Application of DNA Technology

Question 1

What percentage of human DNA is identical?

Answer 1

• 99,9%

Question 2

Where do the differences in the DNA of different human beings occur?

Answer 2

• the differences occur in the highly variable, non-coding part of DNA

Question 3

What does DNA profiling involve?

Answer 3

• extracting and identifying the highly variable regions of a person’s DNA
  -> that contain repeating sequences of base pairs called STRs (short tandem repeats)
• eg CAGACAGACAGA

Question 4

How can STRs be used to distinguish one DNA profile from another?

Answer 4

• at the same point in the DNA of different people, the number of repeated sequences of base pairs varies considerably
• so distinguishing one DNA profile from another

Question 5

How many different sites on DNA molecules are investigated?

Answer 5

• 13-20 different sites
• enough to show that an individual’s profile is unique

Question 6

How can scientists use STRs?

Answer 6

• use STRs that vary to generate a DNA profile of an individual
• using samples from blood, bone, hair and other body tissues and products

Question 7

What is a DNA profile?

Answer 7

• an individual’s unique DNA fragments, separated by electrophoresis

Question 8

DNA is non-reactive and chemically inert. What do these qualities allow for?

Answer 8

• can be recovered from patches of long-dried blood or semen in murder investigations and even extracted from bones of ancient Neanderthals