3.8.4.3 - GENETIC FINGERPRINTING

Question 1

short tandem repeats (STRs) are short sequences of DNA, usually 2 to 7 base pairs. STR are repeated a number of times, one after another.

for example, the STR D5S818 is made up of AGAT repeated 7 to 16 times.

the repeated sequences in STRs are common to all humans. due to variation in the number of repeats, STRs can be used in genetic fingerprinting.

during genetic fingerprinting, the different STRs are separated by gel electrophoresis.

give two features of STRs which enable them to be separated by gel electrophoresis (2)

Answer 1

1. number of nucleotides/bases OR length
2. negative charge