Question

ACTIVITY 1 Discovering the Structure of DNA Materials for This Activity Transparent tape Scissors Part 1: Structure of DNA 1. Cut out the nucleotide molecules on pages 271-272 by cutting along the dashed linen 2. Connect four molecules in the sequence G.C. A-C (from top to bottom) by taping the rectan. gular sugar of one molecule to the plus-shaped phosphate of the next. This will be the left strand of your DNA molecule. Lay this out at on your table with the G at the top and at the bottom With which nucleotide will you start when constructing the right side strand from the top? ber 3. To construct the right side of your DNA, take the cutout of the nucleotide you will place at the top, and try matching up the bonding "arms of the nitrogenous base (which represent hydrogen bonding areas) with the bonding arms of the G nucleotide on the left strand. You should find that they don't seem to line up. What can you do to get those bonding arms to match up with each other? (Hint: Be creative, and leave no stone un- turned when examining the possibilities!) W ... FIGURE 21 2 The double helical structure of DNA. 4. Once you have figured out the trick, line up (but do not tape) the nucleotides together at the central arms, and repeat this process for the remaining three nucleotides. Also remember the sugar-phosphate covalent bonds by lining up (but not taping) those molecules as you build the right strand. In this activity, you have essentially walked in the footsteps of James Watson, who was equally puzzled at first about the way these molecules could fit together. Part 2: Replication of DNA 1. Remove the nucleotides of your untaped right strand, leaving the left strand in place. 2. Now, reattach the loose nucleotides to the left strand in a new order, but be sure to maintain the appropriate bonds with the right strand. Can you do it? Why or why not?

Answer 1

Part 2:

Replication is the process of forming DNA from DNA by means of complementary base pairing.

Yes, we can reattach the loose nucleotides to the left strand in a new order by taking this left strand as a template.

We just have to maintain the correct base pairing of nitrogenous bases with each other,

like Adenine with thymine (with 2 hydrogen bonds), and guanine with cytosine (with 3 hydrogen bonds).

The rest all like deoxyribose sugar and phosphate molecule will be the same.