As one would expect, a long DNA molecule naturally has many such restriction sites. As soon as this recognition occurs, enzyme cuts the sugar-phosphate backbone from specific points, which are generally within the restriction site. For example, the sequence ATTGCAAT is palindromic. Most restriction enzymes recognize palindromic sequences, meaning that both strands of DNA will have the same sequence when read 5′ to 3′.
This is a short DNA sequence (generally 4-8 nucleotide pairs) that an enzyme specifically recognizes. What makes restriction enzymes suitable for gene cloning is that each of them has a specific restriction site.
As they are endonucleases, they can cut foreign DNA from the inside and make it ineffective. Naturally, they are defense systems of bacteria against foreign DNA. restriction endonucleases) are part of the genetic engineering toolbox and make gene cloning possible. In the question, the palindrome sequence’s complimentary strand is “TTCGAA”.Restriction enzymes recognize specific DNA sequences and cut them in a predictable manner. As you can see, it does not resemble the original strand at all. The complementary strand must be the palindrome sequence flipped.īack to the “false” palindrome sequence, it’s complimentary strand is “TAAT”. Therefore, this is not a palindrome sequence!!! This is because a restriction enzyme cuts through the complementary strand and the strand we see in the sequence. For example, “ATTA” follows that mirror copy tule I was talking about, BUT the first BP (A) is the same as the last BP (A). One thing I wanted to mention also is that the first Bp in the sequence CANNOT be the same as the last Bp in the sequence. As you can see, AAG is a “mirror copy” of CTT.
In this question, we have a 6 Bp palindrome sequence. The key to finding these sequences is knowing that they are usually 4 or 6 base pairs in length, and a trick I like to use is that the first “half” of the sequence is a mirror copy of the second “half” of the sequence. In this case, we are talking about southern blot so restriction enzymes are involved. You should be looking for palindrome sequences whenever you get asked a question that involves restriction enzymes.
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