Asimov Press

What Limits a Genome’s Size?

9 snips
Apr 4, 2025
Explore the astonishing fact that a tiny fern harbors a genome 50 times the size of a human’s. Discover the biological mechanisms behind DNA packing and learn why energy and diffusion, rather than nucleus volume, limit genome size. Delve into the environmental factors that support such expansive genomic growth, and consider the challenges researchers face when measuring these colossal genomes.
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ANECDOTE

World's Largest Genome

  • The New Caledonian fork fern, found in a remote South Pacific island, has the world's largest genome.
  • Each cell contains 160.45 billion DNA bases, which would stretch over 100 meters if unfurled.
INSIGHT

Genome Size Bottlenecks

  • While nucleus volume might seem limiting, energy and diffusion are the real bottlenecks for genome size.
  • The fern's genome wasn't sequenced due to repetitive regions.
ANECDOTE

Measuring the Fern Genome

  • Scientists measured the fern's genome using flow cytometry, comparing its fluorescence to an onion's.
  • The fern's nuclei were nine times brighter, indicating a genome nine times larger than the onion's.
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