You may have discovered that the sequence of base pairs is seemingly random and

Question

You may have discovered that the sequence of base pairs is seemingly random and thet the two strands are complementary to each other: As are paired with Ts and Cs are paired with Gs.You may have also noticed that a portion of the top strand GAATTC (read toward the right), has a counterpart in the lower strand, CTTAAG (read toward the left). Example GAATTC AAGCTT TTCGAA CTGCAG GACGTC CTTAAG When such a sequence is looked at together with its complementary sequence the group reads the same in both directions. These sequences, called palindromes, are fairly common along the DNA molecule. Restriction Enzymes-Molecular Scissors Viruses called bacteriophages frequently infect bacteria. These viruses inject their own DNA into bacteria and force the bacteria to multiply the DNA. Bacteria have evolved restriction enzymes, to cut up and destroy the invading viral DNA. Bacteria prevent destruction of their own DNA by modifying certain DNA bases within the specific enzyme recognition sequence, which allows them to protect their own DNA while cutting up viral DNA. This could be considered a very primitive immune system. Restriction enzymes search the viral DNA for specific palindromic sequences of base pairs, such as GAATTC, and cut the DNA at hese sites. The actual sequence of DNA is called a restriction site. Some restriction enzymes may leave a short length of unpaired nucleotide bases, called a "sticky'" end, at the DNA site where they cut, whereas other restriction enzymes make a cut across both strands at the same place creating double stranded DNA fragments with "blunt' ends Look at the DNA sequence below Palindrome G TAGAATTC ATTCAC G CA CATCTTAAG TAAGTGCGT Restriction site GTAG CATCTTAA AA TTCATTCACGCA GTAAGTGCGT Fragment 1 "sticky" end cut Fragment 2 A restriction enzyme cut the DNA between the G and the A in a GAATTC palindrome. 4. How many bases are still paired to the left of the "cut"? 5. How many bases are still paired to the right of the "out"? 6. Counting the number of paired bases, is the right fragment the same size as the left fragment? 7. How could you describe the size of each fragment in terms of the number of base pairs in the fragment?

Explanation / Answer

GTAG                                                    AATTCATTCACGCA

CATCTTAA                                                     GTAAGTGCGT

(Left cut)                                                                             the right cut

4.Ans- 4

5. Ans- 10

6. Ans- No, the right fragment is larger than the left fragment.

7. Ans-

Fragment 1 = 4 base pair

Fragment 2= 10 base pair.

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.