DNA profiling Flashcards
1
Q
What is the genome of an organism?
A
- all the genetic material it contains
- DNA and mitochondrial DNA combines
2
Q
What are exons and introns?
A
- inons are non-conding regions of DNA
- removed from mRNA before it is translated into polypetide chains knwon as introns
- most of the DNA is inons
3
Q
What is DNA profilings?
A
- producing an image of the patterns in the DNA of an individual
4
Q
What is a satellite?
A
- a sequence of base pairs that are repeated many time
- appear in same positions on chromomes, but microsatellites varies between individuals, as different lengths of repeats
- satellite patterns can be compared
5
Q
What is the first stage of DNA profiling?
A
- DNA must be extracted from tissue sample
6
Q
How much DNA is needed?
A
- used to need the equivalent to the DNA from the nuceli of 10,000 humans cells
- now using the polymerase chain reaction, tinisest fragment can be used to develop a profile
7
Q
How is the sample digested?
A
- DNA cut into small fragments using enzymes called restriciton endonucleases
- make 2 cuts, once through each strand of the DNA double helix
8
Q
What are the function of different restriction endonucleases?
A
- Different restriction endonucleases cut DNA at a specific nucleotide sequence, knwon as the restriction or recognition site
- allow scientists to cut DNA at defined points in the introns
- leaves satellite regions unharmed as cut at
9
Q
How are the DNA fragments separated?
A
- must be separated to form a clear, recognisable pattern
- done using electrphoresis
- utilises the way charged particles move throiugh a gel medium under the influence of an electric current
- the gel is then immersed in alkali to separate the DNA double strands into single strands
- fragmetns are then transferred onto a membrane by Southern blotting
10
Q
What is hybridisation?
A
- radioactive or fluorescent DNA probes are now added in excess to the DNA fragments on the mebrane
- DNA probes are short DNA or RNA sequences complementary to a known DNA sequence
- they bind to the complementary strands of DNA under particular conditions of pH and temperature
- this is hybridisations
- excess probesa are washed
11
Q
What is the function of the probes?
A
DNA probes identify the microsatellite regions that are more varied than the larger minisatellite regions
12
Q
How can the evidence be observed?
A
- if radioactive labels added to DNA probes, x-ray images are taken of the paper/membrane
- if fluorescent labels were added to the DNA probes, the paper/membrane is placed under UV light so the fluorescent tags glow
