Report Introduction

Introduction:

The analysis of DNA samples taken from organism allows a better understanding of the function and structure of that organism. DNA fragments can be sequenced and the results recorded in computer databases. Bioinformatic analysis of future experimentally obtained DNA sequences can be compared to known sequences. This aids in taxonomic organization, when comparing related species and establishing evolutionary patterns based on genomic analysis.

DNA analysis functions in this way due to the highly conserved nature of DNA and DNA’s role as the genetic origin of all cellular form and function. The sequence of nucleotide base pairs of DNA, which can be 109 bp or larger, changes over time and generations, but only very slowly. Mutations occur, but the rate is very slow, and often mutations do not provide a survival advantage to the individual, and are not conserved.

Many techniques have been developed that use molecular biological and genetic knowledge. Amplification of a DNA is often necessary for further analysis. This can be accomplished in vivo or in vitro. In vivo amplification requires the use of a vector, such as a plasmid or a virus, and host cells. The DNA fragment is ligated into the vector, which makes its way into the host cells. Bacteria are used as host cells due to their high rates of population growth. Once the fragment and vector are amplified using the replication machinery of the host cell, the DNA can be recovered. In vitro amplification (polymerase chain reaction, PCR) utilizes a mixture of the raw ingredients of DNA replication in optimal pH conditions. Temperature changes are used to denature, anneal, and extend the DNA. The key to PCR is the use of Taq (from Thermus aquaticus) polymerase, which is not degraded by high temperatures.

Blots and probes can verify the presence of specific DNA sequences. A probe is a marker-containing sequence complimentary to the target sequence. The probe will hybridize to the target sequence if the target is present. Hybridization can be verified by the presence of the marker. If hybridization does not occur, the probe will be washed off, and the marker will not be observed.

Studies using fruit flies have given significant credibility to theories involving allele distribution and genetic coding of traits. Fruit flies are useful organisms for the study of genetics for several reasons. They are small and easy to grow in laboratory settings. They have a short generation time (around 2 weeks), and females often produce many offspring, allowing greater statistical significance in calculated ratios used for allele distribution. Males and females are easily discernable, facilitating the mating process. Also, fruit flies have only four pairs of chromosomes (3 autosomal, 1 sex), and the genomes of some species, such as Drosophila melanogaster, have been entirely sequenced.

Actin is a globular structural protein that forms in an actin filament, which form the cytoskeleton (structural support) of eukaryotic cells. Actin also combines with myosin form actomyosin in muscle cells, which uses ATP as an energy source for muscle contraction. Actin-coding genes are some of the most highly conserved genes among different species. For example, the actin gene of Homo sapiens is over 80% similar to the actin gene of Saccharomyces cerevisiae, a budding yeast.

In this experiment, our objective was to isolate a fragment of genomic DNA from Bactrocera dorsalis and characterize and sequence this segment, noting the function of genes present in the region.