Pregunta de Natural Sciences and their Technologies #019e354a
O desenvolvimento da biotecnologia e da clonagem gênica em procariotos fez com que a produção de proteínas se tornasse mais intensa, rápida e econômica. Para a produção de hormônios, enzimas e proteínas de resistência a drogas, uma variação da técnica de reação em cadeia pela polimerase (PCR, na sigla em inglês) utiliza a enzima transcriptase reversa (RT-PCR), que sintetiza moléculas de DNA complementares a partir de fitas de RNA.
Nesse contexto, essa técnica é importante para detectar genes
express.
plasmidial.
bacteria.
dominant.
autosomal.
Explicación Oficial / Explicaciones de la Comunidad
Analysis of the RT-PCR Technique in Biotechnology
The correct answer is option A. A) expressed.
1. Understanding Central Dogma and Gene Expression
To understand the technique, it is crucial to revisit the flow of genetic information in a cell:
- DNA: It contains the complete genetic code of an organism, like a giant cookbook. * Transcription: When a cell needs a specific protein, the stretch of DNA corresponding to that protein (the gene) is transcribed into a molecule of **Messenger RNA (mRNA)**Think of it as copying a single recipe from the book onto a sheet of paper. * Translation: The mRNA travels to the ribosomes, where the information is read and the protein is synthesized.
A gene being "express" This means that it is active in a cell at that moment, that is, it is being transcribed into mRNA to subsequently produce a protein.
2. How the RT-PCR Technique Works
The statement describes the technique of RT-PCR (Reverse Transcriptase Polymerase Chain Reaction). Let's analyze the process:
- Starting Point (RNA): The technique uses as starting material RNA present in a sample. Specifically, mRNA. 2. Action of Reverse Transcriptase (RT): The enzyme reverse transcriptase It performs the reverse process of transcription. It reads the mRNA strand and synthesizes a molecule of Complementary DNA (cDNA) from there. 3. PCR action: Now, with the cDNA molecule in hand, the technique of PCR Conventional methods are used to amplify (create millions of copies of) this specific DNA.
The logic is as follows: if the technique can detect and amplify a cDNA corresponding to a gene, it's because the The mRNA for that gene was present in the cell. at the time of collection. The presence of mRNA is definitive proof that the gene was being express.
3. Evaluation of Other Alternatives
- B) plasmid-linked: Incorrect. The technique can detect plasmid genes, but only if they are being expressed (transcribed into RNA). The focus of the technique is not the origin of the gene (plasmid or chromosome), but rather its activity (expression). * C) Bacteria: Incorrect. Like the previous one, the technique can detect bacterial genes, but only if they are expressed. The technique is not limited to bacteria. * D) dominant: Incorrect. Dominance and recessiveness are concepts from Mendelian genetics related to the expression of phenotypes in diploid organisms. RT-PCR is a molecular technique that detects the transcription of a gene, regardless of whether it is dominant or recessive. Both can be expressed. * E) autosomal: Incorrect. Autosomal refers to a gene located on a non-sex chromosome. RT-PCR can detect gene expression on both autosomal and sex chromosomes. The chromosomal location of the gene is irrelevant to the principle of the technique.
4. Conclusion
The fundamental importance of RT-PCR lies in its ability to synthesize DNA from RNA. Since the presence of messenger RNA is a direct indicator of gene activity, the technique serves to detect and quantify which genes are active. express in a specific cell or tissue at a specific time.