7.1 Using gene sequencing

Question 1

What is a definition of a genome

Answer 1

• All the DNA of the human species

Question 2

What is the aim of PCR

Answer 2

• To amplify a sample of DNA

Question 3

Explain the stages in PCR

Answer 3

1 - A culture is set up including : DNA primers, Free nucleotides, primers and heat resistant DNA polymerase
2 - Mixture is then heated up to break the hydrogen bonds between DNA and form two strands
3 - Mixture is then cooled so the primers can then bind to the strand

Question 4

What are the temperatures of each stage

Answer 4

T1 = 90-05 degrees
T2 = 50-55 degrees
T3 = 75 degrees

Question 5

Why is DNA polymerase from human sources not suitable for a PCR machine

Answer 5

• Human enzymes will not work above 37 degrees
• Enzyme becomes denatured at temperatures in PCR

Question 6

Why can species of plants cannot be identified from woody xylem material using PCR and DNA profiling

Answer 6

• Xylem has no living material
• No DNA present

Question 7

Why is PCR used before GE to produce DNA profiles

Answer 7

• Because DNA needs to be amplified
• As only small samples are taken

Question 8

State the role of a restriction endonuclease

Answer 8

• Cut DNA to produce short sections of DNA

Question 9

Describe the process of PCR.

Answer 9

• Use DNA primers
• Use high temperature for 30 seconds to separate strand of DNA
• Use lower temperatures for 20 seconds to bind the primers

Question 10

Describe how a DNA profile can be made from a small sample of DNA

Answer 10

• Multiple copies of DNA made using PCR
• Use of restriction enzymes to produce DNA fragments
• GE to separate samples by size
• Apply potential difference