How ar rna and dna similar? how are they different?

Both DNA and RNA are polymeric molecules, meaning they are formed from many repeating units, formed from a sugar-phosphate backbone and genetic bases. However the sugar in the DNA backbone is deoxyribose, while in RNA it is ribose, and while DNA and RNA both use Adenine (A), Cytosine (C) and Guanine (G) bases, DNA uses Thymine (T) which is replaced by Uracil (U) in RNA. Additionally, DNA is almost always double stranded, while RNA can be double or single stranded, depending on the organism the RNA is from.
Hope this helps!

Di think it’s d shidd