Topic 7.1 Using gene sequencing

Question 1

Define genome

Answer 1

The complete set of genetic information contained in the cells of an organism

Question 2

What is DNA sequencing?

Answer 2

Identifying the base sequence of a DNA fragment

Question 3

How can we amplify DNA fragments in order to sequence them?

Answer 3

Using the polymerase chain reaction. Makes millions of copies of a fragments.

Question 4

Describe the reaction mixture in the first stage of PCR

Answer 4

Contains DNA fragments to be amplified, primers that are complementary to the start of the fragment, free nucleotides to match up to exposed bases, and DNA polymerase to create the new DNA.

Question 5

Summarise the process of amplifying DNA fragments using PCR

Answer 5

1. Heated to 90-95^oC for 30 seconds to break apart the DNA strands
2. Cooled to 50-55^oC for 20 secs to allow primer to bind
3. Heated again to 72^oC for at least a minute to activate DNA polymerase and allow free nucleotides to join
4. New DNA acts as template for next cycle

Question 6

How can DNA sequencing be used in medicine?

Answer 6

To screen for heritable conditions. When the base sequence for a particular allele or gene is known, we can a person’s DNA to see if that allele or gene is present.

Question 7

How can be DNA sequencing be used in forensics?

Answer 7

To compare DNA obtained during crime investigations against the DNA of victins or suspects, in order to identify them or discount them.

Question 8

In which other ways can DNA sequencing be used?

Answer 8

• To predict the amino acid sequence of proteins
• To test relatedness of two individuals, including paternity testing

Question 9

How is DNA profiled to identify individuals or relationships

Answer 9

• Restriction enzymes cut an individuals DNA inso fragments in a way that is unique
• Fragments are separated by gel electrophoresis
• This gives a pattern that can be compared to a forensic sample of relatives (can be saved using southern blot method on nitrile paper)