9-L2

What is a common characteristic of proteins that can be exploited to separate them from one another?

Only their size
Only their affinity for other molecules
Their size, shape, charge, hydrophobicity, and affinity for other molecules (correct)
Only their shape

What happens to the electrophoretic movement of larger molecules when an electric field is applied to a solution containing protein molecules?

They do not move at all
Their movement is delayed relative to that of smaller molecules (correct)
They move at the same speed as smaller molecules
They move faster than smaller molecules

What is the direction of movement of negatively charged proteins in an electric field?

Towards the anode (correct)
Towards the cathode
No movement at all
In a random direction

What is the purpose of the detergent SDS in SDS-PAGE?

To denature protein molecules and mask their intrinsic charge (C) Signup and view all the answers

What is the basis of protein separation in SDS-PAGE?

Molecular weight (A) Signup and view all the answers

What is the function of the gel in Gel Electrophoresis?

To act as a sieve and separate proteins based on their size (A) Signup and view all the answers

What is the ratio of SDS molecules to amino acids in a protein molecule?

One SDS molecule for every two amino acids (B) Signup and view all the answers

What is the purpose of a pH gradient in isoelectric focusing?

To determine the isoelectric point of proteins (C) Signup and view all the answers

Why do proteins stop migrating in isoelectric focusing?

Because they reach a pH equal to their isoelectric point (D) Signup and view all the answers

What is the purpose of staining in gel electrophoresis?

To detect proteins in a gel (A) Signup and view all the answers

Which of the following stains is 50 times more sensitive than Coomassie brilliant blue?

Silver stain (B) Signup and view all the answers

What is the purpose of an immunoblot (Western blot) in gel electrophoresis?

To specifically detect a protein in the presence of many other proteins (D) Signup and view all the answers

What is the term for the pH at which a protein has no net charge?

Isoelectric point (A) Signup and view all the answers

Why do proteins migrate in an electric field?

Because they have a net charge (C) Signup and view all the answers

What is the purpose of blocking the unoccupied binding sites on the nitrocellulose with casein?

To prevent non-specific binding of the antibody (C) Signup and view all the answers

What is the function of the enzyme-linked goat anti-rabbit antibody in immunoblotting?

To catalyze a colorimetric reaction (C) Signup and view all the answers

What is the term for the process of separating proteins based on their isoelectric points in the first dimension and molecular masses in the second dimension?

2D-SDS-PAGE (B) Signup and view all the answers

What is the term for any molecule that induces production of antibodies when introduced in the body of an animal?

Antigen (C) Signup and view all the answers

What is the purpose of the rabbit antibody in immunoblotting?

To bind to the protein of interest (D) Signup and view all the answers

What is the term for the method of separating proteins based on their molecular masses using sodium dodecyl polyacrylamide sulfate?

SDS-PAGE (B) Signup and view all the answers

What is the component of an antibody that binds to the antigen?

Variable region (D) Signup and view all the answers

What does ELISA stand for?

ENZYME-LINKED IMMUNOSORBENT ASSAY (D) Signup and view all the answers

What is the purpose of the enzyme in ELISA?

To convert a colorless substrate to a colored product (A) Signup and view all the answers

When was ELISA developed?

1970 (A) Signup and view all the answers

What can ELISA be used to detect?

Either antigens or antibodies (A) Signup and view all the answers

What is immobilized on a solid support in ELISA?

Antibody (D) Signup and view all the answers

What is the role of the second antibody in ELISA?

To covalently link to an assayable enzyme (C) Signup and view all the answers

What is the purpose of incubating with a protein-containing sample in ELISA?

To allow antigen-antibody binding (B) Signup and view all the answers

What is the result of the enzyme converting the substrate in ELISA?

A colored product (C) Signup and view all the answers

What is the use of ELISA in estimating?

Nanograms to picograms (D) Signup and view all the answers

What is the benefit of using ELISA?

It is a powerful method (A) Signup and view all the answers

What is the main purpose of enzyme assays?

To study enzyme kinetics and enzyme inhibition (B) Signup and view all the answers

Under what conditions are enzyme assays typically performed?

At optimal pH, temperature, and ionic strength (C) Signup and view all the answers

What is the significance of measuring enzyme activity in serum?

It is an indicator of tissue damage (D) Signup and view all the answers

What is the purpose of adding high concentrations of substrate in enzyme assays?

To ensure the enzyme is working at its maximum level (D) Signup and view all the answers

What is the diagnostic significance of enzyme assays in metabolic disease?

It detects specific enzymes that are absent or present at lower levels (A) Signup and view all the answers

What is the role of ions or cofactors in enzyme assays?

They are necessary for enzyme action (A) Signup and view all the answers

What is the significance of elevated levels of a specific enzyme in serum?

It is an indicator of tissue damage caused by a disease (B) Signup and view all the answers