Sequencing is the arrangement of nucleotides. It includes different technologies that are used to arrange or know the arrangement of adenine, guanine, cytosine and thymine. It is used for molecular study of genomes and protiens that are encoded. Information that’s obtained by sequencing help us to understand the changes in genome of an organism. Even by sequencing we can understand the effect of phenotypes on genome.
DNA sequencing technique is also known as electrophoresis. It separates the pieces of DNA that are different in length one by one. In this technique the DNA that is supposed to be sequenced is present at the end of the gel. Gelatin type substance runs down. Gel contains electrodes when current is provided the molecules move. Smaller molecules move rapidly while larger molecules take time in this way DNA molecules are separated.
TYPES OF GENOME SEQUENCING
There are different types of genome sequencing. Just by focusing on very specific areas of DNA the whole genome can be sequenced. Names of different types of sequencing are given below.
- Whole genome sequencing
- De novo sequencing
- Targeted genome sequencing
- Exome pulldown
Whole Genome sequencing:
It is the process of determining the complete sequence of DNA of any kind of organism at a single time. In this type sequence of chromosomal DNA and mitochondrial DNA are obtained at the same time. Basic purpose is to map out the uniqueness of DNA of a specific person. A doctor or a genetic counsellor can do it if patient is suffering from genetic disorder. It can be used for different purposes.
- It can be used in agriculture.
- It can be used in Public health
This technique is so versatile. It can be used in variety of settings and variety of different reasons. With whole genome sequencing we can identify what kind of pathogen is present within a specific person or a specie. Even with the help of this sequencing we can identify that what kind of bacteria can effect human beings to what extent. In the given diagram process of whole genome sequencing is shown
DE NOVO SEQUENCING
De novo is a Latin word which means again or anew. It is a form of peptide sequencing that is performed without prior knowledge of amino acids sequence. This method can obtain the sequence without protein databases. It can overcome the limitations of data base dependent methods like peptide mass fingerprinting. In addition it can be used for un sequenced organisms antibodies and peptides with post translational methods.
This is the type of sequencing when the whole genome is sequenced for the 1st time without having REFERENCE GENOME. It is typically accomplished by arranging whole genome in such a way that it can be read a full sequence. They yield a primary genetic sequence of a particular organism if the data is not previously available.
Targeted genome sequencing
As it is clear from its name that targeted genome sequencing basically focus on a targeted area of interest within the genome.
There are many purposes for which targeted genome sequencing is used one of them is to find ‘single nucleotide polymorphisms’. They bring the most common type of variations within the organism so by gaining the knowledge about snps it will be easy for the scientists to recognize the diseased gene.
During targeted genome sequence the amplification of gene of interest is done. This process of amplification is called polymerase chain reaction. After amplification the high throughput sequencing is done. Time needed for sequencing process is reduced by this method. It allows for more in depth studies of region of genome.
Different focused panels are made so that they can study about those genes that are associated with diseases.
Exom pulldown sequencing is a type of targeted sequencing. Targeted sequencing is basically defined as the type in which the researchers focus only on the specific areas within a genome. In case of exom pulldown sequencing, the researchers focus only on the genes of genomes. The exomes contain all the instructions and information needed to make protein in our body. Also the sequencing in an exome is much more cheaper as compared to sequencing the whole genome. In this type of sequencing, the scientists only focus on a small part of the genome so it helps them to focus completely on the parts of the DNA sequence which is more likely to be linked with the disease. But the comes a fact that the exom sequencing is only able to focus on the variants of coding regions that mainly affects the protein function. It is not able to study the non-coding variants that can be related to the disease so for this purpose whole genome sequencing is more suitable.
- Many cancer sequencing schemes has helped the doctors by providing the catalogue of somatic mutations. E.g TCGA, ICGC. Most of these kind of projects have both exom and whole genome sequencing elements. So sequencing is very useful to know mutation pathways
- Family data base studies are also available so we can understand certain genetic disorders that run through generations. This might seem like old fashion but helping people to combat many diseases. With a large family pedigree you can link the mutations with the history of patient
- Now medicines can also be personalized. Just by using SNP arrays many pharmacogenomics projects are on their way
- WGS is even very important for the clinical trials. As by knowing the family history before we can easily implement s specific medicine on the group of interest.
- Samples of well phenotype cohorts was one of the basic need of genetic studies. Overtime many of these cohorts or interests are grown in number because of sequencing.
IMPACT ON HUMAN LIFE
Impact of Genome Sequencing on Human Life:
Genome sequencing is a technology that has taken the world by storm. It has made many impacts on human life since it has been started. It has positive and negative aspects as well.
We are aware of the worldwide outbreak of Severe Acute Respiratory Syndrome (SARS). It has affected many people till date. Its origin was not known. Doctors didn’t know the reason of its spread. After that, this virus was studied in detail and its genome was sequenced. The information that the biotechnologists got from its sequencing was quite valuable. They got to know its origin. It also helped in the diagnosis of the disease. This has made a great impact on mankind as well as the technology.
Now humans have better understanding of different viruses and the diseases and now they can treat those diseases by using all the information they have got by genome sequencing.
Genome sequencing has helped to form many things that are of great commercial use hence providing humans with more benefits. The sequencing has helped us to find new growth factors, hormones that were undiscovered before and immunity mediators.
By studying the sequence of different genomes, we can reach the depth of that particular organism whose genome is being studied and this can help us to change it the way we want and in this way GMOs come into existence that are making our life better. For example, cows with more milk production, vegetables with attractive colours and great taste, fruits that are more juicy and tasty, all of this has become possible because of this technology.
Great medicines and great agriculture is the promise of genome sequencing for humans. As we get more information about the sequence of the genome of different organisms, we are more likely to make them better and mould them according to our needs.
The Human Genome Project has made a huge economic impact and its success has earned great amount of money for the workers.
Genome sequencing has made a great impact as it can help to treat rare and inherited diseases. Moreover, it can inform us about a man’s risk of developing and having a disease and his response towards the treatment.
The process of genome sequencing is very complexed. It must be made sure that the sequence has been read carefully and with high accuracy. A wrong sequence can change the whole information and then it can change the whole process of developing medicines and treatments and can have a bad impact on everyone.
Genomic sequencing can unveil such kind of information that can affect a person and his family psychologically. For example, sometimes such condition can occur that causes indecisiveness in the patient and his family regarding their health conditions.
Another negative impact of genome sequencing is that it can cause discrimination that is based upon genetic information among different people. The process of genome sequencing needs a lot of human and computer resources that requires a huge investment and can be quite troublesome for many developing countries.
I conclude that gene sequencing has helped us in many ways and we can gain more benefit from it if it is less expensive.