A gene in yeast, a unicellular eukaryote, is successfully transcribed in E. coli
ID: 167470 • Letter: A
Question
A gene in yeast, a unicellular eukaryote, is successfully transcribed in E. coli. However, the length of RNA from this gene in E. coli is much longer than RNA transcribed from the same gene in yeast. Explain why this result might have occurred. You performed northern blot analysis with Fragments A, B, and C. This blot has mRNA molecules isolated from HeLa cells. When you probed the blot with Fragment A, you detected a signal on the blot, which corresponds to 3 kb long mRNA. On the other hand, Fragments B or C did not detect any mRNA molecule on the blot. How do you interpret this result in terms of genes in the human genome?Explanation / Answer
Answer:
4. In eukaryotic cells, the DNA sequences contains both exons and introns. The introns are spliced out (deleted) while the exons join together to form the coding region of the gene. Bacteria, such as E. coli do not possess the splicing machinery like the eukaryotic yeast cells.
Thus, the introns are retained along with exons in bacteria, producing a longer transcript compared to the yeast cells.
5. A northern blot is a laboratory method used to detect specific RNA molecules among a mixture of RNA. Northern blotting can be used to analyze a sample of RNA from a particular tissue or cell type in order to measure the RNA expression of particular genes. Following hybridization, the probe permits the RNA molecule of interest to be detected from among the many different RNA molecules on the membrane.
Fragment A gives a band in the blot. This suggests that the protein corresponding to fragment A is being expressed in the HeLa cells. Similarly, the absence of bands for the fragments B and C infers the absence of the corresponding mRNA in the sample. This means that the mRNA corresponding to fragments B and C are not getting expressed in HeLa cells.
The overall result from the northern blot denotes the tissue specific expression of genes in the human genome. Some genes gets expressed in one tissue type while some genes gets expressed in others.
Few genes gets expressed in all tissue types and are referred to as house keeping genes.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.