1. Tell me about the different kinds of DNA sequences.
There are three kinds of DNA sequences. Genomic DNA comes from the genome and includes both genes and extragenic material. cDNA is reverse transcribed from mRNA and corresponds only to the expressed parts of the genome. Recombinant DNA is man-made and is composed of artificial DNA.
2. If you had 1,500 base pair pieces of random DNA and you wanted to know how many of them had homology to known genes, what would you do to determine that?
I would use a BLASTX search against a known protein database - such MCBI's NR database. I would then sort them to determine how many were unique.
3. What technique is used to measure the number of copies of a gene or an RNA molecule in human tissues?
PCR or polymerase chain reaction in real time, as opposed to the conventional method, because the number of copies of the target molecule can be monitored for each PCR cycle.
4. What are the limitations of blotting techniques and what alternatives can you suggest?
The major limitation of blotting procedures is the length of time needed and the fact that they can accommodate only one probe at a time. DNA microchip technology permits the analysis of thousands of genes at the same time. DNA molecules are attached to the wafers in an organized array and are called the probes. DNA molecules taken from tissues are hybridized to the chips and are called targets, which are labeled with fluorescent light. The probes that have hybridized to the fluorescent targets are then identified by fluorescence microscopy.