Download Lecture 10

Genomics
DNA Marker
Lecture 10
BY Ms. Shumaila Azam
DNA Markers
• A genetic marker is a gene or DNA sequence
with a known location on a chromosome that
can be used to identify individuals or species.
• It can be described as a variation that can be
observed.
• Which may arise due to mutation or alteration
in the genomic loci.
Types
• Some commonly used types of genetic markers are
• RFLP (or Restriction fragment length polymorphism)
– RFLP was an important tool in genome mapping,
localization of genes for genetic disorders, determination
of risk for disease, and paternity testing.
• SSLP (or Simple sequence length polymorphism)
– can be used to understand genetic variance between two
individuals in a certain species
• AFLP (or Amplified fragment length polymorphism)
– AFLP has become widely used for the identification of
genetic variation in strains or closely related species of
plants, fungi, animals, and bacteria.
Types
• RAPD (or Random amplification of polymorphic DNA)
– RAPD has been used to characterize, and trace, the
phylogeny of diverse plant and animal species.
• VNTR (or Variable number tandem repeat)
– Their analysis is useful in genetics and biology research,
forensics, and DNA fingerprinting.
• SSR Microsatellite polymorphism, (or Simple sequence
repeat)
– They can also be used for studies of gene duplication or
deletion, marker assisted selection, and fingerprinting.
Types
• SNP (or Single nucleotide polymorphism)
– SNPs are also critical for personalized medicine.
• STR (or Short tandem repeat)
– Their analysis is useful in genetics and biology
research, forensics, and DNA fingerprinting.
Categories of markers
• Biochemical markers which detect variation at
the gene product level such as changes in
proteins and amino acids
• Molecular markers which detect variation at
the DNA level such as nucleotide changes:
deletion, duplication, inversion and/or
insertion.
Mode of inheritance
• Dominance/recessive
• Co-dominance
– If the genetic pattern of homozygotes can be
distinguished from that of heterozygotes, then a
marker is said to be co-dominant.
– Co-dominant markers are more informative than
the dominant markers.
Uses of Markers
• Genetic markers can be used to study the relationship
between an inherited disease and its genetic cause
• Genetic markers are employed in genealogical DNA
testing for genetic genealogy to determine genetic
distance between individuals or populations.
• With the aid of genetic markers, researchers were able
to provide conclusive evidence that the cancerous
tumor cell evolved into a transmissible parasite.
• molecular genetic markers were used to resolve the
issue of natural transmission, the breed of origin
(phylogenetics), and the age of the canine tumor.
• Genetic markers have also been used to measure the
genomic response to selection in livestock.