3.8.4.3. Genetic Fingerprinting Flashcards
Not all of an organisms genome codes for….
proteins.
What does genome mean?
All of the genetic material in an organism.
What does some of the genome consist of?
Variable number tandem repeats (VNTRs).
What are VNTRs?
Base sequences that don’t code for proteins and repeat next to each other over and over (thousands of times).
Why is the probability of two individuals having the same VNTRs very low?
Number of times the sequences repeat differs from person to person, so the length of these sequences in nucleotides differs too.
E.g. a four nucleotide seq repeated 12 times in one person = 48 nucelotides; but repeated 16 times in another person (64 nucleotides)
Chance of two individuals having the same number of VNTRs at each place they’re found in DNA very low.
What is genetic fingerprinting?
Repeated sequences occur in lots of places in the genome. Number of times a sequence is repeated (and so the number of nucleotides) at different places in genome can be compared between individuals.
What is electrophoresis? ?????? wrong
It separates DNA fragments to make a genetic fingerprint.
- Sample of DNA obtained e.g. from blood, saliva
- PCR used to make many copies of the areas of DNA that contain the VNTRs
- Primers are used
What are primers???
Short pieces of DNA that are complementary to the bases at the start of the fragment you want.
Why are primers used when making genetic fingerprints????
They bind to either side of the repeats and so the whole repeat is amplified.
What do you end up with in electrophoresis???????
DNA fragments where the length (in nucleotides) corresponds to the number of repeats the person has at each specific position e.g. one person may have 80 nucelotides, another person 120.
