Question

erwin chargaff (1905 - 2002), an austrian - american biochemist, investigated the ratio of nucleotide bases found in the dna from a variety of organisms. from his research, as well as research by rosalind franklin and maurice wilkins, watson and crick developed the complementary base - pair rule during their race to discover the structure of dna. the complementary base - pair rule states that adenine and thymine form pairs across two strands, and guanine and cytosine form pairs across two strands.
*9. fill in the complementary bases on the strand below according to the base - pair rule.
atccag
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1. the ladder model of dna is a simplified representation of the actual structure and shape of a dna molecule. in reality, the strands of dna form a double helix. refer to the double helix diagram in model 1 and describe its shape using a complete sentence.

share out/discussion (5 minutes)

Explanation:

Step1: Recall base - pair rules

In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G).

Step2: Complement each base

For the given strand “ATCCAG”:

• The first base A pairs with T.
• The second base T pairs with A.
• The third base C pairs with G.
• The fourth base C pairs with G.
• The fifth base A pairs with T.
• The sixth base G pairs with C.

Answer:

T AGGTC