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Arindam Paul posted an Question
September 21, 2020 • 22:40 pm 30 points
  • IIT JAM
  • Biotechnology (BT)

The tetrapeptide gly-ala-ala-gly is a palindrome. how many such palindromic tetrapeptides can be formed from 20 different amino acids? (a) 20 (b) 4 440 (c) 202

The tetrapeptide Gly-Ala-Ala-Gly is a palindrome. How many such palindromic tetrapeptides can be formed from 20 different amino acids? (A) 20 (B) 4 440 (C) 202 (D) 220

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  • Abhijeet Gaurav Best Answer

    Answer is (C). First amino acid can take 20 as there are 20 types of Amino acids. Similarily 2nd Amino acids can take 20 types of Amino acids. But once you choose first and second then you don't have option at 3rd and 4th as you they are repetitive.

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    Priyanshu kumar best-answer

    Option C is correct

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    20^2 ways

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    First you choose it by 20 ways as it is palindrome so In 2nd tym you choose again by 20 ways...so 20×20 ways

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    Sir please explain more clearly, there are 4 space so for the first two it will be 20×19, is it right?

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