Isoelectric focusing (IEF) separates proteins based on their isoelectric point (pI), which is the pH at which a protein has no net charge.

What is the basis of isoelectric focusing separation of protein.
(a) Relative content of positively charged residues only
(b) Relative content of negatively charged residues only

(c) Size
(d) Relative content of positively and negatively charged residues

 

The correct answer is:

(d) Relative content of positively and negatively charged residues

Explanation:

  • Isoelectric focusing (IEF) separates proteins based on their isoelectric point (pI), which is the pH at which a protein has no net charge.
  • Proteins contain both positively charged (basic) residues (e.g., lysine, arginine, histidine) and negatively charged (acidic) residues (e.g., aspartic acid, glutamic acid).
  • During IEF, proteins migrate in a pH gradient under an electric field until they reach their pI, where their net charge is zero and they stop moving.

Why Not the Other Options?

  • (a) Relative content of positively charged residues only → Incorrect because both positive and negative charges influence the pI, not just positive residues.
  • (b) Relative content of negatively charged residues only → Incorrect because proteins also have basic residues that contribute to their net charge and pI.
  • (c) Size → Incorrect because IEF does not separate proteins by size, unlike SDS-PAGE or gel filtration.

Conclusion:

Isoelectric focusing depends on the balance of both positive and negative charges in a protein, making option (d) correct.

66 Comments
  • Prami Masih
    February 27, 2025

    Okay sir

  • Akshay mahawar
    March 19, 2025

    Done 👍

  • Arushi
    April 2, 2025

    👍✔️

  • Anita choudhary
    April 18, 2025

    Done 👍✅

  • Aman Choudhary
    August 13, 2025

    option d is correct Relative content of positively and negatively charged residues

  • Mohd juber Ali
    August 14, 2025

    Option (4)
    Protein content both positive and negative charge
    ° positive=basic accept H+ ion
    ° negative= acidic release H+ ion
    IEF seprate protein on the basis of charge or PI
    In IEF protein migrate in pH gradient until reach their PI

    • Monika meena
      August 27, 2025

      Both positively and negatively charge

  • shruti sharma
    August 14, 2025

    d is correct

    • Mahima Sharma
      August 24, 2025

      Relative content of positivity and negativity charge reduce

  • Khushi Agarwal
    August 14, 2025

    Option 4 is correct bcz
    Net charge is zero

  • Dharmpal Swami
    August 14, 2025

    On the basis of charge molecules [+.-]

  • Anurag Giri
    August 14, 2025

    Ans 4 Isoelectric focusing depends on the balance of both positive and negative charges in a protein

  • Priya dhakad
    August 14, 2025

    Isoelectric focusing depends on the balance of both positive and negative charges in a protein.

  • Neelam Sharma
    August 14, 2025

    Relative content of positively and negatively charged residues

  • Devika
    August 14, 2025

    Done sir positive and negative both ke basis pr separation hota h

  • Soniya Shekhawat
    August 14, 2025

    Done sir ✅

  • Mansukh Kapoor
    August 14, 2025

    The correct answer is option 4th The relative content of positive and negative charge content residue
    IEF is the technique which separates the protein on the basis of pH where the net charge becomes zero and protein stops in the pH gradient

  • Pratibha sethiya
    August 14, 2025

    Correct answer is 4
    IEF separates proteins based on the pH at which the net charge on a protein is zero

  • Pratibha sethiya
    August 14, 2025

    Correct answer is 4
    Relative content of positive and negative charge residue
    IEF separates proteins based on the pH at which the net charge on a protein is zero

  • Aafreen
    August 14, 2025

    Ans-4
    Relative content of positively and negatively charged residues
    IEF is the technique which separates the protein on the basis of pH ,the net charge is zero

  • Dipti Sharma
    August 14, 2025

    The pH at which a protein has no net charge is IEF as
    Proteins contain both positively charged and negatively charged residues correct answer is 4

  • Manisha gujar
    August 14, 2025

    IEF separate the protein on basis of positive and negative charged

  • Karishma
    August 14, 2025

    relative content of +VEly and -vely charged residues

  • Priti khandal
    August 14, 2025

    option d is right because IEF is the technique which separate the protein on the basis of PH the net charge of zero and relative content of positively and negatively Charged residues

  • Priya khandal
    August 14, 2025

    Relative content of positively and negatively charged residues

  • Roopal Sharma
    August 14, 2025

    Done

  • Deepika Sheoran
    August 15, 2025

    Option 4th is correct answer
    Releative content of positive & Negative charge residue. Net charge on a protein is zero.

  • Santosh Saini
    August 15, 2025

    Option 4th is correct bcz IEF = separation of protein on the basis of iso electric point (pi) or change so net charge is zero (positive and negative charge reduced)

  • Priyanka choudhary
    August 16, 2025

    Correct answer is option d, because net charge hi 0

  • Nilofar Khan
    August 16, 2025

    Correct answer is d

  • Manisha choudhary
    August 17, 2025

    Done sir
    Protein p negative and positive charge dono hota h protein ph gradient p electric charge ki presence m move krti h isliye pi value tk
    Pi value = ph at which net charge on protein is zero

  • Kavita choudhary
    August 17, 2025

    Relative contant of positive and negative charge reduse because net charge is zero

  • Surbhi Rajawat
    August 17, 2025

    IEF is basically a technique to identify the Pi of a protein which is the ph at which it’s neutral. And neutrality of anything depends upon the relative content of both positive and negative charge. Hence answer is D

  • Kajal
    August 17, 2025

    Relative content of positively and negatively charged protein

  • Avni
    August 17, 2025

    Relative content of positively and negatively charged residue

  • Varsha Tatla
    August 19, 2025

    IEF is a protin sep. Tech on the basis of isoilectric point PI means which have +ve basic or -ve acidic amino acid residue
    Easily seprate by IEF

  • Sneha .......
    August 20, 2025

    D is correct

  • Bhavana Kankhedia
    August 24, 2025

    relatively content of positively and negatively charged residues

  • Bharti Yadav
    August 24, 2025

    Isoelectric focusing depends on both positive and negative charges in a protein

  • Payal Gaur
    August 24, 2025

    Relative content positively and negatively charge residue

  • Priyanka Choudhary
    August 24, 2025

    Option d is correct answer because the Relative content of positively and negatively charged residues,and the net charge will be 0

  • Sonan saini
    August 24, 2025

    D is Right answer

  • Niti Tanwar
    August 24, 2025

    D is right answer

  • Alec
    August 24, 2025

    option d – relative content of positively and negatively charged molecules.

  • Anjali
    August 24, 2025

    Option d is correct bcz net charge is 0

  • Falguni Prakash
    August 24, 2025

    Option d. Coz it depends on both charge

  • Sakshi
    August 24, 2025

    Relative content of negative and positive charge residue is correct

  • Vijay kumar Meena
    August 24, 2025

    D ✔️ 👍

  • Devika
    August 25, 2025

    Relative content of positively and negatively charged residues

  • Kashish yadav
    August 25, 2025

    Option d

  • sakshi khatri
    August 25, 2025

    done

  • Shivani Panwar
    August 25, 2025

    Relative content of positively and negatively charged molecule

  • Ayush Dubey
    August 25, 2025

    Relative content of positively and negatively charged residues

  • Pratibha Jain
    August 30, 2025

    Correct answer is option (d)
    Relative content of positively and negatively charged residues

  • Sheikh Aleen
    August 30, 2025

    Relative content of positively and negatively charged residues

  • Anisha Beniwal
    August 30, 2025

    Relative content of positively and negatively charged residues

  • Vanshika Sharma
    August 30, 2025

    Iso electric focusing seperate protiens on the basis of their isoelectric point at which net charge is zero

  • anjani sharma
    August 30, 2025

    Answer d
    Relative content of positively and negatively charged residues

  • Akshita Jangid
    August 31, 2025

    Isoelectric focusing depends on the balance of both positive and negative charges in a protein

  • Shobha Kanwar
    August 31, 2025

    Correct answer is 4 bcoz IEF separates proteins based on the pH at which the net charge on a protein is zero

  • Asha Gurzzar
    August 31, 2025

    D is correct relative content of both type charges residues

  • Anisha jakhar
    September 3, 2025

    (d) Relative content of positively and negatively charged residues

  • Muskan Yadav
    September 3, 2025

    Relative content of positively and negatively charged residues.

  • Somya Yadav
    September 5, 2025

    Relative content of positively and negatively charged residues

  • Aakansha sharma Sharma
    October 1, 2025

    The correct answer is:

    (d) Relative content of positively and negatively charged residues

  • Vanshika Sharma
    January 16, 2026

    Relative content of positively and negatively charged residues

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