Question

Topic: Recent molecular biology advance in tumor diagnosis (write a review on it more than 2000 words) Please answer the question only if you can observe the minimum limit of 2000 words. Thank you

Answer 1

Recent advancement in molecular biology has contributed in better understanding, diagnosis, prognosis and treatment of various diseases. Molecular biology unfolds the mechanisms of different biological activities at molecular level. Recent techniques based on molecular biology have been found to be very effective in early detection and treatment of a tumor. These techniques focus on identifying certain biomarkers (present in blood, urine, saliva or tumor) which are primary indicators of a growing tumor. Some of these techniques are given below-

1. DNA microarray technique- These are the tools which consists of numerous single stranded DNA molecules, attached to a glass plate. DNA microarrays are also called as biochips or molecular chips. These tools are efficient in detecting the BRCA1 and BRCA2 mutations in the patient’s samples. In this technique, RNA is isolated from the patient’s sample and this RNA is transformed into complementary DNAs (cDNAs). These cDNA molecules are then place on the microarray plate where they hybridize with DNA spots. This hybridization is visualized and monitored with a specialized radioactive instrument. This technique helps in identifying the difference in the gene expression between healthy and affected cells (tumor cells).

2. Allele-specific oligonucleotide technique- This technique is useful in identifying single nucleotide mutations without requiring any prior amplification or electrophoretic techniques. Allele-specific oligonucleotides are the small DNA molecules (consist of 20-23 bases) which are hybridized with target DNA fragments, fixed on a silicon membrane. After the process of hybridization is done, the membrane containing target DNA is washed so that the non-hybridized probe and DNA are removed from it. These target DNA molecules are then tagged with fluorescent dyes to identify any mutation.

3. Western blotting- This technique is widely used to identify and detect certain proteins and enzymes which are considered as the indicators of a tumor. In this technique, the patient’s sample is first denaturated and then this sample undergoes the process of gel electrophoresis. This step allows the separation of proteins and enzymes according to their size and molecular weight. These molecules are then transferred to a nitocellulose membrane where they are stained with specific antibodies (primary antibodies) that are complementary to the target proteins. These primary antibodies are then stained with secondary, florescent antibodies that can be easily visualized with the help of radioactive monitor.