Question

Question 1.

Describe in detail how a protein-encoding gene in a eukaryote is transcribed as mRNA, and what events happen to the mRNA before it can be translated into a protein.

Question 2.

You want to investigate the effect of a probiotic on your gut microbiome- the population of bacteria living in your digestive tract. You collect faecal samples prior to and after consumption of the probiotic. Describe in detail how you would sequence the metagenome of the bacteria in these faecal samples and what bioinformatic analyses you would undertake.

Answer 1

The protein encoding gene in eukaryote is transcribed as mRNA from DNA by the process of transcription.

During the transcription the one strand of the DNA serve as the template strand for the complemtary base pairing and the whole process of formation of transctription of this template into RNA is catalysed by the enzyme RNA polymerase II. The product formed after this is called pre mRNA.

This pre mRNA is then processed by the process of methylation, capping, and tailing to protect the mRNA from hydrolysis or degradation by the enzymes and pH in nucleus. The product formed after posttranscriptional modification is knoem as mRNA which is a single-stranded copy of the gene, ready for translation into protein.

the diagram suggest the transcription process in detail.

In the process of translation of mRNA into protein, the mRNA is "read" according to the genetic code (triplet codons). 80S ribosome plays an important part on which the codon lies and transfer from A site to the P site. In this way triplet of codon formed which encodes the amino acid lead to the formation of desired protein with the help of peptide bonds.

This diagram is schematic of whole process

2.

For metagenomics of this sample we will process the sample and then extract the whole DNA from the sample. Simultaneously we will process the sample without probiotic. Following process will be done for both the samples.

This will be followed by the digestion of the gene with some known restriction enzyme that suggests the the effect of this probiotic.

The fragments will be then cloned in a vector followed by positive selection.

the positive clones will be sequence by DNA sequencer.

Then by the BLAST analysis on NCBI we will compare the sequences of the clones to the available sequences of the microbes.

The sequences will be the aligned by CLUTAL W in MEGA software followed by phylogenetic analysis.

At final stage we will have a list of microbes present in our gut( in sample with probiotic effect and without probiotic effect). So we will be able to compare the difference of the microflora in the both cases. And we will have a conclusion about the effect of probiotic on microflora of gut.