8.4.2 Differences In DNA

Question 1

What are probes

Answer 1

Short single stranded peices of DNA

With base sequence that’s complementary to bases of target allele

Usually labels with radioactive tag

Question 2

What are they longer that a few bases

Answer 2

A sequence of a few genes would occur many times through a genome

Target specific allele

Question 3

What is DNA hybridisation

Answer 3

Binding of probe to complementary single strand of DNA

Forming H bonds

Question 4

How could screening be used to
Locate alleles

Answer 4

Extract cut and amplify by PCR

Cut at specific base sequences using restriction enzymes

Separate DNA fragments using gel electrophoresis

Treat to form single strands and exposed bases

Add probes which hybridise to target alleles

Using UV light is fluorescent label
Using autoradiography (x-ray) is radioactive probe was used

Question 5

What is gel electrophoresis

Answer 5

Method used to separate DNA/RNA fragments or proteins

According to length and charge

Question 6

How is gel electrophoresis used

Answer 6

DNA samples in a porous gel can covered in buffer solution(conducts electricity)

Electrical current passed though (DNA negatively charged to moved to the positive end )

Shorter fragments tracked further

Question 7

How can data from gel electrophoresis be interpreted

Answer 7

Run standard fragments of know lengths

Compared to posting of unknown to estimate their size

Question 8

Examples of using probes

Answer 8

Screening patients for heritable conditions (cystic fibrosis)
Screening for drug responses and health risks

Question 9

Role in a genetic counsellor

Answer 9

Explains results of screening

Discuss treatments

Discuss lifestyle choices

Explain probability of condition being passed down

Question 10

What is personalised medicine

Answer 10

Specific to a patients DNA

Increasing effectiveness