21.1 DNA Profiling

Question 1

Why is it incorrect to say that everyone has unique DNA?

Answer 1

Everybody has a unique COMBINATION of DNA

Question 2

What is the genome of an organism?

Answer 2

All the genetic material the organism contains. The DNA in the nucleus and mitochondria combined

Question 3

What are exons?

Answer 3

Coding parts of DNA

Question 4

What are introns?

Answer 4

Non-coding parts of DNA

Question 5

What is satellite DNA?

Answer 5

Also known as short-tandem repeats, short sequences of DNA that are repeated many times in introns

Question 6

What is DNA profiling?

Answer 6

Producing an image of the patterns in the DNA of an individual

Question 7

Where is DNA extracted from?

Answer 7

A tissue sample, e.g semen, saliva, blood, skin cells, hair roots

Question 8

What is the function of electrophoresis?

Answer 8

Separates cut fragments of DNA

Question 9

How does electrophoresis work?

Answer 9

DNA is negatively charged, the smaller the fragment the further it moves towards the positive electrode. Fragments can be identified by comparing their movement to other DNA bands

Question 10

What is the purpose of PCR?

Answer 10

Artificially making more natural DNA

Question 11

Describe how PCR works.

Answer 11

• At ~90 degrees, hydrogen bonds break, so 2 strands of separate template DNA left
• At ~60 degrees, hydrogen bonds reformed between primer and template DNA
• New strands of DNA synthesised by polymerase at ~ 70 degrees

Question 12

What are the limitations to PCR?

Answer 12

• Taq polymerase has to be used because human DNA polymerase is denatured
• Free nucleotides have to be added. Not enough = no new strands of DNA
• Template DNA may bind to other strand, not to free nucleotides/primer

Question 13

What is the purpose of digesting a DNA sample?

Answer 13

Separating it into small fragments

Question 14

What is used to separate DNA into small fragments?

Answer 14

Restriction endonucleases

Question 15

What are the uses of DNA profiling?

Answer 15

• Forensic sciences in criminal investigations
• Proving paternity of a child
• Proving familial relations
• Identifying species of organisms
• Identifying individuals at risk of developing diseases