| A | B |
|---|
| nucleotides | building blocks joined to form DNA |
| deoxyribose | sugar found in DNA nucleotides |
| purines | double ringed nitrogen bases such as guanine and adenine |
| pyrimidines | single ringed nitrogen bases such as thymine and cytosine |
| Erwin Chargaff | determined that nitrogen bases formed specific base pairs formed by a purine and a pyrimidine |
| adenine | purine that pairs with the pyrimidine thymine |
| thymine | pyrimidine that pairs with the purine adenine |
| guanine | purine that pairs with the pyrimidine cytosine |
| cytosine | pyrimidine that pairs with the purine guanine |
| Rosalind Franklin | took x-ray pictures of DNA showing it was a helix |
| James Watson & Francis Crick | determined that the structure of DNA was a double helix |
| deoxyribose | together with phosphate groups form the sides of DNA molecule |
| phosphate groups | together with deoxyribose form the sides of DNA molecules |
| nitrogen base pairs | form the center of the DNA molecule |
| hydrogen bonds | weak bonds that connect base pairs in DNA |
