What is the purpose of denaturation as a first step in the P

•What is the purpose of denaturation as a first step in the PCR technique?

• Explain briefly how the 2 following techniques work (Gel electrophoresis and Southern blot)?

• Define: genetic mapping

• Define DNA fingerprinting

• What is a xenotransplant?

• Give one example where a transgenic application helped farmers fight a toxic plant or toxic insects that usually harm their crops?

• What did scientists exactly do to make a plant tolerant for salt (=can be watered with salt water) which normally kill plants by dehydration?

• How was the golden rice (with vitamin A) made genetically?

• Cite one consequence of genetically modified foods that scientists are afraid may cause harm to people?

• Define: conjugation and transformation in bacterial and viral behavior

Solution

The purpose of denaturation step is to unzip the double stranded DNA molecule into single stranded DNA templates which can be amplified furthur. Gel electrophoresis - In gel electrophoresis, wells are created at one end in which the samples which are to be quantified are loaded. Then electric current is passed through it. Then depending on their charges and size the molecules move across the pores of the gel. Southern blot - It is done to investigate the presence of particular DNA fragment. For this, DNA is extracted and purified. It is run by gel electrophoresis. It is denatured after it and then transferred on nitrocellulose paper. Then it is hybridized with radiolabelled probe, which can be autoradiographed after washing off the unboud probes. Genetic mapping mean to find the distances or localising the distances between various genes on particular chromosomes. DNA fingerprinting- It is a forensic technique in which two DNA samples are matched for similarity or dissimilarity based on certain characteristics. xenotransplant - When tranplant is done between two different species, such transplant is xenotransplant . For eg, Skin transplant from pig to human.