GENETIC MARKER WHAT IS A GENETIC MARKER?A genetic marker is a gene sequence with a
known location on a chromosome that can be used to identify species. It can be
used to study the genetics of an organism.
TYPES OF GENETIC
MARKERS
1.Restriction
Fragment length polymorphism(RFLP). 2.Simple sequence length polymorphism(SSLP). 3.Amplified
fragment Length Polymorphism(AFLP). 4.Variable number tandem repeat(VNTR)
What is
polymorphism? It is a term that describes
multiple forms of a single gene that exists in an individual
RESTRICTION
FRAGMENT LENGTH POLYMORPHISM (RFLP) This was the first DNA based marker developed. It is a method that allows individuals to be identified, based on the
pattern of the restriction enzyme, cutting in a specific region of DNA. They are mainly co-dominant.
It
is used to detect a mutation in a gene
Method of DNA
analysis by RFLP
First, a
particular region of the DNA is cut with a restriction enzyme (enzyme that cuts
the restriction site) Then ,
separate the DNA fragments using gel electrophoresis
Then it is
transferred to a membrane by the southern blot (it is used to detect a specific
DNA sequence)
Lastly determine
the number of fragments according to their lengths and pattern of fragment
sizes.
APPLICATION
OF RFLP
1.DNA fingerprinting: helps identify suspects based on the samples
taken from crime scenes. 2.Paternity
: It is used to determine the father of a child. Negative
Aspect of RFLP 1.Tedious and slow 2.Large
amount of DNA Sample is required.
Positive Aspect of RFLP 1.Can be easily transferred between labs.
What is VNTR? VNTR is a location in a genome where a short nucleotide sequence is
organized as a tandem .It is a part the DNA that is different for every
individual. It is found on many chromosomes and the size is about 7 – 10 base
pair long
APPLICATION OF
VNTR
1.DNA fingerprinting 2. Genetic diversity (total number of genetic characteristics in the
makeup of a specie
. Examples of Genetic markers a.Green Fluorescent Markers b.Enzyme Beta glucuronidase
Green Fluorescent Marker a.GFP is found in a jellyfish that lives in
cold regions. b.GFP monitors gene expression and cell division.
APPLICATION 1.Jellyfish
contains a bio luminescent protein that emits blue light. The GFP converts the
blue light to green light. And this is what we see when a jellyfish lights up. 2.GFP does this by absorbing UV Light from the sun and emits as green
light.
Green Fluorescent Protein a.Comes from bio luminescent jellyfish- Aequorea Victoria. b. GFP is widely used as a marker to determine if transformation is
effective
What is the use of GFP?
1.It
allows us to see the inner workings of the cells. 2.Easy to locate because it will glow bright green. ENZYME Beta glucuronidase. 1.The enzyme Beta
glucuronidase (GUS), originates from E.coli. 2.Any cell incubated with some specific colorless substrate, is
transformed into a colored product. 3.It
is mainly used to determine the activity of inserted genes in plants.
Why fluorescent Markers are used in place of
Antibiotic Resistance. 1.They are easier to identify.
2.It
is time saving.
3.The
resistance gene can be passed to other bacteria. 4.The antibiotics are no longer effective and require new treatment because
of the spread of the antibiotic gene resistance.
PROMOTER A promoter is a region of the DNA to which RNA polymerase binds as
it starts transcription. For example E.coli make the enzyme Beta galactosidase
when growing in a medium with lactose. It maps ends of mRNA onto a DNA. It
allows RNA polymerase to bind to DNA, and it ensures that it recognizes which
of the two DNA strands is the template strand .It controls the gene expression.Most promoters are located at the 5’ end of the gene. Can be about
100-1000 base pair long. Promoters have specific sequences and determine whether
a gene gets transcribed .Without a promoter DNA will not be transcribed.
Why
a promoter must be transferred with a desired gene
The promoter acts as a binding site for RNA
polymerase, and initiates transcription. This makes it easier for the gene to
be inserted into the promoter. FUNCTION OF PROMOTER
1.RNA polymerase binding site
2.Initiates transcription
3.Control the gene expression
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