Biotechniques | Principles of SDS-PAGE (Protein Separation)

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

• To provide a positive charge to proteins

• To denature proteins and provide a uniform negative charge

• To enhance protein folding

• To separate DNA molecules

Which type of gel is used in SDS-PAGE for protein separation?

• Silica gel

• Polyacrylamide gel

• Agarose gel

• Cellulose gel

What type of bond is a disulfide bridge?

• Metallic bond

• Hydrogen bond

• Ionic bond

• Covalent bond

Which chemical is used to reduce disulfide bonds in proteins?

• Beta-mercaptoethanol

• Sodium chloride

• Acetic acid

• Ethanol

How does SDS affect the charge of proteins?

• It has no effect on protein charge

• It makes proteins negatively charged

• It neutralizes the charge of proteins

• It makes proteins positively charged

In SDS-PAGE, why do larger proteins migrate less than smaller ones?

• Larger proteins are attracted to the negative electrode

• Larger proteins have more charge

• Larger proteins are more hydrophobic

• Larger proteins experience more resistance in the gel

What is the role of the electric field in SDS-PAGE?

• To provide a medium for protein folding

• To heat the gel

• To drive the migration of proteins based on charge

• To neutralize the proteins

Which stain is commonly used to visualize proteins in SDS-PAGE?

• Crystal Violet

• Safranin

• Methylene Blue

• Coomassie Blue

What is the purpose of a Western blot following SDS-PAGE?

• To denature proteins further

• To separate DNA molecules

• To visualize all proteins in a sample

• To identify specific proteins of interest

What is the function of a molecular weight ladder in SDS-PAGE?

• To stain the proteins

• To provide a reference for protein size

• To denature the proteins

• To increase the speed of electrophoresis