Like DNA, __________ is composed of a sugar and phosphate backbone, along with varying sequences of four bases.

The correct answer is RNA.

RNA (ribonucleic acid) is similar to DNA (deoxyribonucleic acid) in that both have a sugar and phosphate backbone. However, RNA contains ribose sugar instead of deoxyribose and uses uracil as one of its bases instead of thymine. The varying sequences of these four bases (adenine, guanine, cytosine, and uracil) carry genetic information and are crucial for protein synthesis. If you have more questions or need further explanation, feel free to ask!