DNA fingerprinting Flashcards
(25 cards)
What is the definition of DNA fingerprinting ?
A technique for identifying individuals using their DNA profiles.
What kind of person will have the same DNA sequence ?
Identical twins.
What is the principle behind DNA fingerprinting ?
VNTRs.
What is VNTRs ?
Variation in different loci of non-coding DNA.
(1) a short base sequence to repeat in linear order.
(2) repeat pattern is called tandem repeat.
(3) the number of time they repeated tends to be different between individuals.
(4) difference in number of repeats results in VNTRs of different length.
Why is there a larger number of variation in VNTRs than that in functional genes ?
VNTRs located in non-coding DNA.
Mutation will not affect the survival of the organisms.
The mutation can be inherited to the next generation.
What will happen if mutations occurs in functional gene ?
Non-functional protein will be produced.
This will affect the survival of the organisms.
The mutation will not be passed to the next generation.
What is the method of generating DNA fingerprint called ?
Restriction fragment length polymorphism. (RFLP analysis)
What is the process of RFLP ?
(1) DNA extraction
(2) Restriction enzymes preparation
(3) Gel electrophoresis
(4) Blotting
(5) Incubation of nylon membrane with radioactive DNA probes and DNA hybridization.
(6) Production of DNA fingerprint
What is the process of DNA extraction ?
Putting the tissues into extraction solution.
What is the process of Restriction fragment preparation ?
add specific restriction enzymes to digest the DNA sample into DNA fragment.
What is the purpose of Restriction fragment preparation ?
To produce a large number of DNA fragments of different lengths.
DNA is negatively or positively charged ?
Negatively.
In Gel electrophoresis, the sample of DNA fragment should be put at anode or cathode ?
Cathode (the negatively charged side)
In gel electrophoresis, the sample of DNA fragment will move towards which side of the tank ? Anode or Cathode ?
Anode (the positively charged side) as DNA fragments are negatively charged.
What is the expected conclusion from gel electrophoresis ?
The shorter the DNA fragment, the faster it moves than the long ones.
What can be observe when gel electrophoresis is done ?
DNA fragments are separated according to their molecular size into different bands.
Sometimes, a DNA ladder is used. What is it and what is the function of it ?
DNA ladder is a DNA with known size. It is used as a reference to estimate the size of DNA fragment sample.
What is the process of blotting ?
Adding alkaline solution to the gel.
Transfer the gel to a buffer solution and put a nylon membrane on top on a gel.
Put a pile of towel on top of the nylon membrane.
What is the purpose of the use of alkaline solution in blotting ?
To break down hydrogen bond in order to denature the DNA fragments.
What is the purpose of the use of nylon membrane in blotting ?
Act as a filter to adhere with DNA fragments.
What is the purpose of the use of paper towel in blotting ?
To draw the buffer solution with the DNA fragments from the gel through the nylon membrane.
What is the function of radioactive DNA probes ?
(1) They have base sequence complementary to VNTRs.
(2) Invisible DNA bands can be seen by labelling with radioactive or fluorescent substance which act as a marker.
What is DNA hybridization ?
(1) Due to complementary base pairing between the base sequence of these two strands,
(2) DNA probes bind to DNA fragments containing VNTRs being examined.
How to improve the discriminatory power to identify an individual form a huge population.
Looking at several loci instead of one loci.
