A short fragment of a double-stranded DNA molecule is 100 nitrogenous base pairs in length. Adenine constitutes 30% of the nitrogenous bases in this DNA molecule. How many hydrogen bonds are there between all the nitrogenous bases this DNA fragment has? That is, the two complementary strands of this DNA fragment are held together by how many hydrogen bonds? 120 135 270

Which of the following statements about the DNA double helix is FALSE? O The base pairs are located in the center of the helix O The plane of the base pairs is perpendicular to the direction of the deoxyribose- phosphate backbone O The two strands have the same 5' to 3' direction (i.e, are parallel) O The base pairs stack on one another O The deoxyribose-phosphate backbone is on the outside of the helix

A double-stranded molecule of DNA contains 120 cytosine (C) bases and 80 adenine (A) bases. How many nitrogenous bases does this molecule contain all together? O 80 100 O 120 O 200 400

A circular double-stranded DNA molecule contains 4700 base pairs. In solution the molecule is in a B-form helix, with about 10.6 base pairs per turn. The DNA circle has 12 superhelical turns. Calculate superhelix density

What chemical group (phosphate group, hydroxyl group, or anitrogenous base) is found at the 3′ end of a DNA strand? Whatgroup is found at the 5′ end?