3.8.4.2 Differences in DNA between individuals of the same species can be exploited for identification and diagnosis of heritable conditions

Question 1

What is a DNA probe?

Answer 1

1. (Short) single strand of DNA;
2. Bases complementary (with DNA/allele/gene);

Question 2

How is a DNA probe labelled?

Answer 2

It is labelled with a radioactive isotope (32P) or a fluorescent marker.

Question 3

How do DNA probes locate specific alleles?

Answer 3

The probe binds to the complementary base sequence of the target allele through DNA hybridisation.

Question 4

What is DNA hybridisation?

Answer 4

A process where a single-stranded DNA probe binds to a complementary DNA sequence via complementary base pairing.

Question 5

How can labelled DNA probes be used in genetic screening?

Answer 5

They detect specific alleles linked to heritable conditions, drug responses, or disease risk.

Question 6

Why are DNA probes useful in genetic screening?

Answer 6

They allow early detection of genetic disorders, enabling informed decisions about treatment or lifestyle changes.

Question 7

How can DNA probes be used in personalised medicine?

Answer 7

They identify genetic variations affecting drug response, allowing tailored treatment for maximum effectiveness.

Question 8

What is genetic counselling?

Answer 8

A process where individuals receive advice on the risk of inheriting genetic conditions based on DNA screening results.

Question 9

How does genetic counselling assist individuals with inherited conditions?

Answer 9

It helps individuals understand genetic risks, make informed reproductive choices, and consider treatment options.

Question 10

What are the ethical concerns of genetic screening?

Answer 10

Privacy issues, psychological impact, potential discrimination by insurers or employers.

Question 11

What are the benefits of genetic screening?

Answer 11

Early detection, informed medical decisions, personalised treatment plans.

Question 12

What are limitations of genetic screening?

Answer 12

May not predict severity of a condition, false positives/negatives, ethical concerns.

Question 13

Why is DNA probe specificity important in genetic screening?

Answer 13

Ensures accurate binding to the correct allele, reducing false results and misdiagnosis.

Question 14

How do fluorescent-labelled probes aid in allele detection?

Answer 14

They emit fluorescence under UV light when bound to the target allele, allowing easy identification.

Question 15

How does genetic screening improve drug prescription?

Answer 15

Identifies genetic factors affecting drug metabolism, ensuring the most effective and safe medication.

Question 16

What factors should be considered when evaluating genetic screening?

Answer 16

Accuracy, reliability, ethical implications, psychological impact, and cost-effectiveness.

Question 17

Describe how the DNA is broken down into smaller fragments.

Answer 17

1. Restriction endonuclease/enzyme;
2. (Cuts DNA at specific) base sequence
   OR
   (Breaks) phosphodiester bonds
   OR
   (Cuts DNA) at recognition/restriction site;
   Accept palindromic sequence.

Question 18

The DNA on the nylon membrane is treated to form single strands. Explain
why

Answer 18

(So DNA) probe binds/attaches/annea

Question 19

Suggest and explain why it is important to be able to identify the specific
strain of M. tuberculosis infecting a patient.

Answer 19

1. To see if strain is resistant to any antibiotics;
2. So can prescribe effective/right antibiotic;
   OR
3. To see whether (any) vaccine works against
   this strain/ see which vaccine to use/ to
   produce specific vaccine;
4. (So) can vaccinate potential contacts/to stop
   spread;
   OR
5. Can test other people to see if they have the
   same strain/ to trace where people caught
   TB;
6. Allowing control of spread of
   disease/vaccinate/treat contacts (of people
   with same strain) before they get TB;
   Do not allow mix and match of points from different
   alternative pairs