What is the Difference Between Gene Mapping and Gene Sequencing

The main difference between gene mapping and gene sequencing is that the gene mapping identifies the locus of genes and their relative distance within the genome whereas the gene sequencing spells out the order of the nucleotides, which makes up the genes in the genome. Furthermore, gene mapping results in a less-detailed outcome while gene sequencing results in a fully-detailed outcome. 

Gene mapping and gene sequencing are two types of genome analyzing methods which help to obtain various types of information about genomes. 

Key Areas Covered 

1. What is Gene Mapping
     – Definition, Method, Importance
2. What is Gene Sequencing
     – Definition, Method, Importance
3. What are the Similarities Between Gene Mapping and Gene Sequencing
     – Outline of Common Features
4. What is the Difference Between Gene Mapping and Gene Sequencing
     – Comparison of Key Differences

Key Terms 

Gene Mapping, Gene Sequencing, Locus, Nucleotide Sequence, Physical Mapping, Relative Distance

What is Gene Mapping 

Gene mapping is the identification of the locus of genes and their relative distance in the genome. Hence, a gene map contains a series of landmarks of short DNA sequences or regulatory sites, which turn on and turn off genes. Thus, it is a one-dimensional map, which is linear. Also, the genes or the other important sequences in a gene map are named by letters and numbers; for example, D14S72 and GATA-P7042. Furthermore, the unit of measurement of the distance between two genes is centimorgan. One centimorgan is equal to the percentage of two independently inherited genes. It helps to explore a particular genome and to navigate around the genome. It also helps to identify new genes in the genome.  

Figure 1: Gene Map in Drosophila

Gene mapping enables the scientists to identify the genes involved in diseases. For this, they can map the genomes of the families affected by a particular disease. Here, the other landmarks that are close to the disease-causing genes become markers for that particular gene. The identification of such landmarks helps to identify the exact location of the disease-causing gene in the genome. Hence, this will narrow down the size of the DNA piece to be investigated out of the whole genome. Then, the scientists can test the selected set of landmarks with the same landmarks from healthy individuals to identify the exact gene related to the disease. Thus, gene mapping can identify the genes responsible for diseases such as Huntington’s disease, cystic fibrosis, etc. 

What is Gene Sequencing 

Gene sequencing is a more advanced method than gene mapping. It identifies each and every nucleotide in a particular piece of DNA. Therefore, since it reveals up to the nucleotide level of DNA, gene sequencing can give more detailed information about the genome. Going further into the methods of gene sequencing; the main method of gene sequencing is the shotgun sequencing. Here, the shattering of the genome into small fragments allow the characterization of each fragment. Then, the sequences of each fragment are put together to obtain the whole sequence of the genome.

Figure 2: Difference Between Gene Mapping and Gene Sequencing

Although gene sequencing is completely a different process, it resembles the process of physical mapping. Physical mapping and gene mapping are the two types of genome mapping. In physical mapping, the restriction digestion of the genome yields short fragments, which are then analyzed. The ultimate physical map is made by assembly of all the restriction fragments together. However, physical mapping cannot give a detailed result like gene sequencing. 

Similarities Between Gene Mapping and Gene Sequencing 

• Gene mapping and gene sequencing are two methods of genome analyzing. 
• They provide information about the location of genes. 
• Also, both methods have advantages in the determination of disease-causing genes in the genome. 

Difference Between Gene Mapping and Gene Sequencing 

Definition 

Gene mapping refers to the charting of the positions of genes on a DNA molecule or chromosome and the distance, in linkage units or physical units between genes while gene sequencing refers to the process of ascertaining the sequence of nucleotides in a segment of DNA. Thus, this explains the main difference between gene mapping and gene sequencing.

Significance 

Another difference between gene mapping and gene sequencing is that the gene mapping identifies the landmarks of the genome while gene sequencing spells out the sequence of nucleotides in the genome. 

Detailedness 

Also, the outcome of the gene mapping provides less details while the outcome of the gene sequencing is fully-detailed. This is also a major difference between gene mapping and gene sequencing.

Time and the Cost 

However, the gene mapping is a cheap method, which is less time-consuming while gene sequencing is an expensive method, which takes time.  

Conclusion 

Gene mapping is a method of identification of landmarks such as genes and their regulatory sequences in the genome. To be specific, it gives the exact location of these landmarks in the genome and their relative distances. On the other hand, gene sequencing is an advanced method of genome analyzing, which spells out all the nucleotides of the genome and their order of appearance. Therefore, the main difference between gene mapping and gene sequencing is the detailedness of the information they provide. 

Reference:

1. “GENOME MAP.” GNN – Genome News Network, J. Craig Venter Institute, 15 Jan. 2003, Available Here

Image Courtesy:

1. “Drosophila Gene Linkage Map” By Twaanders17 – Own work (CC BY-SA 4.0) via Commons Wikimedia  
2. “NHGRI Fact Sheet- Genetic Mapping (27058469495)” By National Human Genome Research Institute (NHGRI) from Bethesda, MD, USA – NHGRI Fact Sheet: Genetic Mapping (CC BY 2.0) via Commons Wikimedia