Genetic and Physical map of Genome

By
KAUSHAL KUMAR SAHU
Assistant Professor (Ad Hoc)
Department of Biotechnology
Govt. Digvijay Autonomous P. G. College
Raj-Nandgaon ( C. G. )

SYNOPSIS
Introduction
History
Genetic mapping
DNA Markers
Physical mapping
Importance
Drawback
Conclusion
References

INTRODUCTION
GENOMIC MAP: Detailed schematic description of
structural & functional organization of complete genome of
organism.
AIM: obtain DNA sequence of complete genome.
Interest on DNA markers & genome organisation and function
led to complete sequencing of genomes.

HISTORY
1990: International Human Genome project
begins.
1. To generate physical, genetic, and
sequence map of the human genome.
2. To sequence the genome of a variety of
model organisms.
3. To develop improved technologies for
mapping and sequencing.

Types of
genetic
mappingGENETIC MAPPING
PHYSICAL MAPPING
[1]GENETIC
MAPPING uses genetic techniques to construct
maps showing the positions of genes and
other sequence features on a genome.
Genetic techniques include cross-
breeding experiments or, in the case of

Schematic representation of the
various genetic markers in specific
order in which they are located in a
chromosome .
The first genetic maps,
constructed in the organisms such
as the fruit fly, used genes as
markers.

DNA Markers
There are three types of DNA sequence feature that
satisfy this requirement:
restriction fragment length polymorphisms
(RFLPs),
simple sequence length polymorphisms (SSLPs),
single nucleotide polymorphisms (SNPs).

The DNA molecule on the left has a polymorphic restriction site
(marked with the asterisk) that is not present in the molecule on
the right. The RFLP is revealed after treatment with the restriction
enzyme because one of the molecules is cut into four fragments
whereas the other is cut into three fragments.
RFLP
Generated by presence and absence of recogination sites.

This is highly sensitive method for detecting
polymorphism throughout the genome and is becoming
increasingly popular.
The AFLP technique is based on the principle of
selectively amplifying a subset of restriction fragments
from a complex mixture of DNA fragments obtained after
digestion of genomic DNA with restriction endonucleases.
It permits detection in any background or complexity
including pooled DNA samples and colned DNA
segments
AFLP:Amplified fragment length polymorphism

To detect various polymorphisms in different genomic
regions.
For the identification of genetic variation in strains or
closely related species of plants, fungi, animals, and
bacteria.
 The AFLP technology has been used in criminal and
paternity tests.
 In linkage studies to generate maps for qualitative trait
locus (QTL) analysis.
APPLICATION

[2]PHYSICAL
MAPPING
uses molecular biology
techniques to examine DNA
molecules directly in order to
construct maps showing the
positions of sequence features,
including genes.It is the distance between
genes are shown in base pairs
rather than map units.
Preparation of physical maps
requires cloning of many pieces

Genetic and Physical map of Genome

Physical mapping techniques
Restriction mapping , which locates the relative positions on a DNA
molecule of the recognition sequences for restriction endonucleases;
Fluorescentin situhybridization (FISH), in which marker
locations are mapped by hybridizing a probe containing the marker to
intact chromosomes;
Sequence tagged site (STS) mapping, in which the positions of
short sequences are mapped by PCR and/or hybridization analysis of
genome fragments.

Importance of gene mapping
#Gene map is the anatomy of human genome. It is a
perrequisite to understand functioning of human
genome.
#Helps in analysis of the heterogeneity and segregation
of human genetic diseases.
#Helps to develop methods for gene therapy.
#Provides clinically useful information about linkage

Drawbacks of using gene as marker
Genes are very useful markers but they are by no means
ideal. One problem, especially with larger genomes such as
those of vertebrates and flowering plants, is that a map based
entirely on genes is not very detailed

1. There are approximately 30,000 human genes.
2. Genes encodes either noncoding RNAs or proteins
Non-coding RNAs:
tRNA,
snoRNA (small nucleolar RNAs)
snRNA (small nuclear RNAs)
Major insights from the Human and model organism
genome sequence

Major insights from the Human and model
organism
genome sequence
Repeated sequences constitute more than 50% of the
human genome.
The genome contains distinct types of gene
organization

6000 19,00014,000
The Encyclopedia of Life
20,500

Conclusion
The first and highest step in genome
mapping is development of high resolution
genetic maps.
The second step is production of physical
maps.
The final and highest resolution level of
genetic mapping is complete genetic
sequences

Biotechnology- U. satyanarayana
Biotechnology- B. D. Singh
www.ncbi.com
www.Wikipedia.com

Genetic and Physical map of Genome

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