16.8 Genetic fingerprinting Flashcards
What percentage of DNA is introns?
95%
introns are…
non coding DNA bases
Each individual has different lengths and numbers of…
core sequences
The more closely related two individuals are…
the more similar their core sequences will be
Five main stages of genetic fingerprinting
extraction digestion separation hybridisation development
Genetic fingerprinting; extraction
DNA is extracted from the rest of the cell
and amplified using PCR
Genetic fingerprinting; digestion
DNA is cut into fragments using restriction endonucleases,
that are chosen by their ability to cut close to core sequences
Genetic fingerprinting; separation
by gel electrophoresis,
then immersed in alkali to separate double strands,
transferred to nylon membrane by Southern blotting
Southern blotting stages;
- nylon membrane laid over the gel
- covered with absorbent paper, drawing up the DNA
- transfers the DNA to membrane in same positions as on gel
- fixed using UV light
Genetic fingerprinting; hybridisation
radioactive probes are used to bind within core sequences
complementary bases to core sequences of specific fragments
Genetic fingerprinting; development
X-ray film put over nylon membrane
exposed by radiation from radioactive probes,
corresponds to position of fragments in electrophoresis
Interpreting genetic fingerprinting
Two samples are visually checked, patterns of bars and fragment sizes are compared.
the closer the match between two patterns from genetic fingerprinting,
the greater the probability that two sets of DNA are from the same person
Uses of genetic fingerprinting
- determining if individuals are connected with a crime
- resolving paternity testing as half genetic material from mother/father
- determine genetic variability
Genetic fingerprinting is based on the fact…
the DNA of every individual, except identical twins, is unique
