Central Dogma of Biology

Biochemical Engineering

Problem Statement: Consider the following DNA sequence.

   ...atcgatggcaaatggataaaac

Find the complementary sequence. Identify the 3' and 5' ends. Be sure you follow standard notations.
Find the mRNA sequence. Identify the 3' and 5' ends.
Find the peptide sequence. Identify the amine and acid terminus.
Which DNA strand in Part a) is the sense strand?

Solution:

    Given sequence:
      5'...atcgatggcaaatggataaaac...3'

    Complementary to the given sequence, reverse of standard notation:
      3'...tagctaccgtttacctattttg...5'

    Complementary to the given sequence, standard notation, sense strand:
      5'...gttttatccatttgccatcgat...3'

    mRNA    5'...aucg-aug-gca-aau-gga-uaa-aac...3'
    peptide       NH2-Met-Ala-Asn-Gly-COOH
                  NH2--M---A---N---G--COOH

    On the other hand, if one decides to use the original given strand as the
    sense strand (i.e., a template to make mRNA), you get:

    mRNA    5'...guuuuauccauuugccaucgau...3'

    which does not code for any polypeptides because the start codon "aug"
    is absent.

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Department of Chemical & Biomolecular Engineering

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