1.
KARNATAKACOLLEGE OF PHARMACY
Thirumenahalli, Hegde Nagar, Bangalore
Department of Pharmacology
Session (2022-2024)
A Presentation
on
GENE MAPPING
Presented To Presented By
Dr. Deepak Kumar Jha Satyanand Sahu
M. Pharm (1st Sem)

2.
Content
• Introduction
• Types of Gene mapping
• Linkage Mapping
• Physical Mapping
• Difference between genetic mapping and physical mapping
• Importance of Gene Mapping

3.
Introduction
➢Gene mapping refers to the mapping or determining the location (loci
or locus) of a gene and distance between gene on a chromosome. e.g.
➢Gene mapping is also known as genome mapping.
➢Gene mapping is done by the help of molecular marker.
➢Gene can be viewed as one special type of genetic marker in the
construction of genome map.

4.
Types of Gene mapping
➢There are two different types of gene mapping,
1. Genetic mapping (Linkage mapping)
2. Physical mapping

5.
Genetic mapping
➢Also known as linkage mapping or chromosome mapping.
➢The first genetic map of the chromosome(gene) was constructed by A.
H. Sturtevant in 1913 AD.
➢In Linkage mapping genetic technique is use to construct maps
showing the position of gene.
• Genetic technique includes Cross breeding experiments or
• Case of humans i.e. examination of pedigrees.
➢Linkage mapping tells about the corresponding location between
genes on chromosome and relative distance between them.

6.
➢In Linkage mapping genes are linearly arranged according to
percentage crossing over(distance between gene).
e.g.- let %age crossing over of gene A and B is 80%, it means the
distance between gene A and B is so far and lesser the probability that
they will be inherited together.
The closer two markers are to each other on a chromosome, the greater
the probability that they inherited together.
➢By the studying inheritance patterns the relative order and location of
genetic markers along a chromosome can be established.

7.
➢In linkage mapping, during the meiosis the
segment of chromosomes are swamped with
each other and crossing over takes place.
➢Recombinant frequency can be find out by
using linkage mapping.
➢Recombinant frequency = (No. of recombinant
chromosome / Total chromosome)×100
➢Recombinant frequency is directly
proportional to the distance between two gene.

8.
Purpose of Linkage mapping
➢It provides evidence about some genetic disease which are
transmitted from parents to the child.
➢It also provide evidence about chromosomal aberrations.
➢Reduction of saturation of organic compounds for the production
of items such as margarine.
Limitations of linkage mapping
➢Exact location and distance can not be explained by this mapping.
➢Unable to tell us where the gene is present on a chromosome i.e. gene
is present on chromosome no. 1 or 2 or on long arm or short arm.

9.
Physical mapping
• It provides exact location and distance between the genes.
• It use molecular biology technique to determine the absolute position
of a gene on a chromosome.
• The different steps in physical mapping include:
1. The blood/tissue is collected from family members that carry a
prominent disease/trait and from family members that do not carry
disease.
2. Then, DNA is isolated and closely examined to identify the unique
patterns in the DNA.

10.
3. The unique patterns are identified by first cutting DNA into small
pieces using restriction endonuclease enzyme or physical process by
sonication.
4. The DNA fragments are separated by gel electrophoresis and the
pattern of DNA migration is used as its genetic fingerprint( unique
pattern).
5. The difference in DNA pattern is identified between the family
members who carry the disease and those who do not carry the disease.
These unique molecular patterns in the DNA are called as
‘polymorphism’ .
6. The genetic markers are linked to a physical map by process like
‘Fluorescent In Situ Hybridization‘.

11.
Fluorescent In Situ Hybridization
• The most accurate and reliable techniques approach to the physical
mapping.
• This method or technique is most reliable because in this we can
directly visualize a gene or DNA sequence on a chromosome.
• It is of two types
1. Molecular FISH
2. Radioactive type

12.
➢Fish is a powerful techniques for detecting RNA or DNA sequence in
cells, tissues, or tumors
➢This technique is rapid and Simple.
➢The basic element of FISH are:
i. DNA Probes
ii. Target

13.
GENETIC MAPPING V/S PHYSICAL MAPPING
GENETIC MAPPING
1. Process of determining the
relative distance between genes
2. Marker: Gene marker
3. Genetic maps relay on the
recombination and crossing over
4. Genetic maps determine the
probabilities of the
recombination event between
two point
5. Less Accurate
PHYSICAL MAPPING
1. Process of determining the exact
distance between genes
2. Marker: DNA marker
3. Physical maps relay on the DNA
sequence of the genome
4. Physical maps determine the
exact no of bases(gene) between
two point
5. More Accurate

14.
Importance of Gene Mapping
1. It provides the information about loci of gene and distance between
them.
2. It helps to develop methods for gene therapy.
3. It provides useful information about linkage.
4. It helps in analysis of the heterogeneity and segregation of human
genetic disease.
5. It provides evidence about some genetic disease which are
transmitted from parents to the child.
6. It also provide evidence about chromosomal aberrations.

15.
Thank You