Chromosome 1 is the largest human chromosome.
Human Chromosomes: Size and Significance
The human genome comprises 23 pairs of chromosomes, for a total of 46. These chromosomes vary in size, with Chromosome 1 holding the distinction of being the largest. It's made up of approximately 249 million base pairs of DNA and accounts for roughly 8% of the total human DNA. https://medlineplus.gov/genetics/chromosome/1/ This size correlates to a higher number of genes; Chromosome 1 contains nearly 3,000 genes. https://www.genome.gov/genetics-glossary/Autosome
Chromosome 2 is the second largest human chromosome, containing approximately 243 million base pairs. https://medlineplus.gov/genetics/chromosome/2/
Beyond Human Chromosomes
It's important to note that the largest chromosome isn't universally Chromosome 1. The Paris japonica, a Japanese canopy plant, boasts the largest known genome among all organisms. https://www.darwintreeoflife.org/news_item/genomes-great-and-small-the-diversity-of-plants/ While this doesn't necessarily mean it has the single largest chromosome, it highlights the diversity in chromosome size across different species. Additionally, recent synthetic biology has created large synthetic chromosomes, exceeding those found in nature, such as synIV, a 1,454,621-base pair yeast chromosome. https://pubmed.ncbi.nlm.nih.gov/37944526/
Conclusion
The size of the largest chromosome depends on the organism. In humans, it's Chromosome 1. However, other organisms and synthetic constructs possess even larger chromosomes or genomes.
