Palindromes and DNA Symmetry—Concept Attainment Activity

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Why will a restriction enzyme cut DNA at a 5'-TCGA-3' site, but not at a 5'-ACGA-3' site? In the first example, the base sequence on the complementary strand is 3'-AGCT-5'. The base sequence at a restriction enzyme site always “reads” the same-in the 5' to 3' direction-on the parent and complementary strand. When this type of symmetry occurs in words, phrases, or numbers, it is called a palindrome. Use this concept attainment activity to help students recognize and identify palindromes, first in words and phrases, then in DNA sequences. Kit includes “Yes” and “No” header cards and 20 sample cards containing both palindromes and non-palindromes. The first card is always a “Yes” example, the second is always a “No” example. As the teacher silently displays additional cards, the students must decide whether the example is a palindrome. This “minds-on” activity forces students to look for connections between examples and to develop their own working definition of palindromes. Cards are printed on colorful 8 1/2"x 5 1/2" card stock and laminated for durability. Velcro Dot Tape or Magnetic Tape, available separately, can be used to display these cards during the activity.