Which statement about origins of replication in eukaryotes is true?

• A. They Are Always at the Same Locations in Every Chromosome
• B. They Are Limited to the Ends of Linear Chromosomes
• C. They Are Short Stretches of DNA With Specific Sequences
• D. They Can Be Numerous and Scattered Across Chromosomes

Answer: (D)

In eukaryotes, replication starts at many origins spread across each chromosome. This many-start setup is needed because the genome is large, so having multiple origins allows replication to proceed in many directions at once and complete during S phase. Each potential origin is licensed in G1, so it can fire once per cycle, and the actual origins that fire can vary in efficiency between cells and organisms. There isn’t a single universal origin sequence that marks every origin across all eukaryotes, especially in higher eukaryotes, where origin locations are more flexible. Origins are not confined to chromosome ends; they can occur internally as well. Therefore, the statement that origins can be numerous and scattered across chromosomes best captures the true nature of eukaryotic origins of replication.