Protein gel electrophoresis

Question

Show the image of the SDS-PAGE gel; identify the band(s) of the RS and NS samples and indicate the molecular size of the band(s). (1 mark)

        

            

Q2.  How many bands(s) do you see in RS and NS lanes on the SDS-PAGE gel? What are they? (1 mark)

   

Q3.  Why must you add sample buffer to the protein sample before subjecting it to SDS-PAGE? (Provide at least 3 reasons) (3 marks)

Q4.  Briefly explain why proteins can be separated on an SDS-PAGE gel. (2.5 marks)

Q5.  What is the protein sample used in the experiment? Briefly describe the properties of the protein sample in terms of its structure and functional role.  (1.5 marks)

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Q6.  Give two safety considerations when performing electrophoresis and explain why. (1 mark)

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Answer 1

Protein gel electrophoresis

SDS-PAGE gel

Q1. Identify the RS and NS bands and indicate their molecular sizes

Based on the gel:

1. The RS lane shows two bands:
2. A strong band at approximately ~50 kDa → Half antibody (heavy chain + light chain still linked under non‑reducing conditions).
3. A smaller band around ~25 kDa → Free light chain.
4. The NS lane shows one main band:
5. A band at approximately ~25 kDa, corresponding to free light chain

Q2. How many bands do you see in RS and NS lanes? What are they?

1. RS lane: Two bands
2. Half antibody (~50 kDa)
3. Free light chain (~25 kDa)
4. NS lane: One band
5. Free light chain (~25 kDa)