[Campbell Biology P.379] Histones are positively charged proteins crucial for DNA packing du... | Practice Question

Histones are positively charged proteins crucial for DNA packing due to their strong electrostatic attraction to the negatively charged DNA. If a genetic mutation caused histones to lose their positive charge and become negatively charged instead, what would be the most likely consequence for DNA organization and cellular function?

  • A: DNA would become hyper-compacted, leading to significantly reduced gene expression across the genome.
  • B: The DNA would remain unpackaged, but this would increase its accessibility, thereby enhancing all gene transcription.
  • C: DNA packing would be severely impaired due to electrostatic repulsion between histones and DNA, resulting in an unstable chromatin structure and likely affecting essential processes like gene regulation and chromosome segregation during cell division.
  • D: Histones would detach completely from DNA, allowing for easier DNA replication but preventing any gene transcription.

Explanation

Histones' positive charge is essential for binding to negatively charged DNA, facilitating its dense packing. If histones became negatively charged, they would repel DNA, severely disrupting chromatin formation. This instability would hinder precise gene regulation and make proper chromosome condensation and segregation during cell division nearly impossible, leading to severe cellular dysfunction or death.