These are genetic markers . What is a marker u are wondering right ?
Marker is a stretch of dna which is useful in marking or taging .
RFLP- Restriction fragment length polymorphism (Non PCR based method)
Restriction fragments are found in bacteria which cut specific sites of a Dna. Let say we have 4 individuals first of all take dna from all the individuals and digest by a restriction enzyme .What we can see ?
We will get a number of fragments with variable length. The next step is to put all the fragments in the agarose gel and run the gel. What we get is a difference in homologous Dna sequence which may be due to some kind of mutations(deletion or duplication ).
In simple words we can say it is used to identify the differences or change (polymorphism ) in the sequence where the restriction enzyme cuts .
RAPD -Random amplified polymorphic Dna (PCR based method )
The amplification is random (Amplified dna are random ). It creates several short primers and then amplified with the help of PCR.
The steps of RAPD involves-
1.Isolation of desired Dna from a species.Small quantity of Dna is required.
2.Oligonucloetides are added and then subjected to PCR for several rounds of denaturation,renaturation and amplification .
3.Amplification occurs only on those regions which have sequence complementary.
4.After several cycles of amplification dna is subjected to gel electrophoresis.
5.We can get a band of amplified Dna which we can see by ethidium bromide staining .
AFLP-(Amplified fragment length polymorphism ) PCR based technique .
It is used for detecting polymorphism in DNA and to detect the presence and absence of fragments.The process involves following steps -
1.Genomic DNA is digested with one or more restriction enzymes.
2.Ligate adapters to the restriction fragment and amplify by PCR and then run it in a gel electrophoresis.
3.Detection by autoradiography or fluroscence).
MCQs.
1. Molecular markers are
A.RFLP B. RAPD C.AFLP D.ALL Ans. D
2.PCR based markers are -
a.RFLP b.RAPD &AFLP c. only RAPD d. none Ans.B
3.Radioactive probes are not required in -
a.RAPD b.RFLP c.AFLP d. none Ans.A
Fill in the blanks -
Marker is a stretch of dna which is useful in marking or taging .
RFLP- Restriction fragment length polymorphism (Non PCR based method)
Restriction fragments are found in bacteria which cut specific sites of a Dna. Let say we have 4 individuals first of all take dna from all the individuals and digest by a restriction enzyme .What we can see ?
We will get a number of fragments with variable length. The next step is to put all the fragments in the agarose gel and run the gel. What we get is a difference in homologous Dna sequence which may be due to some kind of mutations(deletion or duplication ).
In simple words we can say it is used to identify the differences or change (polymorphism ) in the sequence where the restriction enzyme cuts .
RAPD -Random amplified polymorphic Dna (PCR based method )
The amplification is random (Amplified dna are random ). It creates several short primers and then amplified with the help of PCR.
The steps of RAPD involves-
1.Isolation of desired Dna from a species.Small quantity of Dna is required.
2.Oligonucloetides are added and then subjected to PCR for several rounds of denaturation,renaturation and amplification .
3.Amplification occurs only on those regions which have sequence complementary.
4.After several cycles of amplification dna is subjected to gel electrophoresis.
5.We can get a band of amplified Dna which we can see by ethidium bromide staining .
AFLP-(Amplified fragment length polymorphism ) PCR based technique .
It is used for detecting polymorphism in DNA and to detect the presence and absence of fragments.The process involves following steps -
1.Genomic DNA is digested with one or more restriction enzymes.
2.Ligate adapters to the restriction fragment and amplify by PCR and then run it in a gel electrophoresis.
3.Detection by autoradiography or fluroscence).
- Note-Digestion of DNA with restriction enzymes followed by two PCR steps (pre selective primer in the first case and selective primer in the second case of PCR).
MCQs.
1. Molecular markers are
A.RFLP B. RAPD C.AFLP D.ALL Ans. D
2.PCR based markers are -
a.RFLP b.RAPD &AFLP c. only RAPD d. none Ans.B
3.Radioactive probes are not required in -
a.RAPD b.RFLP c.AFLP d. none Ans.A
Fill in the blanks -
| 1. -------------------- is an example of a sequence tagged site. Ans.AFLP 2.In a PCR reaction with an amplification efficiency of 100%, if the reaction starts with only one copy of the target sequence, ---------------- copies of that sequence will be obtained after 20 amplification cycles? Ans.220 copies 3.An amplification cycle of the PCR consists of -------------------------order: Ans. Denaturation -Hybridization-Elongation 4.Nature of allele in RFLP and AFLP markers are mostly ------ Ans. Co-dominant 5.RFLP is used to a) construct high resolution linkage maps b) identify single gene diseases c) construct QTL maps d) all of these Ans. C 6. 2017 JUNE CSIR NET Q.139 ans is 1 (A and B)
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