Human genome composition: approximately what percentage of human nuclear DNA consists of repetitive sequences (including transposable-element–derived repeats and other repeats)?

Introduction / Context:
The human genome contains large fractions of repetitive DNA. These include interspersed repeats from transposable elements (LINEs, SINEs such as Alu, LTR elements), segmental duplications, and satellite DNA. Understanding their approximate proportion helps contextualize genome size and annotation.

Given Data / Assumptions:

• Question asks for a broad percentage range, not an exact single value.
• Repetitive content varies by definition and method, but standard textbooks report a substantial fraction.

Concept / Approach:
Classic estimates place repetitive content around half the human genome. Interspersed repeats alone account for roughly 45% by many annotations; adding other classes keeps the overall in the ~40–50% band used in foundational courses.

Step-by-Step Solution:

Verification / Alternative check:
Genome annotation resources frequently cite ~45% interspersed repeats; different pipelines can nudge the total but remain near this bracket.

Why Other Options Are Wrong:

• 10–20% and 20–30% underestimate the known repeat content.
• 30–40% is closer, but still usually low relative to common figures.
• 60–70% overshoots typical accepted ranges for humans.

Common Pitfalls:
Confusing coding sequence fraction (~1–2%) with repetitive fraction; mixing nuclear vs mitochondrial DNA; assuming repeats are functionless—some have regulatory or structural roles.

Final Answer:
40 to 50%