The nitrogen bases form the rungs of the ladder. Which component forms the rungs?

The nitrogen bases form the rungs of the ladder. Which component forms the rungs?

• A. Nitrogen bases
• B. Phosphate groups
• C. Sugar molecules
• D. Hydrogen bonds

Answer: (A)

Base pairs form the rungs of the DNA ladder. The rungs are created when a nitrogen base on one strand pairs with its complementary base on the opposite strand (A with T, C with G). These pairs make up the steps, and they are held together by hydrogen bonds between the bases. The sugar and phosphate molecules form the backbone that runs along the sides of the ladder, not the rungs themselves. So the component that forms the rungs is the nitrogen bases.

Base pairs form the rungs of the DNA ladder. The rungs are created when a nitrogen base on one strand pairs with its complementary base on the opposite strand (A with T, C with G). These pairs make up the steps, and they are held together by hydrogen bonds between the bases. The sugar and phosphate molecules form the backbone that runs along the sides of the ladder, not the rungs themselves. So the component that forms the rungs is the nitrogen bases.