1. What is the basic structure of DNA?
   Check your answer. a double helix, or twisted ladder Close
2. What are the building blocks of DNA?
   Check your answer. nucleotides Close
3. What are the parts of a nucleotide?
   Check your answer. phosphate group, deoxyribose sugar, and a nitrogen base Close
4. The sides of the DNA ladder are made up of what 2 alternating molecules?
   Check your answer. phosphate and deoxyribose sugar Close
5. What does it mean to have antiparallel strands?
   Check your answer. The different strands in the helix run in opposite (anti-parallel) directions. At each end of the double helix, one strand is 5' and the other is 3'. Close
6. What makes up the steps or rungs of the ladder?
   Check your answer. nitrogen bases Close
7. What is special about the order of the nitrogen bases?
   Check your answer. It is the order of the nitrogen bases that carries our genetic code. Close
8. What are the 4 nitrogen bases?
   Check your answer. adenine, thymine, guanine and cytosine Close
9. According to the base pairing rules adenine always pairs with __________ .
   Check your answer. thymine Close
10. What type of bond hold the nitrogen bases together?
    Check your answer. a weak hydrogen bond Close