Molecular marker and gene mapping ppt properties of molecular marker types of molecular marker mapping genetic mapping application of molecular marker

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2. Molecular marker is a fragment
of DNA that is associated with a certain
location within the genome. Molecular markers
are used in molecular biology and
biotechnology to identify a particular sequence
of DNA in a pool of unknown DNA.
They may be due to;
 Base pair changes
 Rearrangement
 Insertion or deletion
 Variation in the number of tandem repeats
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3.  It must be polymorphic so that diversity must
be measured.
 It should be clearly distributed through out
the genome.
 It should distinguishes the homologues and
heterologous.
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4.  RFLP(Restriction Fragment length
polymorphism)
 AFLP(Amplified Fragment Length
Polymorphism)
 RAPD(Randem Amplify of Polymorphic DNA)
 SNP(Short Nucleotide Polymorphism)
 VNTR(Variable Number Tandem Repeats)
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5. ```1).RAPD
It doesn’t required sequence information and
involved amplified random DNA fragments.
 It PCR based
 Dominant
 Used in genetic map and plant breeding
2).AFLP
Restrictive enzyme cuts restrictive fragments
of DNA under restriction process.
 Fast
 Inexpensive
 Variable
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6.  VNTR
 A variable number tandem repeat is a location in
a genome where a short nucleotide sequence is
organized as a tandem repeat. These can be
found on many chromosomes, and often show
variations in length (number of repeats) among
individual.
 Use in genetic analysis
 VNTRs have become essential to forensic crime
investigations, via DNA fingerprinting
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7.  Measure of genetic diversity
 Finger printing
 Genotypic selection
 Identification of genotype
 Marker assisted selection
 Long shelf life of the DNA sample
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8.  Genetic mapping is the processes of
determining the order of and relative
distance between genetic markers on a
chromosome.
 It is based on recombination frequency.
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9.  Recombination fraction is the measure of the
distance between two loci.
 Two loci that show 1% recombination are defined
as being 1 centimorgan (cM) apart in a genetic
map.
 1 map unit= 1cM
 Two genes that undergo independent assortment
have recombination frequency of 50 percent and
are located on non homologous chromosome or far
apart on the same chromosome=Unlinked
 Genes with recombination frequency less than 50%
are on the same chromosome= Linked
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10.  The percentage of recombination progeny
produced in a across is called the
recombination frequency.
RecombinatioFrequency:
=no of recombinant progeny ×100
total no of progeny
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11.  The purpose of genetic mapping is to determine the linear
order and distance of separation among the genes that are
linked to each other along the same chromosome.
 They are useful in predicting results of dihybrid and
trihybrid crosses.
 A genetic map can provide plant and animal breeders with
helpful information for improving agriculturally important
strains through selective breeding.
 Useful from evolutionary point of view. A comparison of
genetic maps for different species can improve our
understanding of the evolutionary relationships among
those species.
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12.  Map generated by genetic techniques is rarely
sufficient for directing the sequences phase of a
genome project. This is for two reasons:
 The resolution of genetic map depends on the
number of crossovers that have been scored.
 Genes that are several tens of kb apart may
appear at the same position in the genetic Map.
 Genetic Maps have limited accuracy.
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