Virginia 7th Grade Science SOL Practice Test

DNA is packed into chromosomes, threadlike structures that carry the genetic information. Chromosomes form when long DNA molecules wrap around proteins, allowing the genome to fit inside the cell and be organized for division and inheritance. They carry genes—the specific sequences that code for traits. Nucleotides are the individual building blocks of DNA, not the overall structure. Chromatids are the identical copies that make up a duplicated chromosome, and genes are particular segments of DNA found along a chromosome. So the threadlike structures made up of DNA are chromosomes.