Genetic fingerprinting Flashcards
What does some of the genome consist of?
Variable number tandem repeats (VNTR)
What are variable number tandem repeats?
Base sequences that don’t code for proteins and repeat next to each other over and over.
Why does the length of the nucleotide differ?
The number of time VNTRs repeat differ from person to person
What is genetic fingerprinting?
Comparing the number of times a sequence is repeated at different places in their genome between individuals
Why is the probability of 2 individuals having the same genetic fingerprint low?
The chance of 2 individuals having the same number of VNTRs at each place they are found in the DNA is very low
Explain the process of electrophoresis
- the DNA mixture is placed into a well in a slab of gel and covered in a buffer solution that conducts electricity
- an electrical current is passed through the gel (DNA fragments are negatively charged so they move towards the positive electrode as the far end of the gel)
- small DNA fragments move faster and travel further through the gel, so the DNA fragments separate according to size
How is a genetic fingerprint made?
- a sample of DNA is obtained
- PCR is used to make many copies of the areas of DNA that contains VNTRs. Primers are used that bind to either sides of the repeat so that the whole repeat is amplified
- this created DNA fragments where the length corresponds to the number of repeats the person has at each specific position
- a fluorescent tag is added to all DNA fragments so they can be viewed under UV light
- the DNA fragments undergo electrophoresis
- the DNA fragments are viewed as bands under UV light
- 2 genetic fingerprints can be compared
Describe what would be seen if 2 genetic fingerprints matched
Both fingerprints would have a band at the same location on the gel which means that they have the same number of nucleotides and so the same number of VNTRs at the place
How is genetic fingerprinting used to determine genetic relationships?
We inherit VNTR base sequences from our parents. Roughly half of the sequence comes from each parents. This means that the more bands on a genetic fingerprint that match the more closely related 2 people are
How is genetic fingerprinting used to determine the genetic variability within a population?
The greater the number of bands that don’t match on a genetic fingerprint the more genetically different people are
Why do forensic scientists use genetic fingerprinting?
To compare samples of DNA collected from the crime scene to samples from possible suspects which could link them to the crime
Why is genetic fingerprinting used in medical diagnose?
Genetic fingerprinting can be used to diagnose genetic disorders and cancers.
It is useful when the specific mutation isn’t known or where several mutations could have caused the disorder as it identifies a broader altered genetic pattern.
Why is genetic fingerprinting used in animal and plant breeding?
It can be used to prevent interbreeding.
It can be used to identify how closely related individuals are. The more closely related 2 individuals are the more similar their genetic fingerprint will be. The least related individuals will be bred together.
What can interbreeding cause?
A decrease in the gene pool.
It can lead to an increased risk of genetic disorders leading the health, productivity and reproduction problems
