How is the DNA of a human the same as the DNA of a butterfly?

Humans and butterflies, despite their vast differences, share a surprisingly large amount of DNA.

Similarities:

  • Shared core DNA: About 70-80% of our DNA is shared with all animals, including butterflies. This "core" DNA contains essential genes for basic functions like cell division, energy production, and protein synthesis.

  • Conserved genes: Specific genes responsible for fundamental processes like development, sensory perception, and metabolism are often similar or even identical across species. For example, both humans and butterflies share genes involved in sight, limb development, and certain metabolic pathways.

  • Genetic "toolkits": Both humans and butterflies have the same "genetic toolkit" - the basic mechanisms for reading and interpreting DNA, replicating it, and passing it on to offspring.

Differences:

  • Non-coding DNA: While we share a significant portion of core DNA, the remaining 20-30% (around 3 billion base pairs) is what truly sets us apart. This "non-coding (Junk) DNA" doesn't directly code for proteins but plays crucial roles in regulating gene expression, development, and adaptation.

  • Gene order: The arrangement of genes on chromosomes contribute to the vast phenotypic differences between humans and butterflies.

  • Gene expression: Even with similar genes, how and when they're expressed makes a huge difference. Epigenetics, which studies the factors that influence gene expression without altering the DNA sequence as per neo darwinism itself, plays a vital role here.

Epigenetics and its impact:

  • DNA methylation: One key epigenetic mechanism is DNA methylation, where methyl groups attach to DNA, altering gene expression. For instance, certain genes crucial for butterfly wing development might be methylated in humans, hence not expressed, leading to vastly different structures.

  • Histone modifications: Chemical modifications to histone proteins, which package DNA, also influence gene expression. Specific histone modifications in butterflies might activate genes for wing development and patterns, while remaining inactive in humans.

  • Non-coding RNA molecules: These molecules can bind to DNA or other molecules, influencing gene expression. Some non-coding RNA molecules in butterflies might activate genes for wing coloration or flight, while having different effects in humans.

In essence, the similarities in core DNA and conserved genes provide the basic foundation for life, while the differences in non-coding DNA, gene order, mutations, and most importantly, epigenetics, contribute to the incredible diversity of species like humans and butterflies. Epigenetics acts like a dimmer switch, turning genes on or off, and its influence is crucial in shaping the unique characteristics of each organism.

So, “pounds” of similar genes is not the way to view development but how these genes are “shaped” by their epigenetics.

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