genetic fingerprinting Flashcards
what does it rely on
the fact that the genome has many non coding bases of dna variable number tandem repeats
what is in every individual
different vrtn which is a unique pattern
what is gel electrophoresis
is used to separate dna fragments according to their size
where are they placed
onto a agar gel which is supplied with by a current
how do the fragments move
as a result of the resistance larger fragments with more bases move more slowly than smaller one and travel a shorter distance
what if the dna fragments are labelled
we can put an xray film over it and then where it is darkened create bands
what do we have to do to larger dna sequences
split them into smaller fragments
what are the 5 main stages of genetic fingerprinting
extraction, digestion, separation, hybridisation, development
how do we extract
the dna need to be separated from the rest of the cell
how do we increase its number
using the polymerase chain reaction
what is digestion
the dna is cut into smaller fragments into target dna using restriction endonucleases
what is separation
the fragments of dna are separated according to its size due to electric voltage
what is happened to the gel
it is transferred to a nylon membrane to distinguish the strands and then it is immersed in alkali to sperate the double strands into single strands
what is hybridisation
radioactive or fluorescent dna probes are used to bind to the vntr
what must the be
complimentary to the base sequence of the vntr and bind under specific conditions
what is developmet
the x ray film is placed over the nylon membrane and darkened bands show the separated dna fragments
what else can be used
uv light to identifiy the fluorescent probes
how will the patterns be amongst individuals
they will be different those colosely related will have simmilair bands
only twins will have the same bands
what happens if dna bars by sight seem to be identical
it is analysed using a machine to calculate the actual distance travele by the dna fragment
what happens finally
the odds are calculated that two people may just have the same dna
if individuals inherit half their dna from mum and half from dad what does this mean
the bands of dna will be identical to some of the mothers dna and identical to some of the fathers dna
what can also see between population by analysing fingerprints
the gnetic variability within a population, ethnic communities very simmilair
why cannot genetic fingerprinting be used all the time in forensic science
the dna may have been left on another innocent occasion
the dna belongs to a very close relative
the dna sample may have been contaminiated
