Now that the human genome has been sequenced, we know that there are fewer than

Question

Now that the human genome has been sequenced, we know that there are fewer than expected protein coding genes (approximately 20,000). Yet, the total number of proteins produced in humans approaches 100,000. What accounts for this discrepancy in numbers? a. We have not yet fully sequenced the human genome. b. The various mechanisms of mRNA processing lead to more proteins being produced than the DNA directly encodes. c. There has been a gross over-estimation of the number of proteins produced in humans. d. Some proteins are converted into completely new proteins after translation. e. We have not yet identified all of the open reading frames in the human genome.

Explanation / Answer

The answer is B. mRNA can be processed in many ways to provide multiple protein products from a single encoding region of DNA. For example, if a gene has 10 exons (protein coding regions), the mRNA can be any combination of those exons. It can be exon 1+2+8 or 2+3+4+8+9 or any other combination. These will all give different protein products when translated.

Related Questions

Navigate

• Browse (All)
• Browse N
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.