3.8.4.1 - RECOMBINANT DNA TECHNOLOGY

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.

describe how STRs could be removed from a sample of DNA (2)

Answer 1

1. use restriction endonucleases
2. cut DNA at specific base sequences

Question 2

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.

genetic fingerprinting using STRs requires amplification of the STRs using the polymerase chain reaction (PCR). the short base sequences either side of a specific STR are known.

explain the importance of knowing these base sequences in PCR (2)

Answer 2

1. for primers
2. to produce a complementary base sequence OR primers provide starting sequence for DNA polymerase OR primers stop original DNA strands re-joining