DNA vs RNA Structure and Replication
DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid) are both made of nucleotides, but they're built differently. DNA lives mainly in the nucleus, has a deoxyribose sugar, uses thymine as a base, and forms a double helix structure. RNA, found in both nucleus and cytoplasm, contains a ribose sugar, uses uracil instead of thymine, and forms a single helix.
Base-pairing is crucial for both molecules. In DNA, adenine (A) pairs with thymine (T), and cytosine (C) pairs with guanine (G). RNA follows similar rules but pairs adenine with uracil (U) instead. These molecules are anti-parallel, meaning they run in opposite directions (5' to 3').
DNA replication happens during the S phase of the cell cycle so daughter cells get a copy of DNA. Several enzymes work together in this process Helicase unzips the DNA strands, primase signals where to start building, DNA polymerase builds the new strands, and ligase connects DNA fragments. The lagging strand takes longer to build because it must wait for more DNA to be unzipped.
Did you know? Your body contains about 6 feet of DNA in EACH cell, but it's packed so tightly that it fits in a space thousands of times smaller than a grain of sand!