Reverse Transcription-Polymerase Chain Reaction... ¿Qué es?

The abstract of this article talks about RT-PCR. Well what exactly is RT-PCR? RT-PCR stands for Reverse Transcription-Polymerase Chain Reaction. It is a technique used in genetic studies that allows the detection and quantification of mRNA , particularly in samples with limited quantities of extracted RNA. It is a very sensitive method that shows whether or not a specific gene is being expressed in a given sample. RT-PCR is a very important test in the field of Genetically-Modified Organisms (GMO's) because it gives researchers a mechanism to test whether any specific gene is turned on (active) or turned off (inactive). This allows researchers to identify the benefits of genetically-modified organisms with respect to their "natural" counterparts and search for any significant differences in which genes are expressed in the two types of organisms.

Article:

Real-time reverse-transcription polymerase chain reaction: technical considerations for gene expression analysis.

Has it all been a lie???

According to the latest findings from researchers of the Max Delbrück Center for Molecular Medicine (MDC) Berlin-Buch of the Helmholtz Association, Germany, control mainly occurs in the cytoplasm of the cell and not in the 'high-security tract' of the cell nucleus. Their results also highlight where gene expression (the activation of a gene for protein production) can get out of control. This study was researched by a team of scientists led by biologists Björn Schwanhäusser and Matthias Selbach, biomathematician Jana Wolf (all from MDC) and the biotechnologist Wei Chen of the Berlin Institute for Medical Systems Biology (BIMSB) of the MDC.

As described in my previous post, transcription is the process of creating a complementary RNA copy of a sequence of DNA. Translation is the process that converts an mRNA sequence into a string of amino acids that form a protein. Both of these processes work in cohesion with one another to go through the journey from DNA sequence to a functional protein. The researchers questioned which of the two processes (transcription or translation) plays the dominant role in regulating cellular protein levels.

To answer this question the MDC researchers measured the turnover of cellular mRNAs and proteins and mRNA and protein levels as their starting point. They used high-throughput technologies such as quantitative mass spectrometry and the latest sequencing techniques. In total, they evaluated proteins and mRNAs for more than 5,000 genes. The researchers drew conclusions from the collected data about the control of protein levels by using mathematical modeling. They observed that cellular protein levels mainly depend on translation of mRNAs in the protein factories of the cytoplasm.

The researchers found that cells use their resources very efficiently. Most mRNAs and proteins of abundantly expressed housekeeping genes (these genes maintain the normal operations of the body) are very stable. This is good because the cells will save worthy energy for future needs. However, the proteins responsible for rapid signaling processes are usually unstable. Therefore, cells can quickly adapt to changes in their surroundings. This may also explain why the decisive control step takes place in the cytoplasm and not in the nucleus.

According to Matthias Selbach, "so far, this is purely basic research. But we also know that the production of proteins is disturbed in many diseases, for example cancer." There is not much information about where the process gets out of control. Until now, researchers focused mainly on the nucleus to find answers to this question. However, the new findings show that the protein factories in the cytoplasm have great significance.

Article:

From Gene to Protein: Control Is Mainly in the Cytoplasm, Not Cell Nucleus

Chapter 12: Useful Materials

These animations for both transcription (CLICK HERE: TRANSCRIPTION) and translation (CLICK HERE: TRANSLATION) are from the Institute of Agriculture and Natural Resources at the University of Nebraska. I think these animations are interesting because they go into detail about the process of transcription and translation.

Now I shall somewhat explain both these processes...yay!

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. During transcription, a DNA sequence is read by RNA polymerase, which produces a complementary, antiparallel RNA strand. Transcription is initiated when the RNA polymerase complex assembles at the promoter. RNA polymerase catalyzes the elongation of the RNA while the DNA template is unwound and rewound.

Translation is the process that converts an mRNA sequence into a string of amino acids that form a protein. This fundamental process is responsible for creating the proteins that make up most cells. It also marks the final step in the journey from DNA sequence to a functional protein; the last piece of the central dogma to molecular biology.