. Proteins of similar densities will be found in the same fraction either pellet or supernatant. The speed of centrifugation does not determine whether a proteasome or a chaperone will be in the supernatant or pellet. The pellet may contain impurities and is not necessarily a purified protein. The pellet may contain dense material, such as organelles like mitochondria or nuclei that have been centrifuged to the bottom.

Question 7

Proteomics allows researchers to:
A)examine where a protein is located within the cytosol of a cell.
B)compare thousands of samples from different people in the same experiment.
C)examine which proteins differ in abundance between a normal sample and a disease sample.
D)use antibodies to label specific proteins on an SDS-PAGE gel.

Accepted Answer

Proteomics enables the comparison of protein abundance between a normal and disease sample, as they can detect and quantify proteins within a sample. This makes it useful for identifying biomarkers and potential therapeutic targets for various diseases. Option A is more related to cellular localization studies, and option B is more related to high-throughput screening. Option D describes immunoblotting, which is not always directly related to proteomics.

Question 8

Mass spectrometry techniques are used in proteomics for all of the following purposes EXCEPT:
A)identification of thousands of proteins' amino acid sequences within a single cell.
B)characterization of proteolytically digested pieces of proteins from the sample.
C)identification of all the protein complexes present in certain yeast species.
D)identification of proteins within each organelle in liver tissue.

Accepted Answer

The answer of Mass spectrometry techniques are used in proteomics...

Question 9

Western blotting is a method for detecting:
A)DNA.
B)RNA.
C)protein.
D)carbohydrate.

Accepted Answer

Western blotting is specifically designed to detect and analyze proteins. It involves separating proteins based on size and then transferring them onto a membrane, which is then probed with specific antibodies to detect the target protein. While other techniques such as PCR and gel electrophoresis can detect DNA and RNA, western blotting is exclusively used for protein analysis. Therefore, the correct answer is C) protein.

Question 10

Medical researchers are developing new clinical tests that detect and analyze the expression of multiple proteins and protein complexes in the hope that they might improve diagnosis of diseases such as early stage cancers.What techniques might researchers use in these studies?

Accepted Answer

The answer of Medical researchers are developing new clinical tests...

Question 11

What is Western blotting? How can this technique be used to detect proteins?

Accepted Answer

The answer of What is Western blotting? How can this...

Quiz 3: Protein Structure and Function

What is the basis for separation of proteins by two-dimensional gel electrophoresis? Why is this better for resolving a mixture of proteins?

In two-dimensional gel electrophoresis,proteins are first resolved by _ and then by _.

Starting with 1 mCi (milliCurie) of a phosphorus-32-labeled compound,how long would it take until only 0.125 mCi remains?

How can gel filtration chromatography separate proteins based on their mass?

Gel filtration chromatography separates proteins on the basis of their:

A chunk of tissue is treated so that each cell's membrane is broken open to release the contents inside,and then subjected to differential centrifugation.Which of the following is true at the end of the centrifugation?

Proteomics allows researchers to:

Mass spectrometry techniques are used in proteomics for all of the following purposes EXCEPT:

Western blotting is a method for detecting:

Medical researchers are developing new clinical tests that detect and analyze the expression of multiple proteins and protein complexes in the hope that they might improve diagnosis of diseases such as early stage cancers.What techniques might researchers use in these studies?

What is Western blotting? How can this technique be used to detect proteins?